fix(android): There were invalidate conflicts due to asynchronous executions. (#71)

Author: CatchABus

packages/canvas/src-native/canvas-android/canvas/src/main/java/org/nativescript/canvas/CPUView.kt

@@ -71,7 +71,7 @@ class CPUView @JvmOverloads constructor(
 						canvas.queueEvent {
 							TNSCanvas.nativeCustomWithBitmapFlush(canvas.nativeContext, it)
 							handler!!.post {
-								canvas.pendingInvalidate = false
+								canvas.invalidateState = TNSCanvas.InvalidateState.NONE
 								invalidate()
 							}
 						}

packages/canvas/src-native/canvas-android/canvas/src/main/java/org/nativescript/canvas/GLContext.kt

@@ -149,19 +149,19 @@ internal class GLContext {
 		queueEvent {
 			if (reference != null) {
 				val canvasView = reference!!.get()
-				if (canvasView != null && canvasView.nativeContext != 0L && canvasView.pendingInvalidate) {
+				if (canvasView != null && canvasView.nativeContext != 0L && canvasView.invalidateState == TNSCanvas.InvalidateState.INVALIDATING) {
 					TNSCanvas.nativeFlush(canvasView.nativeContext)
 					if (!mGLThread!!.getPaused() && !swapBuffers(mEGLSurface)) {
 						Log.e("JS", "GLContext: Cannot swap buffers!")
 					}
-					canvasView.pendingInvalidate = false
+					canvasView.invalidateState = TNSCanvas.InvalidateState.NONE
 				} else {
 					// WebGL
 					if (!mGLThread!!.getPaused() && !swapBuffers(mEGLSurface)) {
 						Log.e("JS", "GLContext: Cannot swap buffers!")
 					}
 					if (canvasView != null) {
-						canvasView.pendingInvalidate = false
+						canvasView.invalidateState = TNSCanvas.InvalidateState.NONE
 					}
 				}
 			}

packages/canvas/src-native/canvas-android/canvas/src/main/java/org/nativescript/canvas/TNSCanvas.kt

@@ -46,7 +46,7 @@ class TNSCanvas : FrameLayout, FrameCallback, ActivityLifecycleCallbacks {
 		}
 
 	@JvmField
-	internal var pendingInvalidate = false
+	internal var invalidateState = InvalidateState.NONE
 	internal var contextType = ContextType.NONE
 	internal var actualContextType = ""
 	internal var useCpu = false
@@ -122,9 +122,14 @@ class TNSCanvas : FrameLayout, FrameCallback, ActivityLifecycleCallbacks {
 
 	private val mainHandler = Handler(Looper.getMainLooper())
 
+	enum class InvalidateState {
+		NONE, PENDING, INVALIDATING
+	}
+
 	override fun doFrame(frameTimeNanos: Long) {
 		if (!isHandleInvalidationManually) {
-			if (pendingInvalidate) {
+			if (invalidateState == InvalidateState.PENDING) {
+				invalidateState = InvalidateState.INVALIDATING
 				flush()
 			}
 		}

packages/canvas/src-native/canvas-android/canvas/src/main/java/org/nativescript/canvas/TNSCanvasRenderingContext2D.kt

@@ -523,7 +523,7 @@ class TNSCanvasRenderingContext2D internal constructor(val canvas: TNSCanvas) :
 
 	private fun updateCanvas() {
 		// synchronized (canvasView.lock) {
-		canvas.pendingInvalidate = true
+		canvas.invalidateState = TNSCanvas.InvalidateState.PENDING
 		//}
 	}
 

packages/canvas/src-native/canvas-android/canvas/src/main/java/org/nativescript/canvas/TNSWebGLRenderingContext.kt

@@ -39,7 +39,7 @@ open class TNSWebGLRenderingContext : TNSCanvasRenderingContext {
 
 	fun updateCanvas() {
 		// synchronized (canvasView.lock) {
-		canvas.pendingInvalidate = true
+		canvas.invalidateState = TNSCanvas.InvalidateState.PENDING
 		//}
 	}
 

packages/canvas/typings/android.d.ts

@@ -309,7 +309,7 @@ declare module org {
 		export module canvas {
 			export class TNSCanvas {
 				public static class: java.lang.Class<org.nativescript.canvas.TNSCanvas>;
-				public pendingInvalidate: boolean;
+				public invalidateState: org.nativescript.canvas.TNSCanvas.ContextType;
 				public contextAlpha: boolean;
 				public contextAntialias: boolean;
 				public contextDepth: boolean;
@@ -459,6 +459,14 @@ declare module org {
 					public constructor();
 					public onResult(param0: string): void;
 				}
+				export class InvalidateState {
+					public static class: java.lang.Class<org.nativescript.canvas.TNSCanvas.InvalidateState>;
+					public static NONE: org.nativescript.canvas.TNSCanvas.InvalidateState;
+					public static PENDING: org.nativescript.canvas.TNSCanvas.InvalidateState;
+					public static INVALIDATING: org.nativescript.canvas.TNSCanvas.InvalidateState;
+					public static valueOf(param0: string): org.nativescript.canvas.TNSCanvas.InvalidateState;
+					public static values(): androidNative.Array<org.nativescript.canvas.TNSCanvas.InvalidateState>;
+				}
 				export class Listener {
 					public static class: java.lang.Class<org.nativescript.canvas.TNSCanvas.Listener>;
 					/**