如何從UIImageView以全分辨率獲得旋轉，縮放和平移圖像？

Question

我有一個UIImageView，可以通過手勢識別器旋轉，平移和縮放。 因此，它在其封閉視圖中被裁剪 。 一切都很好，但我不知道如何以完整的分辨率保存圖片的可見部分 。 這不是一個屏幕抓取。

我知道我直接從UIImageView的可見內容中獲取UIImage，但它僅限於屏幕的分辨率。

我假設我必須在UIImage上進行相同的轉換並裁剪它。 有一個簡單的方法嗎？

更新 ：例如，我有一個高分辨率圖像的UIImageView，讓我們說一張800萬像素的iPhone 4s相機照片，它是用手勢轉換的，因此它會在其封閉視圖中縮放，旋轉和移動。 顯然有一些裁剪正在進行，因此只顯示了部分圖像。 顯示的屏幕分辨率和下划線圖像分辨率之間存在巨大差異，我需要圖像分辨率中的圖像。 UIImageView位於UIViewContentModeScaleAspectFit中 ，但是使用UIViewContentModeScaleAspectFill的解決方案也沒問題。

這是我的代碼：

- (void)rotatePiece:(UIRotationGestureRecognizer *)gestureRecognizer {

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
        [gestureRecognizer view].transform = CGAffineTransformRotate([[gestureRecognizer view] transform], [gestureRecognizer rotation]);
        [gestureRecognizer setRotation:0];
    }
}

- (void)scalePiece:(UIPinchGestureRecognizer *)gestureRecognizer {

    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {
        [gestureRecognizer view].transform = CGAffineTransformScale([[gestureRecognizer view] transform], [gestureRecognizer scale], [gestureRecognizer scale]);
        [gestureRecognizer setScale:1];
    }
}

-(void)panGestureMoveAround:(UIPanGestureRecognizer *)gestureRecognizer;
{
    UIView *piece = [gestureRecognizer view];

    //We pass in the gesture to a method that will help us align our touches so that the pan and pinch will seems to originate between the fingers instead of other points or center point of the UIView    
    if ([gestureRecognizer state] == UIGestureRecognizerStateBegan || [gestureRecognizer state] == UIGestureRecognizerStateChanged) {

        CGPoint translation = [gestureRecognizer translationInView:[piece superview]];
        [piece setCenter:CGPointMake([piece center].x + translation.x, [piece center].y+translation.y)];
        [gestureRecognizer setTranslation:CGPointZero inView:[piece superview]];
    } else if([gestureRecognizer state] == UIGestureRecognizerStateEnded) {
        //Put the code that you may want to execute when the UIView became larger than certain value or just to reset them back to their original transform scale
    }
}


- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
    // if the gesture recognizers are on different views, don't allow simultaneous recognition
    if (gestureRecognizer.view != otherGestureRecognizer.view)
        return NO;

    // if either of the gesture recognizers is the long press, don't allow simultaneous recognition
    if ([gestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]] || [otherGestureRecognizer isKindOfClass:[UILongPressGestureRecognizer class]])
        return NO;

    return YES;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    appDelegate = (AppDelegate *)[[UIApplication sharedApplication] delegate];    
    faceImageView.image = appDelegate.faceImage;

    UIRotationGestureRecognizer *rotationGesture = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotatePiece:)];
    [faceImageView addGestureRecognizer:rotationGesture];
    [rotationGesture setDelegate:self];

    UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scalePiece:)];
    [pinchGesture setDelegate:self];
    [faceImageView addGestureRecognizer:pinchGesture];

    UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panGestureMoveAround:)];
    [panRecognizer setMinimumNumberOfTouches:1];
    [panRecognizer setMaximumNumberOfTouches:2];
    [panRecognizer setDelegate:self];
    [faceImageView addGestureRecognizer:panRecognizer];


    [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:UIStatusBarAnimationNone];

    [appDelegate fadeObject:moveIcons StartAlpha:0 FinishAlpha:1 Duration:2];
    currentTimer = [NSTimer timerWithTimeInterval:4.0f target:self selector:@selector(fadeoutMoveicons) userInfo:nil repeats:NO];

