Objective-C UIImageをアスペク比を保ったままリサイズ
UIImageのアスペクト比を保ったまま、画像をリサイズする。
引数で渡す、NIIntegerでsizeを指定したサイズ未満に画像をリサイズします。
縦長い画像はheightが、横長画像の場合はがwidthが指定したサイズになります。
参考プログラム
http://stackoverflow.com/questions/1282830/uiimagepickercontroller-uiimage-memory-and-more
#import "ImageResize.h" @implementation ImageResize #define radians( degrees ) ( degrees * M_PI / 180 ) + (UIImage*)resizeAspectFit:(UIImage*)sourceImage size:(NSInteger)size { CGImageRef imageRef = [sourceImage CGImage]; size_t w = CGImageGetWidth(imageRef); size_t h = CGImageGetHeight(imageRef); CGFloat targetWidth, targetHeight; if (w>h) { targetWidth = size; targetHeight = h * targetWidth / w; } else { targetWidth = size; targetHeight = w * targetWidth / h; } NSLog(@"image resize w=%ld h=%ld -> w=%f h=%f", w, h, targetWidth, targetHeight); CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef); CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef); if (bitmapInfo == kCGImageAlphaNone) { bitmapInfo = kCGImageAlphaNoneSkipLast; } CGContextRef bitmap; if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) { bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo); } else { bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo); } if (sourceImage.imageOrientation == UIImageOrientationLeft) { CGContextRotateCTM (bitmap, radians(90)); CGContextTranslateCTM (bitmap, 0, -targetHeight); } else if (sourceImage.imageOrientation == UIImageOrientationRight) { CGContextRotateCTM (bitmap, radians(-90)); CGContextTranslateCTM (bitmap, -targetWidth, 0); } else if (sourceImage.imageOrientation == UIImageOrientationUp) { // NOTHING } else if (sourceImage.imageOrientation == UIImageOrientationDown) { CGContextTranslateCTM (bitmap, targetWidth, targetHeight); CGContextRotateCTM (bitmap, radians(-180.)); } CGContextDrawImage(bitmap, CGRectMake(0, 0, targetWidth, targetHeight), imageRef); CGImageRef ref = CGBitmapContextCreateImage(bitmap); UIImage* newImage = [UIImage imageWithCGImage:ref]; CGContextRelease(bitmap); CGImageRelease(ref); return newImage; } @end