UIImage 裁剪图片和等比列缩放图片

转自 http://www.tedz.me/ios/uiimage-crop-resize-image

@interface UIImage(UIImageScale)

-(UIImage*)getSubImage:(CGRect)rect;

-(UIImage*)scaleToSize:(CGSize)size;

@end

 

@implementation UIImage(UIImageScale)

 

//截取部分图像

-(UIImage*)getSubImage:(CGRect)rect

{

    CGImageRef subImageRef = CGImageCreateWithImageInRect(self.CGImage, rect);

    CGRect smallBounds = CGRectMake(0, 0, CGImageGetWidth(subImageRef), CGImageGetHeight(subImageRef));

 

    UIGraphicsBeginImageContext(smallBounds.size);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextDrawImage(context, smallBounds, subImageRef);

    UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];

    UIGraphicsEndImageContext();

 

    return smallImage;

}

 

//等比例缩放

-(UIImage*)scaleToSize:(CGSize)size

{

    CGFloat width = CGImageGetWidth(self.CGImage);

    CGFloat height = CGImageGetHeight(self.CGImage);

 

    float verticalRadio = size.height*1.0/height;

    float horizontalRadio = size.width*1.0/width;

 

    float radio = 1;

    if(verticalRadio>1 && horizontalRadio>1)

    {

        radio = verticalRadio > horizontalRadio ? horizontalRadio : verticalRadio;

    }

    else

    {

        radio = verticalRadio < horizontalRadio ? verticalRadio : horizontalRadio;

    }

 

    width = width*radio;

    height = height*radio;

 

    int xPos = (size.width - width)/2;

    int yPos = (size.height-height)/2;

 

    // 创建一个bitmap的context

    // 并把它设置成为当前正在使用的context

    UIGraphicsBeginImageContext(size);  

 

    // 绘制改变大小的图片

    [self drawInRect:CGRectMake(xPos, yPos, width, height)];  

 

    // 从当前context中创建一个改变大小后的图片

    UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();  

 

    // 使当前的context出堆栈

    UIGraphicsEndImageContext();  

 

    // 返回新的改变大小后的图片

    return scaledImage;

}

@end

 

然后在下面方法里面调用就可以了！

 

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

{

    // Override point for customization after application launch.

    UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://img21.mtime.cn/mg/2011/09/24/112524.53149978.jpg"]] ];

 

    // 裁剪图片

    //image = [image getSubImage:CGRectMake(10, 10, 70, 80)];

 

    //等比列缩放

 

    image = [image scaleToSize:CGSizeMake(200, 300)];

 

    UIImageView *imageView = [[UIImageView alloc] initWithImage:image];

 

    [self.window addSubview:imageView];

 

    NSLog(@"image.size:%@",NSStringFromCGSize(CGSizeMake(imageView.image.size.width, imageView.image.size.height)));   //打印获取的网络图片的宽度和高度

 

    [self.window makeKeyAndVisible];

    return YES;

}

 

//--------------截取部分图片到指定位置-------------------------

 

图片(UIImage*) img

要截取的起始坐标sx:(int) sx1 sy:(int)sy1

要截取的长度和宽度sw:(int) sw1 sh:(int) sh1

最终要显示的坐标desx:(int) desx1 desy:(int)desy1

 

-(UIImage*)objectiveDrawRegion:(UIImage*) img sx:(int) sx1 sy:(int)sy1 sw:(int) sw1 sh:(int) sh1 desx:(int) desx1 desy:(int)desy1{

[self saveImage:img name:@"objectiveDrawRegion1.png"];

 

//创建图片缓冲

void *imageDataRegion=malloc(screenWidth*screenHeight*32);

CGColorSpaceRef iColorSpaceRegion=CGColorSpaceCreateDeviceRGB();

    CGContextRefiDeviceRegion=CGBitmapContextCreate(imageDataRegion,screenWidth,screenHeight,8,4*screenWidth,iColorSpaceRegion,kCGImageAlphaPremultipliedLast);

 

//剪切区域

    CGRect clipRegion=CGRectMake(sx1,sy1,sw1,sh1);

    CGContextClipToRect(iDeviceRegion, clipRegion);

 

    CGFloat widthf=img.size.width;

    CGFloat heightf=img.size.height;

 

CGRect  cg=CGRectMake(0.0, 0.0, widthf, heightf);

//画底图

    CGContextDrawImage(iDeviceRegion,cg, img.CGImage);

 

//将缓冲形成图片

    CGImageRef ioffRegion=CGBitmapContextCreateImage(iDeviceRegion);

 

CGRect  cg1=CGRectMake(desx1, desy1, sw1, sh1);

UIImage *ui=[UIImage imageWithCGImage:ioffRegion];

 

CGContextDrawImage(当前context,cg1, ui.CGImage);

 

//清除缓冲

   CGColorSpaceRelease(iColorSpaceRegion);

   CGContextRelease(iDeviceRegion);

   CGImageRelease(ioffRegion);

   free(imageDataRegion);

//    iDeviceRegion=NULL;

//    imageDataRegion=0;

 

return ui;

}