    [[NSRunLoop mainRunLoop] addTimer: currentTimer forMode: NSDefaultRunLoopMode];

}

Answer 1

以下代碼使用計算的比例因子創建封閉視圖的快照（ faceImageView的clipsToBounds視圖，其中clipsToBounds設置為YES ）。

它假定faceImageView的內容模式是UIViewContentModeScaleAspectFit並且faceImageView的框架設置為enclosingView的邊界。

- (UIImage *)captureView {

    float imageScale = sqrtf(powf(faceImageView.transform.a, 2.f) + powf(faceImageView.transform.c, 2.f));    
    CGFloat widthScale = faceImageView.bounds.size.width / faceImageView.image.size.width;
    CGFloat heightScale = faceImageView.bounds.size.height / faceImageView.image.size.height;
    float contentScale = MIN(widthScale, heightScale);
    float effectiveScale = imageScale * contentScale;

    CGSize captureSize = CGSizeMake(enclosingView.bounds.size.width / effectiveScale, enclosingView.bounds.size.height / effectiveScale);

    NSLog(@"effectiveScale = %0.2f, captureSize = %@", effectiveScale, NSStringFromCGSize(captureSize));

    UIGraphicsBeginImageContextWithOptions(captureSize, YES, 0.0);        
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextScaleCTM(context, 1/effectiveScale, 1/effectiveScale);
    [enclosingView.layer renderInContext:context];   
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return img;
}

根據當前變換，生成的圖像將具有不同的大小。 例如，放大時，尺寸會變小。 您還可以將effectiveScale設置為常量值，以獲得具有恆定大小的圖像。

您的手勢識別器代碼不會限制比例因子，即您可以縮小/縮小而不受限制。 那可能非常危險！ 當你縮小時，我的捕捉方法可以輸出非常大的圖像。

如果縮小，捕獲圖像的背景將為黑色。 如果希望它是透明的，則必須將UIGraphicsBeginImageContextWithOptions的opaque參數設置為NO 。

Answer 2

如果您有原始圖像，為什么要捕獲視圖？ 只需將轉換應用於它。 這樣的事情可能是一個開始：

UIImage *image = [UIImage imageNamed:@"<# original #>"];

CIImage *cimage = [CIImage imageWithCGImage:image.CGImage];

// build the transform you want
CGAffineTransform t = CGAffineTransformIdentity;
CGFloat angle = [(NSNumber *)[self.faceImageView valueForKeyPath:@"layer.transform.rotation.z"] floatValue];
CGFloat scale = [(NSNumber *)[self.faceImageView valueForKeyPath:@"layer.transform.scale"] floatValue];    
t = CGAffineTransformConcat(t, CGAffineTransformMakeScale(scale, scale));
t = CGAffineTransformConcat(t, CGAffineTransformMakeRotation(-angle));

// create a new CIImage using the transform, crop, filters, etc.
CIImage *timage = [cimage imageByApplyingTransform:t];

// draw the result
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef imageRef = [context createCGImage:timage fromRect:[timage extent]];
UIImage *result = [UIImage imageWithCGImage:imageRef];

// save to disk
NSData *png = UIImagePNGRepresentation(result);
NSString *path = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/result.png"];
if (png && [png writeToFile:path atomically:NO]) {
    NSLog(@"\n%@", path);
}
CGImageRelease(imageRef);

如果這是您想要的，您可以輕松裁剪輸出（請參閱-[CIImage imageByCroppingToRect]或考慮轉換，應用核心圖像過濾器等，具體取決於您的確切需求。

Answer 3

我認為Bellow Code捕捉你當前的觀點......

- (UIImage *)captureView {

    CGRect rect = [self.view bounds];

    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    [self.yourImage.layer renderInContext:context];   
    UIImage *img = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return img;

}

我想你要保存顯示屏並使用它，所以我發布這個代碼...希望，這有助於你...... :)