D2D emulation: render target API

M64RPFW.Services/Abstractions/SkiaRenderEventArgs.cs

@@ -4,5 +4,5 @@ namespace M64RPFW.Services.Abstractions;
 
 public class SkiaRenderEventArgs : EventArgs
 {
-    public SKCanvas Canvas { get; init; }
+    public ISkiaSurfaceManagerService SkiaSurfaceManager { get; init; }
 }

M64RPFW.Services/ISkiaSurfaceManagerService.cs

@@ -0,0 +1,9 @@
+using SkiaSharp;
+
+namespace M64RPFW.Services;
+
+public interface ISkiaSurfaceManagerService
+{
+    public SKCanvas PrimaryCanvas { get; }
+    public SKSurface CreateOffscreenBuffer(int width, int height);
+}

M64RPFW.ViewModels/Scripting/LuaEnvironment.cs

@@ -42,7 +42,8 @@ public LibFunctionAttribute(string path)
 
     public event Action<bool>? StateChanged;
 
-    private SKCanvas? _skCanvas;
+    private ISkiaSurfaceManagerService? _skiaSurfaceManagerService;
+
     private List<LuaFunction> _viCallbacks = new();
     private List<LuaFunction> _inputCallbacks = new();
     private List<LuaFunction> _stopCallbacks = new();
@@ -154,13 +155,13 @@ private void LuaLoadDotnetClasses()
     {
         const string code =
             """
-            # Load SkiaSharp
+            -- Load SkiaSharp
             luanet.load_assembly("SkiaSharp")
             skiasharp = {}
             for k, v in pairs(luanet.SkiaSharp) do
                 skiasharp[k] = v
             end
-            # disable CLR importing (safety)
+            -- disable CLR importing (safety)
             import = function () end
             """;
         _lua.DoString(code);
@@ -257,15 +258,15 @@ private void AtUpdateScreen(object? sender, SkiaRenderEventArgs args)
         {
             try
             {
-                _skCanvas = args.Canvas;
+                _skiaSurfaceManagerService = args.SkiaSurfaceManager;
                 foreach (LuaFunction callback in _updateScreenCallbacks)
                 {
                     callback.GuardedCall(_lua);
                 }
             }
             finally
             {
-                _skCanvas = null;
+                _skiaSurfaceManagerService = null;
             }
         }
         if (!_isActive)

M64RPFW.ViewModels/Scripting/LuaEnvironment_D2D.cs

@@ -1,3 +1,5 @@
+using System.Collections.ObjectModel;
+using System.Diagnostics;
 using BitFaster.Caching.Lru;
 using M64RPFW.ViewModels.Scripting.Extensions;
 using M64RPFW.ViewModels.Scripting.Graphics;
@@ -13,14 +15,28 @@ public partial class LuaEnvironment
 {
     private const int CACHE_LIMIT = 100;
 
+    private SKCanvas? CurrentCanvas => _renderStack.TryPeek(out var canvas) ? 
+        canvas : _skiaSurfaceManagerService?.PrimaryCanvas;
+
     private int _textAntialiasMode;
-    private readonly Dictionary<string, SKImage> _imageDict = new();
+    private readonly Dictionary<string, SKImage> _images = new();
+    private readonly Dictionary<string, SKSurface> _offscreenSurfaces = new();
+    private readonly Stack<SKCanvas> _renderStack = new();
 
     private readonly ClassicLru<TextPaintParams, SKPaint> _textPaintCache = new(CACHE_LIMIT);
     private readonly ClassicLru<FillPaintParams, SKPaint> _fillPaintCache = new(CACHE_LIMIT);
     private readonly ClassicLru<StrokePaintParams, SKPaint> _strokePaintCache = new(CACHE_LIMIT);
     private readonly ClassicLru<ImagePaintParams, SKPaint> _imagePaintCache = new(CACHE_LIMIT);
 
