我從相機獲取UIimage，并將它們分配給UIImageViews進行顯示。當我這樣做時，相機會給我一個1200 x 1600像素的圖像，然后將其分配給我的應用程序中的UIImageView。在這種情況下，圖像將按預期顯示在圖像視圖中。但是，當我嘗試在將檢索到的UIImage分配給UIImageView之前重新調整其大小時，該圖像正在按預期調整大小，但是在某個地方（在RESIZING代碼中）存在一個問題，我的UIImage變得旋轉了...結果，當我將調整大小的UIImage分配給UIImageView時，圖像將旋轉90度并顯示為拉伸，因為縱橫比（1200 x 1600像素）未更改...我正在使用它從Camera獲取UIImage：- (void) imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info{ myImg = [info objectForKey:@"UIImagePickerControllerOriginalImage"]; myResizedImg = [self resizeImage:myImg width:400 height:533]; [myImageView setImage:myResizedImg];}我正在使用它來調整它的大小：-(UIImage *)resizeImage:(UIImage *)anImage width:(int)width height:(int)height{ CGImageRef imageRef = [anImage CGImage]; CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef); if (alphaInfo == kCGImageAlphaNone) alphaInfo = kCGImageAlphaNoneSkipLast; CGContextRef bitmap = CGBitmapContextCreate(NULL, width, height, CGImageGetBitsPerComponent(imageRef), 4 * width, CGImageGetColorSpace(imageRef), alphaInfo); CGContextDrawImage(bitmap, CGRectMake(0, 0, width, height), imageRef); CGImageRef ref = CGBitmapContextCreateImage(bitmap); UIImage *result = [UIImage imageWithCGImage:ref]; CGContextRelease(bitmap); CGImageRelease(ref); return result; }問題：如何在不旋轉像素的情況下調整從相機拉出的UIImage的大??？
3 回答
慕哥6287543
TA貢獻1831條經驗 獲得超10個贊
您的代碼不起作用的原因是因為沒有考慮您所擁有的代碼上的imageOrientation。具體來說，如果imageOrientation為右/左，則需要同時旋轉圖像和交換寬度/高度。這是執行此操作的一些代碼：
-(UIImage*)imageByScalingToSize:(CGSize)targetSize
{
UIImage* sourceImage = self;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGImageRef imageRef = [sourceImage CGImage];
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;
}
這將調整圖像的大小并將其旋轉到正確的方向。如果需要弧度的定義，則為：
static inline double radians (double degrees) {return degrees * M_PI/180;}
Daniel給出的答案也是正確的，但是由于您使用的是UIGraphicsBeginImageContext（），因此它存在線程不安全的問題。由于上述代碼僅使用CG功能，因此已全部準備就緒。我還有一個類似的功能，可以調整大小并在圖像上進行適當的縱橫比填充-讓我知道這是否是您要的內容。
江戶川亂折騰
TA貢獻1851條經驗 獲得超5個贊
我那里的一些代碼也遇到了這個問題，我發現此代碼有效，請檢查一下，讓我知道您找到了什么
+ (UIImage*)imageWithImage:(UIImage*)image
scaledToSize:(CGSize)newSize;
{
UIGraphicsBeginImageContext( newSize );
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
白板的微信
TA貢獻1883條經驗 獲得超3個贊
如果要通過在矩形圖像（水平或垂直）中通過在兩側的寬度或高度進行裁剪來制作正方形圖像，請使用我的代碼。所不同的是，我不會伸展，但會收割。我通過修改從最上面的代碼中獲得了它：
//Cropping _image to fit it to the square by height or width
CGFloat a = _image.size.height;
CGFloat b = _image.size.width;
CGRect cropRect;
if (!(a==b)) {
if (a<b) {
cropRect = CGRectMake((b-a)/2.0, 0, a, a);
b = a;
}
else if (b<a) {
cropRect = CGRectMake(0, (a-b)/2.0, b, b);
a = b;
}
CGImageRef imageRef = CGImageCreateWithImageInRect([_image CGImage], cropRect);
UIImage* sourceImage = _image;
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);
CGContextRef bitmap;
if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
bitmap = CGBitmapContextCreate(NULL, a, a, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
} else {
bitmap = CGBitmapContextCreate(NULL, a, a, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
}
if (sourceImage.imageOrientation == UIImageOrientationLeft) {
CGContextRotateCTM (bitmap, radians(90));
CGContextTranslateCTM (bitmap, 0, -a);
} else if (sourceImage.imageOrientation == UIImageOrientationRight) {
CGContextRotateCTM (bitmap, radians(-90));
CGContextTranslateCTM (bitmap, -a, 0);
} else if (sourceImage.imageOrientation == UIImageOrientationUp) {
// NOTHING
} else if (sourceImage.imageOrientation == UIImageOrientationDown) {
CGContextTranslateCTM (bitmap, a, a);
CGContextRotateCTM (bitmap, radians(-180.));
}
CGContextDrawImage(bitmap, CGRectMake(0, 0, a, a), imageRef);
CGImageRef ref = CGBitmapContextCreateImage(bitmap);
_image = [UIImage imageWithCGImage:ref];
CGImageRelease(imageRef);
}
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