On Mon, Feb 18, 2013 at 6:07 PM, Kyle Sluder <k...@ksluder.com> wrote:
> On Sun, Feb 17, 2013, at 05:12 PM, iain wrote: > > > > Does anyone have any hints of something I may have missed, or something > > I'm > > going about the wrong way? > > Unless there's something you haven't told us, you shouldn't need to keep > track of your visible rect at all. > It sounds like you're trying to be really smart and only cache the > drawing necessary for your visible rect rather than the more naive > approach of drawing a cache for your entire view whenever its bounds > change. Yup, that's exactly what I'm trying to do. > Is this really a performance boost for you? You say that the > drawing is complicated; if by this you mean that you spend a lot of time > doing things other than blitting pixels, you are doing yourself a > disservice by drawing minimally. It would be faster for you to cache the > entire view at once. > I'm trying to draw a sample waveform so for some of the audio files I have which come in around 30minutes long, even drawing to a reduction of 8192 frames/pixel you're looking at views of 10,000pixels wide (at 44100hz). Drawing 1frame per pixel would be a view 80million pixels wide. Admittedly that's the extreme case but drawing only the visible area is a good performance boost, especially when I need to draw things on top of the waveform. I do have the data points cached at certain zoom levels as well but it's all a memory/speed trade off. I can't cache the data points at all zoom levels, so I need to loop through the (cached) data to redraw, but equally I can't have a pixmap backing store at each zoom level, so only caching a pixmap of the visible area is a trade off I'm happy with. > If it really is an advantage for you to cache only the pixels that are > going to be in your visible rect, you can override -viewWillDraw to call > -getRectsBeingDrawn:… and be super-smart about your caching. > > But I suggest you do some profiling and see whether you gain time by > overriding -setFrameSize: to set a flag that you pick up in an override > of -viewWillDraw to render a cache for the entire bounds of your view. I'll give this a go, does -setFrameSize just deal with the visible portion when inside an NSScrollView/NSClipView? If so, thank you, that's great. iain holmes _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
