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@kmamal/sdl

Package Dependencies License: MIT

SDL bindings for Node.js. Provides window management, input events (keyboard, mouse, joysticks, controllers, sensors), audio playback and recording, clipboard manipulation, and battery status.

It should work on Linux, Mac, and Windows. Prebuilt binaries are available for x64 architectures, arm-based Macs, and Raspberry Pi.

Canvas, WebGL, and WebGPU

One goal of this project is to allow using Canvas, WebGL, and WebGPU without a browser. You can use the canvas package to render using the canvas API. For WebGL you can use @kmamal/gl and for WebGPU you can use @kmamal/gpu. Both WebGL and WebGPU support rendering directly to the window (without any intermediate buffer copying). Canvas still uses an intermediate buffer, but that might change in the future.

Installation

SDL is bundled along with the binaries so a separate installation is not necessary. This package is self-contained. Just run:

npm install @kmamal/sdl

(But if things go wrong do look over here)

Examples

"Hello, World!"

import sdl from '@kmamal/sdl'

const window = sdl.video.createWindow({ title: "Hello, World!" })
window.on('*', console.log)

Canvas

import sdl from '@kmamal/sdl'
import { createCanvas } from 'canvas'

// Setup
const window = sdl.video.createWindow({ title: "Canvas" })
const { pixelWidth: width, pixelHeight: height } = window
const canvas = createCanvas(width, height)
const ctx = canvas.getContext('2d')

// Clear screen to red
ctx.fillStyle = 'red'
ctx.fillRect(0, 0, width, height)

// Render to window
const buffer = canvas.toBuffer('raw')
window.render(width, height, width * 4, 'bgra32', buffer)

WebGL

import sdl from '@kmamal/sdl'
import createContext from '@kmamal/gl'

// Setup
const window = sdl.video.createWindow({ title: "WebGL", opengl: true })
const { pixelWidth: width, pixelHeight: height, native } = window
const gl = createContext(width, height, { window: native })

// Clear screen to red
gl.clearColor(1, 0, 0, 1)
gl.clear(gl.COLOR_BUFFER_BIT)

// Render to window
gl.swap()

WebGPU

import sdl from '@kmamal/sdl'
import gpu from '@kmamal/gpu'

// Setup
const window = sdl.video.createWindow({ title: "WebGPU", webgpu: true })
const instance = gpu.create([])
const adapter = await instance.requestAdapter()
const device = await adapter.requestDevice()
const renderer = gpu.renderGPUDeviceToWindow({ device, window })

// Clear screen to red
const commandEncoder = device.createCommandEncoder()
const renderPass = commandEncoder.beginRenderPass({
  colorAttachments: [
    {
      view: renderer.getCurrentTextureView(),
      clearValue: { r: 1.0, g: 0.0, b: 0.0, a: 1.0 },
      loadOp: 'clear',
      storeOp: 'store',
    },
  ],
})
renderPass.end()
device.queue.submit([ commandEncoder.finish() ])

// Render to window
renderer.swap()

More examples

Check the examples/ folder.

API Reference

Contents

sdl

sdl.info

  • <object>
    • version: <object>
      • compile: <object> The SDL version the bindings were compiled against.
        • major, minor, patch: <semver> The components of the version.
      • runtime: <object> The SDL version of the dynamic library the is loaded.
        • major, minor, patch: <semver> The components of the version.
    • platform: <string> The name of the platform we are running on. Possible values are: 'Linux', 'Windows', and 'Mac OS X'.
    • drivers: <object>
      • video: <object>
        • all: <string>[] A list of all video drivers.
        • current: <string>|<null> The video driver that is currently selected.
      • audio: <object>
        • all: <string>[] A list of all audio drivers.
        • current: <string>|<null> The audio driver that is currently selected.

This object is filled with the information produced during the initialization of SDL. All the values will remain constant throughout the execution of the program. If you want to initialize SDL with drivers other than the default ones, you can do so via its environment variables.

Note that the current video or audio driver can be null. This can happen on systems that don't have any compatible devices, such as on a CI pipeline.

Sample data for Ubuntu:

{
  version: {
    compile: { major: 2, minor: 0, patch: 10 },
    runtime: { major: 2, minor: 0, patch: 10 },
  },
  platform: 'Linux',
  drivers: {
    video: {
      all: [ 'x11', 'wayland', 'dummy' ],
      current: 'x11',
    },
    audio: {
      all: [ 'pulseaudio', 'alsa', 'sndio', 'dsp', 'disk', 'dummy' ],
      current: 'pulseaudio',
    },
  },
}

sdl.video

Image data

There are 3 places in the API where you will need to provide an image to the library:

All three of these functions accept the image as a series of arguments:

  • width: <number> The width of the image in pixels.
  • height: <number> The height of the image in pixels.
  • stride: <number> How many bytes each row of the image takes up in the buffer. This is usually equal to width * bytesPerPixel, but can be larger if the rows of the buffer are padded to always be some multiple of bytes.
  • format: <PixelFormat> The binary representation of the data in the buffer.
  • buffer: <Buffer> Holds the actual pixel data for the image, in the format and layout specified by all the above arguments.

So for example, to fill the window with a red+green gradient you could do:

const { pixelWidth: width, pixelHeight: height } = window
const stride = width * 4
const buffer = Buffer.alloc(stride * height)

let offset = 0
for (let i = 0; i < height; i++) {
  for (let j = 0; j < width; j++) {
    buffer[offset++] = Math.floor(256 * i / height) // R
    buffer[offset++] = Math.floor(256 * j / width)  // G
    buffer[offset++] = 0                            // B
    buffer[offset++] = 255                          // A
  }
}

window.render(width, height, stride, 'rgba32', buffer)

High-DPI

On a high-dpi display, windows have more pixels that their width and height would indicate. On such systems width and height (and all other measurements such as x and y) are in "points". Points are abstract and don't have to correspond to pixels. If you need to know a window's width and height in pixels, you should use the pixelWidth and pixelHeight properties. You should be doing this always, since you don't know beforehand if your program will be running on a high-dpi system.

Pixel formats

String values used to represent how the pixels of an image are stored in a Buffer.

Value Corresponding SDL_PixelFormatEnum Comment
'rgb332' SDL_PIXELFORMAT_RGB332
'rgb444' SDL_PIXELFORMAT_RGB444
'rgb555' SDL_PIXELFORMAT_RGB555
'bgr555' SDL_PIXELFORMAT_BGR555
'argb4444' SDL_PIXELFORMAT_ARGB4444
'rgba4444' SDL_PIXELFORMAT_RGBA4444
'abgr4444' SDL_PIXELFORMAT_ABGR4444
'bgra4444' SDL_PIXELFORMAT_BGRA4444
'argb1555' SDL_PIXELFORMAT_ARGB1555
'rgba5551' SDL_PIXELFORMAT_RGBA5551
'abgr1555' SDL_PIXELFORMAT_ABGR1555
'bgra5551' SDL_PIXELFORMAT_BGRA5551
'rgb565' SDL_PIXELFORMAT_RGB565
'bgr565' SDL_PIXELFORMAT_BGR565
'rgb24' SDL_PIXELFORMAT_RGB24
'bgr24' SDL_PIXELFORMAT_BGR24
'rgb888' SDL_PIXELFORMAT_RGB888
'rgbx8888' SDL_PIXELFORMAT_RGBX8888
'bgr888' SDL_PIXELFORMAT_BGR888
'bgrx8888' SDL_PIXELFORMAT_BGRX8888
'argb8888' SDL_PIXELFORMAT_ARGB8888
'rgba8888' SDL_PIXELFORMAT_RGBA8888
'abgr8888' SDL_PIXELFORMAT_ABGR8888
'bgra8888' SDL_PIXELFORMAT_BGRA8888
'argb2101010' SDL_PIXELFORMAT_ARGB2101010
'rgba32' SDL_PIXELFORMAT_RGBA32 alias for 'rgba8888' on big endian machines and for 'abgr8888' on little endian machines
'argb32' SDL_PIXELFORMAT_ARGB32 alias for 'argb8888' on big endian machines and for 'bgra8888' on little endian machines
'bgra32' SDL_PIXELFORMAT_BGRA32 alias for 'bgra8888' on big endian machines and for 'argb8888' on little endian machines
'abgr32' SDL_PIXELFORMAT_ABGR32 alias for 'abgr8888' on big endian machines and for 'rgba8888' on little endian machines
'yv12' SDL_PIXELFORMAT_YV12 planar mode: Y + V + U (3 planes)
'iyuv' SDL_PIXELFORMAT_IYUV planar mode: Y + U + V (3 planes)
'yuy2' SDL_PIXELFORMAT_YUY2 packed mode: Y0+U0+Y1+V0 (1 plane)
'uyvy' SDL_PIXELFORMAT_UYVY packed mode: U0+Y0+V0+Y1 (1 plane)
'yvyu' SDL_PIXELFORMAT_YVYU packed mode: Y0+V0+Y1+U0 (1 plane)
'nv12' SDL_PIXELFORMAT_NV12 planar mode: Y + U/V interleaved (2 planes)
'nv21' SDL_PIXELFORMAT_NV21 planar mode: Y + V/U interleaved (2 planes)

Event: 'displayAdd'

  • device: <object>: An object from sdl.video.displays indicating the display that caused the event.

Fired when a display is added to the system. Check sdl.video.displays to get the new list of displays.

Event: 'displayRemove'

  • device: <object>: An object from sdl.video.displays indicating the display that caused the event.

Fired when a display is removed from the system. Check sdl.video.displays to get the new list of displays.

Event: 'displayOrient'

  • device: <object>: An object from sdl.video.displays indicating the display that caused the event.

Fired when a display changes orientation. Check sdl.video.displays to get the new list of displays.

sdl.video.displays

  • <object>[]
    • name: <string> The name of the display.
    • format: <PixelFormat> The pixel format of the display.
    • frequency: <number> The refresh rate of the display.
    • geometry: <object> The desktop region represented by the display.
      • x, y, width, height: <Rect> The position and size of the display's geometry.
    • usable: <object> Similar to geometry, but excludes areas taken up by the OS or window manager such as menus, docks, e.t.c.
      • x, y, width, height: <Rect> The position and size of the display's usable region.
    • dpi: <object>|<null> Return pixel density for the display in dots/pixels-per-inch units. Might be null on some devices if DPI info can't be retrieved.
      • horizontal: <number> The horizontal density.
      • vertical: <number> The vertical density.
      • diagonal: <number> The diagonal density.

