RE: Extracting from NSImage (NSImageView)

[Vaisburd, Haim]

Andreas Hoeschler <ahoesch@smartsoft.de> wrote:

> Hi Vaisburd, 

My name is Tima :-)

>  [compositeImage compositeToPoint: fromRect: operation: fraction]
>  [compositeImage drawAtPoint: fromRect: operation: fraction:]
>
> Both methods still aren't implemented (latest snapshot).
> Is anybody actually working on this?

Yes, I'm curious about this too. Maybe the people in the know can answer?

> Is there any other approach to accomplish - compositing images
> and extracting a subregion - on GNUstep?

Yes. Here is an adapted piece of code from PhotoClip
(http://www.vaisburd.net/PhotoClip/index.html), development has been
interrupted, but I still hope to continue ;)

Cropping works if one draws NSImageRep instead of NSImage.


@implementation NSImage (PhotoClip)

- (NSImage *) imageFromRect: (NSRect) rect
{
    NSImage * canvas = [[NSImage alloc] initWithSize: rect.size];

    // we are going to draw self on canvas and return canvas
    [canvas lockFocus];

    // Prepare affine transformation to translate 'self'
    // so that rect.origin maps to (0,0)
    NSAffineTransform * xform = [NSAffineTransform transform];
    [xform translateXBy: -rect.origin.x yBy: -rect.origin.y];

    // Apply transform
    [xform concat];

    // Get NSImageRep of image
    NSImageRep * rep = [self bestRepresentationForDevice: nil];

    [rep drawAtPoint: NSZeroPoint];

    [canvas unlockFocus];
    return [canvas autorelease];
}

@end


Enjoy!
Tima.