CALayer - backgroundColor flipped?

Question

I'm creating a CALayer like this:

UIColor *color = [UIColor colorWithPatternImage:[UIImage imageNamed:@"MyPattern.png"]];
backgroundLayer = [[CALayer alloc] init];
[backgroundLayer setBackgroundColor:[color CGColor]];
[[self layer] addSublayer:backgroundLayer];

For some reason, the pattern is drawn upside down. I've already tried setting geometryFlipped and applying sublayer transforms, but it doesn't work.

score 11 · Accepted Answer · answered Apr 09 '11 at 13:03

11

Using [backgroundLayer setTransform:CATransform3DMakeScale(1.0, -1.0, 1.0)]; actually does work.

answered Apr 09 '11 at 13:03

ryyst

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but it also flipped its sublayers, that i dont want – Jagveer Singh Apr 06 '17 at 11:39

score 2 · Answer 2 · answered Apr 09 '11 at 11:08

I would rather use this method:

CALayer *backgroundLayer = [CALayer layer];

backgroundLayer.frame = CGRectMake(50, 50, 200, 200);

UIImage *img = [UIImage imageNamed:@"MyPattern.png"];

CGImageRef imgRef = CGImageRetain(img.CGImage);


backgroundLayer.contents = (id) imgRef;


[self.layer addSublayer:backgroundLayer];

This will provide image content inside the layer and it fits automatically, so it works great for backgrounds. Im not sure why your method isnt working, sorry about that, but I thought it would be nice to provide you with this method.

I'm using a background color because I want to tile the image, not stretch it. — ryyst, Apr 09 '11 at 12:48

score 1 · Answer 3 · edited May 23 '17 at 11:59

Instead of using CATransform3DMakeScale you can flip image yourself:

UIImage* img = [UIImage imageNamed:@"MyPattern.png"];
img = [UIImage imageWithCGImage:img.CGImage
                          scale:img.scale 
                    orientation:UIImageOrientationDownMirrored];
UIColor* color = [UIColor colorWithPatternImage:img];
…

This works fine for me.

Or you can go further and actually redraw the image.

- (UIImage*)flipImage:(UIImage*)image {
    UIGraphicsBeginImageContext(image.size);
    CGContextDrawImage(UIGraphicsGetCurrentContext(),CGRectMake(0.,0., image.size.width, image.size.height),image.CGImage);
    UIImage* img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return img;
}

Details why it can be useful are in this answer.

The first method did not work, but the second worked. Anyone knows why? The first worked when i used the image in a UIImageView but. — Rakesha Shastri, Aug 03 '21 at 05:20

CALayer - backgroundColor flipped?

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