+    private SKImage? D2DPrivate_FindImage(string key)
+    {
+        if (_images.TryGetValue(key, out var image))
+            return image;
+        if (_offscreenSurfaces.TryGetValue(key, out var surface))
+            return surface.Snapshot();
+        return null;
+    }
+
     [LibFunction("d2d.fill_rectangle")]
     private void D2D_FillRectangle(float x, float y, float right, float bottom, float red, float green, float blue,
         float alpha)
@@ -29,7 +45,7 @@ private void D2D_FillRectangle(float x, float y, float right, float bottom, floa
             new FillPaintParams(red, green, blue, alpha),
             PaintFactories.MakeFillPaint
         );
-        _skCanvas?.DrawRect(x, y, right - x, bottom - y, paint);
+        CurrentCanvas?.DrawRect(x, y, right - x, bottom - y, paint);
     }
 
     [LibFunction("d2d.draw_rectangle")]
@@ -40,7 +56,7 @@ private void D2D_DrawRectangle(float x, float y, float right, float bottom, floa
             new StrokePaintParams(thickness, red, green, blue, alpha),
             PaintFactories.MakeStrokePaint
         );
-        _skCanvas?.DrawRect(x, y, right - x, bottom - y, paint);
+        CurrentCanvas?.DrawRect(x, y, right - x, bottom - y, paint);
     }
 
     [LibFunction("d2d.fill_ellipse")]
@@ -51,7 +67,7 @@ private void D2D_FillEllipse(float x, float y, float radiusX, float radiusY, flo
             new FillPaintParams(red, green, blue, alpha),
             PaintFactories.MakeFillPaint
         );
-        _skCanvas?.DrawOval(x, y, radiusX, radiusY, paint);
+        CurrentCanvas?.DrawOval(x, y, radiusX, radiusY, paint);
     }
 
     [LibFunction("d2d.draw_ellipse")]
@@ -64,7 +80,7 @@ private void D2D_DrawEllipse(float x, float y, float radiusX, float radiusY, flo
             new StrokePaintParams(thickness, red, green, blue, alpha),
             PaintFactories.MakeStrokePaint
         );
-        _skCanvas?.DrawRect(x, y, radiusX, radiusY, paint);
+        CurrentCanvas?.DrawRect(x, y, radiusX, radiusY, paint);
     }
 
     [LibFunction("d2d.draw_line")]
@@ -75,7 +91,7 @@ private void D2D_DrawLine(float x0, float y0, float x1, float y1, float red, flo
             new StrokePaintParams(thickness, red, green, blue, alpha),
             PaintFactories.MakeStrokePaint
         );
-        _skCanvas?.DrawLine(x0, y0, x1, y1, paint);
+        CurrentCanvas?.DrawLine(x0, y0, x1, y1, paint);
     }
 
 
@@ -90,7 +106,7 @@ private void D2D_DrawText(float x, float y, float right, float bottom, float red
         float alpha, string text, string fontName, float fontSize, int fontWeight, int fontStyle,
         int horizontalAlignment, int verticalAlignment, int options)
     {
-        if (_skCanvas == null)
+        if (CurrentCanvas == null)
             return;
 
         var paint = _textPaintCache.GetOrAdd(new TextPaintParams(
@@ -129,14 +145,14 @@ private void D2D_DrawText(float x, float y, float right, float bottom, float red
 
         if (doClip)
         {
-            _skCanvas.Save();
-            _skCanvas.ClipRect(new SKRect(x, y, right, bottom));
-            _skCanvas.DrawText(blob, x, yPos, paint);
-            _skCanvas.Restore();
+            CurrentCanvas.Save();
+            CurrentCanvas.ClipRect(new SKRect(x, y, right, bottom));
+            CurrentCanvas.DrawText(blob, x, yPos, paint);
+            CurrentCanvas.Restore();
         }
         else
         {
-            _skCanvas.DrawText(blob, x, yPos, paint);
+            CurrentCanvas.DrawText(blob, x, yPos, paint);
         }
     }
 
