Re: Drawing over a transparent background
Re: Drawing over a transparent background
- Subject: Re: Drawing over a transparent background
- From: Steve Christensen <email@hidden>
- Date: Mon, 24 Aug 2009 13:21:35 -0700
On Aug 23, 2009, at 10:00 PM, Ron Fleckner wrote:
On 24/08/2009, at 2:29 PM, Rob Keniger wrote:
On 24/08/2009, at 9:33 AM, Ron Fleckner wrote:
My borderless window has a semi-transparent background. When the
drawing in a subview changes, the background retains a ghost of
the original drawing in the subview. I don't want that ghost image!
What are you returning for the -isOpaque method of your custom
view? If your view has any parts that have an alpha less than 1.0
then you must return NO from this method.
On 24/08/2009, at 2:36 PM, Kyle Sluder wrote:
On Aug 23, 2009, at 4:33 PM, Ron Fleckner
<email@hidden> wrote:
My borderless window has a semi-transparent background. When the
drawing in a subview changes, the background retains a ghost of
the original drawing in the subview. I don't want that ghost image!
Have you remembered to override -isOpaque to return NO?
Yes, I return NO. There are four views, each one a subview (built
in IB) of the one below. The background is the content view of the
window with hourHand as a subview, which has minuteHand as a
subview, which has secondHand as a subview. To draw, a timer
callback tells the bottom view to setNeedsDisplay:YES every
second. Each 'hand' view then rotates by the correct amount and
draws it's hand.
1. Are you erasing the view before redrawing the hand?
2. Is there any reason why you couldn't be drawing the entire clock
(face + hands) in a single view? If it's only being updated once a
second, it'll still take considerably less than a second to draw it
all unless you're doing something horribly complicated.
steve
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