Re: GNUstep slowness while drawing

Hi Fred,

>> Hi Fred,
>>> Andreas Höschler wrote:
>>>> Hi all,
>>>> I have a view subclass with
>>>> - (void)mouseDown:(NSEvent *)theEvent
>>>> {
>>>>    NSPoint locA = [self
convertPoint:[theEvent locationInWindow] 
>>>> fromView:nil];
>>>>    BOOL shiftPressed = (([theEvent
modifierFlags] & NSShiftKeyMask) 
>>>> > 0);
>>>>    BOOL keepOn = YES;
>>>>    BOOL hasDragged = NO;
>>>>    while (keepOn)
>>>>      {
>>>>       theEvent = [[self window] 
>>>> nextEventMatchingMask:NSLeftMouseUpMask |
NSLeftMouseDraggedMask];
>>>>       switch ([theEvent type])
>>>>         {
>>>>          case NSLeftMouseDragged:
>>>>            {
>>>>               NSPoint locB = [self
convertPoint:[theEvent 
>>>> locationInWindow] fromView:nil];
>>>>               NSSize offset = 
NSMakeSize(locB.x - locA.x, locB.y - 
>>>> locA.y);
>>>>               NSRect oldRect =
_selectionRect;
>>>>               _selectionRect.origin =
locA;
>>>>               if (offset.width < 0)
>>>>                 {
>>>>                  _selectionRect.origin.x =
locB.x;
>>>>                  offset.width =
-offset.width;
>>>>                 }
>>>>               if (offset.height < 0)
>>>>                 {
>>>>                  _selectionRect.origin.y =
locB.y;
>>>>                  offset.height =
-offset.height;
>>>>                 }
>>>>               _selectionRect.size =
offset;
>>>>               _selecting = YES;
>>>>               [self 
>>>>
setNeedsDisplayInRect:NSUnionRect(_selectionRect,
oldRect)];
>>>>               hasDragged = YES;
>>>>            }
>>>>             break;
>>>>          case NSLeftMouseUp:
>>>>            {
>>>>               keepOn = NO;
>>>>            }
>>>>             break;
>>>>          default:
>>>>             break;
>>>>         }
>>>>      }
>>>> }
>>>> - (void)drawRect:(NSRect)rect
>>>> {
>>>>    [super drawRect:rect];
>>>>    if (_selecting)
>>>>      {
>>>>       [[NSColor grayColor] set];
>>>>       NSFrameRect(_selectionRect);
>>>>      }
>>>> }
>>>> This draws a rectangle following the mouse
until the user releases 
>>>> the mouse button. On MacOSX the rectangle
follows the mouse 
>>>> instantly. Under GNUstep I see a
significant delay. Dragging 
>>>> rectangles makes no fun there. Any idea why
this is so slow? This 
>>>> of course has nothing to do with rectangles
in special but with 
>>>> slow drawing code in general. In my app I
want to drag objects 
>>>> around with the mouse. This works under
GNUstep and MacOX but on 
>>>> GNustep it is almost too slow to be usable.
Is this a known (may be 
>>>> even already improved) issue? My GNUstep
tree is already a year 
>>>> old. 
>>>
>>> Most likely the slow drawing speed you see in
GNUstep has nothing to 
>>> do with the drawing itself, but with the event
handling in GNUstep. 
>>> The window will just not get a chance to redraw
itself.
>>> One possible reason for this may be that in
>>> [NSApplication
nextEventMatchingMask:untilDate:inMode:dequeue:] we 
>>> handle an expiration date of nil different from
Cocoa. There 
>>> distantPast is used while we use distantFuture,
resulting in the 
>>> loop to wait until the next event happens.
>>>
>>> As I am no expert in this area, I would like to
get some comments 
>>> from other developers before changing this
code. That change may 
>>> result in the need to adopt a lot of places
that rely on the old 
>>> behaviour.
>> For a qick test I changed all occurances of
distantFuture to 
>> distantPast in NSApplication.m. This had no obvious
effect, neither 
>> good nor bad. Drawing (event handling) is still
(far too) slow!? Any 
>> more ideas?
>
> As this simple change isn't working, I will need a
stripped down 
> version of your application to reproduce the issue.

While preparing the stripped down application I figured out
that this 
has nothing to do with event handling but is indeed a
drawing problem. 
The stripped down version (subclass of NSView) worked
perfectly also 
under GNUstep. My ObjectBrowserView was actually a subclass
or 
NSImageView since I wanted to have a background image.  Now this 
NSImageView was setup with  [_platformObject 
setImageScaling:NSScaleToFit]. This turned out to be the
problem. After 
adding

#ifndef __APPLE__
- (void)setImageScaling:(NSImageScaling)image
{
    [super setImageScaling:NSScaleNone];
}
#endif

to my NSImageView subclass the performance problem was gone.
Now I have 
a rather ugly blue frame around the image but I can at least
reasonably 
select objects now which is much more important.

On MacOSX (10.2.8) I see no performance problem even with
NSScaleToFit. 
However, I can live with this solution.

Thanks a lot!

Regards,

  Andreas

_______________________________________________
Discuss-gnustep mailing list
Discuss-gnustepgnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnustep

Re: GNUstep slowness while drawing

Thread: Re: GNUstep slowness while drawing