How to use nsview.layer?

[bors-servo]

Issue by paulrouget
Friday Mar 17, 2017 at 08:08 GMT
Originally opened as servo/core-graphics-rs#78

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I'm trying to animate a Cocoa nsview via its layer. But with no luck. What would it take to make it work?

I'm trying for example to set the opacity of a layer. All the conditions to enable core animation are met.

This code crashes:

let content_view: id = msg_send![nswindow, contentView];
let layer: id = msg_send![content_view, layer];
let transform: CGAffineTransform = msg_send![layer, affineTransform];
msg_send![layer, setAffineTransform:transform];

And this code behaves in a strange way:

let content_view: id = msg_send![nswindow, contentView];
let layer: id = msg_send![content_view, layer];
let opacity: CGFloat = msg_send![layer, opacity];
// opacity is equal to 0.
let opacity: CGFloat = 0.5;
msg_send![layer, setOpacity:opacity];
// view disappear
let opacity: CGFloat = msg_send![layer, opacity];
// opacity is still equal to 0.

[bors-servo]

Comment by metajack
Saturday Mar 18, 2017 at 11:59 GMT

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cc @pcwalton

[bors-servo]

Comment by oluseyi
Wednesday Apr 26, 2017 at 02:55 GMT

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@paulrouget Did you call setWantLayer:YES on the NSView? Unlike on iOS, macOS views are not CALayer-backed by default.

[bors-servo]

Comment by paulrouget
Wednesday Apr 26, 2017 at 05:11 GMT

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Did you call setWantLayer:YES on the NSView? Unlike on iOS, macOS views are not CALayer-backed by default.

Yes.

[bors-servo]

Comment by oluseyi
Wednesday Apr 26, 2017 at 10:48 GMT

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For the first snippet, any chance you got a stack trace?

For the second snippet, did you call setNeedsDisplay:YES, or displayIfNeeded if you wanted to evaluate attributes in the same runloop?

Sorry if the questions seem obvious, just eliminating the low-hanging fruit.

[bors-servo]

Comment by pcwalton
Wednesday Apr 26, 2017 at 14:05 GMT

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You might have to do something special to the NSWindow in order to get Core Animation to work. I think Interface Builder does this for you if you use nibs, but if you're setting things up manually there may be something magic you have to invoke.

[bors-servo]

Comment by paulrouget
Thursday Apr 27, 2017 at 07:29 GMT

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@pcwalton: Interface Builder does this for you if you use nibs

I use nibs.

@oluseyi: For the first snippet, any chance you got a stack trace?
For the second snippet, did you call setNeedsDisplay:YES, or displayIfNeeded if you wanted to evaluate attributes in the same runloop?

I'll try to get a backtrace and try these later.