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Backend: refactoring #126

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merged 4 commits into from
Apr 13, 2023
Merged

Backend: refactoring #126

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ffda930
backend: refaactoring
gucio321 Apr 12, 2023
433cfa3
rename: backend{_interface => }.go
gucio321 Apr 12, 2023
8826e6f
rename: { => glfw_}backend.(cpp/h)
gucio321 Apr 12, 2023
235cb6c
backend: add comment
gucio321 Apr 12, 2023
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201 changes: 75 additions & 126 deletions backend.go
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Original file line number Diff line number Diff line change
@@ -1,161 +1,110 @@
//go:build !exclude_cimgui_glfw
// +build !exclude_cimgui_glfw

package imgui

// #cgo amd64,linux LDFLAGS: ${SRCDIR}/lib/linux/x64/libglfw3.a -ldl -lGL -lX11
// #cgo amd64,windows LDFLAGS: -L${SRCDIR}/lib/windows/x64 -l:libglfw3.a -lgdi32 -lopengl32 -limm32
// #cgo darwin LDFLAGS: -framework Cocoa -framework IOKit -framework CoreVideo
// #cgo amd64,darwin LDFLAGS: ${SRCDIR}/lib/macos/x64/libglfw3.a
// #cgo arm64,darwin LDFLAGS: ${SRCDIR}/lib/macos/arm64/libglfw3.a
// #cgo !gles2,darwin LDFLAGS: -framework OpenGL
// #cgo gles2,darwin LDFLAGS: -lGLESv2
// #cgo CPPFLAGS: -DCIMGUI_GO_USE_GLFW
// extern void glfwWindowLoopCallback();
// extern void glfwBeforeRender();
// extern void glfwAfterRender();
// extern void glfwAfterCreateContext();
// extern void glfwBeforeDestoryContext();
// #include <stdint.h>
// #include "backend.h"
// extern void loopCallback();
// extern void beforeRender();
// extern void afterRender();
// extern void afterCreateContext();
// extern void beforeDestoryContext();
import "C"

import (
"image"
"unsafe"
)

type GLFWWindowFlags int

const (
GLFWWindowFlagsNone GLFWWindowFlags = GLFWWindowFlags(C.GLFWWindowFlagsNone)
GLFWWindowFlagsNotResizable GLFWWindowFlags = GLFWWindowFlags(C.GLFWWindowFlagsNotResizable)
GLFWWindowFlagsMaximized GLFWWindowFlags = GLFWWindowFlags(C.GLFWWindowFlagsMaximized)
GLFWWindowFlagsFloating GLFWWindowFlags = GLFWWindowFlags(C.GLFWWindowFlagsFloating)
GLFWWindowFlagsFrameless GLFWWindowFlags = GLFWWindowFlags(C.GLFWWindowFlagsFrameless)
GLFWWindowFlagsTransparent GLFWWindowFlags = GLFWWindowFlags(C.GLFWWindowFlagsTransparent)
)

type voidCallbackFunc func()

var (
afterCreateContext voidCallbackFunc
loopFunc voidCallbackFunc
beforeRender voidCallbackFunc
afterRender voidCallbackFunc
beforeDestoryContext voidCallbackFunc
)

type GLFWwindow uintptr

func (w GLFWwindow) handle() *C.GLFWwindow {
return (*C.GLFWwindow)(unsafe.Pointer(w))
}

func SetAfterCreateContextHook(hook func()) {
afterCreateContext = hook
}

func SetBeforeDestroyContextHook(hook func()) {
beforeDestoryContext = hook
}

func SetBeforeRenderHook(hook func()) {
beforeRender = hook
}

func SetAfterRenderHook(hook func()) {
afterRender = hook
}
var currentBackend Backend

func SetBgColor(color Vec4) {
C.igSetBgColor(color.toC())
}

func (w GLFWwindow) Run(loop func()) {
loopFunc = loop
C.igRunLoop(w.handle(), C.VoidCallback(C.glfwWindowLoopCallback), C.VoidCallback(C.glfwBeforeRender), C.VoidCallback(C.glfwAfterRender), C.VoidCallback(C.glfwBeforeDestoryContext))
}

func (w GLFWwindow) DisplaySize() (width int32, height int32) {
widthArg, widthFin := wrapNumberPtr[C.int, int32](&width)
defer widthFin()

heightArg, heightFin := wrapNumberPtr[C.int, int32](&height)
defer heightFin()

C.igGLFWWindow_GetDisplaySize(w.handle(), widthArg, heightArg)

return
}

func (w GLFWwindow) SetShouldClose(value bool) {
C.igGLFWWindow_SetShouldClose(w.handle(), C.int(castBool(value)))
}

//export glfwWindowLoopCallback
func glfwWindowLoopCallback() {
if loopFunc != nil {
loopFunc()
//export loopCallback
func loopCallback() {
if currentBackend != nil {
if f := currentBackend.loopFunc(); f != nil {
f()
}
}
}

//export glfwBeforeRender
func glfwBeforeRender() {
if beforeRender != nil {
beforeRender()
//export beforeRender
func beforeRender() {
if currentBackend != nil {
if f := currentBackend.beforeRenderHook(); f != nil {
f()
}
}
}

//export glfwAfterRender
func glfwAfterRender() {
if afterRender != nil {
afterRender()
//export afterRender
func afterRender() {
if currentBackend != nil {
if f := currentBackend.afterRenderHook(); f != nil {
f()
}
}
}

