I was looking to be able to turn any UIColor into a gradient. The way I am intending to do this is by using Core Graphics to draw a gradient. What I am trying to do is to ge
- (UIColor *)lighterColorForColor:(UIColor *)c
{
CGFloat r, g, b, a;
if ([c getRed:&r green:&g blue:&b alpha:&a])
return [UIColor colorWithRed:MIN(r + 0.2, 1.0)
green:MIN(g + 0.2, 1.0)
blue:MIN(b + 0.2, 1.0)
alpha:a];
return nil;
}
- (UIColor *)darkerColorForColor:(UIColor *)c
{
CGFloat r, g, b, a;
if ([c getRed:&r green:&g blue:&b alpha:&a])
return [UIColor colorWithRed:MAX(r - 0.2, 0.0)
green:MAX(g - 0.2, 0.0)
blue:MAX(b - 0.2, 0.0)
alpha:a];
return nil;
}
Use it like this:
UIColor *baseColor = // however you obtain your color
UIColor *lighterColor = [self lighterColorForColor:baseColor];
UIColor *darkerColor = [self darkerColorForColor:baseColor];
EDIT: as @Anchu Chimala pointed out, for maximum flexibility, these methods should be implemented as an UIColor category. Also, from @Riley's idea, it may be a better idea to make the color proprtionally darker or lighter instead of adding or subtracting constant values. As @jrturton pointed out, it's not necessary to manipulate the RGB components; it's better to modify the brightness property itself. All in all:
@implementation UIColor (LightAndDark)
- (UIColor *)lighterColor
{
CGFloat h, s, b, a;
if ([self getHue:&h saturation:&s brightness:&b alpha:&a])
return [UIColor colorWithHue:h
saturation:s
brightness:MIN(b * 1.3, 1.0)
alpha:a];
return nil;
}
- (UIColor *)darkerColor
{
CGFloat h, s, b, a;
if ([self getHue:&h saturation:&s brightness:&b alpha:&a])
return [UIColor colorWithHue:h
saturation:s
brightness:b * 0.75
alpha:a];
return nil;
}
@end
I'm not sure if you're looking for some sort of Objective-C answer, but based on how colors specified by RGBA work, I think you can simply scale the RGB values according to an arbitrary factor to get a "lighter" or "darker" shade. For example, you might have a blue:
[UIColor colorWithRed:0.0 green:0.0 blue:1.0 alpha:1.0];
Want a darker blue? Multiply the RGB values by 0.9:
[UIColor colorWithRed:0.0 green:0.0 blue:0.9 alpha:1.0];
Voila. Or maybe you have an orange:
[UIColor colorWithRed:1.0 green:0.4 blue:0.0 alpha:1.0];
Choose another scale factor, say, 0.8:
[UIColor colorWithRed:0.8 green:0.32 blue:0.0 alpha:1.0];
Is that the sort of effect you're looking for?
None of the solutions posted quite worked for all colours and shades, but then I stumbled across this library which provides a set of very well implemented extensions to UIColor.
Specifically it has a lighten function as part of its HSL implementation: (UIColor *)lighten:(CGFloat)amount
- which works perfectly.
I render coloured cells based on a status value:
For this I wrote a swift extension based on some old objc code after I got an error using CryingHippo's suggestion:
extension UIColor{
func darker(darker: CGFloat) -> UIColor{
var red: CGFloat = 0.0
var green: CGFloat = 0.0
var blue: CGFloat = 0.0
if self.colorSpace == UIColorSpace.genericGrayColorSpace(){
red = whiteComponent - darker
green = whiteComponent - darker
blue = whiteComponent - darker
} else {
red = redComponent - darker
green = greenComponent - darker
blue = blueComponent - darker
}
if red < 0{
green += red/2
blue += red/2
}
if green < 0{
red += green/2
blue += green/2
}
if blue < 0{
green += blue/2
red += blue/2
}
return UIColor(
calibratedRed: red,
green: green,
blue: blue,
alpha: alphaComponent
)
}
func lighter(lighter: CGFloat) -> UIColor{
return darker(-lighter)
}
}
The same works for NSColor
as well. Simply replace UIColor
with NSColor
.
user529758's solution in Swift:
Darker color:
func darkerColorForColor(color: UIColor) -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if color.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: max(r - 0.2, 0.0), green: max(g - 0.2, 0.0), blue: max(b - 0.2, 0.0), alpha: a)
}
return UIColor()
}
Lighter color:
func lighterColorForColor(color: UIColor) -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if color.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: min(r + 0.2, 1.0), green: min(g + 0.2, 1.0), blue: min(b + 0.2, 1.0), alpha: a)
}
return UIColor()
}
Sebyffffd
solution as an extension:
extension UIColor {
func darker() -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if self.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: max(r - 0.2, 0.0), green: max(g - 0.2, 0.0), blue: max(b - 0.2, 0.0), alpha: a)
}
return UIColor()
}
func lighter() -> UIColor {
var r:CGFloat = 0, g:CGFloat = 0, b:CGFloat = 0, a:CGFloat = 0
if self.getRed(&r, green: &g, blue: &b, alpha: &a){
return UIColor(red: min(r + 0.2, 1.0), green: min(g + 0.2, 1.0), blue: min(b + 0.2, 1.0), alpha: a)
}
return UIColor()
}
}
Usage:
let darkerYellow = UIColor.yellow.darker()
let lighterYellow = UIColor.yellow.lighter()