UIView / UIImage 截圖(capture), 縮放(scale), 設定大小(resize), 儲存(save)

转载：http://hi.baidu.com/%B0%D9ii%D6%AAi%B5%C0/blog/item/04bfba11799d5cc5f6039e41.html

寫iOS App我最怕遇到的三樣處理, 大概就是1.影音, 2.網路 3.圖片

沒了這三樣還能叫App嗎? 大概是我coding功力不夠吧

今天來講講圖片的處理...

圖片的處理大概就分這幾樣了截圖(capture), 縮放(scale),設定大小(resize), 儲存(save)

這幾樣比較好處理, 另外還有濾鏡, 擦拭等, 以後再說

在這個Demo code裡, 我寫了幾個方法

1.等比率縮放

- (UIImage *)scaleImage:(UIImage *)imagetoScale:(float)scaleSize

{

UIGraphicsBeginImageContext(CGSizeMake(image.size.width*scaleSize,image.size.height*scaleSize);

[image drawInRect:CGRectMake(0, 0,image.size.width * scaleSize, image.size.height *scaleSize)];

UIImage *scaledImage =UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return scaledImage;

}

2.自定長寬

- (UIImage *)reSizeImage:(UIImage *)imagetoSize:(CGSize)reSize

{

UIGraphicsBeginImageContext(CGSizeMake(reSize.width,reSize.height));

[image drawInRect:CGRectMake(0, 0, reSize.width,reSize.height)];

UIImage *reSizeImage =UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return reSizeImage;

}

3.處理某個特定View

只要是繼承UIVIEW的object 都可以處理

必須先importQuzrtzCore.framework

-(UIImage*)captureView:(UIView *)theView

{

CGRect rect = theView.frame;

UIGraphicsBeginImageContext(rect.size);

CGContextRef context =UIGraphicsGetCurrentContext();

[theView.layer renderInContext:context];

UIImage *img =UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return img;

}

4.儲存圖片

儲存圖片這裡我分成儲存到app的文件裡, 儲存到手機的圖片庫裡

儲存到app

NSString *path = [[NSHomeDirectory()stringByAppendingPathComponent:@"Documents"]stringByAppendingPathComponent:@"image.png"];

[UIImagePNGRepresentation(image) writeToFile:pathatomically:YES];

這樣就把你要處理的圖片, 以image.png這個檔名存到app home底下的Documents目錄裡

儲存到手機圖片庫裡

CGImageRef screen = UIGetScreenImage();

UIImage* image = [UIImage imageWithCGImage:screen];

CGImageRelease(screen);

UIImageWriteToSavedPhotosAlbum(image, self, nil, nil);

UIGetScreenImage()原本是private(私有)api, 用來截取整個畫面

不過SDK 4.0後apple就開放了

另外儲存到手機的圖片庫裡, 必須在實機使用, 模擬器無法使用