On Feb 28, 2009, at 10:20 PM, Jerry Krinock wrote:
On 2009 Feb 28, at 20:10, Graham Cox wrote:
Create the new image, swapping width and height, lock focus onto
it, apply a transform that rotates 90 degrees, and draw the first
into the second.
You can't do it without drawing, but the drawing doesn't need to
be onscreen.
Thanks, Graham. Fun stuff....
@implementation NSImage (Transform)
[snip]
@end
That version only works for a ±90° rotation since you're just
swapping the width and height for the rotated image size. A more
generalized solution would be:
- (NSImage*)imageRotatedByDegrees:(CGFloat)degrees
{
// calculate the bounds for the rotated image
NSRect imageBounds = {NSZeroPoint, [self size]};
NSBezierPath* boundsPath = [NSBezierPath
bezierPathWithRect:imageBounds];
NSAffineTransform* transform = [NSAffineTransform transform];
[transform rotateByDegrees:degrees];
[boundsPath transformUsingAffineTransform:transform];
NSRect rotatedBounds = {NSZeroPoint, [boundsPath bounds].size};
NSImage* rotatedImage = [[[NSImage alloc]
initWithSize:rotatedBounds.size] autorelease];
// center the image within the rotated bounds
imageBounds.origin.x = NSMidX(rotatedBounds) - (NSWidth
(imageBounds) / 2);
imageBounds.origin.y = NSMidY(rotatedBounds) - (NSHeight
(imageBounds) / 2);
// set up the rotation transform
transform = [NSAffineTransform transform];
[transform translateXBy:+(NSWidth(rotatedBounds) / 2) yBy:+
(NSHeight(rotatedBounds) / 2)];
[transform rotateByDegrees:degrees];
[transform translateXBy:-(NSWidth(rotatedBounds) / 2) yBy:-
(NSHeight(rotatedBounds) / 2)];
// draw the original image, rotated, into the new image
[rotatedImage lockFocus];
[transform set];
[self drawInRect:imageBounds fromRect:NSZeroRect
operation:NSCompositeCopy fraction:1.0] ;
[rotatedImage unlockFocus];
return rotatedImage;
}
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