学步园

做一个UIImage的category，直接上代码：

- (UIImage *) imageWithBackgroundColor:(UIColor *)bgColor<br /> shadeAlpha1:(CGFloat)alpha1<br /> shadeAlpha2:(CGFloat)alpha2<br /> shadeAlpha3:(CGFloat)alpha3<br /> shadowColor:(UIColor *)shadowColor<br /> shadowOffset:(CGSize)shadowOffset<br /> shadowBlur:(CGFloat)shadowBlur {<br /> UIImage *image = self;<br /> CGColorRef cgColor = [bgColor CGColor];<br /> CGColorRef cgShadowColor = [shadowColor CGColor];<br /> CGFloat components[16] = {1,1,1,alpha1,1,1,1,alpha1,1,1,1,alpha2,1,1,1,alpha3};<br /> CGFloat locations[4] = {0,0.5,0.6,1};<br /> CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();<br /> CGGradientRef colorGradient = CGGradientCreateWithColorComponents(colorSpace, components, locations, (size_t)4);<br /> CGRect contextRect;<br /> contextRect.origin.x = 0.0f;<br /> contextRect.origin.y = 0.0f;<br /> contextRect.size = [image size];<br /> //contextRect.size = CGSizeMake([image size].width+5,[image size].height+5);<br /> // Retrieve source image and begin image context<br /> UIImage *itemImage = image;<br /> CGSize itemImageSize = [itemImage size];<br /> CGPoint itemImagePosition;<br /> itemImagePosition.x = ceilf((contextRect.size.width - itemImageSize.width) / 2);<br /> itemImagePosition.y = ceilf((contextRect.size.height - itemImageSize.height) / 2);<br /> UIGraphicsBeginImageContext(contextRect.size);<br /> CGContextRef c = UIGraphicsGetCurrentContext();<br /> // Setup shadow<br /> CGContextSetShadowWithColor(c, shadowOffset, shadowBlur, cgShadowColor);<br /> // Setup transparency layer and clip to mask<br /> CGContextBeginTransparencyLayer(c, NULL);<br /> CGContextScaleCTM(c, 1.0, -1.0);<br /> CGContextClipToMask(c, CGRectMake(itemImagePosition.x, -itemImagePosition.y, itemImageSize.width, -itemImageSize.height), [itemImage CGImage]);<br /> // Fill and end the transparency layer<br /> CGContextSetFillColorWithColor(c, cgColor);<br /> contextRect.size.height = -contextRect.size.height;<br /> CGContextFillRect(c, contextRect);<br /> CGContextDrawLinearGradient(c, colorGradient,CGPointZero,CGPointMake(contextRect.size.width*1.0/4.0,contextRect.size.height),0);<br /> CGContextEndTransparencyLayer(c);<br /> //CGPointMake(contextRect.size.width*3.0/4.0, 0)<br /> // Set selected image and end context<br /> UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();<br /> UIGraphicsEndImageContext();<br /> CGColorSpaceRelease(colorSpace);<br /> CGGradientRelease(colorGradient);<br /> return resultImage;<br /> } 

用法如下：

UIImage *niceImage = [[UIImage imageNamed:@"image_name"] imageWithBackgroundColor:[UIColor colorWithRed:41.0/255.0 green:147.0/255.0 blue:239.0/255.0 alpha:1.0]<br /> shadeAlpha1:0.6<br /> shadeAlpha2:0.0<br /> shadeAlpha3:0.4<br /> shadowColor:[UIColor blackColor]<br /> shadowOffset:CGSizeMake(0.0f, -1.0f)<br /> shadowBlur:3.0];<br />