Re: NSDrawNinePartImage draws slowly in CALayer
Re: NSDrawNinePartImage draws slowly in CALayer
- Subject: Re: NSDrawNinePartImage draws slowly in CALayer
- From: Sebastian Morsch <email@hidden>
- Date: Sun, 08 Mar 2009 11:43:28 +0100
Thank you Jean-Daniel for your thoughts on this!
Shark revealed that the most time was spend inside
NSDrawNinePartImage, so I replaced that function by a self-made
lightweight version. Here I discovered that most time was spend on
drawing the center image, which is scaled along both the X and Y axis.
Luckily I didn't need that for my bezel.
It didn't seem to be a specific problem of CA though. I tried the same
with a "traditional" non-layer-backed NSView subclass and redrawing
performance was even worse than with the CALayer.
I still wonder how resizable 9-parts are supposed to be implemented.
The documentation of NSDrawNinePartImage state that
"you should prefer the use of this function over your own custom code
for handling multi-part images whose size can change".
(I don't want to rant and rave, I'm just curious...)
Sebastian
Am 06.03.2009 um 20:59 schrieb Jean-Daniel Dupas:
Le 6 mars 09 à 20:42, Jean-Daniel Dupas a écrit :
Le 6 mars 09 à 20:33, Sebastian Morsch a écrit :
Hello,
I wrote a delegate that draws a bezel inside a CALayer using
NSDrawNinePartImage. The drawing happens inside the
drawLayer:inContext: method and it works well. The only problem is
that it redraws really slow when the layers frame is resized by
the user.
The layer is simply attached to a custom view for testing the
whole thing. This view is the only view of a window, and when I
resize that window, my layer is resized too. But it feels very
clunky.
I was wondering if I'm doing something really stupid here... Does
anybody know if there's a better way to tackle this?
Thank you!
Sebastian
If you want to know why your code is slow, use the Xcode Debug Menu
> Launch Using Performance Tool > Shark.
To be exact, this is the Menu
Run > Start With Performance Tool > Shark
Shark will give you better and more accurate answer.
My guess is that you are creating the images at each call, which
require to read them from disk, and decode them and is very slow.
Just an other details, instead of creating the color at each call,
you can use CGContextSetRGBFillColor(ctx, 0, 0, 1, .2).
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