On 28 Mar 2012, at 09:19, Graham Cox wrote:
>
> On 28/03/2012, at 6:36 PM, Kenneth Baxter wrote:
>>
>> Draw each object individually (admittedly it's just a simple oval in rect
>> which is filled and stroked): 12fps
>> Generate an NSImage of the object once and cache it, then just
>> drawInRect...: 8fps
>> Cache a CIImage and draw that: 8fps
>> Cache a CGLayer and draw that: 8fps
>>
>> This sure does seem to be awfully slow. Instruments tell that the time is
>> all being spent in drawing the object, no matter how I do the drawing.
>>
>> Is there some better way to get decent drawing performance from drawing into
>> an NSView?
>
> 200 x 400 is quite a big area to fill, whether by using stroke/fill or
> blitting an image. Multiply by 100 and you are doing a lot of work pushing
> pixels (equivalent to blitting 8 million pixels!). Though I'm surprised that
> the NSImage method is slower than fill/stroke, in most cases I would expect
> that to be faster, so there might be an inefficiency there somewhere.
>
Like graham I am surprised that the NSImage cache approach is slower than
fill/stroke.
My dynamic drawing requirements are minimal but the outline below is way
quicker than native redrawing (of course the graphical complexity of the view
plays a major role here).
Is your NSImage caching approach similar to below?
- (void)drawRect:(NSRect)rect
{
// if cache exists use it to update rect.
// otherwise draw into our rect
if (_imageCache) {
[self drawRectFromCache:rect];
return;
}
// draw to image cache
_cacheRect = [self bounds];
_imageCache = [[NSImage alloc] initWithSize:_cacheRect.size];
[_imageCache lockFocus];
// now draw into _imageCache
// done with drawing
[_imageCache unlockFocus]
}
- (void)drawRectFromCache:(NSRect)rect
{
[_imageCache drawInRect:rect fromRect:rect
operation:NSCompositeSourceOver fraction:alpha];
}
Regards
Jonathan Mitchell
Mugginsoft LLP
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