Re: [bug #4749] GWorkspace thumbnail views are not correct

[Enrico Sersale]

On 2003-08-16 13:58:43 +0300 nobody@savannah.gnu.org wrote:

> =================== BUG #4749: FULL BUG SNAPSHOT ===================
> http://savannah.gnu.org/bugs/?func=detailbug&bug_id=4749&group_id=99
>         
> Submitted by: None                    Project: GNUstep                      
> Submitted on: Sat 08/16/2003 at 06:58
> Category:  Application                Severity:  5 - Major                  Bug 
> Group:  Bug                       Resolution:  None                     
> Assigned to:  None                    Status:  Open
> Summary:  GWorkspace thumbnail views are not correct
>
> Original Submission:  When I thumbnail an image file in GWorkspace, the 
> resulting thumbnail does not adequately represent the original image.
>
> I am running a CVS version of GWorkspace from 20030813 on NetBSD/i386.
>
> While the thumbnail image might be considered attractive in an impressionist 
> way, the image cannot be used to identify the contents of the file.

This is an almost old problem, so let me give a little explication.

I wrote the thumbnailer Service keeping in mind that it had to be something 
capable to generate thumbnails for many file types, not only for images.
The objects that generate the thumbnails are, or bundles, as the 
ImageThumbnailer, or any application, tool, what you want, that registers 
itself as a thumbnailer provider using the thumbnailer's 
-registerExternalProvider: method.
This part (the most important) works well and I'm very glad of this :-)

Done this, I've written the only actually available bundle, that is, the 
imageThumbnailer.

Theorically, this had to be very easy, doing something like this:
{
 NSImage* bigImage = [[NSImage alloc] initWithContentsOfFile: path];
 NSSize size = TMBSIZE;
 NSImage* thumbImage = [[NSImage alloc] initWithSize: size];
 NSBitmapImageRep* rep;

 [bigImage setScalesWhenResized: YES];
 [bigImage setSize: size];

 [thumbImage lockFocus];

 [bigImage compositeToPoint: NSZeroPoint operation: NSCompositeSourceOver];

 rep = [[NSBitmapImageRep alloc]
               initWithFocusedViewRect: NSMakeRect(0, 0, size.width, 
size.height)];

 [thumbImage unlockFocus];

 RELEASE (bigImage);
 RELEASE (thumbImage);

 return (AUTORELEASE (rep));
}

But NSBitmapImageRep doesn't implement -initWithFocusedViewRect:, so, since I've had 
already written the service itself, I've had to find a provvisional solution. The 
solution was to "resize" the image data itself, using some methods taken from 
ToyViewer.

Here, this seems to work with almost all the tiff ang jpeg files but has 
problems with many xpm, png and gif files.

Anyway, I'm not going to try to fix this part of the code anymore, because I 
think that the right way is to implement -initWithFocusedViewRect: in 
NSBitmapImageRep.