iPhone剪切技巧

iPhone中的剪切技巧: 

1.获取图形上下文 
2.构造剪切的路径(形状)

3.构建剪切区域 
4.贴上你的画

 

1. // 1  
2. CGContextRef context = UIGraphicsGetCurrentContext();  
3.   
4. // 2  
5. CGRect bounds = CGRectMake(0.0f, 0.0f, SIDELENGTH, SIDELENGTH);  
6. CGMutablePathRef path = CGPathCreateMutable();  
7. CGPathAddEllipseInRect(path, NULL, bounds);  
8.   
9. // 3  
10. CGContextAddPath(context, path);  
11. CGContextClip(context);  
12.   
13. // 4  
14. [LOGO drawInRect:bounds];  

-(UIImage*)getClipImageRect:(CGRect)cropRect

{

    CGImageRef imageRef =CGImageCreateWithImageInRect([self.photoCGImage], cropRect);

    UIImage *result = [UIImage imageWithCGImage:imageRef];

    CGImageRelease(imageRef);

    return result;

}

    // Create appropriately modified image.

UIImage *image = nil;

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= 40000

if ([[[UIDevice currentDevice] systemVersion] floatValue] >= 4.0) {

UIGraphicsBeginImageContextWithOptions(destRect.size, NO, 0.0); // 0.0 for scale means "correct scale for device's main screen".

CGImageRef sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect); // cropping happens here.

image = [UIImage imageWithCGImage:sourceImg scale:0.0 orientation:self.imageOrientation]; // create cropped UIImage.

[image drawInRect:destRect]; // the actual scaling happens here, and orientation is taken care of automatically.

CGImageRelease(sourceImg);

image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

}

#endif

if (!image) {

// Try older method.

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

CGContextRef context = CGBitmapContextCreate(NULL, fitSize.width, fitSize.height, 8, (fitSize.width * 4), 

colorSpace, kCGImageAlphaPremultipliedLast);

CGImageRef sourceImg = CGImageCreateWithImageInRect([self CGImage], sourceRect);

CGContextDrawImage(context, destRect, sourceImg);

CGImageRelease(sourceImg);

CGImageRef finalImage = CGBitmapContextCreateImage(context);

CGContextRelease(context);

CGColorSpaceRelease(colorSpace);

image = [UIImage imageWithCGImage:finalImage];

CGImageRelease(finalImage);

}