Re: refresh problem when resizing split panes

[Eric Wasylishen]

Great, that sounds like an excellent plan. Should be only half an hour's work 
or so - but it should wait until after the freeze.
Eric

On 2012-01-24, at 3:35 PM, Fred Kiefer wrote:

> I had almost forgotten about this old problem, as we no longer use XOR
> operations directly in the normal GNUstep code. There are at least to 
> different issues here. First the Cocoa documentation states that 
> NSCompositeHighlight gets mapped to NSCompositeSourceOver just as we do in 
> the cairo backend. But on the other hand gui still uses this operator as XOR, 
> which of course wont work.
> As far as I am aware we only use this in the function NSHighlightRect() in 
> gui and we should come up with an operation here that just inverts the colour 
> values. I vaguely remember some discussion on the cairo mailing list about 
> subtracting the current colour from white
> Something like:
> 
> cairo_set_operator (cr, CAIRO_OPERATOR_DIFFERENCE);
> cairo_set_source_rgb (cr, 1, 1, 1);
> 
> We should introduce a new operator for this GSCompositeXOR and implement it 
> with the old NSCompositeHighlight code in the other backends. Not sure 
> whether we should add this now in the middle of a code freeze. We need 
> somebody to remind us to do it afterwards though.
> 
> I just looked at the currently available composite operators in cairo 
> (http://cairographics.org/operators/) and they have extended a lot since we 
> started to use it. Maybe we should recheck some of our operator mappings now.
> 
> Fred
> 
> On 24.01.2012 22:39, Eric Wasylishen wrote:
>> I get this too with GSUseGhostResize YES. It's not clear to me how
>> the ghost resize code in NSSplitView is supposed to work. Is that
>> code expecting NSHighlightRect to be a bitwise XOR where drawing the
>> same rect twice gives you the original image back? NSHighlightRect
>> doesn't appear to do that, at least with cairo.
>> 
>> e.g. see
>> http://lists.cairographics.org/archives/cairo/2004-July/001593.html
>> 
>> On 2012-01-24, at 8:44 AM, Riccardo Mottola wrote:
>>> when resizing split panes we have some sort of refresh problem
>>> where the "grey" of the moving bar just erases what's in the view.
>>> I can verify this in Grr and its reading panes but also in Vespucci
>>> when viewing pages with frames.
>