通过手势识别器操作后裁剪UIImageView

Question

I'm having issues figuring this out! All of the examples I have seen have to do with a scrollView and I am not using one. I need to crop an image within a predetermined CGRect area after the image has been manipulated through pinch, pan, and rotate. The code I have below crops the unmanipulated image in the upper left hand corner.

To Clarify pendantCanvasView is the view (container) and pendantImageView is a subclass of pendantCanvasView. PendantFrame is just a CGRect that has the coords of the rect in pendantImageView I want to crop.

Can someone help me?

Here is the code i have so far:

- (void)addMoveImageToolbox {

   UIPinchGestureRecognizer *pinchRec = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(handlePinch:)];
   [self.pendantCanvasView addGestureRecognizer:pinchRec];

   UIRotationGestureRecognizer *rotateRec = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(handleRotate:)];
   [self.pendantCanvasView addGestureRecognizer:rotateRec];

   UIPanGestureRecognizer *panRec = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
   [self.pendantCanvasView addGestureRecognizer:panRec];
}

- (void)handlePinch:(UIPinchGestureRecognizer*)pinch {
   self.pendantImageView.transform = CGAffineTransformScale(self.pendantImageView.transform, pinch.scale, pinch.scale);
   self.zoomScale = pinch.scale;
   pinch.scale = 1;
}

- (void)handleRotate:(UIRotationGestureRecognizer*)rotate {
   self.pendantImageView.transform =   CGAffineTransformRotate(self.pendantImageView.transform, rotate.rotation);
   rotate.rotation = 0;
}

- (void)handlePan:(UIPanGestureRecognizer *)pan {

   CGPoint translation = [pan translationInView:self.pendantCanvasView];
   self.pendantImageView.center = CGPointMake(self.pendantImageView.center.x + translation.x,
                                     self.pendantImageView.center.y + translation.y);
   [pan setTranslation:CGPointMake(0, 0) inView:self.pendantImageView];
}

Crop Method:

- (UIImage *)captureScreenInRect {

   UIGraphicsBeginImageContextWithOptions(pendantFrame.size, NO, [UIScreen mainScreen].scale);
   [self.pendantCanvasView drawViewHierarchyInRect:pendantFrame afterScreenUpdates:YES];
   UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
   UIGraphicsEndImageContext();self.pendantImageView.constraints

   return image;
}

Answer 1

I believe drawViewHierarchyInRect re-renders the view hierarchy so it may be losing your alterations to the imageView.

you could try using snapshotViewAfterScreenUpdates instead.

I'm not sure what the relationships between pendantCanvasView, pendantImageView, and pendantFrame are but it may be possible to use the renderInContext method of the layer property of one or the other to get the cropped image.