A GTK GLArea widget that renders pyramidal slide tiles directly on the GPU. Eliminates ReadPixels overhead by rendering to screen instead of copying to CPU. Supports SkiaSharp overlay for annotations via GRContext. More...

Inheritance diagram for BioGTK.SlideGLArea:

Public Member Functions
void	DiscardCompleteFrame ()

void	UploadTileTexture (TileIndex index, byte[] pixelData, int tileWidth, int tileHeight)
	Upload a tile texture to the GPU. Call from the main thread.

void	GetUploadedTileSize (TileIndex index, out int w, out int h)
	Get the uploaded texture dimensions for a cached tile. Returns (0,0) if the tile is not in the cache.

bool	HasTileTexture (TileIndex index)
	Check if a tile texture is already in the GPU cache.

void	ReleaseTileTexture (TileIndex index)
	Release a specific tile texture.

void	ReleaseLevelTextures (int level)
	Release all textures for a specific pyramid level.

void	ClearTextureCache ()
	Clear all cached textures.

void	RequestRedraw ()
	Request a redraw of the GLArea.

void	CaptureNextWholeImageFrame (Action< byte[], int, int > callback)
	Captures the next complete fit-to-window image frame. A newer request replaces an older one because only the current image/coordinate matters.

void	CancelWholeImageFrameCapture (Action< byte[], int, int > callback)

void	SetTilesToRender (IEnumerable< TileRenderInfo > tiles)
	Prepare tiles for rendering. Call before RequestRedraw().

void	SetProtectedTileIndices (IEnumerable< TileIndex > indices)
	Protects incoming visible tiles from FIFO eviction. The currently displayed set is included automatically so progressive level changes retain both the fallback frame and the target frame under construction.

byte[]	ReadPixels ()
	Read pixels from the current framebuffer (for export/save operations). This is slow - only use for export, not display.

Properties
List< TileRenderInfo >	TilesToRender = new() `[get]`

bool	NeedsRedraw = true `[get, set]`

bool	PreservePreviousFrameWhileIncomplete = false `[get, set]`

float	ImageScreenX = -1 `[get, set]`

float	ImageScreenY = -1 `[get, set]`

float	ImageScreenW = -1 `[get, set]`

float	ImageScreenH = -1 `[get, set]`

int	CachedTextureCount `[get]`

Events
Action< SKCanvas, int, int >	OnSkiaRender
	Event fired during Skia rendering phase for annotation drawing.

Detailed Description

A GTK GLArea widget that renders pyramidal slide tiles directly on the GPU. Eliminates ReadPixels overhead by rendering to screen instead of copying to CPU. Supports SkiaSharp overlay for annotations via GRContext.

Definition at line 19 of file SlideGLArea.cs.

Constructor & Destructor Documentation

◆ SlideGLArea()

BioGTK.SlideGLArea.SlideGLArea ( )

Definition at line 141 of file SlideGLArea.cs.

        {
            HasDepthBuffer = false;
            HasStencilBuffer = false;
            // Skia wraps this framebuffer as GL_RGBA8, so GTK must allocate an
            // alpha-capable color attachment too. The final render pass explicitly
            // writes alpha=1 across the surface, keeping presentation opaque while
            // avoiding the undefined RGB-buffer-as-RGBA mismatch.
            HasAlpha = true;
            AutoRender = false;  // We control when to render
 
            Realized += OnRealized;
            //Unrealize += OnUnrealize;
            Render += OnRender;
            Resize += OnResized;
        }

Member Function Documentation

◆ CancelWholeImageFrameCapture()

void BioGTK.SlideGLArea.CancelWholeImageFrameCapture ( Action< byte[], int, int > callback )

Definition at line 874 of file SlideGLArea.cs.

        {
            if (ReferenceEquals(_pendingWholeImageCapture, callback))
                _pendingWholeImageCapture = null;
        }

◆ CaptureNextWholeImageFrame()

void BioGTK.SlideGLArea.CaptureNextWholeImageFrame ( Action< byte[], int, int > callback )

Captures the next complete fit-to-window image frame. A newer request replaces an older one because only the current image/coordinate matters.

