Re: TIFFRpresentation problem

[Renaud Molla]

I experimented a few ways to make the same work with Cocoa and GNUstep.
So here is the result.

At the beginning I was doing this:

[ anImage lockFocus ];
// Draw...
[ anImage unlockFocus ];

data = [ anImage TIFFRepresentation ];

-> Works with Cocoa, should be working with GNUstep but current  
implementation doesn't support it.

Then tried:

NSBitmapImageRep ir = [ [ NSBitmapImageRep alloc ]  
initWithBitmapDataPlanes: ..... ];
[ anImage addRepresentation: ir ];
[ anImage lockFocusOnRepresentation: ir ];

// Draw

[ anImage unlockFocus ];
data = [ ir TIFFRepresentation ];

--> yields an empty/transparent image (i think because my bitmap was  
supporting transparency)

WORKING CODE FOLLOWS:

[ anImage lockFocus ];
// Draw...
[ anImage unlockFocus ];

//...some code... but i think could be collapsed if needed within the  
previous lockFocus/unlockFocus pair

[ anImage lockFocus ];
ir = [ [ NSBitmapImageRep alloc ] initWithFocusedViewRect: NSMakeRect 
( 0.0, 0.0, imageWidth, imageHeight ) ];
[ anImage unlockFocus ];
data = [ ir TIFFRepresentation ];

So, I think, the most simple thing to do in order to get a working  
NSImage -(NSData *)TIFFRepresentation is:

If there is already a bitmap rep available, then return its  
TIFFRepresentation data.
If not, create one with the code above and add the representation in  
the rep set for the image, then return the TIFFRepresentation.

What do you thing about this?
I don't think this is the best way to go, but this should work.

Regards.
PS: I started this thread, but accidentally posted from a different  
address.

On Mar 8, 2007, at 12:07 AM, Fred Kiefer wrote:

> Vaisburd, Haim wrote:
> > Fred Kiefer wrote:
> >
> > > Half Activist wrote:
> >
> > > >     i wrote a little application, that locks focus on an NSImage,
> > > > draws to it, then unlock the focus.
> > > >     I then try to get the TIFFRepresentation data, but it always
> > > > returns nil.
> >
> > > This currently is a limitation of GNUstep.
> >
> > I'm among the ones who would be very pleased to get this working.
> >
> >
> > > Should we create bitmap representations for images as well and draw
> > into them
> > > or allow to grap the content of a cached image representation and
> > return it as tiff?
> > > The later may not be to hard to implement.
> >
> > What would be the difference for the user? I do not know internals  
> > well
> > enough
> > to make an opinion, my own attitude is to strive for clarity and  
> > use the
> > most
> > straigtforward approach.
> >
> > It would be really great to have
> >  [NSBitmapImageRep -representationUsingType:properties:] also  
> > working,
> > at least for JPEG.
>
> Sorry, I don't want to sound negative, but there are a lot of bits
> missing in GNUstep that would be great to have. Contributions are more
> than welcome.
>
> Fred
>
>
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