Updating Apple's LayerBackedOpenGLView example for high resolution - macos

Question

When I run the LayerBackedOpenGLView example on a high resolution display, the OpenGL context is not rendered at high resolution (the layer's contentScale is 1.0).
I've followed the steps in Apple's documentation, but the contentScale is still 1.0.
Specifically, I would have thought adding the following in the MyOpenGLView's init method would give me a high-resolution layer:
[self setWantsBestResolutionOpenGLSurface:YES];
But contentScale is still 1.0.
What are the steps required to update the example to render OpenGL in high resolution?

Answer 1

I was able to get the appropriate content scale.
I added self.wantsLayer = YES in -[MyOpenGLView init]. Even though that is set in -[MainController awakeFromNib], it doesn't seem to be early enough.
Also I added the following method to MyOpenGLView
- (void)viewDidChangeBackingProperties
{
[super viewDidChangeBackingProperties];
self.layer.contentsScale = self.window.backingScaleFactor;
}
This was necessary despite the following claim in the documentation:
When it comes to high resolution, layer-backed views are scaled automatically by the system. You don’t have any work to do to get content that looks great on high-resolution displays.
UPDATE
According to an Apple dev, this is a known bug in OS X 10.10.
Hi. This is a known bug in 10.10.0. For the moment, you can workaround it by adding this to your NSOpenGLView subclass (note this code will be harmless on older versions of Mac OS X.) Sorry for the inconvenience!
static CGFloat scaleFactorForOpenGLView(NSView *view) {
if ([view wantsBestResolutionOpenGLSurface]) {
NSWindow *window = [view window];
if (window) {
return [window backingScaleFactor];
}
}
return 1;
}
- (void)viewDidChangeBackingProperties {
[super viewDidChangeBackingProperties];
[[self layer] setContentsScale:scaleFactorForOpenGLView(self)];
}
- (CALayer *)makeBackingLayer {
CALayer *layer = [super makeBackingLayer];
[layer setContentsScale:scaleFactorForOpenGLView(self)];
return layer;
}