Re: ScreenSaverView/NSQuickDrawView/Opaque issue [update]
Re: ScreenSaverView/NSQuickDrawView/Opaque issue [update]
- Subject: Re: ScreenSaverView/NSQuickDrawView/Opaque issue [update]
- From: "Andy O'Meara" <email@hidden>
- Date: Fri, 03 Jun 2005 09:40:20 -0400
On 6/3/05 9:29 AM, "glenn andreas" <email@hidden> wrote:
>
> On Jun 3, 2005, at 8:17 AM, Andy O'Meara wrote:
>> So that folks like me may benefit, I wanted to share my root
>> issues/mysteries (and this doesn't just apply to screen savers--if
>> you use
>> NSQuickDrawView, this is also for you). I apologize in advance if
>> some of
>> there are novice Cocoa comments/mysteries... If anyone can shed
>> some light
>> on the following issues, I'd be very grateful.
>
> Quickdraw (and by extension, NSQuickDrawView) has absolutely no
> concept of alpha/transparency in bitmaps. While it can store an
> extra byte that would, in theory, be usable for an alpha channel,
> it's value is often overwritten with even simple quickdraw
> operations. The end result is that transparent views/windows do not
> support quickdraw (this is even true under a purely Carbon approach -
> you need to use CoreGraphics if you want anything other than a solid
> rectangle (though some things do support clipping regions, but that
> doesn't solve the problem)).
>
>
Yes, that's why it's humorous (and frustrating) that changing my
NSQuickDrawView's isOpaque to return YES results in its drawRect() never
getting called.
Andy
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