@@ -155,17 +171,17 @@ private LuaTable D2D_GetTextSize(string text, string fontName, float fontSize, f
     [LibFunction("d2d.push_clip")]
     private void D2D_PushClip(float x, float y, float right, float bottom)
     {
-        if (_skCanvas == null)
+        if (CurrentCanvas == null)
             return;
 
-        _skCanvas.Save();
-        _skCanvas.ClipRect(SKRect.Create(x, y, right - x, bottom - y));
+        CurrentCanvas.Save();
+        CurrentCanvas.ClipRect(SKRect.Create(x, y, right - x, bottom - y));
     }
 
     [LibFunction("d2d.pop_clip")]
     private void PopClip()
     {
-        _skCanvas?.Restore();
+        CurrentCanvas?.Restore();
     }
 
     [LibFunction("d2d.fill_rounded_rectangle")]
@@ -177,7 +193,7 @@ private void D2D_FillRoundedRectangle(float x, float y, float right, float botto
             new FillPaintParams(red, green, blue, alpha),
             PaintFactories.MakeFillPaint
         );
-        _skCanvas?.DrawRoundRect(x, y, right - x, bottom - y, radiusX, radiusY, paint);
+        CurrentCanvas?.DrawRoundRect(x, y, right - x, bottom - y, radiusX, radiusY, paint);
     }
 
     [LibFunction("d2d.draw_rounded_rectangle")]
@@ -189,7 +205,7 @@ private void D2D_DrawRoundedRectangle(float x, float y, float right, float botto
             new StrokePaintParams(thickness, red, green, blue, alpha),
             PaintFactories.MakeStrokePaint
         );
-        _skCanvas?.DrawRoundRect(x, y, right - x, bottom - y, radiusX, radiusY, paint);
+        CurrentCanvas?.DrawRoundRect(x, y, right - x, bottom - y, radiusX, radiusY, paint);
     }
 
     [LibFunction("d2d.gdip_fillpolygona")]
@@ -217,23 +233,23 @@ private void D2D_GdiPlusFillPolygonA(LuaTable pointsTable, byte alpha, byte red,
             PaintFactories.MakeFillPaint
         );
 
-        _skCanvas?.DrawPath(path, paint);
+        CurrentCanvas?.DrawPath(path, paint);
     }
 
 
     [LibFunction("d2d.load_image")]
     private void D2D_LoadImage(string path, string identifier)
     {
-        if (_imageDict.ContainsKey(identifier))
+        if (_images.ContainsKey(identifier))
             throw new InvalidOperationException($"{identifier} already exists");
         var image = SKImage.FromEncodedData(path);
-        _imageDict.Add(identifier, image);
+        _images.Add(identifier, image);
     }
 
     [LibFunction("d2d.free_image")]
     private void D2D_FreeImage(string identifier)
     {
-        if (!_imageDict.Remove(identifier, out var image))
+        if (!_images.Remove(identifier, out var image))
             return;
 
         image.Dispose();
@@ -244,13 +260,14 @@ private void D2D_DrawImage(float destinationX, float destinationY, float destina
         float sourceY, float sourceRight, float sourceBottom,
         string identifier, float opacity, int interpolation)
     {
-        if (!_imageDict.TryGetValue(identifier, out var image))
+        SKImage? image;
+        if ((image = D2DPrivate_FindImage(identifier)) == null)
             throw new ArgumentException("Identifier does not exist");
         var paint = _imagePaintCache.GetOrAdd(
             new ImagePaintParams(interpolation, opacity),
             PaintFactories.MakeImagePaint
         );
-        _skCanvas?.DrawImage(image,
+        CurrentCanvas?.DrawImage(image,
             source: SKRect.Create(sourceX, sourceY, sourceRight - sourceX, sourceBottom - sourceY),
             dest: SKRect.Create(destinationX, destinationY, destinationRight - destinationX, destinationBottom - destinationY),
             paint
@@ -260,12 +277,54 @@ private void D2D_DrawImage(float destinationX, float destinationY, float destina
     [LibFunction("d2d.get_image_info")]
     private LuaTable D2D_GetImageInfo(string identifier)
     {
-        if (!_imageDict.TryGetValue(identifier, out var image))
+        SKImage? image;
+        if ((image = D2DPrivate_FindImage(identifier)) == null)
             throw new ArgumentException("Identifier does not exist");
 
