CODEWITHSUNDEEP
objective-ciosxcodeipadcore-graphics
SeongHo
SeongHo

Reputation: 1040

Objective C: How to Use the kCGBlendModeHue and kCGBlendModeSaturation?

i tried using the CGContextSetRGBStrokeColor before now i want to use other way to do the color change.

I am using now an image as a stroke and i want to change it's color with the use of those CGBlendModes.

How will i able to control the Hue and Saturation using kCGBlendModeHue and kCGBlendModeSaturation? i'll use it to change the stroke color on button click.

Upvotes: 3

Views: 1433

Answers (2)

Dan Rosenstark
Dan Rosenstark

Reputation: 69787

Thanks to @Patrick Tescher's answer, this works:

- (void) changeToHue:(float)hue saturation:(float)saturation {
    UIGraphicsBeginImageContext(self.bounds.size);
    CGContextRef context = UIGraphicsGetCurrentContext();    
    UIView *hueBlend = [[UIView alloc] initWithFrame:self.bounds];
    hueBlend.backgroundColor = [UIColor colorWithHue:hue saturation:saturation brightness:1 alpha:1];
    CGContextDrawImage(context, self.bounds, self.image.CGImage);
    CGContextSetBlendMode(context, kCGBlendModeHue);
    [hueBlend.layer renderInContext:context];
    self.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();    
}

Upvotes: 1

Patrick Tescher
Patrick Tescher

Reputation: 3447

You will want to do something like this:

CGContextRef context = UIGraphicsGetCurrentContext();
CGContextDrawImage(context, rect, image.CGImage);
CGContextSetBlendMode(context, kCGBlendModeHue);
CGContextDrawImage(context, rect, overlay.CGImage);

Upvotes: 1

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