Don't destroy the same texture twice

Bug #7221449

SurfaceTexture already deletes the GL texture when detachFromContext
is invoked. The newly introduced refcount would casue the Layer
object to be destroyed later and attempt to delete the GL texture
again. By the time the second cleanup occurs, the texture name
might have been reused by somebody else, resulting in erroneous
behaviors.

Change-Id: I257c589fea64b34c00f46fbfaa7732e6854a5e41

core/java/android/view/GLES20Canvas.java

@@ -166,6 +166,7 @@ class GLES20Canvas extends HardwareCanvas {
     static native void nSetLayerColorFilter(int layerId, int nativeColorFilter);
     static native void nUpdateTextureLayer(int layerId, int width, int height, boolean opaque,
             SurfaceTexture surface);
+    static native void nClearLayerTexture(int layerId);
     static native void nSetTextureLayerTransform(int layerId, int matrix);
     static native void nDestroyLayer(int layerId);
     static native void nDestroyLayerDeferred(int layerId);

core/java/android/view/GLES20Layer.java

@@ -66,6 +66,11 @@ abstract class GLES20Layer extends HardwareLayer {
         mLayer = 0;
     }
 
+    @Override
+    void clearStorage() {
+        if (mLayer != 0) GLES20Canvas.nClearLayerTexture(mLayer);
+    }
+
     static class Finalizer {
         private int mLayerId;
 

core/java/android/view/GLES20TextureLayer.java

@@ -39,7 +39,7 @@ class GLES20TextureLayer extends GLES20Layer {
             mFinalizer = new Finalizer(mLayer);
         } else {
             mFinalizer = null;
-        }        
+        }
     }
 
     @Override

core/java/android/view/HardwareLayer.java

@@ -204,4 +204,9 @@ abstract class HardwareLayer {
      * @param dirtyRect The dirty region of the layer that needs to be redrawn
      */
     abstract void redrawLater(DisplayList displayList, Rect dirtyRect);
+
+    /**
+     * Indicates that this layer has lost its underlying storage.
+     */
+    abstract void clearStorage();
 }

core/java/android/view/TextureView.java

@@ -224,6 +224,7 @@ public class TextureView extends View {
     private void destroySurface() {
         if (mLayer != null) {
             mSurface.detachFromGLContext();
+            mLayer.clearStorage();
 
             boolean shouldRelease = true;
             if (mListener != null) {

core/jni/android_view_GLES20Canvas.cpp

@@ -822,6 +822,11 @@ static void android_view_GLES20Canvas_updateRenderLayer(JNIEnv* env, jobject cla
     layer->updateDeferred(renderer, displayList, left, top, right, bottom);
 }
 
+static void android_view_GLES20Canvas_clearLayerTexture(JNIEnv* env, jobject clazz,
+        Layer* layer) {
+    layer->clearTexture();
+}
+
 static void android_view_GLES20Canvas_setTextureLayerTransform(JNIEnv* env, jobject clazz,
         Layer* layer, SkMatrix* matrix) {
 
@@ -1016,6 +1021,7 @@ static JNINativeMethod gMethods[] = {
     { "nUpdateTextureLayer",     "(IIIZLandroid/graphics/SurfaceTexture;)V",
             (void*) android_view_GLES20Canvas_updateTextureLayer },
     { "nUpdateRenderLayer",      "(IIIIIII)V", (void*) android_view_GLES20Canvas_updateRenderLayer },
+    { "nClearLayerTexture",      "(I)V",       (void*) android_view_GLES20Canvas_clearLayerTexture },
     { "nDestroyLayer",           "(I)V",       (void*) android_view_GLES20Canvas_destroyLayer },
     { "nDestroyLayerDeferred",   "(I)V",       (void*) android_view_GLES20Canvas_destroyLayerDeferred },
     { "nDrawLayer",              "(IIFFI)V",   (void*) android_view_GLES20Canvas_drawLayer },

libs/hwui/Layer.h

@@ -134,10 +134,6 @@ struct Layer {
         return fbo;
     }
 
-    inline GLuint* getTexturePointer() {
-        return &texture.id;
-    }
-
     inline GLuint getTexture() {
         return texture.id;
     }
@@ -181,15 +177,31 @@ struct Layer {
     ANDROID_API void setColorFilter(SkiaColorFilter* filter);
 
     inline void bindTexture() {
-        glBindTexture(renderTarget, texture.id);
+        if (texture.id) {
+            glBindTexture(renderTarget, texture.id);
+        }
     }
 
     inline void generateTexture() {
-        glGenTextures(1, &texture.id);
+        if (!texture.id) {
+            glGenTextures(1, &texture.id);
+        }
     }
 
     inline void deleteTexture() {
-        if (texture.id) glDeleteTextures(1, &texture.id);
+        if (texture.id) {
+            glDeleteTextures(1, &texture.id);
+            texture.id = 0;
+        }
+    }
+
+    /**
+     * When the caller frees the texture itself, the caller
+     * must call this method to tell this layer that it lost
+     * the texture.
+     */
+    void clearTexture() {
+        texture.id = 0;
     }
 
     inline void deleteFbo() {