internal/graphicsdriver/metal: Set framebufferOnly true

Updates #1196

internal/graphicsdriver/metal/ca/ca.go

@@ -147,6 +147,18 @@ func (ml MetalLayer) NextDrawable() (MetalDrawable, error) {
 	return MetalDrawable{md}, nil
 }
 
+// SetFramebufferOnly sets a Boolean value that determines whether the layer’s textures are used only for rendering.
+//
+// https://developer.apple.com/documentation/quartzcore/cametallayer/1478168-framebufferonly
+func (ml MetalLayer) SetFramebufferOnly(framebufferOnly bool) {
+	switch framebufferOnly {
+	case true:
+		C.MetalLayer_SetFramebufferOnly(ml.metalLayer, 1)
+	case false:
+		C.MetalLayer_SetFramebufferOnly(ml.metalLayer, 0)
+	}
+}
+
 // MetalDrawable is a displayable resource that can be rendered or written to by Metal.
 //
 // Reference: https://developer.apple.com/documentation/quartzcore/cametaldrawable.

internal/graphicsdriver/metal/ca/ca.h

@@ -30,5 +30,6 @@ void MetalLayer_SetDisplaySyncEnabled(void *metalLayer,
                                       uint8_t displaySyncEnabled);
 void MetalLayer_SetDrawableSize(void *metalLayer, double width, double height);
 void *MetalLayer_NextDrawable(void *metalLayer);
+void MetalLayer_SetFramebufferOnly(void *metalLayer, uint8_t framebufferOnly);
 
 void *MetalDrawable_Texture(void *drawable);

internal/graphicsdriver/metal/ca/ca.m

@@ -98,3 +98,7 @@ void *MetalLayer_NextDrawable(void *metalLayer) {
 void *MetalDrawable_Texture(void *metalDrawable) {
   return ((id<CAMetalDrawable>)metalDrawable).texture;
 }
+
+void MetalLayer_SetFramebufferOnly(void *metalLayer, uint8_t framebufferOnly) {
+  [((CAMetalLayer *)metalLayer) setFramebufferOnly:framebufferOnly];
+}

internal/graphicsdriver/metal/graphics.go

@@ -1215,7 +1215,7 @@ func (i *Image) mtlTexture() mtl.Texture {
 	if i.screen {
 		g := i.graphics
 		if g.screenDrawable == (ca.MetalDrawable{}) {
-			drawable := g.view.drawable()
+			drawable := g.view.nextDrawable()
 			if drawable == (ca.MetalDrawable{}) {
 				return mtl.Texture{}
 			}

internal/graphicsdriver/metal/view.go

@@ -73,10 +73,12 @@ func (v *view) reset() error {
 
 	// The vsync state might be reset. Set the state again (#1364).
 	v.ml.SetDisplaySyncEnabled(v.vsync)
+	v.ml.SetFramebufferOnly(true)
+
 	return nil
 }
 
-func (v *view) drawable() ca.MetalDrawable {
+func (v *view) nextDrawable() ca.MetalDrawable {
 	d, err := v.ml.NextDrawable()
 	if err != nil {
 		// Drawable is nil. This can happen at the initial state. Let's wait and see.