implement SurfaceView.lockCanvas() using GskCanvas

src/api-impl-jni/generated_headers/android_view_SurfaceView.h

@@ -207,6 +207,22 @@ extern "C" {
 JNIEXPORT jlong JNICALL Java_android_view_SurfaceView_native_1constructor
   (JNIEnv *, jobject, jobject, jobject);
 
+/*
+ * Class:     android_view_SurfaceView
+ * Method:    native_createSnapshot
+ * Signature: ()J
+ */
+JNIEXPORT jlong JNICALL Java_android_view_SurfaceView_native_1createSnapshot
+  (JNIEnv *, jobject);
+
+/*
+ * Class:     android_view_SurfaceView
+ * Method:    native_postSnapshot
+ * Signature: (JJ)V
+ */
+JNIEXPORT void JNICALL Java_android_view_SurfaceView_native_1postSnapshot
+  (JNIEnv *, jobject, jlong, jlong);
+
 #ifdef __cplusplus
 }
 #endif

src/api-impl-jni/widgets/android_view_SurfaceView.c

@@ -103,6 +103,11 @@ JNIEXPORT jlong JNICALL Java_android_view_SurfaceView_native_1constructor(JNIEnv
 	// TODO: is this correct for all usecases? how do we know when it's not?
 	gtk_widget_set_hexpand(wrapper, true);
 	gtk_widget_set_vexpand(wrapper, true);
+#if GTK_CHECK_VERSION(4, 14, 0)
+	gtk_widget_insert_after(gtk_graphics_offload_new(gtk_picture_new()), dummy, NULL);
+#else
+	gtk_widget_insert_after(gtk_picture_new(), dummy, NULL);
+#endif
 
 	JavaVM *jvm;
 	(*env)->GetJavaVM(env, &jvm);
@@ -117,3 +122,30 @@ JNIEXPORT jlong JNICALL Java_android_view_SurfaceView_native_1constructor(JNIEnv
 
 	return _INTPTR(dummy);
 }
+
+JNIEXPORT jlong JNICALL Java_android_view_SurfaceView_native_1createSnapshot(JNIEnv *env, jclass class)
+{
+	return _INTPTR(gtk_snapshot_new());
+}
+
+extern GtkWindow *window;
+
+JNIEXPORT void JNICALL Java_android_view_SurfaceView_native_1postSnapshot(JNIEnv *env, jclass class, jlong surface_view, jlong snapshot_ptr)
+{
+	GtkWidget *view = GTK_WIDGET(_PTR(surface_view));
+#if GTK_CHECK_VERSION(4, 14, 0)
+	GtkPicture *picture = GTK_PICTURE(gtk_widget_get_first_child(gtk_widget_get_first_child(view)));
+#else
+	GtkPicture *picture = GTK_PICTURE(gtk_widget_get_first_child(view));
+#endif
+	GtkSnapshot *snapshot = GTK_SNAPSHOT(_PTR(snapshot_ptr));
+	GskRenderer *renderer = gsk_renderer_new_for_surface(gtk_native_get_surface(GTK_NATIVE(window)));
+	GskRenderNode *node = gtk_snapshot_free_to_node(snapshot);
+	GdkTexture *paintable = gsk_renderer_render_texture(renderer, node, NULL);
+	gsk_render_node_unref(node);
+	gsk_renderer_unrealize(renderer);
+	g_object_unref(renderer);
+
+	gtk_picture_set_paintable(picture, GDK_PAINTABLE(paintable));
+	g_object_unref(paintable);
+}

src/api-impl/android/view/SurfaceView.java

@@ -2,6 +2,7 @@ package android.view;
 
 import android.content.Context;
 import android.graphics.Canvas;
+import android.graphics.GskCanvas;
 import android.graphics.Rect;
 import android.util.AttributeSet;
 
@@ -38,6 +39,9 @@ public class SurfaceView extends View {
 	@Override
 	protected native long native_constructor(Context context, AttributeSet attrs);
 
+	protected native long native_createSnapshot();
+	protected native void native_postSnapshot(long surfaceView, long snapshot);
+
 	public SurfaceHolder getHolder() {
 		return mSurfaceHolder;
 	}
@@ -125,8 +129,7 @@ public class SurfaceView extends View {
 		 */
 		@Override
 		public Canvas lockCanvas() {
-			//		return internalLockCanvas(null);
+			return internalLockCanvas(null);
-			return null;
 		}
 
 		/**
@@ -146,8 +149,7 @@ public class SurfaceView extends View {
 		 */
 		@Override
 		public Canvas lockCanvas(Rect inOutDirty) {
-			//		return internalLockCanvas(inOutDirty);
+			return internalLockCanvas(inOutDirty);
-			return null;
 		}
 
 		private final Canvas internalLockCanvas(Rect dirty) {
@@ -186,7 +188,10 @@ public class SurfaceView extends View {
 					mLastLockTime = now;
 					mSurfaceLock.unlock();
 			*/
-			return null;
+			if(getWidth() == 0 || getHeight() == 0)
+				return null;
+
+			return new GskCanvas(native_createSnapshot());
 		}
 
 		/**
@@ -197,6 +202,7 @@ public class SurfaceView extends View {
 		 */
 		@Override
 		public void unlockCanvasAndPost(Canvas canvas) {
+			native_postSnapshot(widget, ((GskCanvas)canvas).snapshot);
 			//		mSurface.unlockCanvasAndPost(canvas);
 			//		mSurfaceLock.unlock();
 		}