Definition at line 868 of file SlideGLArea.cs.

        {
            _pendingWholeImageCapture = callback;
            RequestRedraw();
        }

◆ ClearTextureCache()

void BioGTK.SlideGLArea.ClearTextureCache ( )

Clear all cached textures.

Definition at line 804 of file SlideGLArea.cs.

        {
            if (!_glInitialized) return;
 
            MakeCurrent();
 
            foreach (var tex in _textureCache.Values)
            {
                GL.DeleteTexture(tex);
            }
            _textureCache.Clear();
            _textureSizes.Clear();
            _protectedTileIndices.Clear();
            _textureBytes = 0;
        }

◆ DiscardCompleteFrame()

void BioGTK.SlideGLArea.DiscardCompleteFrame ( )

Definition at line 562 of file SlideGLArea.cs.

        {
            if (_completeFrameTexture != 0 && _glInitialized)
            {
                MakeCurrent();
                GL.DeleteTexture(_completeFrameTexture);
            }
            _completeFrameTexture = 0;
            _completeFrameWidth = 0;
            _completeFrameHeight = 0;
        }

◆ GetUploadedTileSize()

void BioGTK.SlideGLArea.GetUploadedTileSize	(	TileIndex	index,
		out int	w,
		out int	h )

Get the uploaded texture dimensions for a cached tile. Returns (0,0) if the tile is not in the cache.

Definition at line 745 of file SlideGLArea.cs.

        {
            if (_textureSizes.TryGetValue(index, out var sz))
            { w = sz.w; h = sz.h; }
            else
            { w = 0; h = 0; }
        }

◆ HasTileTexture()

bool BioGTK.SlideGLArea.HasTileTexture ( TileIndex index )

Check if a tile texture is already in the GPU cache.

Definition at line 756 of file SlideGLArea.cs.

        {
            return _textureCache.ContainsKey(index);
        }

◆ ReadPixels()

byte[] BioGTK.SlideGLArea.ReadPixels ( )

Read pixels from the current framebuffer (for export/save operations). This is slow - only use for export, not display.

Definition at line 910 of file SlideGLArea.cs.

        {
            if (!_glInitialized) return null;
 
            MakeCurrent();
 
            int width = AllocatedWidth;
            int height = AllocatedHeight;
 
            byte[] pixels = new byte[width * height * 4];
            GL.ReadPixels(0, 0, width, height, PixelFormat.Rgba, PixelType.UnsignedByte, pixels);
 
            return pixels;
        }

◆ ReleaseLevelTextures()

void BioGTK.SlideGLArea.ReleaseLevelTextures ( int level )

Release all textures for a specific pyramid level.

Definition at line 782 of file SlideGLArea.cs.

        {
            if (!_glInitialized) return;
 
            MakeCurrent();
 
            var toRemove = _textureCache.Where(kvp => kvp.Key.Level == level).ToList();
            foreach (var kvp in toRemove)
            {
                GL.DeleteTexture(kvp.Value);
                if (_textureSizes.TryGetValue(kvp.Key, out var sz))
                {
                    _textureBytes -= (long)sz.w * sz.h * 4;
                    _textureSizes.Remove(kvp.Key);
                }
                _textureCache.Remove(kvp.Key);
            }
        }

◆ ReleaseTileTexture()

void BioGTK.SlideGLArea.ReleaseTileTexture ( TileIndex index )

Release a specific tile texture.

Definition at line 764 of file SlideGLArea.cs.

        {
            if (_textureCache.TryGetValue(index, out int tex))
            {
                MakeCurrent();
                GL.DeleteTexture(tex);
                _textureCache.Remove(index);
                if (_textureSizes.TryGetValue(index, out var sz))
                {
                    _textureBytes -= (long)sz.w * sz.h * 4;
                    _textureSizes.Remove(index);
                }
            }
        }

◆ RequestRedraw()

void BioGTK.SlideGLArea.RequestRedraw ( )

Request a redraw of the GLArea.

