Re: Extracting from NSImage (NSImageView)

[Andreas Hoeschler]

Hi Vaisburd,

> I do not whether NSImageView can be used for this purpose,
> but, as far as I understand, cropping is the job of NSImage class.

Thanks for the hint. I finally realized that I made a mistake while calculating the rect for the extraction. It works now with dataWithPDFInsideRect: on Cocoa, but not on GNUstep. Here is what I get

NSPrintOperation (instance) does not recognize initPDFOperatonWithView:insideRect:toData:printInfo:

> I think you can use Cocoa's method
> [NSImage -compositeToPoint:fromRect:operation:fraction:]
>
> If you want to create an image from a portion of original one,
> you need to calculate the new size, create this new image and
> then draw _on it_ by locking focus:
>
> [newImage lockFocus];
> [originalImage compositeToPoint: ....];
> [newImage unlockFocus];
>
> I say "I think" because I never used Cocoa,

On Cocoa this works with 

[compositeImage compositeToPoint:NSMakePoint(0,0) fromRect:subFrame operation:NSCompositeCopy];

It does not work or at least produces a different result (what I don't understand) with 


[compositeImage drawAtPoint:NSMakePoint(0,0) fromRect:subFrame operation:NSCompositeCopy fraction:1];

This does not work on GNUstep though! :-(

> and
> [NSImage -compositeToPoint:fromRect:operation:fraction:]
> was not implemented in GNUstep the last time I checked.
>
> Does anybody know why it's not implemented?

Both methods still aren't implemented (latest snapshot). Is anybody actually working on this? Is there any other approach to accomplish - compositing images and extracting a subregion - on GNUstep?

Thanks!

Regards,

Andreas