On Oct 23, 2012, at 2:44 PM, David Rowland <[email protected]> wrote:
> There are several paths to be animated. I want each to appear when the user > does some action. It seemed the best to but them in a method called by > drawRect and redraw the view when something changed. Why would the memory > footprint be enlarged? Because simply by implementing -drawRect:, your view will now consume pixelWidth * pixelHeight * 4 bytes of memory, and will need to be rendered onto the screen every time something changes. You could do the exact same thing by just implementing an arbitrarily named method that you call instead of -setNeedsDisplay without the overhead. > > thanks for pointing to didMoveToWindow. > > David > > > > On Oct 23, 2012, at 1:25 PM, David Duncan <[email protected]> wrote: > >> >> On Oct 23, 2012, at 12:34 PM, David Rowland <[email protected]> wrote: >> >>> This worked for me. When initializing your UIView, add an instance variable >>> "shapeLayer" and do this, >>> >>> shapeLayer = [CAShapeLayer layer]; >>> [[self layer] addSublayer:shapeLayer]; >>> >>> >>> In drawRect, set up your path and do this, >> >> There is no need to do this inside of drawRect. In fact by doing so (unless >> your UIView actually needs to draw something) you've unnecessarily increased >> your memory footprint and reduce the performance to start the animation. >> >> If you want the animation to happen as soon as the view is placed in the >> window, the correct place to do this is inside of -[UIView >> didMoveToWindow:]. Just check that the moved to window is not nil (or >> nothing will happen). >> >>> >>> CABasicAnimation *pathAnimation = [CABasicAnimation >>> animationWithKeyPath:@"strokeEnd"]; >>> pathAnimation.duration = 4.0; >>> pathAnimation.fromValue = [NSNumber numberWithFloat:0.0f]; >>> pathAnimation.toValue = [NSNumber numberWithFloat:1.0f]; >>> [shapeLayer addAnimation:pathAnimation forKey:@"strokeEndAnimation"]; >> >> You can also do this implicitly once the layer is in a layer tree by setting >> the animation duration on the current CATransaction and setting the >> strokeEnd directly. >> >>> >>> >>> >>> That seems to be all that is needed. >>> >>> David >>> >>> >>> >>> >>> On Oct 23, 2012, at 11:37 AM, David Duncan <[email protected]> wrote: >>> >>>> On Oct 23, 2012, at 4:37 AM, Roland King <[email protected]> wrote: >>>> >>>>> I want to animate the drawing of CGPath in a UIView, so it looks as if >>>>> it's being drawn. I have the UIView, I have the CGPath, I am able to >>>>> split the CGPath at any point from 0 to 100% into that which should be >>>>> drawn and that which shouldn't yet, that's all done, so I can, fairly >>>>> efficiently, call -(CGPath)[ myObject fractionalPath:(CGFloat)fraction ] >>>>> and get a path. >>>> >>>> >>>> You can do this with a CAShapeLayer by animating the strokeEnd property. >>>> Should be very simple to do, although if your path is very complex it may >>>> make more sense to break it into pieces and use multiple shape layers >>>> animated sequentially. >>>> -- >>>> David Duncan >>>> >>>> >>>> _______________________________________________ >>>> >>>> Cocoa-dev mailing list ([email protected]) >>>> >>>> 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/rowlandd%40sbcglobal.net >>>> >>>> This email sent to [email protected] >>> >> >> -- >> David Duncan >> > -- David Duncan _______________________________________________ Cocoa-dev mailing list ([email protected]) 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 [email protected]