A list of all detected displays. Sample output for two side-to-side monitors is below. Notice how the geometries don't overlap:

[
  {
    name: '0',
    format: 'rgb888',
    frequency: 60,
    geometry: { x: 0, y: 0, width: 1920, height: 1080 },
    usable: { x: 0, y: 27, width: 1920, height: 1053 },
    dpi: { horizontal: 141.76, vertical: 142.13, diagonal: 141.85 }
  },
  {
    name: '1',
    format: 'rgb888',
    frequency: 60,
    geometry: { x: 1920, y: 0, width: 1920, height: 1080 },
    usable: { x: 1920, y: 27, width: 1920, height: 1053 },
    dpi: { horizontal: 141.76, vertical: 142.13, diagonal: 141.85 }
  },
]

sdl.video.windows

A list of all open windows.

sdl.video.focused

The window that has the current keyboard focus, or null if no window has the keyboard focus.

sdl.video.hovered

The window that the mouse is hovered over, or null if the mouse is not over a window.

sdl.video.createWindow([options])

  • options: <object>
    • title: <string> Will appear in the window's title bar. Default: ''
    • display: <number> An object from sdl.video.displays to specify in which display the window will appear (if you have multiple displays). Default: sdl.video.displays[0]
    • x: <number> The x position in which the window will appear relative to the screen, or null for centered. Default: null
    • y: <number> The y position in which the window will appear relative to the screen, or null for centered. Default: null
    • width: <number> The width of the window. Default: 640
    • height: <number> The height of the window. Default: 480
    • visible: <boolean> Set to false to create a hidden window that will only be shown when you call window.show(). Default: true
    • fullscreen: <boolean> Set to true to create the window in fullscreen mode. Default: false
    • resizable: <boolean> Set to true to allow resizing the window by dragging its borders. Default: false
    • borderless: <boolean> Set to true to completely hide the window's borders and title bar. Default: false
    • alwaysOnTop: <boolean> Set to true to always show this window above others. Default: false
    • accelerated: <boolean> Set to false to disable hardware accelerated rendering. Default: true
    • vsync: <boolean> Set to false to disable frame rate synchronization. Default: true
    • opengl: <boolean> Set to true to create an OpenGL-compatible window (for use with @kmamal/gl). Default: false
    • webgpu: <boolean> Set to true to create an WebGPU-compatible window (for use with @kmamal/gpu). Default: false
    • skipTaskbar: <boolean> X11 only. Set to true to not add this window to the taskbar. Default: false
    • popupMenu: <boolean> X11 only. Set to true to treat this window like a popup menu. Default: false
    • tooltip: <boolean> X11 only. Set to true to treat this window like a tooltip. Default: false
    • utility: <boolean> X11 only. Set to true to treat this window like a utility window. Default: false
  • Returns: <Window> an object representing the new window.

Creates a new window.

The following restrictions apply:

  • If you specify the display option, you can't also specify the x or y options, and vice-versa.
  • The resizable and borderless options are mutually exclusive.
  • The opengl and webgpu options are mutually exclusive.
  • The vsync option only applies to windows that are also accelerated.
  • The accelerated and vsync options have no effect if either opengl or webgpu is also specified.

If you set the opengl or webgpu options, then you can only render to the window with OpenGL/WebGPU calls. Calls to render() will fail.

class Window

This class is not directly exposed by the API so you can't use it with the new operator. Instead, objects returned by sdl.video.createWindow() are of this type.

Event: 'show'

Fired when a window becomes visible.

Event: 'hide'

Fired when a window becomes hidden.

Event: 'expose'

Fired when a window becomes exposed and should be redrawn.

Event: 'minimize'

Fired when a window becomes minimized.

Event: 'maximize'

Fired when a window becomes maximized.

Event: 'restore'

Fired when a window gets restored.

Event: 'move'

  • x: <number> The window's new x position, relative to the screen.
  • y: <number> The window's new y position, relative to the screen.

Fired when the window changes position.

Event: 'resize'

  • width: <number> The window's new width.
  • height: <number> The window's new height.
  • pixelWidth: <number> The window's new width in pixels. See high-dpi.
  • pixelHeight: <number> The window's new height in pixels. See high-dpi.

Fired when the window changes size.

Event: 'focus'

Fired when a window gains the keyboard focus.

Event: 'blur'

Fired when a window loses the keyboard focus.

Event: 'hover'

Fired when the mouse enters the window.

Event: 'leave'

Fired when the mouse leaves the window.

Event: 'beforeClose'

  • prevent: <function (void) => void> Call this to prevent the window from closing.

Fired to indicate that the user has requested the window to close (usually by clicking the "x" button). If you need to display any confirmation dialogs you should call event.prevent() and handle destruction manually. If prevent is not called, then this event will be followed by a 'close' event.

Event: 'close'

Indicates that the window is about to be destroyed. Handle any cleanup here.

Event: 'keyDown'

  • scancode: <Scancode> The scancode of the key that caused the event.
  • key: <Key>|<null> The virtual key that caused the event, or null if the physical key does not correspond to any virtual key.
  • repeat: <boolean> Is true if the event was generated by holding down a key for a long time.
  • shift: <boolean> Is true if the Shift key was pressed when the event was generated.
  • ctrl: <boolean> Is true if the Ctrl key was pressed when the event was generated.
  • alt: <boolean> Is true if the Alt key was pressed when the event was generated.
  • super: <boolean> Is true if the "Windows" key was pressed when the event was generated.
  • altgr: <boolean> Is true if the AltGr key was pressed when the event was generated.
  • capslock: <boolean> Is true if CapsLock was active when the event was generated.
  • numlock: <boolean> Is true if NumLock was active when the event was generated.

Fired when a key is pressed, and will also be fired repeatedly afterwards if the key is held down.

Event: 'keyUp'

  • scancode: <Scancode> The scancode of the key that caused the event.
  • key: <Key>|<null> The virtual key that caused the event, or null if the physical key does not correspond to any virtual key.
  • shift: <boolean> Is true if the Shift key was pressed when the event was generated.
  • ctrl: <boolean> Is true if the Ctrl key was pressed when the event was generated.
  • alt: <boolean> Is true if the Alt key was pressed when the event was generated.
  • super: <boolean> Is true if the "Windows" key was pressed when the event was generated.
  • altgr: <boolean> Is true if the AltGr key was pressed when the event was generated.
  • capslock: <boolean> Is true if CapsLock was active when the event was generated.
  • numlock: <boolean> Is true if NumLock was active when the event was generated.

Fired when a key is released.

Event: 'textInput'

  • text: <string> The unicode representation of the character that was entered.

Fired when the user enters text via the keyboard.

Event: 'mouseButtonDown'

  • x: <number> The mouse's x position when the event happened, relative to the window.
  • y: <number> The mouse's y position when the event happened, relative to the window.
  • touch: <boolean> Will be true if the event was caused by a touch event.
  • button: <sdl.mouse.BUTTON> The button that was pressed.

Fired when a mouse button is pressed.

Event: 'mouseButtonUp'

  • x: <number> The mouse's x position when the event happened, relative to the window.
  • y: <number> The mouse's y position when the event happened, relative to the window.
  • touch: <boolean> Will be true if the event was caused by a touch event.
  • button: <sdl.mouse.BUTTON> The button that was released.

Fired when a mouse button is released.

Event: 'mouseMove'

  • x: <number> The mouse's x position when the event happened, relative to the window.
  • y: <number> The mouse's y position when the event happened, relative to the window.
  • touch: <boolean> Will be true if the event was caused by a touch event.

Fired when the mouse moves.

Event: 'mouseWheel'

  • x: <number> The mouse's x position when the event happened, relative to the window.
  • y: <number> The mouse's y position when the event happened, relative to the window.
  • touch: <boolean> Will be true if the event was caused by a touch event.
  • dx: <number> The wheel's x movement, relative to its last position.
  • dy: <number> The wheel's y movement, relative to its last position.
  • flipped: <boolean> Will be true if the underlying platform reverses the mouse wheel's scroll direction. Multiply dx and dy by -1 to get the correct values.

Fired when the mouse wheel is scrolled.

Event: 'dropBegin'

When dropping a set of items onto a window, first the 'dropBegin' event will be fired, then a number of 'dropText' and/or 'dropFile' events will be fired, corresponding to the contents of the drop, then finally the 'dropComplete' event will be fired.

Event: 'dropText'

  • text: <string>: The text that was dropped onto the window.

Fired when one of the drops is a text item.

Event: 'dropFile'

  • file: <string>: The path to the file that was dropped onto the window.

Fired when one of the drops is a file.

Event: 'dropComplete'

Fired after a set of items has been dropped on a window.

window.id

  • <number>

A unique identifier for the window.

window.title

  • <string>

The text that appears in the window's title bar.

window.setTitle(title)

  • title: <string>: The new title.

Changes the text that appears in the window's title bar.

window.x

  • <number>

The window's x position, relative to the screen.

window.y

  • <number>

The window's y position, relative to the screen.

window.setPosition(x, y)

  • x: <number>: The new x position, relative to the screen.
  • y: <number>: The new y position, relative to the screen.

Moves the window to a new position on the screen.

window.width

  • <number>

The window's width.

window.height

  • <number>

The window's height.

window.pixelWidth

  • <number>

The window's width in pixels. This will be larger than width on high-dpi displays.

window.pixelHeight

  • <number>

The window's height in pixels. This will be larger than height on high-dpi displays.

window.setSize(width, height)

  • width: <number>: The new width.
  • height: <number>: The new height.

Changes the size of the window.

window.visible

  • <boolean>

Will be true if the window is visible.

window.show([show])

  • show: <boolean> Set to true to make the window visible, false to hide it. Default: true

Shows or hides the window.

window.hide()

Equivalent to window.show(false).

window.fullscreen

  • <boolean>

Will be true if the window is fullscreen. A fullscreen window is displayed over the entire screen.

window.setFullscreen(fullscreen)

  • fullscreen: <boolean> The new value of the property.

Changes the window's fullscreen property.

window.resizable

  • <boolean>

Will be true if the window is resizable. A resizable window can be resized by dragging it's borders.

window.setResizable(resizable)

  • resizable: <boolean> The new value of the property.

Changes the window's resizable property.

window.borderless

  • <boolean>

Will be true if the window is borderless. A borderless window has no borders or title bar.

window.setBorderless(borderless)

  • borderless: <boolean> The new value of the property.

Changes the window's borderless property.

window.alwaysOnTop

  • <boolean>

Will be true if the window was created with alwaysOnTop: true. Such a window will always be shown above other windows.

window.accelerated

  • <boolean>

Will be true if the window is using hardware accelerated rendering.

window.setAccelerated(accelerated)

  • accelerated: <boolean> The new value of the property.

Changes the window's accelerated property.

If you have set the opengl or webgpu options, then calls to this function will fail.

window.vsync

  • <boolean>

Will be true if the window is using vsync. A window with vsync enabled will have its frame rate synchronized to the display's refresh rate to prevent tearing. Note that vsync can only be used if that window is also accelerated

window.setVsync(vsync)

  • vsync: <boolean> The new value of the property.

Changes the window's vsync property.

If you have set the opengl or webgpu options, then calls to this function will fail.

window.opengl

  • <boolean>

Will be true if the window was created in OpenGl mode. In OpenGL mode, you can only render to the window with OpenGL calls. Calls to render() will fail.

window.webgpu

  • <boolean>

Will be true if the window was created in WebGPU mode. In WebGPU mode, you can only render to the window with WebGPU calls. Calls to render() will fail.

window.native

  • <any>

Holds a copy of the native (platform-specific) representation of the window. Only used for passing to @kmamal/gl or @kmamal/gpu.

window.maximized

  • <boolean>

Will be true if the window is maximized.

window.maximize()

Maximizes the window.

window.minimized

  • <boolean>

Will be true if the window is minimized.

window.minimize()

Minimizes the window.

window.restore()

Restores the window so it's neither minimized nor maximized.

window.focused

  • <boolean>

Will be true if the window has keyboard input.

window.focus()

Gives the window the keyboard focus.

window.hovered

  • <boolean>

Will be true if the mouse is over the window.

window.skipTaskbar

  • <boolean>

X11 only. Will be true if the window was created with skipTaskbar: true. Such a window will not be added to the taskbar.

window.popupMenu

  • <boolean>

X11 only. Will be true if the window was created with popupMenu: true. Such a window will always be treated as a popup menu.

window.tooltip

  • <boolean>

X11 only. Will be true if the window was created with tooltip: true. Such a window will always be treated as a tooltip.

window.utility

  • <boolean>

X11 only. Will be true if the window was created with utility: true. Such a window will always be treated as a utility window.

window.render(width, height, stride, format, buffer)

  • width, height, stride, format, buffer: <Image> The image to display on the window.

