checkpoint: Manual collect of pixelBuffer.Pix

Author: pchampio

embedder/embedder.go

@@ -55,12 +55,14 @@ const (
 
 // FlutterOpenGLTexture corresponds to the C.FlutterOpenGLTexture struct.
 type FlutterOpenGLTexture struct {
-	// Target texture of the active texture unit (example GL_TEXTURE_2D).
+	// Target texture of the active texture unit (example GL_TEXTURE_2D)
 	Target uint32
-	// The name of the texture.
+	// The name of the texture
 	Name uint32
-	// The texture format (example GL_RGBA8).
+	// The texture format (example GL_RGBA8)
 	Format uint32
+	// Callback invoked to collect the texture
+	Collect func()
 }
 
 // FlutterEngine corresponds to the C.FlutterEngine with his associated callback's method.
@@ -81,7 +83,7 @@ type FlutterEngine struct {
 	GLFboCallback                  func() int32
 	GLMakeResourceCurrent          func() bool
 	GLProcResolver                 func(procName string) unsafe.Pointer
-	GLExternalTextureFrameCallback func(textureID int64, width int, height int) (bool, *FlutterOpenGLTexture)
+	GLExternalTextureFrameCallback func(textureID int64, width int, height int) *FlutterOpenGLTexture
 
 	// platform message callback function
 	PlatfromMessage func(message *PlatformMessage)

embedder/embedder_proxy.go

@@ -1,8 +1,10 @@
 package embedder
 
 // #include "embedder.h"
+// void proxy_texture_destruction_callback(void* user_data);
 import "C"
 import (
+	"runtime"
 	"unsafe"
 )
 
@@ -68,12 +70,28 @@ func proxy_gl_external_texture_frame_callback(userData unsafe.Pointer,
 	texture *C.FlutterOpenGLTexture) C.bool {
 	flutterEnginePointer := *(*uintptr)(userData)
 	flutterEngine := (*FlutterEngine)(unsafe.Pointer(flutterEnginePointer))
-	res, embedderGLTexture := flutterEngine.GLExternalTextureFrameCallback(textureID, int(width), int(height))
+	embedderGLTexture := flutterEngine.GLExternalTextureFrameCallback(textureID, int(width), int(height))
 	if embedderGLTexture == nil {
-		return C.bool(res)
+		return C.bool(false)
 	}
 	texture.target = C.uint32_t(embedderGLTexture.Target)
 	texture.name = C.uint32_t(embedderGLTexture.Name)
 	texture.format = C.uint32_t(embedderGLTexture.Format)
-	return C.bool(res)
+	collectPointer := (unsafe.Pointer(&embedderGLTexture.Collect))
+	texture.user_data = collectPointer
+	texture.destruction_callback = (C.VoidCallback)(C.proxy_texture_destruction_callback)
+	defer func() {
+		runtime.KeepAlive(collectPointer)
+	}()
+	return C.bool(true)
+}
+
+//export proxy_texture_destruction_callback
+func proxy_texture_destruction_callback(userData unsafe.Pointer) {
+	defer recover()
+	destroyCB := (*func())(userData)
+	if destroyCB != nil {
+		destroyCB := *destroyCB
+		destroyCB()
+	}
 }

texture-registry.go

@@ -21,6 +21,13 @@ type TextureRegistry struct {
 	texturesLock sync.Mutex
 }
 
+type externalTextureHanlder struct {
+	// handle is called when flutter needs the PixelBuffer
+	handle ExternalTextureHanlderFunc
+	// gl texture to refer to for this handler
+	texture uint32
+}
+
 func newRegistry(engine *embedder.FlutterEngine, window *glfw.Window) *TextureRegistry {
 	return &TextureRegistry{
 		window:   window,
@@ -59,13 +66,6 @@ type PixelBuffer struct {
 	Width, Height int
 }
 
-type externalTextureHanlder struct {
-	// handle is called when flutter needs the PixelBuffer
-	handle ExternalTextureHanlderFunc
-	// gl texture to refer to for this handler
-	texture uint32
-}
-
 // setTextureHandler registers a handler to be invoked when the Flutter
 // application want to get a PixelBuffer to draw into the scene.
 //
@@ -84,23 +84,23 @@ func (t *TextureRegistry) setTextureHandler(textureID int64, handler ExternalTex
 }
 
 func (t *TextureRegistry) handleExternalTexture(textureID int64,
-	width int, height int) (bool, *embedder.FlutterOpenGLTexture) {
+	width int, height int) *embedder.FlutterOpenGLTexture {
 
 	t.channelsLock.RLock()
 	registration, registrationExists := t.channels[textureID]
 	t.channelsLock.RUnlock()
 
 	if !registrationExists {
 		fmt.Printf("go-flutter: no texture handler found for Texture ID: %v\n", textureID)
-		return false, nil
+		return nil
 	}
 	res, pixelBuffer := registration.handle(width, height)
 	if !res || pixelBuffer == nil {
-		return false, nil
+		return nil
 	}
 
 	if len(pixelBuffer.Pix) == 0 {
-		return false, nil
+		return nil
 	}
 
 	t.window.MakeContextCurrent()
@@ -131,10 +131,14 @@ func (t *TextureRegistry) handleExternalTexture(textureID int64,
 		gl.UNSIGNED_BYTE,
 		gl.Ptr(pixelBuffer.Pix))
 
-	return true, &embedder.FlutterOpenGLTexture{
+	return &embedder.FlutterOpenGLTexture{
 		Target: gl.TEXTURE_2D,
 		Name:   registration.texture,
 		Format: gl.RGBA8,
+		Collect: func() {
+			// runtime delete the pixelBuffer.Pix, (should be done by the GC)
+			// gl.DeleteTextures(1, &registration.texture) // not this, this is for destroy not collect!!
+		},
 	}
 
 }

texture.go

@@ -13,7 +13,7 @@ type Texture struct {
 	registry *TextureRegistry
 }
 
-// Register registers a textureID
+// Register registers a textureID with his associated handler
 func (t *Texture) Register(handler ExternalTextureHanlderFunc) error {
 	t.registry.setTextureHandler(t.ID, handler)
 	result := t.registry.engine.RegisterExternalTexture(t.ID)