在网上发现很多人使用
CGContextDrawImage(context,CGRectMake(0,0,self.width,self.height),[image CGImage]); //原图
CGContextDrawImage(context,rect,[mask CGImage]); //水印图
添加水印,图像会颠倒,还需要改变坐标
CGAffineTransform myTr = CGAffineTransformMake(1, 0, 0, -1, 0, self.height);
CGContextConcatCTM(context, myTr);
其实用drawInRect很方便,图片、文字都可以加
原理可参看前面转的图片相关操作(截取,缩略,翻转。。。。)
做了Category,下载
// 画水印
- (UIImage *) imageWithWaterMask:(UIImage*)mask inRect:(CGRect)rect
{
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000
if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0)
{
UIGraphicsBeginImageContextWithOptions([self size], NO, 0.0); // 0.0 for scale means "scale for device‘s main screen".
}
#else
if ([[[UIDevice currentDevice] systemVersion] floatValue] < 4.0)
{
UIGraphicsBeginImageContext([self size]);
}
#endif
//原图
[self drawInRect:CGRectMake(0, 0, self.size.width, self.size.height)];
//水印图
[mask drawInRect:rect];
UIImage *newPic = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newPic;
}