Displays an image in the window. The provided image will be stretched over the entire window.

If you set the opengl or webgpu options, then you can only render to the window with OpenGL/WebGPU calls. Calls to render() will fail.

window.setIcon(width, height, stride, format, buffer)

  • width, height, stride, format, buffer: <Image> The image to display as the icon of the window.

Set's the window's icon, usually displayed in the title bar and the taskbar.

window.flash(untilFocused)

  • untilFocused: <boolean> Whether to keep flashing the window until the user focuses it. Default: false

Flash the window briefly to get attention. If untilFocused is set, the window will flash until the user focuses it.

window.stopFlashing()

Stop the window from flashing.

window.destroyed

  • <boolean>

Will be true if the window is destroyed. A destroyed window object should not be used any further.

window.destroy()

Destroys the window.

sdl.keyboard

There are three levels at which you can deal with the keyboard: physical keys (scancodes), virtual keys (keys), and text ('textInput' events).

On the physical level, each of the physical keys corresponds to a number: the key's scancode. For any given keyboard, the same key will always produce the same scancode. If your application cares about the layout of the keyboard (for example using the "WASD" keys as a substitute for arrow keys), then you should handle key events at this level using the scancode property of 'keyDown' and 'keyUp' events.

For the most part it's better to treat scancode values as arbitrary/meaningless, but SDL does provide a scancode enumeration with values based on the USB usage page standard so you should be able to derive some meaning from the scancodes if your keyboard is compatible.

More commonly, you don't care about the physical key itself but about the "meaning" associated with each key: the character that it produces ("a", "b", "@", " ", .e.t.c) or the function that it corresponds to ("Esc", "F4", "Ctrl", e.t.c.). Your operating system provides a "keyboard mapping" that associates physical keys with their corresponding meaning. Changing the keyboard mapping (for example by changing the language from English to German) will also change the corresponding meaning for each key (in the English-German example: the "y" and "z" keys will be switched). These meanings are represented as virtual key strings. If your application cares about the meaning associated with individual keys then you should handle key events at this level using the key property of 'keyDown' and 'keyUp' events.

Note that not all physical keys correspond to a well-defined meaning and thus don't have a virtual key value associated with them. The key events for these keys will have a null value for the key property.

But sometimes the application doesn't care about individual keys at all, but about the resulting text that the user is entering. Consider for example what happens when a user on a Greek keyboard layout enters an accent mark "ยด" followed by the letter "ฮฑ" to produce the character "ฮฌ": Two keys were pressed, but only a single character was produced. Trying to handle text input by manually translating key presses to text is not a very viable solution. It's better to let the OS handle all the text logic, and get the final text by handling the rasulting ('textInput') events.

Virtual keys

String values used to represent virtual keys in the context of the current keyboard mapping. Note that some keys do not correspond to any virtual key. A Key can be either one of the values below or any unicode character. Keys that produce characters are represented by that character. All others are represented by one of these values:

'&&', '+/-', '||', '00', '000', 'again', 'alt', 'altErase', 'app1', 'app2', 'application', 'audioFastForward', 'audioMute', 'audioNext', 'audioPlay', 'audioPrev', 'audioRewind', 'audioStop', 'back', 'backspace', 'binary', 'bookmarks', 'brightnessDown', 'brightnessUp', 'calculator', 'cancel', 'capsLock', 'clear', 'clearEntry', 'computer', 'copy', 'crSel', 'ctrl', 'currencySubUnit', 'currencyUnit', 'cut', 'decimal', 'decimalSeparator', 'delete', 'displaySwitch', 'down', 'eject', 'end', 'enter', 'escape', 'execute', 'exSel', 'f1', 'f2', 'f3', 'f4', 'f5', 'f6', 'f7', 'f8', 'f9', 'f10', 'f11', 'f12', 'f13', 'f14', 'f15', 'f16', 'f17', 'f18', 'f19', 'f20', 'f21', 'f22', 'f23', 'f24', 'find', 'forward', 'gui', 'help', 'hexadecimal', 'home', 'illumDown', 'illumToggle', 'illumUp', 'insert', 'left', 'mail', 'mediaSelect', 'memAdd', 'memClear', 'memDivide', 'memMultiply', 'memRecall', 'memStore', 'memSubtract', 'menu', 'modeSwitch', 'mute', 'numlock', 'octal', 'oper', 'out', 'pageDown', 'pageUp', 'paste', 'pause', 'power', 'printScreen', 'prior', 'refresh', 'return', 'right', 'scrollLock', 'search', 'select', 'separator', 'shift', 'sleep', 'space', 'stop', 'sysReq', 'tab', 'thousandsSeparator', 'undo', 'up', 'volumeDown', 'volumeUp', 'www', 'xor'.

Enum: SCANCODE

Used to represent physical keys on the keyboard. The same key will always produce the same scancode. Values are based on the USB usage page standard.

