Comments on: Manipulating UIColors http://www.cocoanetics.com/2009/10/manipulating-uicolors/ Our DNA is written in Objective-C Mon, 14 May 2012 19:43:35 +0100 hourly 1 http://wordpress.org/?v=3.3.2 By: mariomariani.myopenid.com/ http://www.cocoanetics.com/2009/10/manipulating-uicolors/#comment-1427 mariomariani.myopenid.com/ Fri, 12 Mar 2010 16:23:29 +0000 http://www.drobnik.com/touch/?p=1352#comment-1427 Good stuff, but... Why not? - (UIColor *)colorByDarkeningColorBy:(CGFloat)alpha { CGColorRef oldColor = CGColorCreateCopyWithAlpha([self CGColor], alpha); UIColor *newColor = [UIColor colorWithCGColor:oldColor]; CGColorRelease(oldColor); return newColor; } Good stuff, but… Why not?

- (UIColor *)colorByDarkeningColorBy:(CGFloat)alpha
{
CGColorRef oldColor = CGColorCreateCopyWithAlpha([self CGColor], alpha);
UIColor *newColor = [UIColor colorWithCGColor:oldColor];
CGColorRelease(oldColor);

return newColor;
}

]]> By: rudifa http://www.cocoanetics.com/2009/10/manipulating-uicolors/#comment-1426 rudifa Tue, 03 Nov 2009 16:54:18 +0000 http://www.drobnik.com/touch/?p=1352#comment-1426 Manipulating UIColor : just what I was looking for. Thank you! I made a generalization of your darkening method, here it is for anyone interested : <code> - (UIColor *)colorByDarkeningColorBy:(CGFloat)factor0to1 { // oldComponents is the array INSIDE the original color // changing these changes the original, so we copy it CGFloat *oldComponents = (CGFloat *)CGColorGetComponents([self CGColor]); CGFloat newComponents[4]; int numComponents = CGColorGetNumberOfComponents([self CGColor]); switch (numComponents) { case 2: { //grayscale newComponents[0] = oldComponents[0]*factor0to1; newComponents[1] = oldComponents[0]*factor0to1; newComponents[2] = oldComponents[0]*factor0to1; newComponents[3] = oldComponents[1]; break; } case 4: { //RGBA newComponents[0] = oldComponents[0]*factor0to1; newComponents[1] = oldComponents[1]*factor0to1; newComponents[2] = oldComponents[2]*factor0to1; newComponents[3] = oldComponents[3]; break; } } CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); CGColorRef newColor = CGColorCreate(colorSpace, newComponents); CGColorSpaceRelease(colorSpace); UIColor *retColor = [UIColor colorWithCGColor:newColor]; CGColorRelease(newColor); return retColor; } </code> Manipulating UIColor : just what I was looking for. Thank you!

I made a generalization of your darkening method, here it is for anyone interested :

- (UIColor *)colorByDarkeningColorBy:(CGFloat)factor0to1
{
// oldComponents is the array INSIDE the original color
// changing these changes the original, so we copy it
CGFloat *oldComponents = (CGFloat *)CGColorGetComponents([self CGColor]);
CGFloat newComponents[4];

int numComponents = CGColorGetNumberOfComponents([self CGColor]);

switch (numComponents)
{
case 2:
{
//grayscale
newComponents[0] = oldComponents[0]*factor0to1;
newComponents[1] = oldComponents[0]*factor0to1;
newComponents[2] = oldComponents[0]*factor0to1;
newComponents[3] = oldComponents[1];
break;
}
case 4:
{
//RGBA
newComponents[0] = oldComponents[0]*factor0to1;
newComponents[1] = oldComponents[1]*factor0to1;
newComponents[2] = oldComponents[2]*factor0to1;
newComponents[3] = oldComponents[3];
break;
}
}

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGColorRef newColor = CGColorCreate(colorSpace, newComponents);
CGColorSpaceRelease(colorSpace);

UIColor *retColor = [UIColor colorWithCGColor:newColor];
CGColorRelease(newColor);

return retColor;
}

]]> By: wuf810 http://www.cocoanetics.com/2009/10/manipulating-uicolors/#comment-1425 wuf810 Tue, 06 Oct 2009 11:14:37 +0000 http://www.drobnik.com/touch/?p=1352#comment-1425 Brilliantly useful. Just last night I was looking up the native values of the default colors (like redColor etc.) just so I could set an lapha by re-creating them using colorWithRed.... Thanks, M. Brilliantly useful.

Just last night I was looking up the native values of the default colors (like redColor etc.) just so I could set an lapha by re-creating them using colorWithRed….

Thanks, M.

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