         var table = _lua.NewUnnamedTable();
         table["width"] = image.Width;
         table["height"] = image.Height;
         return table;
     }
+
+    [LibFunction("d2d.create_render_target")]
+    private string? D2D_CreateRenderTarget(int width, int height)
+    {
+        var surface = _skiaSurfaceManagerService?.CreateOffscreenBuffer(width, height);
+        if (surface == null)
+            return null;
+
+        string key;
+        do
+        {
+            key = $"__sksurface_{Guid.NewGuid():N}";
+        } while (!_offscreenSurfaces.TryAdd(key, surface));
+
+        return key;
+    }
+
+    [LibFunction("d2d.destroy_render_target")]
+    private void D2D_DestroyRenderTarget(string key)
+    {
+        if (_offscreenSurfaces.Remove(key, out var surface))
+            surface.Dispose();
+    }
+
+    [LibFunction("d2d.begin_render_target")]
+    private void D2D_BeginRenderTarget(string key)
+    {
+        if (!_offscreenSurfaces.TryGetValue(key, out var surface))
+            return;
+        var canvas = surface.Canvas;
+        canvas.Clear(SKColors.Transparent);
+        _renderStack.Push(canvas);
+    }
+
+    [LibFunction("d2d.end_render_target")]
+    private void D2D_EndRenderTarget(string key)
+    {
+        if (!_renderStack.TryPop(out var canvas))
+            return;
+        canvas.Flush();
+    }
 }

M64RPFW.ViewModels/Scripting/LuaEnvironment_Skia.cs

@@ -5,8 +5,14 @@ namespace M64RPFW.ViewModels.Scripting;
 public partial class LuaEnvironment
 {
     [LibFunction("skiasharp.get_canvas()")]
-    private SKCanvas? SkiaGetCanvas()
+    private SKCanvas? SkiaSharp_GetCanvas()
     {
-        return _skCanvas;
+        return CurrentCanvas;
+    }
+
+    [LibFunction("skiasharp.create_offscreen_surface()")]
+    private SKSurface? SkiaSharp_CreateOffscreenSurface(int width, int height)
+    {
+        return _skiaSurfaceManagerService?.CreateOffscreenBuffer(width, height);
     }
 }

M64RPFW.Views.Avalonia/Controls/OpenGL/WindowedGlControl.cs

@@ -20,7 +20,7 @@
 
 namespace M64RPFW.Views.Avalonia.Controls.OpenGL;
 
-public unsafe class WindowedGlControl : NativeControlHost, IOpenGLContextService, IFrameCaptureService
+public unsafe class WindowedGlControl : NativeControlHost, IOpenGLContextService, IFrameCaptureService, ISkiaSurfaceManagerService
 {
 
     internal SDL.Window* _sdlWin;
@@ -268,7 +268,7 @@ private void SkiaRenderImpl()
             _grContext.ResetContext();
             SkiaRender(this, new SkiaRenderEventArgs
             {
-                Canvas = _skSurface!.Canvas
+                SkiaSurfaceManager = this
             });
 
 
@@ -285,4 +285,9 @@ private void SkiaQuit()
     }
 
     #endregion
+    public SKCanvas PrimaryCanvas => _skSurface!.Canvas;
+    public SKSurface CreateOffscreenBuffer(int width, int height)
+    {
+        return SKSurface.Create(_grContext, false, new SKImageInfo(width, height));
+    }
 }