Re: Interesting error in GWorkspace

[Riccardo Mottola]

Hi,

some updates

On 09/08/11 21:04, Eric Wasylishen wrote:
> I added two extra checks: one against creating a NSCachedImageRep with a size 
> of zero (it looks like that is where the NSView with size 0,0 was coming from), 
> and a check against locking focus on an image with a size of 0,0.
>
> Maybe those will help isolate the problem a bit..
>
> Actually, I just looked at Dock.m:
>
> - (void)setBackImage
> {
>    NSImage *image = [[manager desktopView] backImage];
>    int i;
>
>    DESTROY (backImage);
>
>    if (image) {
>      NSRect r = [self bounds];
>
>      backImage = [[NSImage alloc] initWithSize: r.size];
>      [backImage lockFocus];
>      [image compositeToPoint: NSZeroPoint
>                     fromRect: r
>                    operation: NSCompositeCopy];
>
> I bet "r" has a size of (0, 0).. I wonder why the bounds would be zero?

The exceptions in the console are now more terse after your fix.

2011-09-09 10:07:12.568 GWorkspace[2677] Problem posting notification: 
<NSException: 0xb9eab664> NAME:NSInvalidArgumentException 
REASON:NSCachedImageRep created with size {width = -1.49882; height = 
1.28695e-41} pixelsWide -1 pixelsHigh 0 INFO:(null)

a negative width and a near-zero height :)

Except wondering why "problem posting" the contents is bad.

Now I can see the dock, I attach a screen shot. It seems that the dock 
has a reasonable width/height as expected (Everything worked here before 
my departure in August...) and some icons are drawn on top of each 
other. I smell something dishy but difficult to understand what.

I put a breakpoint in Dock.m. Interestingly, I never break into line 
419, but I put it in 412.

At the first occurrence,
(gdb) p r
$3 = {origin = {x = 0, y = 0}, size = {width = 64, height = 192}}

It is also the only run I get in that breakpoint. Thus it is not caused 
by r = 0.
backImage gets alloc'd... and then te lock gets called.

I tried stepping through:

(gdb) finish
Run till exit from #0  0xbb8ac305 in -[NSImage lockFocusOnRepresentation:] (
    self=0xb901a674, _cmd=0xbba8bc98, imageRep=0x0) at NSImage.m:1063

2011-09-09 13:11:03.790 GWorkspace[1942] Problem posting notification: 
<NSException: 0xb901d9a4> NAME:NSInvalidArgumentException 
REASON:NSCachedImageRep created with size {width = -0.00359415; height = 
1.28695e-41} pixelsWide 0 pixelsHigh 0 INFO:(null)
2011-09-09 13:11:05.728 GWorkspace[1942] Unable to obtain lock (null)

So it appears that the image is alloc'd but at least one representation 
is invalid (imageRep=0x0) and we are calling a lock on it.

Riccardo

broken_dock.gif
Description: GIF image