Click to expand table
Value Corresponding SDL_Scancode Comment
sdl.keyboard.SCANCODE.A SDL_SCANCODE_A
sdl.keyboard.SCANCODE.B SDL_SCANCODE_B
sdl.keyboard.SCANCODE.C SDL_SCANCODE_C
sdl.keyboard.SCANCODE.D SDL_SCANCODE_D
sdl.keyboard.SCANCODE.E SDL_SCANCODE_E
sdl.keyboard.SCANCODE.F SDL_SCANCODE_F
sdl.keyboard.SCANCODE.G SDL_SCANCODE_G
sdl.keyboard.SCANCODE.H SDL_SCANCODE_H
sdl.keyboard.SCANCODE.I SDL_SCANCODE_I
sdl.keyboard.SCANCODE.J SDL_SCANCODE_J
sdl.keyboard.SCANCODE.K SDL_SCANCODE_K
sdl.keyboard.SCANCODE.L SDL_SCANCODE_L
sdl.keyboard.SCANCODE.M SDL_SCANCODE_M
sdl.keyboard.SCANCODE.N SDL_SCANCODE_N
sdl.keyboard.SCANCODE.O SDL_SCANCODE_O
sdl.keyboard.SCANCODE.P SDL_SCANCODE_P
sdl.keyboard.SCANCODE.Q SDL_SCANCODE_Q
sdl.keyboard.SCANCODE.R SDL_SCANCODE_R
sdl.keyboard.SCANCODE.S SDL_SCANCODE_S
sdl.keyboard.SCANCODE.T SDL_SCANCODE_T
sdl.keyboard.SCANCODE.U SDL_SCANCODE_U
sdl.keyboard.SCANCODE.V SDL_SCANCODE_V
sdl.keyboard.SCANCODE.W SDL_SCANCODE_W
sdl.keyboard.SCANCODE.X SDL_SCANCODE_X
sdl.keyboard.SCANCODE.Y SDL_SCANCODE_Y
sdl.keyboard.SCANCODE.Z SDL_SCANCODE_Z
sdl.keyboard.SCANCODE.1 SDL_SCANCODE_1
sdl.keyboard.SCANCODE.2 SDL_SCANCODE_2
sdl.keyboard.SCANCODE.3 SDL_SCANCODE_3
sdl.keyboard.SCANCODE.4 SDL_SCANCODE_4
sdl.keyboard.SCANCODE.5 SDL_SCANCODE_5
sdl.keyboard.SCANCODE.6 SDL_SCANCODE_6
sdl.keyboard.SCANCODE.7 SDL_SCANCODE_7
sdl.keyboard.SCANCODE.8 SDL_SCANCODE_8
sdl.keyboard.SCANCODE.9 SDL_SCANCODE_9
sdl.keyboard.SCANCODE.0 SDL_SCANCODE_0
sdl.keyboard.SCANCODE.RETURN SDL_SCANCODE_RETURN
sdl.keyboard.SCANCODE.ESCAPE SDL_SCANCODE_ESCAPE
sdl.keyboard.SCANCODE.BACKSPACE SDL_SCANCODE_BACKSPACE
sdl.keyboard.SCANCODE.TAB SDL_SCANCODE_TAB
sdl.keyboard.SCANCODE.SPACE SDL_SCANCODE_SPACE
sdl.keyboard.SCANCODE.MINUS SDL_SCANCODE_MINUS
sdl.keyboard.SCANCODE.EQUALS SDL_SCANCODE_EQUALS
sdl.keyboard.SCANCODE.LEFTBRACKET SDL_SCANCODE_LEFTBRACKET
sdl.keyboard.SCANCODE.RIGHTBRACKET SDL_SCANCODE_RIGHTBRACKET
sdl.keyboard.SCANCODE.BACKSLASH SDL_SCANCODE_BACKSLASH Located at the lower left of the return key on ISO keyboards and at the right end of the QWERTY row on ANSI keyboards. Produces REVERSE SOLIDUS (backslash) and VERTICAL LINE in a US layout, REVERSE SOLIDUS and VERTICAL LINE in a UK Mac layout, NUMBER SIGN and TILDE in a UK Windows layout, DOLLAR SIGN and POUND SIGN in a Swiss German layout, NUMBER SIGN and APOSTROPHE in a German layout, GRAVE ACCENT and POUND SIGN in a French Mac layout, and ASTERISK and MICRO SIGN in a French Windows layout.
sdl.keyboard.SCANCODE.NONUSHASH SDL_SCANCODE_NONUSHASH ISO USB keyboards actually use this code instead of 49 for the same key, but all OSes I've seen treat the two codes identically. So, as an implementor, unless your keyboard generates both of those codes and your OS treats them differently, you should generate SDL_SCANCODE_BACKSLASH instead of this code. As a user, you should not rely on this code because SDL will never generate it with most (all?) keyboards.
sdl.keyboard.SCANCODE.SEMICOLON SDL_SCANCODE_SEMICOLON
sdl.keyboard.SCANCODE.APOSTROPHE SDL_SCANCODE_APOSTROPHE
sdl.keyboard.SCANCODE.GRAVE SDL_SCANCODE_GRAVE Located in the top left corner (on both ANSI and ISO keyboards). Produces GRAVE ACCENT and TILDE in a US Windows layout and in US and UK Mac layouts on ANSI keyboards, GRAVE ACCENT and NOT SIGN in a UK Windows layout, SECTION SIGN and PLUS-MINUS SIGN in US and UK Mac layouts on ISO keyboards, SECTION SIGN and DEGREE SIGN in a Swiss German layout (Mac: only on ISO keyboards), CIRCUMFLEX ACCENT and DEGREE SIGN in a German layout (Mac: only on ISO keyboards), SUPERSCRIPT TWO and TILDE in a French Windows layout, COMMERCIAL AT and NUMBER SIGN in a French Mac layout on ISO keyboards, and LESS-THAN SIGN and GREATER-THAN SIGN in a Swiss German, German, or French Mac layout on ANSI keyboards.
sdl.keyboard.SCANCODE.COMMA SDL_SCANCODE_COMMA
sdl.keyboard.SCANCODE.PERIOD SDL_SCANCODE_PERIOD
sdl.keyboard.SCANCODE.SLASH SDL_SCANCODE_SLASH
sdl.keyboard.SCANCODE.CAPSLOCK SDL_SCANCODE_CAPSLOCK
sdl.keyboard.SCANCODE.F1 SDL_SCANCODE_F1
sdl.keyboard.SCANCODE.F2 SDL_SCANCODE_F2
sdl.keyboard.SCANCODE.F3 SDL_SCANCODE_F3
sdl.keyboard.SCANCODE.F4 SDL_SCANCODE_F4
sdl.keyboard.SCANCODE.F5 SDL_SCANCODE_F5
sdl.keyboard.SCANCODE.F6 SDL_SCANCODE_F6
sdl.keyboard.SCANCODE.F7 SDL_SCANCODE_F7
sdl.keyboard.SCANCODE.F8 SDL_SCANCODE_F8
sdl.keyboard.SCANCODE.F9 SDL_SCANCODE_F9
sdl.keyboard.SCANCODE.F10 SDL_SCANCODE_F10
sdl.keyboard.SCANCODE.F11 SDL_SCANCODE_F11
sdl.keyboard.SCANCODE.F12 SDL_SCANCODE_F12
sdl.keyboard.SCANCODE.PRINTSCREEN SDL_SCANCODE_PRINTSCREEN
sdl.keyboard.SCANCODE.SCROLLLOCK SDL_SCANCODE_SCROLLLOCK
sdl.keyboard.SCANCODE.PAUSE SDL_SCANCODE_PAUSE
sdl.keyboard.SCANCODE.INSERT SDL_SCANCODE_INSERT insert on PC, help on some Mac keyboards
sdl.keyboard.SCANCODE.HOME SDL_SCANCODE_HOME
sdl.keyboard.SCANCODE.PAGEUP SDL_SCANCODE_PAGEUP
sdl.keyboard.SCANCODE.DELETE SDL_SCANCODE_DELETE
sdl.keyboard.SCANCODE.END SDL_SCANCODE_END
sdl.keyboard.SCANCODE.PAGEDOWN SDL_SCANCODE_PAGEDOWN
sdl.keyboard.SCANCODE.RIGHT SDL_SCANCODE_RIGHT
sdl.keyboard.SCANCODE.LEFT SDL_SCANCODE_LEFT
sdl.keyboard.SCANCODE.DOWN SDL_SCANCODE_DOWN
sdl.keyboard.SCANCODE.UP SDL_SCANCODE_UP
sdl.keyboard.SCANCODE.NUMLOCKCLEAR SDL_SCANCODE_NUMLOCKCLEAR num lock on PC, clear on Mac keyboards
sdl.keyboard.SCANCODE.KP_DIVIDE SDL_SCANCODE_KP_DIVIDE
sdl.keyboard.SCANCODE.KP_MULTIPLY SDL_SCANCODE_KP_MULTIPLY
sdl.keyboard.SCANCODE.KP_MINUS SDL_SCANCODE_KP_MINUS
sdl.keyboard.SCANCODE.KP_PLUS SDL_SCANCODE_KP_PLUS
sdl.keyboard.SCANCODE.KP_ENTER SDL_SCANCODE_KP_ENTER
sdl.keyboard.SCANCODE.KP_1 SDL_SCANCODE_KP_1
sdl.keyboard.SCANCODE.KP_2 SDL_SCANCODE_KP_2
sdl.keyboard.SCANCODE.KP_3 SDL_SCANCODE_KP_3
sdl.keyboard.SCANCODE.KP_4 SDL_SCANCODE_KP_4
sdl.keyboard.SCANCODE.KP_5 SDL_SCANCODE_KP_5
sdl.keyboard.SCANCODE.KP_6 SDL_SCANCODE_KP_6
sdl.keyboard.SCANCODE.KP_7 SDL_SCANCODE_KP_7
sdl.keyboard.SCANCODE.KP_8 SDL_SCANCODE_KP_8
sdl.keyboard.SCANCODE.KP_9 SDL_SCANCODE_KP_9
sdl.keyboard.SCANCODE.KP_0 SDL_SCANCODE_KP_0
sdl.keyboard.SCANCODE.KP_PERIOD SDL_SCANCODE_KP_PERIOD
sdl.keyboard.SCANCODE.NONUSBACKSLASH SDL_SCANCODE_NONUSBACKSLASH This is the additional key that ISO keyboards have over ANSI ones, located between left shift and Y. Produces GRAVE ACCENT and TILDE in a US or UK Mac layout, REVERSE SOLIDUS (backslash) and VERTICAL LINE in a US or UK Windows layout, and LESS-THAN SIGN and GREATER-THAN SIGN in a Swiss German, German, or French layout.
sdl.keyboard.SCANCODE.APPLICATION SDL_SCANCODE_APPLICATION windows contextual menu, compose
sdl.keyboard.SCANCODE.POWER SDL_SCANCODE_POWER The USB document says this is a status flag, not a physical key - but some Mac keyboards do have a power key.
sdl.keyboard.SCANCODE.KP_EQUALS SDL_SCANCODE_KP_EQUALS
sdl.keyboard.SCANCODE.F13 SDL_SCANCODE_F13
sdl.keyboard.SCANCODE.F14 SDL_SCANCODE_F14
sdl.keyboard.SCANCODE.F15 SDL_SCANCODE_F15
sdl.keyboard.SCANCODE.F16 SDL_SCANCODE_F16
sdl.keyboard.SCANCODE.F17 SDL_SCANCODE_F17
sdl.keyboard.SCANCODE.F18 SDL_SCANCODE_F18
sdl.keyboard.SCANCODE.F19 SDL_SCANCODE_F19
sdl.keyboard.SCANCODE.F20 SDL_SCANCODE_F20
sdl.keyboard.SCANCODE.F21 SDL_SCANCODE_F21
sdl.keyboard.SCANCODE.F22 SDL_SCANCODE_F22
sdl.keyboard.SCANCODE.F23 SDL_SCANCODE_F23
sdl.keyboard.SCANCODE.F24 SDL_SCANCODE_F24
sdl.keyboard.SCANCODE.EXECUTE SDL_SCANCODE_EXECUTE
sdl.keyboard.SCANCODE.HELP SDL_SCANCODE_HELP
sdl.keyboard.SCANCODE.MENU SDL_SCANCODE_MENU
sdl.keyboard.SCANCODE.SELECT SDL_SCANCODE_SELECT
sdl.keyboard.SCANCODE.STOP SDL_SCANCODE_STOP
sdl.keyboard.SCANCODE.AGAIN SDL_SCANCODE_AGAIN redo
sdl.keyboard.SCANCODE.UNDO SDL_SCANCODE_UNDO
sdl.keyboard.SCANCODE.CUT SDL_SCANCODE_CUT
sdl.keyboard.SCANCODE.COPY SDL_SCANCODE_COPY
sdl.keyboard.SCANCODE.PASTE SDL_SCANCODE_PASTE
sdl.keyboard.SCANCODE.FIND SDL_SCANCODE_FIND
sdl.keyboard.SCANCODE.MUTE SDL_SCANCODE_MUTE
sdl.keyboard.SCANCODE.VOLUMEUP SDL_SCANCODE_VOLUMEUP
sdl.keyboard.SCANCODE.VOLUMEDOWN SDL_SCANCODE_VOLUMEDOWN
sdl.keyboard.SCANCODE.KP_COMMA SDL_SCANCODE_KP_COMMA
sdl.keyboard.SCANCODE.KP_EQUALSAS400 SDL_SCANCODE_KP_EQUALSAS400
sdl.keyboard.SCANCODE.INTERNATIONAL1 SDL_SCANCODE_INTERNATIONAL1 used on Asian keyboards, see footnotes in USB doc
sdl.keyboard.SCANCODE.INTERNATIONAL2 SDL_SCANCODE_INTERNATIONAL2
sdl.keyboard.SCANCODE.INTERNATIONAL3 SDL_SCANCODE_INTERNATIONAL3 Yen
sdl.keyboard.SCANCODE.INTERNATIONAL4 SDL_SCANCODE_INTERNATIONAL4
sdl.keyboard.SCANCODE.INTERNATIONAL5 SDL_SCANCODE_INTERNATIONAL5
sdl.keyboard.SCANCODE.INTERNATIONAL6 SDL_SCANCODE_INTERNATIONAL6
sdl.keyboard.SCANCODE.INTERNATIONAL7 SDL_SCANCODE_INTERNATIONAL7
sdl.keyboard.SCANCODE.INTERNATIONAL8 SDL_SCANCODE_INTERNATIONAL8
sdl.keyboard.SCANCODE.INTERNATIONAL9 SDL_SCANCODE_INTERNATIONAL9
sdl.keyboard.SCANCODE.LANG1 SDL_SCANCODE_LANG1 Hangul/English toggle
sdl.keyboard.SCANCODE.LANG2 SDL_SCANCODE_LANG2 Hanja conversion
sdl.keyboard.SCANCODE.LANG3 SDL_SCANCODE_LANG3 Katakana
sdl.keyboard.SCANCODE.LANG4 SDL_SCANCODE_LANG4 Hiragana
sdl.keyboard.SCANCODE.LANG5 SDL_SCANCODE_LANG5 Zenkaku/Hankaku
sdl.keyboard.SCANCODE.LANG6 SDL_SCANCODE_LANG6
sdl.keyboard.SCANCODE.LANG7 SDL_SCANCODE_LANG7
sdl.keyboard.SCANCODE.LANG8 SDL_SCANCODE_LANG8
sdl.keyboard.SCANCODE.LANG9 SDL_SCANCODE_LANG9
sdl.keyboard.SCANCODE.ALTERASE SDL_SCANCODE_ALTERASE Erase-Eaze
sdl.keyboard.SCANCODE.SYSREQ SDL_SCANCODE_SYSREQ
sdl.keyboard.SCANCODE.CANCEL SDL_SCANCODE_CANCEL
sdl.keyboard.SCANCODE.CLEAR SDL_SCANCODE_CLEAR
sdl.keyboard.SCANCODE.PRIOR SDL_SCANCODE_PRIOR
sdl.keyboard.SCANCODE.RETURN2 SDL_SCANCODE_RETURN2
sdl.keyboard.SCANCODE.SEPARATOR SDL_SCANCODE_SEPARATOR
sdl.keyboard.SCANCODE.OUT SDL_SCANCODE_OUT
sdl.keyboard.SCANCODE.OPER SDL_SCANCODE_OPER
sdl.keyboard.SCANCODE.CLEARAGAIN SDL_SCANCODE_CLEARAGAIN
sdl.keyboard.SCANCODE.CRSEL SDL_SCANCODE_CRSEL
sdl.keyboard.SCANCODE.EXSEL SDL_SCANCODE_EXSEL
sdl.keyboard.SCANCODE.KP_00 SDL_SCANCODE_KP_00
sdl.keyboard.SCANCODE.KP_000 SDL_SCANCODE_KP_000
sdl.keyboard.SCANCODE.THOUSANDSSEPARATOR SDL_SCANCODE_THOUSANDSSEPARATOR
sdl.keyboard.SCANCODE.DECIMALSEPARATOR SDL_SCANCODE_DECIMALSEPARATOR
sdl.keyboard.SCANCODE.CURRENCYUNIT SDL_SCANCODE_CURRENCYUNIT
sdl.keyboard.SCANCODE.CURRENCYSUBUNIT SDL_SCANCODE_CURRENCYSUBUNIT
sdl.keyboard.SCANCODE.KP_LEFTPAREN SDL_SCANCODE_KP_LEFTPAREN
sdl.keyboard.SCANCODE.KP_RIGHTPAREN SDL_SCANCODE_KP_RIGHTPAREN
sdl.keyboard.SCANCODE.KP_LEFTBRACE SDL_SCANCODE_KP_LEFTBRACE
sdl.keyboard.SCANCODE.KP_RIGHTBRACE SDL_SCANCODE_KP_RIGHTBRACE
sdl.keyboard.SCANCODE.KP_TAB SDL_SCANCODE_KP_TAB
sdl.keyboard.SCANCODE.KP_BACKSPACE SDL_SCANCODE_KP_BACKSPACE
sdl.keyboard.SCANCODE.KP_A SDL_SCANCODE_KP_A
sdl.keyboard.SCANCODE.KP_B SDL_SCANCODE_KP_B
sdl.keyboard.SCANCODE.KP_C SDL_SCANCODE_KP_C
sdl.keyboard.SCANCODE.KP_D SDL_SCANCODE_KP_D
sdl.keyboard.SCANCODE.KP_E SDL_SCANCODE_KP_E
sdl.keyboard.SCANCODE.KP_F SDL_SCANCODE_KP_F
sdl.keyboard.SCANCODE.KP_XOR SDL_SCANCODE_KP_XOR
sdl.keyboard.SCANCODE.KP_POWER SDL_SCANCODE_KP_POWER
sdl.keyboard.SCANCODE.KP_PERCENT SDL_SCANCODE_KP_PERCENT
sdl.keyboard.SCANCODE.KP_LESS SDL_SCANCODE_KP_LESS
sdl.keyboard.SCANCODE.KP_GREATER SDL_SCANCODE_KP_GREATER
sdl.keyboard.SCANCODE.KP_AMPERSAND SDL_SCANCODE_KP_AMPERSAND
sdl.keyboard.SCANCODE.KP_DBLAMPERSAND SDL_SCANCODE_KP_DBLAMPERSAND
sdl.keyboard.SCANCODE.KP_VERTICALBAR SDL_SCANCODE_KP_VERTICALBAR
sdl.keyboard.SCANCODE.KP_DBLVERTICALBAR SDL_SCANCODE_KP_DBLVERTICALBAR
sdl.keyboard.SCANCODE.KP_COLON SDL_SCANCODE_KP_COLON
sdl.keyboard.SCANCODE.KP_HASH SDL_SCANCODE_KP_HASH
sdl.keyboard.SCANCODE.KP_SPACE SDL_SCANCODE_KP_SPACE
sdl.keyboard.SCANCODE.KP_AT SDL_SCANCODE_KP_AT
sdl.keyboard.SCANCODE.KP_EXCLAM SDL_SCANCODE_KP_EXCLAM
sdl.keyboard.SCANCODE.KP_MEMSTORE SDL_SCANCODE_KP_MEMSTORE
sdl.keyboard.SCANCODE.KP_MEMRECALL SDL_SCANCODE_KP_MEMRECALL
sdl.keyboard.SCANCODE.KP_MEMCLEAR SDL_SCANCODE_KP_MEMCLEAR
sdl.keyboard.SCANCODE.KP_MEMADD SDL_SCANCODE_KP_MEMADD
sdl.keyboard.SCANCODE.KP_MEMSUBTRACT SDL_SCANCODE_KP_MEMSUBTRACT
sdl.keyboard.SCANCODE.KP_MEMMULTIPLY SDL_SCANCODE_KP_MEMMULTIPLY
sdl.keyboard.SCANCODE.KP_MEMDIVIDE SDL_SCANCODE_KP_MEMDIVIDE
sdl.keyboard.SCANCODE.KP_PLUSMINUS SDL_SCANCODE_KP_PLUSMINUS
sdl.keyboard.SCANCODE.KP_CLEAR SDL_SCANCODE_KP_CLEAR
sdl.keyboard.SCANCODE.KP_CLEARENTRY SDL_SCANCODE_KP_CLEARENTRY
sdl.keyboard.SCANCODE.KP_BINARY SDL_SCANCODE_KP_BINARY
sdl.keyboard.SCANCODE.KP_OCTAL SDL_SCANCODE_KP_OCTAL
sdl.keyboard.SCANCODE.KP_DECIMAL SDL_SCANCODE_KP_DECIMAL
sdl.keyboard.SCANCODE.KP_HEXADECIMAL SDL_SCANCODE_KP_HEXADECIMAL
sdl.keyboard.SCANCODE.LCTRL SDL_SCANCODE_LCTRL
sdl.keyboard.SCANCODE.LSHIFT SDL_SCANCODE_LSHIFT
sdl.keyboard.SCANCODE.LALT SDL_SCANCODE_LALT alt, option
sdl.keyboard.SCANCODE.LGUI SDL_SCANCODE_LGUI windows, command (apple), meta
sdl.keyboard.SCANCODE.RCTRL SDL_SCANCODE_RCTRL
sdl.keyboard.SCANCODE.RSHIFT SDL_SCANCODE_RSHIFT
sdl.keyboard.SCANCODE.RALT SDL_SCANCODE_RALT alt gr, option
sdl.keyboard.SCANCODE.RGUI SDL_SCANCODE_RGUI windows, command (apple), meta
sdl.keyboard.SCANCODE.MODE SDL_SCANCODE_MODE
sdl.keyboard.SCANCODE.AUDIONEXT SDL_SCANCODE_AUDIONEXT
sdl.keyboard.SCANCODE.AUDIOPREV SDL_SCANCODE_AUDIOPREV
sdl.keyboard.SCANCODE.AUDIOSTOP SDL_SCANCODE_AUDIOSTOP
sdl.keyboard.SCANCODE.AUDIOPLAY SDL_SCANCODE_AUDIOPLAY
sdl.keyboard.SCANCODE.AUDIOMUTE SDL_SCANCODE_AUDIOMUTE
sdl.keyboard.SCANCODE.MEDIASELECT SDL_SCANCODE_MEDIASELECT
sdl.keyboard.SCANCODE.WWW SDL_SCANCODE_WWW
sdl.keyboard.SCANCODE.MAIL SDL_SCANCODE_MAIL
sdl.keyboard.SCANCODE.CALCULATOR SDL_SCANCODE_CALCULATOR
sdl.keyboard.SCANCODE.COMPUTER SDL_SCANCODE_COMPUTER
sdl.keyboard.SCANCODE.AC_SEARCH SDL_SCANCODE_AC_SEARCH
sdl.keyboard.SCANCODE.AC_HOME SDL_SCANCODE_AC_HOME
sdl.keyboard.SCANCODE.AC_BACK SDL_SCANCODE_AC_BACK
sdl.keyboard.SCANCODE.AC_FORWARD SDL_SCANCODE_AC_FORWARD
sdl.keyboard.SCANCODE.AC_STOP SDL_SCANCODE_AC_STOP
sdl.keyboard.SCANCODE.AC_REFRESH SDL_SCANCODE_AC_REFRESH
sdl.keyboard.SCANCODE.AC_BOOKMARKS SDL_SCANCODE_AC_BOOKMARKS
sdl.keyboard.SCANCODE.BRIGHTNESSDOWN SDL_SCANCODE_BRIGHTNESSDOWN
sdl.keyboard.SCANCODE.BRIGHTNESSUP SDL_SCANCODE_BRIGHTNESSUP
sdl.keyboard.SCANCODE.DISPLAYSWITCH SDL_SCANCODE_DISPLAYSWITCH display mirroring/dual display switch, video mode switch
sdl.keyboard.SCANCODE.KBDILLUMTOGGLE SDL_SCANCODE_KBDILLUMTOGGLE
sdl.keyboard.SCANCODE.KBDILLUMDOWN SDL_SCANCODE_KBDILLUMDOWN
sdl.keyboard.SCANCODE.KBDILLUMUP SDL_SCANCODE_KBDILLUMUP
sdl.keyboard.SCANCODE.EJECT SDL_SCANCODE_EJECT
sdl.keyboard.SCANCODE.SLEEP SDL_SCANCODE_SLEEP
sdl.keyboard.SCANCODE.APP1 SDL_SCANCODE_APP1
sdl.keyboard.SCANCODE.APP2 SDL_SCANCODE_APP2
sdl.keyboard.SCANCODE.AUDIOREWIND SDL_SCANCODE_AUDIOREWIND
sdl.keyboard.SCANCODE.AUDIOFASTFORWARD SDL_SCANCODE_AUDIOFASTFORWARD

