Re: Fwd: NSView patch

[Matt Rice]

On Mon, Feb 23, 2009 at 8:50 AM, Fred Kiefer <address@hidden> wrote:
> Matt Rice wrote:
>> On Mon, Feb 23, 2009 at 5:50 AM, Fred Kiefer <address@hidden> wrote:
>>> The other problem that we sometimes mark subviews as still needing
>>> display due to rounding errors should be addressed. Here it would be
>>> helpful to get the detailed values of the involved rectangles. These
>>> surely are in Matts gdb log, but as he is using a changed version of the
>>> NSView code it is hard for me to tell, which is which. What would help
>>> is to have the values of _visibleRect, _invalidRect and aRect at the
>>> beginning of the method displayRectIgnoringOpacity:inContext:
>>
>> the superview at the beginning of the method.
>>
>> Breakpoint 2, -[NSView displayRectIgnoringOpacity:inContext:]
>> (self=0x276ff90, _cmd=0xdc4e70, aRect={origin = {x = 0, y = 0}, size =
>> {width = 476, height = 381}}, context=0x299b740) at NSView.m:2368
>> 2368      BOOL flush = NO;
>> $_invalidRect ={origin = {x = 0, y = 0}, size = {width = 1, height = 1}}
>> $_visibleRect ={origin = {x = 0, y = 0}, size = {width = 476, height = 381}}
>> $aRect ={origin = {x = 0, y = 0}, size = {width = 476, height = 381}}
>>
>> still in the super-view but right before we go to the subview...
>>
>> Breakpoint 3, -[NSView displayRectIgnoringOpacity:inContext:]
>> (self=0x276ff90, _cmd=0xdc4e70, aRect={origin = {x = 0, y = 0}, size =
>> {width = 476, height = 381}}, context=0x299b740) at NSView.m:2450
>> 2450                  if (NSIsEmptyRect(isect) == NO)
>> $_invalidRect ={origin = {x = 0, y = 0}, size = {width = 0, height = 0}}
>> $_visibleRect ={origin = {x = 0, y = 0}, size = {width = 476, height = 381}}
>> $aRect ={origin = {x = 0, y = 0}, size = {width = 476, height = 381}}
>> $isect ={origin = {x = 48.7490425, y = 192.641785}, size = {width =
>> 118, height = 54}}
>> $subviewFrame ={origin = {x = 48.7490425, y = 192.641785}, size =
>> {width = 118, height = 54}}
>>
>> right after we go
>> isect = [subview convertRect: isect fromView: self];
>>
>> Breakpoint 4, -[NSView displayRectIgnoringOpacity:inContext:]
>> (self=0x276ff90, _cmd=0xdc4e70, aRect={origin = {x = 0, y = 0}, size =
>> {width = 476, height = 381}}, context=0x299b740) at NSView.m:2453
>> 2453                      [subview displayRectIgnoringOpacity: isect
>> inContext: context];
>> $new_isect ={origin = {x = 0, y = 0}, size = {width = 117.999985, height = 
>> 54}}
>>
>>
>> now here in the view where the error occurs
>>
>> Breakpoint 2, -[NSView displayRectIgnoringOpacity:inContext:]
>> (self=0x284f7e0, _cmd=0xdc4e70, aRect={origin = {x = 0, y = 0}, size =
>> {width = 117.999985, height = 54}}, context=0x299b740) at
>> NSView.m:2368
>> 2368      BOOL flush = NO;
>> $_invalidRect ={origin = {x = 0, y = 0}, size = {width = 118, height = 54}}
>> $_visibleRect ={origin = {x = 0, y = 0}, size = {width = 118, height = 54}}
>> $aRect ={origin = {x = 0, y = 0}, size = {width = 117.999985, height = 54}}
>>
>> Breakpoint 1, gsbp () at NSView.m:2362
>>
>
> Thank you for checking all these values. It is really just a small
> rounding error in the conversion. What about cheating here? For this
> special case the simplest solution would be to use the bounds rectangle
> of the sub view as new isect, when the real isect before the conversion
> is equal to the frame rect of the sub view.
> I know this will not help us in all cases, but it would quite often save
> us the computation of the conversion and in this specific case it is
> also more correct.
>
> The code would look somewhat like this, plus plenty of comments
> explaining why we do this:
>
>              isect = NSIntersectionRect(aRect, subviewFrame);
>              if (NSIsEmptyRect(isect) == NO)
>                {
>                  if (NSEqualRects(isect, subviewFrame) == YES)
>                    isect = [subview bounds];
>                  else
>                    isect = [subview convertRect: isect fromView: self];
>                  [subview displayRectIgnoringOpacity: isect inContext:
> context];
>                }
>
> The main problem here is that somebody will have to convince me that
> this is correct in all cases, even with scaling and rotation.
>

I don't think that will work because I'm also seeing rounding errors on
the isect = NSIntersectionRect(...) calls... though not in the stuff i
sent earlier for some reason... not sure why...
but that would also only work when displaying whole views,
and i take it you don't like the idea of just using
GSAlmostEqualRects() in NSView?

here's 2 test cases, bar.app is the minimal one and another one that
allows you to drag the purple view around by clicking on it, and
resize it by clicking the black square, rotate and scale and all that
other stuff... (note that scaling doesn't seem to work until its been
rotated)
the one thing it doesn't do is allow you to set the origin at
non-integer increments unless whatever input device your using gives
non-integer coordinates (i don't appear to have one)
if its not reproducable I could add something like a NSStepper to
increment the deal by the value of the value of the top slider or
something...

after adding some NSLog's to NSView....

2009-02-24 21:34:36.263 bar[10292] subviewFrame
displayRectIgnoringOpacity:inContext: <BarView: 0x24cbd70>

146.749039 205.641785 118.000000 54.000000

2009-02-24 21:34:36.263 bar[10292] aRect
displayRectIgnoringOpacity:inContext: <BarView: 0x24cbd70>

0.000000 0.000000 700.000000 500.000000

2009-02-24 21:34:36.271 bar[10292] isect before conversion
displayRectIgnoringOpacity:inContext: <BarView: 0x24cbd70>

146.749039 205.641785 117.999985 54.000000


2009-02-24 21:34:36.271 bar[10292] isect after conversion
displayRectIgnoringOpacity:inContext: <BarView: 0x24cbd70>

0.000000 0.000000 117.999985 54.000000

now i could probably work around this by just flooring the points, but
i am hesitant to work around things in gui for fear they will be
forgotten,
and go unnoticed give someone else the joy of rediscovering this..

foo-0.0.1.tar.gz
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