Can give different color in CGContextSetRGBFillCol

问题:

How can I give the color HEXCOLOR(0xe3f3fbff) in CGContextSetRGBFillColor?

回答1:

Try

CGContextSetRGBFillColor(context, 0xe3 / 255.0, 0xf3 / 255.0, 0xfb / 255.0, 0xff / 255.0);

回答2:

CGContextSetRGBFillColor requires CGFloat values for R,G,B and alpha (from 0.0 to 1.0), so you'll have to convert every component of the hex color to values between 0.0 and 1.0.

In your case:

// R = 0xe3 / 0xff = 0.890
// G = 0xf3 / 0xff = 0.953
// B = 0xfb / 0xff = 0.984
// A = 0xff / 0xff = 1.000

CGContextSetRGBFillColor(context,0.89,0.953,0.984,1.0);

You can convert your hex color string to r,g,b,a values like this:

NSString  *color = @"0xe3f3fbff";

unsigned r,g,b,a;

[[NSScanner scannerWithString:[color substringWithRange:NSMakeRange(2,2)]] scanHexInt:&r];
[[NSScanner scannerWithString:[color substringWithRange:NSMakeRange(4,2)]] scanHexInt:&g];
[[NSScanner scannerWithString:[color substringWithRange:NSMakeRange(6,2)]] scanHexInt:&b];
[[NSScanner scannerWithString:[color substringWithRange:NSMakeRange(7,2)]] scanHexInt:&a];

CGContextSetRGBFillColor(context,r/255.0,g/255.0,b/255.0,a/255.0);