sdl.keyboard.getKey(scancode)

Maps a scancode to the corresponding key based on the current keyboard mapping. Retuns null if the scancode does not currespond to a key in the current mapping.

sdl.keyboard.getScancode(key)

Maps a key to the corresponding scancode based on the current keyboard mapping. Retuns null if the key does not currespond to a scancode in the current mapping. If multiple physical keys produce the same virtual key, then only the first one will be returned.

sdl.keyboard.getState()

  • Returns: <boolean[]> an object representing the state of each key.

The returned array can be indexed with Scancode values. The values will be true for keys that are pressed and false otherwise.

sdl.mouse

Enum: BUTTON

Used to represent the buttons on a mouse. A mouse can have many buttons, but the values for the three most common ones are represented in this enum.

Value Corresponding SDL_BUTTON_*
sdl.mouse.BUTTON.LEFT SDL_BUTTON_LEFT
sdl.mouse.BUTTON.MIDDLE SDL_BUTTON_MIDDLE
sdl.mouse.BUTTON.RIGHT SDL_BUTTON_RIGHT

sdl.mouse.getButton(button)

  • button: <number> The index of the button.
  • Returns: <boolean> Will be true if the button is pressed.

Queries the state of a single mouse button.

sdl.mouse.position

  • <object>
    • x: <number> The x position of the mouse, relative to the screen.
    • y: <number> The y position of the mouse, relative to the screen.

The position of the mouse on the screen.

sdl.mouse.setPosition(x, y)

  • x: <number> The new x position of the mouse, relative to the screen.
  • y: <number> The new y position of the mouse, relative to the screen.

Moves the mouse to the specified position.

sdl.mouse.setCursor(cursor)

  • cursor: <MouseCursor> The icon to use for the cursor.

Changes the icon that is displayed for the mouse cursor.

Possible values for cursor are:

Value Corresponding SDL_SystemCursor Description
'arrow' SDL_SYSTEM_CURSOR_ARROW arrow
'ibeam' SDL_SYSTEM_CURSOR_IBEAM i-beam
'wait' SDL_SYSTEM_CURSOR_WAIT wait
'crosshair' SDL_SYSTEM_CURSOR_CROSSHAIR crosshair
'waitarrow' SDL_SYSTEM_CURSOR_WAITARROW small wait cursor (or wait if not available)
'sizenwse' SDL_SYSTEM_CURSOR_SIZENWSE double arrow pointing northwest and southeast
'sizenesw' SDL_SYSTEM_CURSOR_SIZENESW double arrow pointing northeast and southwest
'sizewe' SDL_SYSTEM_CURSOR_SIZEWE double arrow pointing west and east
'sizens' SDL_SYSTEM_CURSOR_SIZENS double arrow pointing north and south
'sizeall' SDL_SYSTEM_CURSOR_SIZEALL four pointed arrow pointing north, south, east, and west
'no' SDL_SYSTEM_CURSOR_NO slashed circle or crossbones
'hand' SDL_SYSTEM_CURSOR_HAND hand

sdl.mouse.resetCursor()

Switched back to the default cursor.

sdl.mouse.setCursorImage(width, height, stride, format, buffer, x, y)

  • width, height, stride, format, buffer: <Image> The image to use as a cursor.
  • x: <number> The x position of the cursor image's hotspot.
  • y: <number> The y position of the cursor image's hotspot.

