Question

I have an UIColor object that will be the color for a bar in a bar chart graph. I would like to make this color into a linear gradient that will go from the color to a lighter version of that color and back to the initial color. I think CGGradientCreateWithColorComponents is the function for this but I’m not sure how to use it … How do I obtain the lighter version of my color ? and use it in the gradient. I’m fairly new to core graphics .

Thanks …

Answer 1

I use CAGradientLayer in the Quartz Core framework. It accepts an array of CGColorRef colors that can be used to form a gradient. Some example code is displayed below for handling a UIColor in color. You can modify the brightness or other HSB parameters to achieve what you want.

CGFloat hue;
CGFloat saturation;
CGFloat brightness;
CGFloat alpha;
[ color getHue:&hue saturation:&saturation brightness:&brightness alpha:&alpha ]

CAGradientLayer *gradient = [ CAGradientLayer layer ];
gradient.frame = self.bounds;
gradientColorsArray = [ NSArray arrayWithObjects:
    (id) [[ UIColor colorWithHue:1.0 saturation:1.0 brightness:1.0 alpha:1.0 ] CGColor],
    (id) [[ UIColor colorWithHue:1.0 saturation:1.0 brightness:0.75 alpha:1.0 ] CGColor],
     nil ];
gradient.colors = gradientColorsArray;
gradient.startPoint = CGPointMake(0.5f, 0.0f);
gradient.endPoint = CGPointMake(0.5f, 1.0f);
[ self.layer addSublayer:gradient ];