UIImage 裁剪图片和等比列缩放图片

本文转载至 http://blog.csdn.net/cuiweijie3/article/details/9514293

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:[NSURLURLWithString:@"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;