Sets a image to be the mouse cursor. The hotspot represents the pixel that is considered to be under the mouse.

sdl.mouse.showCursor([show])

  • show: <boolean> If true then the mouse cursor will be visible. Default: true

Changes the visibility of the mouse cursor.

sdl.mouse.hideCursor()

Equivalent to [`sdl.mouse.showCursor

sdl.mouse.redrawCursor()

Forces a cursor redraw.

sdl.mouse.capture([capture])

  • capture: <boolean> If true the mouse will be captured by the current window. Default: true

When the mouse has been captured you will continue receiving mouse events even if the mouse is not over a window.

sdl.mouse.uncapture()

Equivalent to sdl.mouse.capture(false).

sdl.joystick

Hat positions

String values used to represent the positions of a joystick hat

Value Corresponding SDL_HAT_*
'centered' SDL_HAT_CENTERED
'up' SDL_HAT_UP
'right' SDL_HAT_RIGHT
'down' SDL_HAT_DOWN
'left' SDL_HAT_LEFT
'rightup' SDL_HAT_RIGHTUP
'rightdown' SDL_HAT_RIGHTDOWN
'leftup' SDL_HAT_LEFTUP
'leftdown' SDL_HAT_LEFTDOWN

Event: 'deviceAdd'

  • device: <object>: An object from sdl.joystick.devices indicating the device that caused the event.

Fired when a new joystick device becomes available. Check sdl.joystick.devices to get the new list of joystick devices.

Event: 'deviceRemove'

  • device: <object>: An object from sdl.joystick.devices indicating the device that caused the event.

Fired when an existing joystick device is removed. Check sdl.joystick.devices to get the new list of joystick devices. When this event is emitted, all instances that were opened from the removed device are closed automatically.

sdl.joystick.devices

  • <object>[]
    • id: <number> The unique id for the device.
    • type: <JoystickType> The type of the device.
    • name: <string> The name of the device.
    • path: <string> The implementation dependent path of the device.
    • guid: <string> The GUID of the device.
    • vendor: <number>|<null> The USB vendor ID of the device. Will be null if it can't be determined.
    • product: <number>|<null> The USB product ID of the device. Will be null if it can't be determined.
    • version: <number>|<null> The USB product version of the device. Will be null if it can't be determined.
    • player: <number>|<null> The player index for the device. Will be null if it can't be determined.

A list of all the detected joystick devices.

Possible values for type are:

Value Corresponding SDL_JoystickType
'gamecontroller' SDL_JOYSTICK_TYPE_GAMECONTROLLER
'wheel' SDL_JOYSTICK_TYPE_WHEEL
'arcadestick' SDL_JOYSTICK_TYPE_ARCADE_STICK
'flightstick' SDL_JOYSTICK_TYPE_FLIGHT_STICK
'dancepad' SDL_JOYSTICK_TYPE_DANCE_PAD
'guitar' SDL_JOYSTICK_TYPE_GUITAR
'drumkit' SDL_JOYSTICK_TYPE_DRUM_KIT
'arcadepad' SDL_JOYSTICK_TYPE_ARCADE_PAD
'throttle' SDL_JOYSTICK_TYPE_THROTTLE

Sample output:

[
  {
    id: 0,
    type: 'gamecontroller',
    name: 'DragonRise Inc. Generic USB Joystick',
    path: '/dev/input/event21',
    guid: '03000000790000000600000010010000',
    vendor: 121,
    product: 6,
    version: 272,
    player: 0,
  },
]

sdl.joystick.openDevice(device)

Initializes a joystick device and returns a corresponding instance.

class JoystickInstance

This class is not directly exposed by the API so you can't use it with the new operator. Instead, objects returned by sdl.joystick.openDevice() are of this type.

Event: 'axisMotion'

  • axis: <number> The index of the axis that moved.
  • value: <number> The new axis position.

Fired when one of the joystick's axes moves.

Event: 'ballMotion'

  • ball: <number> The index of the ball that moved.
  • x: <number> The new x-position of the ball.
  • y: <number> The new y-position of the ball.

Fired when one of the joystick's balls moves.

Event: 'buttonDown'

  • button: <number> The index of the button that was pressed.

Fired when one of the joystick's buttons is pressed.

Event: 'buttonUp'

  • button: <number> The index of the button that was released.

Fired when one of the joystick's buttons is released.

Event: 'hatMotion'

  • hat: <number> The index of the hat that was moved.
  • value: <HatPosition> The new hat position.

Fired when one of the joystick's hats is moved.

Event: 'close'

Fired when the instance is about to close. Handle cleanup here.

joystickInstance.device

  • <object>

The device from which this instance was opened.

joystickInstance.firmwareVersion

  • <number>|<null>

The joystick's firmware version, or null if it's not available..

joystickInstance.serialNumber

  • <string>|<null>

The joystick's serial number, or null if it's not available.

joystickInstance.axes

  • <number>[]

An array of values, each corresponding to the position of one of the joystick's axes. The values are normalized from -1 to +1. It may be necessary to impose certain tolerances on these values to account for jitter.

joystickInstance.balls

  • <object>[]
    • x: <number> The horizontal position of the joystick's ball.
    • y: <number> The vertical position of the joystick's ball.

An array of values, each corresponding to the position of one of the joystick's balls.

joystickInstance.buttons

  • <boolean>[]

An array of values, each corresponding to the state of one of the joystick's buttons. The values will be true for buttons that are pressed and false otherwise.

joystickInstance.hats

An array of values, each corresponding to the position of one of the joystick's hats.

joystickInstance.power

  • <PowerLevel>|<null>

The current power level of the joystick device, or null if it is unknown.

Possible values are:

Value Corresponding SDL_JoystickPowerLevel
'empty' SDL_JOYSTICK_POWER_EMPTY
'low' SDL_JOYSTICK_POWER_LOW
'medium' SDL_JOYSTICK_POWER_MEDIUM
'full' SDL_JOYSTICK_POWER_FULL
'wired' SDL_JOYSTICK_POWER_WIRED
'max' SDL_JOYSTICK_POWER_MAX

joystickInstance.setPlayer(index)

  • index: <number> The player index to assign to the joystick.

Sets the player index of this joystick.

joystickInstance.resetPlayer()

Clears player assignment and player led.

joystickInstance.hasLed

  • <boolean>

Will be true if there is a LED light on the joystick, whose color can be controlled.

joystickInstance.setLed(red, green, blue)

  • red: <number> The red component of the led color, from 0 to 1.
  • green: <number> The green component of the led color, from 0 to 1.
  • blue: <number> The blue component of the led color, from 0 to 1.

Sets the color of the LED light on the joystick.

joystickInstance.hasRumble

  • <boolean>

Will be true if the joystick has rumble motors.

joystickInstance.rumble([low, [high, [duration]]])

  • low: <number> The intensity of the low frequency rumble motor, from 0 to 1. Default: 1
  • high: <number> The intensity of the high frequency rumble motor, from 0 to 1. Default: 1
  • duration: <number> The duration of the rumble, in ms. Default: 1e3

Makes the joystick rumble for a set duration. Calling this function again before duration has ran out, overrides the previous call.

joystickInstance.stopRumble()

Stops the joystick rumbling. Equivalent to joystickInstance.rumble(0, 0).

joystickInstance.hasRumbleTriggers

  • <boolean>

Will be true if the joystick has rumble motors on the triggers.

joystickInstance.rumbleTriggers([left, [right, [duration]]])

  • left: <number> The intensity of the left trigger rumble motor, from 0 to 1. Default: 1
  • right: <number> The intensity of the right trigger rumble motor, from 0 to 1. Default: 1
  • duration: <number> The duration of the rumble, in ms. Default: 1e3

Makes the joystick triggers rumble for a set duration. Calling this function again before duration has ran out, overrides the previous call.

joystickInstance.stopRumbleTriggers()

Stops the joystick trigger rumbling. Equivalent to joystickInstance.rumbleTriggers(0, 0).

joystickInstance.closed

  • <boolean>

Will be true if the instance is closed. A closed instance object should not be used any further.

joystickInstance.close()

Closes the instance.

sdl.controller

An SDL controller is an abstraction over joysticks based on the xbox360 controller: They have a dpad, two analog sticks, 4 buttons on the right (called A, B, X, Y), shoulder buttons (two of which might be axes) and 3 buttons in the middle ("Start", "Back" and usually some kind of logo-button called "Guide"). The SDL controller abstraction uses the naming-conventions of xbox360/XInput for all supported devices (for example devices that have a similar layout, like the Playstation DualShock Controller, but different button names), so you'll know that for example controllerInstance.axes.leftStickX is always the x-axis of the left analog stick, or controllerInstance.buttons.b is always the rightmost buttons of the 4 buttons on the right. This makes it easy to provide consistent input bindings, like "press B to jump, move around with the left analog stick". With a pure joystick instance it's impossible to know which axis or button corresponds to which physical axis/button on the device.

Because controllers are an abstraction over joysticks, they operate on the same set of devices (if a joystick device and a controller device have the same id, then they refer to the same underlying physical device). For a joystick device to also be available as a controller device it needs a "mapping". A mapping is a string that consists of the device's name, it's GUID, and a series of pairings between one joystick axis/button and the corresponding controller axis/button name. See the sample output here for an example. SDL has pretty good default controller mappings, but if you need more, there's a community sourced database available on https://github.com/gabomdq/SDL_GameControllerDB. You can add them via:

const url = 'https://raw.githubusercontent.com/gabomdq/SDL_GameControllerDB/master/gamecontrollerdb.txt'
const result = await fetch(url)
const text = await result.text()
const mappings = text.split('\n')
sdl.controller.addMappings(mappings)

Event: 'deviceAdd'

Fired when a new controller device becomes available. Check sdl.controller.devices to get the new list of controller devices.

Event: 'deviceRemove'

Fired when an existing controller device is removed. Check sdl.controller.devices to get the new list of controller devices. When this event is emitted, all instances that were opened from the removed device are closed automatically.

sdl.controller.addMappings(mappings)

  • mappings: <string>[] An array of mappings to register.

Registers new mappings for controllers. This can cause already opened controller instances to be remapped.

sdl.controller.devices

  • <object>[]
    • id: <number> The unique id for the device.
    • name: <string> The name of the device.
    • path: <string> The implementation dependent path of the device.
    • guid: <string> The GUID of the device.
    • vendor: <number>|<null> The USB vendor ID of the device. Will be null if it can't be determined.
    • product: <number>|<null> The USB product ID of the device. Will be null if it can't be determined.
    • version: <number>|<null> The USB product version of the device. Will be null if it can't be determined.
    • player: <number>|<null> The player index for the device. Will be null if it can't be determined.
    • mapping: <string> The axis and button mapping for this device.