Definition at line 857 of file SlideGLArea.cs.

        {
            NeedsRedraw = true;
            QueueRender();
            QueueDraw();
        }

◆ SetProtectedTileIndices()

void BioGTK.SlideGLArea.SetProtectedTileIndices ( IEnumerable< TileIndex > indices )

Protects incoming visible tiles from FIFO eviction. The currently displayed set is included automatically so progressive level changes retain both the fallback frame and the target frame under construction.

Definition at line 895 of file SlideGLArea.cs.

        {
            _protectedTileIndices.Clear();
            foreach (var index in indices)
                _protectedTileIndices.Add(index);
            foreach (var tile in TilesToRender)
                _protectedTileIndices.Add(tile.Index);
        }

◆ SetTilesToRender()

void BioGTK.SlideGLArea.SetTilesToRender ( IEnumerable< TileRenderInfo > tiles )

Prepare tiles for rendering. Call before RequestRedraw().

Definition at line 883 of file SlideGLArea.cs.

        {
            TilesToRender.Clear();
            TilesToRender.AddRange(tiles);
            LogDiag($"[SetTilesToRender] count={TilesToRender.Count}");
        }

◆ UploadTileTexture()

void BioGTK.SlideGLArea.UploadTileTexture	(	TileIndex	index,
		byte[]	pixelData,
		int	tileWidth,
		int	tileHeight )

Upload a tile texture to the GPU. Call from the main thread.

Definition at line 650 of file SlideGLArea.cs.

        {
            if (!_glInitialized)
            {
                LogDiag($"[UploadTileTexture] gl-not-initialized tile={index}");
                return;
            }
 
            if (pixelData == null || pixelData.Length == 0)
            {
                LogDiag($"[UploadTileTexture] empty pixel data tile={index}");
                return;
            }
 
            // The buffer is always BGRA = 4 bytes per pixel.
            // GetTile pads every tile — including edge tiles — to exactly
            // tileWidth x tileHeight pixels, so the dimensions passed by SlideRenderer
            // (the schema tile size) always match the buffer. We just validate and bail
            // on any genuine mismatch rather than trying to guess new dimensions.
            if (tileWidth <= 0 || tileHeight <= 0)
            {
                LogDiag($"[UploadTileTexture] invalid dimensions tile={index} size={tileWidth}x{tileHeight}");
                return;
            }
 
            int expectedBytes = tileWidth * tileHeight * 4;
            if (pixelData.Length < expectedBytes)
            {
                LogDiag($"[UploadTileTexture] buffer too small tile={index} need={expectedBytes} got={pixelData.Length}");
                return;
            }
 
            MakeCurrent();
 
            // Check if already cached
            if (_textureCache.ContainsKey(index))
            {
                LogDiag($"[UploadTileTexture] already cached tile={index}");
                return;
            }
 
            long newTextureBytes = (long)tileWidth * tileHeight * 4;
 
            // Evict old textures if the cache is full or if the new upload would
            // push the total texture budget over its byte cap.
            while (_textureCache.Count > 0 &&
                   (_textureCache.Count >= MAX_CACHED_TEXTURES ||
                    _textureBytes + newTextureBytes > MAX_CACHED_TEXTURE_BYTES))
            {
                EvictOldestTextures(1);
            }
 
