Drawing Text on UILabel with a gradient image - ios

Question

I have an UILabel subclass that draws some text in drawinRect method using a pattern image. This pattern image is a gradient image I am creating.
-(void)drawRect:(CGRect)rect
{
UIColor *color = [UIColor colorWithPatternImage:[self gradientImage]];
[color set];
[someText drawInRect:rec withFont:font lineBreakMode:UILineBreakModeWordWrap alignment:someAlignment];
}
The gradient image method is
-(UIImage *)gradientImage
{
NSData *colorData = [[NSUserDefaults standardUserDefaults] objectForKey:#"myColor"];
UIColor *co = [NSKeyedUnarchiver unarchiveObjectWithData:colorData];
colors = [NSArray arrayWithObjects:co,co,[UIColor whiteColor],co,co,co,co,nil];
NSArray *gradientColors=colors;
CGFloat width;
CGFloat height;
CGSize textSize = [someText sizeWithFont:font];
width=textSize.width; height=textSize.height;
UIGraphicsBeginImageContext(CGSizeMake(width, height));
// get context
CGContextRef context = UIGraphicsGetCurrentContext();
// push context to make it current (need to do this manually because we are not drawing in a UIView)
UIGraphicsPushContext(context);
//draw gradient
CGGradientRef gradient;
CGColorSpaceRef rgbColorspace;
//set uniform distribution of color locations
size_t num_locations = [gradientColors count];
CGFloat locations[num_locations];
for (int k=0; k<num_locations; k++)
{
locations[k] = k / (CGFloat)(num_locations - 1); //we need the locations to start at 0.0 and end at 1.0, equaly filling the domain
}
//create c array from color array
CGFloat components[num_locations * 4];
for (int i=0; i<num_locations; i++)
{
UIColor *color = [gradientColors objectAtIndex:i];
NSAssert(color.canProvideRGBComponents, #"Color components could not be extracted from StyleLabel gradient colors.");
components[4*i+0] = color.red;
components[4*i+1] = color.green;
components[4*i+2] = color.blue;
components[4*i+3] = color.alpha;
}
rgbColorspace = CGColorSpaceCreateDeviceRGB();
gradient = CGGradientCreateWithColorComponents(rgbColorspace, components, locations, num_locations);
CGRect currentBounds = self.bounds;
CGPoint topCenter = CGPointMake(CGRectGetMidX(currentBounds), 0.0f);
CGPoint midCenter = CGPointMake(CGRectGetMidX(currentBounds), CGRectGetMidY(currentBounds));
CGContextDrawLinearGradient(context, gradient, topCenter, midCenter, 0);
CGGradientRelease(gradient);
CGColorSpaceRelease(rgbColorspace);
// pop context
UIGraphicsPopContext();
// get a UIImage from the image context
UIImage *gradientImage = UIGraphicsGetImageFromCurrentImageContext();
// clean up drawing environment
UIGraphicsEndImageContext();
return gradientImage;
}
Everything is working fine. The text is drawn with nice glossy effect. Now my problem is if I change the x or y position of the text inside the UILabel and then call the
[someText drawinRect:rec]... to redraw, the gloss effect is generated differently. It seems that the pattern image is changing with change of text position..
The following is the effect for the frame rec = CGRectMake(0, 10, self.frame.size.width, self.frame.size.height);
The following is the effect for the frame rec = CGRectMake(0, 40, self.frame.size.width, self.frame.size.height);
I hope I have explained my question well. Could not find any exact answer elsewhere. Thanks in advance.

Answer 1

You might want to look at using an existing 3rd party solution like FXLabel.