调整从相机拉出的UIimage的大小也会旋转UIimage吗？

Question

我从相机获取UIimage，并将它们分配给UIImageViews进行显示。当我这样做时，相机会给我一个1200 x 1600像素的图像，然后将其分配给我的应用程序中的UIImageView。在这种情况下，图像将按预期显示在图像视图中。但是，当我尝试在将检索到的UIImage分配给UIImageView之前重新调整其大小时，该图像正在按预期调整大小，但是在某个地方（在RESIZING代码中）存在一个问题，我的UIImage变得旋转了...结果，当我将调整大小的UIImage分配给UIImageView时，图像将旋转90度并显示为拉伸，因为纵横比（1200 x 1600像素）未更改...

我正在使用它从Camera获取UIImage：

- (void) imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info

{

        myImg = [info objectForKey:@"UIImagePickerControllerOriginalImage"];

        myResizedImg = [self resizeImage:myImg width:400 height:533];

        [myImageView setImage:myResizedImg];

}

我正在使用它来调整它的大小：

-(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;  

}

问题：如何在不旋转像素的情况下调整从相机拉出的UIImage的大小？

Answer 1

您的代码不起作用的原因是因为没有考虑您所拥有的代码上的imageOrientation。具体来说，如果imageOrientation为右/左，则需要同时旋转图像和交换宽度/高度。这是执行此操作的一些代码：-(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; }这将调整图像的大小并将其旋转到正确的方向。如果需要弧度的定义，则为：static inline double radians (double degrees) {return degrees * M_PI/180;}Daniel给出的答案也是正确的，但是由于您使用的是UIGraphicsBeginImageContext（），因此它存在线程不安全的问题。由于上述代码仅使用CG功能，因此已全部准备就绪。我还有一个类似的功能，可以调整大小并在图像上进行适当的纵横比填充-让我知道这是否是您要的内容。

Answer 2

我那里的一些代码也遇到了这个问题，我发现此代码有效，请检查一下，让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;}

Answer 3

如果要通过在矩形图像（水平或垂直）中通过在两侧的宽度或高度进行裁剪来制作正方形图像，请使用我的代码。所不同的是，我不会伸展，但会收割。我通过修改从最上面的代码中获得了它：//Cropping _image to fit it to the square by height or widthCGFloat a = _image.size.height;CGFloat b = _image.size.width;CGRect cropRect;if (!(a==b)) {&nbsp; &nbsp; if (a<b) {&nbsp; &nbsp; &nbsp; &nbsp; cropRect = CGRectMake((b-a)/2.0, 0, a, a);&nbsp; &nbsp; &nbsp; &nbsp; b = a;&nbsp; &nbsp; }&nbsp; &nbsp; else if (b<a) {&nbsp; &nbsp; &nbsp; &nbsp; cropRect = CGRectMake(0, (a-b)/2.0, b, b);&nbsp; &nbsp; &nbsp; &nbsp; a = b;&nbsp; &nbsp; }&nbsp; &nbsp; CGImageRef imageRef = CGImageCreateWithImageInRect([_image CGImage], cropRect);&nbsp; &nbsp; UIImage* sourceImage = _image;&nbsp;&nbsp; &nbsp; CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);&nbsp; &nbsp; CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);&nbsp; &nbsp; CGContextRef bitmap;&nbsp; &nbsp; if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {&nbsp; &nbsp; &nbsp; &nbsp; bitmap = CGBitmapContextCreate(NULL, a, a, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);&nbsp; &nbsp; } else {&nbsp; &nbsp; &nbsp; &nbsp; bitmap = CGBitmapContextCreate(NULL, a, a, CGImageGetBitsPerComponent(imageRef), CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);&nbsp; &nbsp; }&nbsp; &nbsp; if (sourceImage.imageOrientation == UIImageOrientationLeft) {&nbsp; &nbsp; &nbsp; &nbsp; CGContextRotateCTM (bitmap, radians(90));&nbsp; &nbsp; &nbsp; &nbsp; CGContextTranslateCTM (bitmap, 0, -a);&nbsp; &nbsp; } else if (sourceImage.imageOrientation == UIImageOrientationRight) {&nbsp; &nbsp; &nbsp; &nbsp; CGContextRotateCTM (bitmap, radians(-90));&nbsp; &nbsp; &nbsp; &nbsp; CGContextTranslateCTM (bitmap, -a, 0);&nbsp; &nbsp; } else if (sourceImage.imageOrientation == UIImageOrientationUp) {&nbsp; &nbsp; &nbsp; &nbsp; // NOTHING&nbsp; &nbsp; } else if (sourceImage.imageOrientation == UIImageOrientationDown) {&nbsp; &nbsp; &nbsp; &nbsp; CGContextTranslateCTM (bitmap, a, a);&nbsp; &nbsp; &nbsp; &nbsp; CGContextRotateCTM (bitmap, radians(-180.));&nbsp; &nbsp; }&nbsp; &nbsp; CGContextDrawImage(bitmap, CGRectMake(0, 0, a, a), imageRef);&nbsp; &nbsp; CGImageRef ref = CGBitmapContextCreateImage(bitmap);&nbsp; &nbsp; _image = [UIImage imageWithCGImage:ref];&nbsp; &nbsp; CGImageRelease(imageRef);}