A list of all the detected controller devices. Sample output:

[
  {
    id: 0,
    name: 'DragonRise Inc. Generic USB Joystick',
    path: '/dev/input/event21',
    guid: '03000000790000000600000010010000',
    vendor: 121,
    product: 6,
    version: 272,
    player: 0,
    mapping: '03000000790000000600000010010000,DragonRise Inc. Generic USB Joystick,a:b2,b:b1,back:b8,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,dpup:h0.1,leftshoulder:b4,leftstick:b10,lefttrigger:b6,leftx:a0,lefty:a1,rightshoulder:b5,rightstick:b11,righttrigger:b7,rightx:a3,righty:a4,start:b9,x:b3,y:b0,',
  },
]

sdl.controller.openDevice(device)

Initializes an controller device and returns a corresponding instance.

class ControllerInstance

This class is not directly exposed by the API so you can't use it with the new operator. Instead, objects returned by sdl.controller.openDevice() are of this type.

Event: 'axisMotion'

  • axis:<Axis> The axis that moved.
  • value: <number> The new axis position.

Fired when one of the controller's axes moves.

Event: 'buttonDown'

  • button:<Button> The button that was pressed.

Fired when one of the controller's buttons is pressed.

Event: 'buttonUp'

  • button: <number> The index of the button that was released.

Fired when one of the controller's buttons is released.

Event: 'remap'

Fired when a new mapping for this controller is applied (usually via sdl.controller.addMappings()). This can cause all of the controller's axes and buttons to aquire new values.

Event: 'close'

Fired when the instance is about to close. Handle cleanup here.

controllerInstance.device

  • <object>

The device from which this instance was opened.

controllerInstance.firmwareVersion

  • <number>

The controller's firmware version.

controllerInstance.serialNumber

  • <string>|<null>

The controller's serial number, or null if it's not available.

controllerInstance.axes

  • <object>
    • leftStickX: <number> Left stick horizontal position
    • leftStickY: <number> Left stick vertical position
    • rightStickX: <number> Right stick horizontal position
    • rightStickY: <number> Right stick vertical position
    • leftTrigger: <number> Left trigger position
    • rightTrigger: <number> Right trigger position

An object mapping each axis of the controller's axes to its position. The values are normalized from -1 to +1. It may be necessary to impose certain tolerances on these values to account for jitter.

controllerInstance.buttons

  • <object>
    • dpadLeft: <boolean> D-Pad left pressed
    • dpadRight: <boolean> D-Pad right pressed
    • dpadUp: <boolean> D-Pad up pressed
    • dpadDown: <boolean> D-Pad down pressed
    • a: <boolean> A button pressed
    • b: <boolean> B button pressed
    • x: <boolean> X button pressed
    • y: <boolean> Y button pressed
    • guide: <boolean> Middle button pressed
    • back: <boolean> Back button pressed
    • start: <boolean> Start button pressed
    • leftStick: <boolean> Left stick pressed
    • rightStick: <boolean> Right stick pressed
    • leftShoulder: <boolean> Left shoulder button pressed
    • rightShoulder: <boolean> Right shoulder button pressed
    • paddle1: <boolean> Paddle 1 pressed
    • paddle2: <boolean> Paddle 2 pressed
    • paddle3: <boolean> Paddle 3 pressed
    • paddle4: <boolean> Paddle 4 pressed

An object mapping each of the controller's buttons to a boolean value. The values will be true for buttons that are pressed and false otherwise.

controllerInstance.power

The current power level of the controller device.

controllerInstance.setPlayer(index)

  • index: <number> The player index to assign to the controller.

Sets the player index of this controller.

controllerInstance.resetPlayer()

Clears player assignment and player led.

controllerInstance.hasLed

  • <boolean>

Will be true if there is a LED light on the controller, whose color can be controlled.

controllerInstance.setLed(red, green, blue)

  • red: <number> The red component of the led color, from 0 to 1.
  • green: <number> The green component of the led color, from 0 to 1.
  • blue: <number> The blue component of the led color, from 0 to 1.

Sets the color of the LED light on the controller.

controllerInstance.hasRumble

  • <boolean>

Will be true if the controller has rumble motors.

controllerInstance.rumble([low, [high, [duration]]])

  • low: <number> The intensity of the low frequency rumble motor, from 0 to 1. Default: 1
  • high: <number> The intensity of the high frequency rumble motor, from 0 to 1. Default: 1
  • duration: <number> The duration of the rumble, in ms. Default: 1e3

Makes the controller rumble for a set duration. Calling this function again before duration has ran out, overrides the previous call.

controllerInstance.stopRumble()

Stops the controller rumbling. Equivalent to controllerInstance.rumble(0, 0).

controllerInstance.hasRumbleTriggers

  • <boolean>

Will be true if the controller has rumble motors on the triggers.

controllerInstance.rumbleTriggers([left, [right, [duration]]])

  • left: <number> The intensity of the left trigger rumble motor, from 0 to 1. Default: 1
  • right: <number> The intensity of the right trigger rumble motor, from 0 to 1. Default: 1
  • duration: <number> The duration of the rumble, in ms. Default: 1e3

Makes the controller triggers rumble for a set duration. Calling this function again before duration has ran out, overrides the previous call.

controllerInstance.stopRumbleTriggers()

Stops the controller trigger rumbling. Equivalent to controllerInstance.rumbleTriggers(0, 0).

controllerInstance.closed

  • <boolean>

Will be true if the instance is closed. A closed instance object should not be used any further.

controllerInstance.close()

Closes the instance.

sdl.sensor

sdl.sensor.STANDARD_GRAVITY

  • <number>

The readings from accelerometers will include the force of gravity, so a device at rest will have a value of STANDARD_GRAVITY away from the center of the earth. Use this constant to correct for that if your application requires it.

sdl.sensor.devices

  • <object>[]
    • id: <number> The unique id of the device.
    • name: <string> The name of the device.
    • type: <string>|<null> Either 'accelerometer', 'gyroscope'. Will be null if it can't be determined.
    • side: <string>|<null> Some sensors (such as those on the Joy-Con controller) have a 'left' or 'right' side, otherwise this value will be null.

A list of all the detected sensor devices. Sample output:

// TODO

sdl.sensor.openDevice(device)

Initializes a sensor device and returns a corresponding instance.

class SensorInstance

This class is not directly exposed by the API so you can't use it with the new operator. Instead, objects returned by sdl.sensor.openDevice() are of this type.

Event: 'update'

Fired when the sensor's data changes. Get the new data by accessing sensorInstance.data

Event: 'close'

Fired when the instance is about to close. Handle cleanup here.

sensorInstance.device

  • <object>

The device from which this instance was opened.

sensorInstance.data

  • <object>
    • timestamp: <number>|<null> The time this measurement was taken in microseconds, or null if that's not available.
    • x: <number> X axis value.
    • y: <number> Y axis value.
    • z: <number> Z axis value.

An object reporting the latest measurement from the sensor.

For accelerometers, the values correspond to the current acceleration in meters per second squared. This measurement includes the force of gravity, so a device at rest will have an value of sdl.sensor.STANDARD_GRAVITY away from the center of the earth.

For gyroscopes, the values correspond to the current rate of rotation in radians per second. The rotation is positive in the counter-clockwise direction. That is, an observer looking from a positive location on one of the axes would see positive rotation on that axis when it appeared to be rotating counter-clockwise.

For phones held in portrait mode and game controllers held in front of you, the axes are defined as follows:

  • -X ... +X : left ... right
  • -Y ... +Y : bottom ... top
  • -Z ... +Z : farther ... closer

sensorInstance.closed

  • <boolean>

Will be true if the instance is closed. A closed instance object should not be used any further.

sensorInstance.close()

Closes the instance.

sdl.audio

Audio data

The playbackInstance.enqueue() function expects a buffer of audio data as input and the recordingInstance.dequeue() function returns a buffer of audio data as output. The format of the data in these buffers depends on the options you passed to sdl.audio.openDevice().

An audio buffer is a sequence of frames, and each frame is a sequence of samples. A sample is a single number representing the intensity of an audio channel at a point in time. For audio with multiple channels, each point in time is represented by multiple samples (one per channel) that together make up a frame. The samples in a frame are arranged as follows:

  • For 1 channel (mono) a frame contains just the one sample.
  • For 2 channels (stereo) the frame's first sample will be the one for the left channel, followed by the one for the right channel.
  • For 4 channels (quad) the layout is front-left, front-right, rear-left, rear-right.
  • For 6 channels (5.1) the layout is front-left, front-right, center, low-freq, rear-left, rear-right.

So for example, to play 3 seconds of a 440Hz sine wave, you could do:

const TWO_PI = 2 * Math.PI

const {
  channels,
  frequency,
  bytesPerSample,
  minSampleValue,
  maxSampleValue,
  zeroSampleValue,
} = playbackInstance

const range = maxSampleValue - minSampleValue
const amplitude = range / 2

const sineAmplitude = 0.3 * amplitude
const sineNote = 440
const sinePeriod = 1 / sineNote

const duration = 3
const numFrames = duration * frequency
const numSamples = numFrames * channels
const numBytes = numSamples * bytesPerSample
const buffer = Buffer.alloc(numBytes)

let offset = 0
for (let i = 0; i < numFrames; i++) {
  const time = i / frequency
  const angle = time / sinePeriod * TWO_PI
  const sample = zeroSampleValue + Math.sin(angle) * sineAmplitude
  for (let j = 0; j < channels; j++) {
    offset = playbackInstance.writeSample(buffer, sample, offset)
  }
}

playbackInstance.enqueue(buffer)
playbackInstance.play()

Sample formats

String values used to represent how audio samples are stored in a Buffer.

Value Corresponding SDL_AudioFormat Comment
's8' AUDIO_S8 signed 8-bit samples
'u8' AUDIO_U8 unsigned 8-bit samples
's16lsb' AUDIO_S16LSB signed 16-bit samples in little-endian byte order
's16msb' AUDIO_S16MSB signed 16-bit samples in big-endian byte order
's16sys' AUDIO_S16SYS signed 16-bit samples in native byte order
's16' AUDIO_S16 alias for 's16lsb'
'u16lsb' AUDIO_U16LSB unsigned 16-bit samples in little-endian byte order
'u16msb' AUDIO_U16MSB unsigned 16-bit samples in big-endian byte order
'u16sys' AUDIO_U16SYS unsigned 16-bit samples in native byte order
'u16' AUDIO_U16 alias for 'u16lsb'
's32lsb' AUDIO_S32LSB 32-bit integer samples in little-endian byte order
's32msb' AUDIO_S32MSB 32-bit integer samples in big-endian byte order
's32sys' AUDIO_S32SYS 32-bit integer samples in native byte order
's32' AUDIO_S32 alias for 's32lsb'
'f32lsb' AUDIO_F32LSB 32-bit floating point samples in little-endian byte order
'f32msb' AUDIO_F32MSB 32-bit floating point samples in big-endian byte order
'f32sys' AUDIO_F32SYS 32-bit floating point samples in native byte order
'f32' AUDIO_F32 alias for 'f32lsb'

Event: 'deviceAdd'

  • device: <object>: An object from sdl.audio.devices indicating the device that caused the event.

Fired when a new audio device becomes available. Check sdl.audio.devices to get the new list of audio devices.

Event: 'deviceRemove'

  • device: <object>: An object from sdl.audio.devices indicating the device that caused the event.

Fired when an existing audio device is removed. Check sdl.audio.devices to get the new list of audio devices. When this event is emitted, all instances that were opened from the removed device are closed automatically.

sdl.audio.bytesPerSample(format)

  • format: <SampleFormat>: The desired sample format.
  • Returns: <number> The number of bytes.

