Re: PDFView drawPage called often after selecting text
Re: PDFView drawPage called often after selecting text
- Subject: Re: PDFView drawPage called often after selecting text
- From: Kyle Sluder <email@hidden>
- Date: Tue, 08 Jan 2013 00:21:14 -0800
On Jan 7, 2013, at 9:16 AM, Martin Hewitson <email@hidden> wrote:
>
> On 7, Jan, 2013, at 05:52 PM, Kyle Sluder <email@hidden> wrote:
>
>> On Jan 7, 2013, at 2:48 AM, Martin Hewitson <email@hidden> wrote:
>>
>>> Actually, at the risk of having a conversation with myself, I've narrowed the issue down to the actions I'm taking within my override of -drawPage:. Essentially what I'm aiming at is having a focus ring on the PDFView. I do this in my PDFView subclass:
>>>
>>> - (void)drawPage:(PDFPage *)page {
>>> [super drawPage:page];
>>> // focussed?
>>> if ([[self window] firstResponder] == self && [NSApp isActive]) {
>>> [[self superview] lockFocus];
>>> NSRect fr = [self frame];
>>> NSSetFocusRingStyle(NSFocusRingOnly);
>>> [[NSBezierPath bezierPathWithRect:fr] fill];
>>> [[self superview] unlockFocus];
>>> }
>>> }
>>
>> This sounds extremely iffy to me. You're dirtying regions of your window that overlap other views in the middle of a recursive -drawRect:. I'm surprised this doesn't crash or spin infinitely.
>
> This solution was advised on this list (see thread "PDFView focus ring" from Feb 2012), but it certainly doesn't seem to play nicely with my app. What's strange is that it doesn't cause problems in a very basic test app....
I'm still not sure this is a good approach to take.
The drawing machinery is pretty optimized. It's easy to do unsafe things that behave perfectly fine in certain limited circumstances t have deleterious effects in others.
Locking focus on your superview while you're in the middle of a lockFocus operation strikes me as one of those unsafe things that might usually work until it doesn't.
Is there any particular reason you can't use the old -setKeyboardFocusRingNeedsDisplayInRect: method and draw your focus ring in your own graphics context in -drawRect:?
--Kyle Sluder
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