            // Create and upload texture.
            // Pin the managed array explicitly so the GC cannot relocate it while the
            // driver is reading from the pointer (avoids ExecutionEngineException).
            // PixelFormat.Bgra matches the byte order produced by ReadRegionAsync.
            int tex = GL.GenTexture();
            if (tex == 0)
            {
                Console.WriteLine($"OpenGL failed to allocate texture for tile {index}.");
                return;
            }
            GL.BindTexture(TextureTarget.Texture2D, tex);
            GL.PixelStore(PixelStoreParameter.UnpackAlignment, 4);
 
            var handle = System.Runtime.InteropServices.GCHandle.Alloc(pixelData, System.Runtime.InteropServices.GCHandleType.Pinned);
            try
            {
                GL.TexImage2D(TextureTarget.Texture2D, 0, PixelInternalFormat.Rgba,
                              tileWidth, tileHeight, 0,
                              PixelFormat.Bgra, PixelType.UnsignedByte,
                              handle.AddrOfPinnedObject());
            }
            finally
            {
                handle.Free();
            }
 
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMagFilter.Linear);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapS, (int)TextureWrapMode.ClampToEdge);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureWrapT, (int)TextureWrapMode.ClampToEdge);
 
            GL.BindTexture(TextureTarget.Texture2D, 0);
 
            _textureCache[index] = tex;
            _textureSizes[index] = (tileWidth, tileHeight);
            _textureBytes += newTextureBytes;
            LogDiag($"[UploadTileTexture] uploaded tile={index} tex={tex} size={tileWidth}x{tileHeight} bytes={pixelData.Length}");
        }

Property Documentation

◆ CachedTextureCount

int BioGTK.SlideGLArea.CachedTextureCount

get

Definition at line 904 of file SlideGLArea.cs.

◆ ImageScreenH

float BioGTK.SlideGLArea.ImageScreenH = -1

getset

Definition at line 78 of file SlideGLArea.cs.

78{ get; set; } = -1;

◆ ImageScreenW

float BioGTK.SlideGLArea.ImageScreenW = -1

getset

Definition at line 77 of file SlideGLArea.cs.

77{ get; set; } = -1;

◆ ImageScreenX

float BioGTK.SlideGLArea.ImageScreenX = -1

getset

Definition at line 75 of file SlideGLArea.cs.

75{ get; set; } = -1;

◆ ImageScreenY

float BioGTK.SlideGLArea.ImageScreenY = -1

getset

Definition at line 76 of file SlideGLArea.cs.

76{ get; set; } = -1;

◆ NeedsRedraw

bool BioGTK.SlideGLArea.NeedsRedraw = true

getset

Definition at line 68 of file SlideGLArea.cs.

68{ get; set; } = true;

◆ PreservePreviousFrameWhileIncomplete

bool BioGTK.SlideGLArea.PreservePreviousFrameWhileIncomplete = false

getset

Definition at line 69 of file SlideGLArea.cs.

69{ get; set; } = false;

◆ TilesToRender

List<TileRenderInfo> BioGTK.SlideGLArea.TilesToRender = new()

get

Definition at line 67 of file SlideGLArea.cs.

67{ get; } = new();

Event Documentation

◆ OnSkiaRender

Action<SKCanvas, int, int> BioGTK.SlideGLArea.OnSkiaRender

Event fired during Skia rendering phase for annotation drawing.

Definition at line 83 of file SlideGLArea.cs.

The documentation for this class was generated from the following file:

BioGTK/BioGTK/Source/SlideGLArea.cs

Public Member Functions

Properties

Events

Detailed Description

Constructor & Destructor Documentation

◆ SlideGLArea()

Member Function Documentation

◆ CancelWholeImageFrameCapture()

◆ CaptureNextWholeImageFrame()

◆ ClearTextureCache()

◆ DiscardCompleteFrame()

◆ GetUploadedTileSize()

◆ HasTileTexture()

◆ ReadPixels()

◆ ReleaseLevelTextures()

◆ ReleaseTileTexture()

◆ RequestRedraw()

◆ SetProtectedTileIndices()

◆ SetTilesToRender()

◆ UploadTileTexture()

Property Documentation

◆ CachedTextureCount

◆ ImageScreenH

◆ ImageScreenW

◆ ImageScreenX

◆ ImageScreenY

◆ NeedsRedraw

◆ PreservePreviousFrameWhileIncomplete

◆ TilesToRender

Event Documentation

◆ OnSkiaRender