Helper function which maps each sample format to the corresponding number of bytes its samples take up.

This function is also available from @kmamal/sdl/helpers.

sdl.audio.minSampleValue(format)

  • format: <SampleFormat>: The desired sample format.
  • Returns: <number> The minimum sample value.

Helper function which maps each sample format to the corresponding minimum value its samples can take.

This function is also available from @kmamal/sdl/helpers.

sdl.audio.maxSampleValue(format)

  • format: <SampleFormat>: The desired sample format.
  • Returns: <number> The maximum sample value.

Helper function which maps each sample format to the corresponding maximum value its samples can take.

This function is also available from @kmamal/sdl/helpers.

sdl.audio.zeroSampleValue(format)

  • format: <SampleFormat>: The desired sample format.
  • Returns: <number> The zero sample value.

Helper function which maps each sample format to the sample value that corresponds to silence.

This function is also available from @kmamal/sdl/helpers.

sdl.audio.readSample(format, buffer[, offset])

  • format: <SampleFormat>: The desired sample format.
  • buffer: <Buffer> The buffer to read the sample from.
  • offset: <number> The position from which to read the sample. Default: 0
  • Returns: <number> The value of the sample read.

Helper function which calls the appropriate read* method of Buffer based on the format argument. For example, a call to sdl.audio.readSample('f32', buffer, offset) would be equivalent to buffer.readFloatLE(offset).

This function is also available from @kmamal/sdl/helpers.

sdl.audio.writeSample(format, buffer, value[, offset])

  • format: <SampleFormat>: The desired sample format.
  • buffer: <Buffer> The buffer to write the sample to.
  • value: <number> The value of the sample to write.
  • offset: <number> The position at which to write the sample. Default: 0
  • Returns: <number> The updated offset.

Helper function which calls the appropriate write* method of Buffer based on the format argument. For example, a call to sdl.audio.writeSample('f32', buffer, value, offset) would be equivalent to buffer.writeFloatLE(value, offset).

This function is also available from @kmamal/sdl/helpers.

sdl.audio.devices

  • <object>[]
    • type: <string> Will be either 'playback' or 'recording'.
    • name: <string> The name of the device.

A list of all the detected audio devices. Sample output for PulseAudio:

[
  { name: 'Built-in Audio Analog Stereo', type: 'playback' },
  { name: 'Built-in Audio Analog Stereo', type: 'recording' },
]

Note that this list can sometimes be empty. Despite that, in many common cases, it is still possible to successfully open the default device by only passing type to sdl.audio.openDevice() like this:

const playbackInstance = sdl.audio.openDevice({ type: 'playback' })

sdl.audio.openDevice(device[, options])

  • device: <object> An object from sdl.audio.devices, or a custom device.
    • type: <string>: Should be either 'playback' or 'recording'.
    • name: <string>|<null>: The name of the device. Optional.
  • options: <object>
    • channels: <number>: Number of audio channels. Valid values: 1, 2, 4, 6. Default: 1
    • frequency: <number>: The sampling frequency in frames per second. Default: 48e3
    • format: <SampleFormat>: The binary format for each sample. Default: 'f32'
    • buffered: <number>: Number of frames that will be buffered by the driver. Must be a power of 2. Default: 4096
  • Returns: <AudioInstance> an object representing the opened audio device instance.

Initializes an audio device for playback/recording and returns a corresponding instance. If the opened device is a playback device, then the returned object will be an AudioPlaybackInstance, otherwise it will be an AudioRecordingInstance.

Most of the time you will be passing objects from sdl.audio.devices as the first argument to this function. It is also possible to let SDL pick the most appropriate device by only passing the type property without a name like this:

const playbackInstance = sdl.audio.openDevice({ type: 'playback' })

Some audio drivers also support arbitrary and driver-specific strings for the device name such as hostname/IP address for a remote audio server, or a filename in the diskaudio driver. These drivers will usually return an empty list for sdl.audio.devices.

The channels, frequency and format options together define what the data in the Buffer objects you read from or write to the instance will look like. See also the section on audio data.

The buffered option specifies the "delay" that you will experience between the application and the audio driver. With smaller values you will have smaller delays, but you will also have to read/write data from/to the driver more frequently. Applications such as virtual instruments that need to play audio in reaction to user input will want to change this option to lower values.

class AudioInstance

This class is not directly exposed by the API so you can't use it with the new operator. It only serves as the base class for AudioPlaybackInstance and AudioRecordingInstance.

Event: 'close'

Fired when the audio instance is about to close. Handle cleanup here.

audioInstance.id

  • <number>

A unique identifier for the instance.

audioInstance.device

  • <object>

The device passed to sdl.audio.openDevice() when this instance was opened.

audioInstance.channels

  • <number>

The number of channels the instance was opened with.

audioInstance.frequency

  • <number>

The sampling frequency (in frames per second) the instance was opened with.

audioInstance.format

The audio sample format the instance was opened with.

audioInstance.bytesPerSample

  • <number>

The number of bytes that make up a single audio sample, based on the format the instance was opened with.

audioInstance.minSampleValue

  • <number>

The minimum value a sample can take, based on the format the instance was opened with.

audioInstance.maxSampleValue

  • <number>

The maximum value a sample can take, based on the format the instance was opened with.

audioInstance.zeroSampleValue

  • <number>

The sample value that corresponds to silence, based on the format the instance was opened with.

audioInstance.readSample(buffer[, offset])

  • buffer: <Buffer> The buffer to read the sample from.
  • offset: <number> The position from which to read the sample. Default: 0
  • Returns: <number> The value of the sample read.

Helper function which calls the appropriate read* method of Buffer based on the format the instance was opened with. For example, for an instance opened with the 'f32' sample format, a call to audioinstance.readSample(buffer, offset) would be equivalent to buffer.readFloatLE(offset).

audioInstance.writeSample(buffer, value[, offset])

  • buffer: <Buffer> The buffer to write the sample to.
  • value: <number> The value of the sample to write.
  • offset: <number> The position at which to write the sample. Default: 0
  • Returns: <number> The updated offset.

Helper function which calls the appropriate write* method of Buffer based on the format the instance was opened with. For example, for an instance opened with the 'f32' sample format, a call to audioinstance.writeSample(buffer, value, offset) would be equivalent to buffer.writeFloatLE(value, offset).

audioInstance.buffered

  • <number>

The buffer size (in frames) the instance was opened with.

audioInstance.playing

  • <boolean>

Will be true if the instance is currently playing.

audioInstance.play([play])

  • show: <boolean> Set to true to start the instance, false to stop. Default: true

Starts or stops the instance.

audioInstance.pause()

Equivalent to audioInstance.play(false)

audioInstance.queued

  • <number>

The number of bytes that are currently queued up, waiting to be either played by the instance or dequeued by the user.

audioInstance.clearQueue()

Clears the queued data.

audioInstance.closed

  • <boolean>

Will be true if the instance is closed. A closed instance object should not be used any further.

audioInstance.close()

Closes the instance.

class AudioPlaybackInstance extends AudioInstance

This class is not directly exposed by the API so you can't use it with the new operator. Instead, objects returned by sdl.audio.openDevice() are of this type, if a playback device is opened.

playbackInstance.enqueue(buffer[, bytes])

  • buffer: <Buffer> The buffer to read data from.
  • bytes: <number> The number of bytes to read from the buffer. Default: buffer.length

Takes generated audio data from the buffer, and writes it to the queue, from which it will be played back.

class AudioRecordingInstance extends AudioInstance

This class is not directly exposed by the API so you can't use it with the new operator. Instead, objects returned by sdl.audio.openDevice() are of this type, if a recording device is opened.

recordingInstance.dequeue(buffer[, bytes])

  • buffer: <Buffer> The buffer to write data to.
  • bytes: <number> The number of bytes to write to the buffer. Default: buffer.length
  • Returns: <number> The actual number of bytes read.

Takes recorded audio data that has been put on the queue, and writes it to the provided buffer.

sdl.clipboard

Event: 'update'

Fired when the contents of the clipboard have changed. Check sdl.clipboard.text to get the new contents of the clipboard.

sdl.clipboard.text

  • <string>

The current text value on the clipboard.

sdl.clipboard.setText(text)

  • text: <string> The new value to save on the clipboard.

Changes the text contents of the clipboard.

sdl.power

sdl.power.info

  • <object>
    • state: <string>|null One of 'noBattery', 'battery', 'charging', 'charged'. Will be null if it can't be determinded.
    • seconds: <number>|<null> Seconds of battery life left. Will be null if not running on battery, or if it can't be determinded.
    • percent: <number>|<null> Percentage of battery life left. Will be null if not running on battery, or if it can't be determinded.

The curent power information of the device.

Helpers

The @kmamal/sdl library can only be imported from the main thread. If you try importing it from a worker_thread you will get an error. This is mainly due to some limitations in SDL itself (it's often unsafe to call functions from threads other than the one that called SDL_Init) as well as Node.js native modules (each thread gets it's own instance of the module and it's hard to make them talk with each other).

It's often useful however to offload CPU-heavy work to a thread, so the main thread can respond to input events faster. This is still possible! Even if the threads do not have access to the SDL-related functions, they can still write data to buffers and then pass those buffers to the main thread from where they can be passed to SDL. One thing is missing: While the core of the library is not needed, it's nice to have the helper functions, for example when writing an audio renderer it's nice to have the readSample, writeSample, etc functions.

Since these are just helpers and don't call any SLD code underneath it's safe to use them. They are made available through the @kmamal/sdl/helpers sub-module that does not load any of the native code. For an example of their use see this example.

The functions included in @kmamal/sdl/helpers are:

Building from source

If there are no prebuilt binaries available for your platform, @kmamal/sdl will try to compile itself during installation. A few prerequisites are necessary for that to work:

First, make sure you have installed node-gyp as well as its dependencies.

On Mac, you will also need to install xquartz so that SDL can find the X11 headers it needs. You can do that via brew install xquartz.

You don't need to install any SDL libraries or headers. These will be downloaded automatically through the @kmamal/build-sdl package. If @kmamal/build-sdl has no prebuilt library for your platform, it will try to compile one on the spot. You will need to have cmake installed for that to work.

You could also have found your way to the "Building from source" section because you are trying to contribute to this package. There are some npm scripts in package.json that could be of use to you:

  • npm run clean deletes all folders that are created during the build, as well as node_modules.
  • npm run download-release downloads the prebuilt binaries. This is the first thing the install script tries to do.
  • npm run download-sdl downloads the SDL headers and libraries from @kmamal/build-sdl so you can compile against them in later steps. This is the second step in the install script, after download-release has failed.
  • npm run build prepares the environment variables and calls node-gyp to build the package.
  • NODE_SDL_FROM_SOURCE=1 npm install runs the install script normally, but skips the inital attempt to download the binaries, and goes straight to building from source.

The SDL headers and libs get downloaded to sdl/, the build happens in build/, and the final binaries get collected into dist/.

The way I normally work is I run npm run clean to start fresh, then run NODE_SDL_FROM_SOURCE=1 npm i once to prepare everything, then as I make changes I run npm run build to re-build the package.

Have fun!

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๐ŸŽฎ SDL bindings for Node.js

www.npmjs.com/package/@kmamal/sdl

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v0.10.7 Latest
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