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;
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;
}