How to resize NSImage?

Question

I have an NSBitmapImageRep which is WxH size.

I create NSImage and call addRepresentation:. Then I n

Answer 1

For just scaling NSBitmapImageRep

static NSBitmapImageRep *i_scale_bitmap(const NSBitmapImageRep *bitmap, const uint32_t width, const uint32_t height)
{
    NSBitmapImageRep *new_bitmap = NULL;
    CGImageRef dest_image = NULL;
    CGColorSpaceRef space = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
    CGContextRef context = CGBitmapContextCreate(NULL, (size_t)width, (size_t)height, PARAM(bitsPerComponent, 8), PARAM(bytesPerRow, (size_t)(width * 4)), space, kCGImageAlphaPremultipliedLast);
    CGImageRef src_image = [bitmap CGImage];
    CGRect rect = CGRectMake((CGFloat)0.f, (CGFloat)0.f, (CGFloat)width, (CGFloat)height);
    CGContextDrawImage(context, rect, src_image);
    dest_image = CGBitmapContextCreateImage(context);
    CGContextRelease(context);
    CGColorSpaceRelease(space);
    new_bitmap = [[NSBitmapImageRep alloc] initWithCGImage:dest_image];
    CGImageRelease(dest_image);
    return new_bitmap;
}

And for scaling a NSImage based on NSBitmapImageRep

ImageImp *imgimp_create_scaled(const ImageImp *image, const uint32_t new_width, const uint32_t new_height)
{
    NSImage *src_image = (NSImage*)image;
    NSBitmapImageRep *src_bitmap, *dest_bitmap;
    NSImage *scaled_image = nil;
    cassert_no_null(src_image);
    cassert([[src_image representations] count] == 1);
    cassert([[[src_image representations] objectAtIndex:0] isKindOfClass:[NSBitmapImageRep class]]);
    src_bitmap = (NSBitmapImageRep*)[[(NSImage*)image representations] objectAtIndex:0];
    cassert_no_null(src_bitmap);
    dest_bitmap = i_scale_bitmap(src_bitmap, new_width, new_height);
    scaled_image = [[NSImage alloc] initWithSize:NSMakeSize((CGFloat)new_width, (CGFloat)new_height)];
    [scaled_image addRepresentation:dest_bitmap];
    cassert([scaled_image retainCount] == 1);
    [dest_bitmap release];
    return (ImageImp*)scaled_image;
}

Draw directly over NSImage ([NSImage lockFocus], etc) will create a NSCGImageSnapshotRep not a NSBitmapImageRep.