On Oct 21, 2010, at 10:56 AM, Rimas M. wrote: > Hello list, > > I do not have a lot of practice with Core Animation, maybe that is the > reason. I have a real annoying problem. > > All I want to do is: > 1. Create CALayer > 2. Set CGImage for its content > 3. Depending on situation rotate and zoom in that layer (or its content) > > Looks like everything works, but I am getting "rotated" pixels > (http://dl.dropbox.com/u/2030721/ForAppleList/Rotated%20Pixels.png). > That is not what I want. I would like to get rotated content of image > with "straight" pixels. > > I was trying to play with layer transform property, with layer > delegate "- (void)drawLayer:(CALayer *)layer > inContext:(CGContextRef)ctx" and by using CGContextRotateCTM etc. > I have even tried to use layer and sublayer to split transforms (one > layer scales, and other rotates) but result is always the same. > Is there any way to achieve result I want? Currently the only way I know is: > a) to rotate an image by drawing it to the bitmap context > b) create new rotated CGImage from it > c) and then draw it for scaling. > > But this way is quite slow. Is there a better one? > > Any help is very appreciate.
- You should add your new layer as a sublayer to the layer of the view-controller's view - or as a sublayer to any other layer than the controller view's layer. - Usually, you "draw" the contents only once. However, when you set an *image* via the layers's contents property, you don't need to explicitly draw the layer - the layer draws the image for you, when it is required. So, just set the image as the layer's contents. - You can scale/zoom the layers's contents by setting the layer's transform property accordingly. This uses Core Animation, which executes - if possible - on the GPU, and is therefore the fastest method. Note, this doesn't require the image to be "drawn" again (it requires "rendering"). You can create a suitable transform which scales AND zooms at once. - A CALayer's properties are "animatable" (see Core Animation). In fact, changes in properties are animated by default. But you can define any animation, and CA nicely performs them for you. - Using Core Graphics functions is *usually* not as fast as Core Animation (if a CA alternative exists). But certainly, CG has its use. So, if you want to scale and zoom interactively, use CA. Regarding transforms, see also: CATransform3DMakeRotation, CATransform3DMakeScale, CATransform3DConcat Regards, Andreas > > Best Regards, > > Rimas M. > _______________________________________________ > > 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: > http://lists.apple.com/mailman/options/cocoa-dev/agrosam%40onlinehome.de > > This email sent to agro...@onlinehome.de _______________________________________________ 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