//export glfwAfterCreateContext
func glfwAfterCreateContext() {
if afterCreateContext != nil {
afterCreateContext()
//export afterCreateContext
func afterCreateContext() {
if currentBackend != nil {
if f := currentBackend.afterCreateHook(); f != nil {
f()
}
}
}

//export glfwBeforeDestoryContext
func glfwBeforeDestoryContext() {
if beforeDestoryContext != nil {
beforeDestoryContext()
//export beforeDestoryContext
func beforeDestoryContext() {
if currentBackend != nil {
if f := currentBackend.beforeDestroyHook(); f != nil {
f()
}
}
}

func CreateGlfwWindow(title string, width, height int, flags GLFWWindowFlags) GLFWwindow {
titleArg, titleFin := wrapString(title)
defer titleFin()
// Backend is a special interface that implements all methods required
// to render imgui application.
type Backend interface {
SetAfterCreateContextHook(func())
SetBeforeDestroyContextHook(func())
SetBeforeRenderHook(func())
SetAfterRenderHook(func())

window := GLFWwindow(unsafe.Pointer(C.igCreateGLFWWindow(titleArg, C.int(width), C.int(height), C.GLFWWindowFlags(flags), C.VoidCallback(C.glfwAfterCreateContext))))
if window == 0 {
panic("Failed to create GLFW window")
}
SetBgColor(color Vec4)
Run(func())
Refresh()

return window
}
DisplaySize() (width, height int32)
SetShouldClose(bool)

func SetTargetFPS(fps uint) {
C.igSetTargetFPS(C.uint(fps))
}
SetTargetFPS(fps uint)

func Refresh() {
C.igRefresh()
}
CreateTexture(pixels unsafe.Pointer, width, Height int) TextureID
CreateTextureRgba(img *image.RGBA, width, height int) TextureID
DeleteTexture(id TextureID)

// TODO: flags needs generic layer
CreateWindow(title string, width, height int, flags GLFWWindowFlags)

func CreateTexture(pixels unsafe.Pointer, width, height int) TextureID {
return TextureID(C.igCreateTexture((*C.uchar)(pixels), C.int(width), C.int(height)))
// for C callbacks
// What happens here is a bit tricky:
// - user sets these callbacks via Set* methods of the backend
// - callbacks are stored in currentContext variable
// - functions below just returns that callbacks
// - on top of this file is a set of global function with names similar to these below
// - these functions are exported to C
// - backend implementation uses C references to Go callbacks to share them (again ;-) )
// into backend code.
// As you can see this is all to convert Go callback int C callback
afterCreateHook() func()
beforeRenderHook() func()
loopFunc() func()
afterRenderHook() func()
beforeDestroyHook() func()
}

func CreateTextureRgba(img *image.RGBA, width, height int) TextureID {
return TextureID(C.igCreateTexture((*C.uchar)(&(img.Pix[0])), C.int(width), C.int(height)))
func CreateBackend( /*TODO: backend type*/ ) Backend {
currentBackend = &GLFWBackend{}
return currentBackend
}

func DeleteTexture(id TextureID) {
C.igDeleteTexture(C.ImTextureID(id))
func GetBackend() Backend {
return currentBackend
}
15 changes: 8 additions & 7 deletions examples/main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@ var (
a float32
color4 [4]float32 = [4]float32{r, g, b, a}
selected bool
window imgui.GLFWwindow
backend imgui.Backend
img *image.RGBA
texture *imgui.Texture
barValues []int64
Expand All @@ -39,7 +39,7 @@ func showWidgetsDemo() {
imgui.SetNextWindowSizeV(imgui.NewVec2(300, 300), imgui.CondOnce)
imgui.Begin("Window 1")
if imgui.ButtonV("Click Me", imgui.NewVec2(80, 20)) {
w, h := window.DisplaySize()
w, h := backend.DisplaySize()
fmt.Println(w, h)
}
imgui.TextUnformatted("Unformatted text")
Expand Down Expand Up @@ -120,12 +120,13 @@ func main() {
barValues = append(barValues, int64(i+1))
}

imgui.SetAfterCreateContextHook(afterCreateContext)
imgui.SetBeforeDestroyContextHook(beforeDestroyContext)
backend = imgui.CreateBackend()
backend.SetAfterCreateContextHook(afterCreateContext)
backend.SetBeforeDestroyContextHook(beforeDestroyContext)

imgui.SetBgColor(imgui.NewVec4(0.45, 0.55, 0.6, 1.0))
backend.SetBgColor(imgui.NewVec4(0.45, 0.55, 0.6, 1.0))

window = imgui.CreateGlfwWindow("Hello from cimgui-go", 1200, 900, 0)
backend.CreateWindow("Hello from cimgui-go", 1200, 900, 0)

window.Run(loop)
backend.Run(loop)
}
2 changes: 1 addition & 1 deletion backend.cpp → glfw_backend.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,7 @@
#define CIMGUI_USE_GLFW
#define CIMGUI_USE_OPENGL3

#include "backend.h"
#include "glfw_backend.h"
#include "cimgui/cimgui.h"
#include "cimgui/cimgui_impl.h"
#include "thirdparty/glfw/include/GLFW/glfw3.h" // Will drag system OpenGL headers
Expand Down
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