How to Make Uiscrollview Zoom in Only One Direction When Using Auto Layout

How to make UIScrollView zoom in only one direction when using auto layout

Think I figured it out. You need to apply a translation in the transform to offset the centering UIScrollView tries to do while zooming.

Add this to your GridView:

var unzoomedViewHeight: CGFloat?
override func layoutSubviews() {
    super.layoutSubviews()
    unzoomedViewHeight = frame.size.height
}

override var transform: CGAffineTransform {
    get { return super.transform }
    set {
        if let unzoomedViewHeight = unzoomedViewHeight {
            var t = newValue
            t.d = 1.0
            t.ty = (1.0 - t.a) * unzoomedViewHeight/2
            super.transform = t
        }
    }
}

To compute the transform, we need to know the unzoomed height of the view. Here, I'm just grabbing the frame size during layoutSubviews() and assuming it contains the unzoomed height. There are probably some edge cases where that's not correct; might be a better place in the view update cycle to calculate the height, but this is the basic idea.

Zoom only horizontally UIView in UIScrollView

I have figure out a temporary solution thank you to LaurentMaquet. At some point I will post the final soundWaveView as it is in development at the moment.

The changes made are:

1- Create a custom class for soundWave.

class WaveView:UIView{
    var unzoomedViewHeight: CGFloat = 0

    override var transform: CGAffineTransform{
        get{ return super.transform }
        set{
            var t = newValue
            t.d = 1.0
            t.ty = (1.0 - t.a) * unzoomedViewHeight/2
            super.transform = t
        }
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        unzoomedViewHeight = frame.size.height
        print("\(logClassName) did layout to \(AppHelper.traitStatus) -> frame = \(frame)")

    }

}

2- Make my soundView var be a SoundView

private (set) lazy var waveView:WaveView = {

    let rtView = WaveView()

    rtView.translatesAutoresizingMaskIntoConstraints = false
    rtView.backgroundColor = .clear
    rtView.addGestureRecognizer(UITapGestureRecognizer(target: self,
                                                       action: #selector(waveViewDidTouch)))

    return rtView

}()

Result

UIView. How do I constrain scaling to one dimension only

Similar to what I describe in this answer, you can create a UIView subclass and override the -setTransform: accessor method to adjust the transform that the UIScrollView will try to apply to your UIView. Set this UIView to host your content subviews and make it the subview of the UIScrollView.

Within your overridden -setTransform:, you'll need to take in the transform that the UIScrollView would like to apply and adjust it so that the scaling only takes effect in one direction. From the documentation on how CGAffineTransform matrices are constructed, I believe the following implementation should constrain your scaling to be just along the horizontal direction:

- (void)setTransform:(CGAffineTransform)newValue;
{
 CGAffineTransform constrainedTransform = CGAffineTransformIdentity;
 constrainedTransform.a = newValue.a;
 [super setTransform:constrainedTransform];
}

Zooming out from content of UIscrollview

I am not sure if this will help you, but this method works for me when zooming in iOS 8. In this code, an imageView is in the scroll view.

- (void)viewDidLoad {
[super viewDidLoad];

self.scrollView.minimumZoomScale = 0.5;
self.scrollView.maximumZoomScale = 6.0;
self.scrollView.contentSize = self.PhotoView.frame.size;
self.scrollView.delegate = self;
}

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView
{
return self.PhotoView;
}
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView*)view atScale:(CGFloat)scale{
}

UIScrollView with Horizontal Zoom - Bezier Paths Drawn within Subviews Are Blurry

My initial thought, having not done this before exactly, is to store the graph as a bezier path rather than as a set of view line and point views, and based on a single unit axis. You could convert your data into this form just for drawing.

So, all points on the bezier path are normalised into the range 0 to 1.

Once you've done that you can apply a transform to the bezier path to translate (move) and scale (zoom) to the part you want and then draw the bezier path at full resolution.

This will work and is different to your current situation because your current code draws the views and then scales then so you get artifacts. The above option scales the path and then draws it.

Can a UIScrollView be adapted to zoom horizontally but not vertically? (how)

Assuming you don't actually want to stretch/shrink the button text, the easiest way is to resize all the buttons. I know, it's a pain.

UIScrollView: zoom scale for each dimension/axis

I guess in your case you're better off not using a UIScrollView, and instead setting up a UIPinchGestureRecognizer yourself on the views you want to transform.

The GestureRecognizer would track the fingers and decide whether (and how much) to scale in which dimension. Based on this, you can set your view's transform property. As an example, a transformation matrix that doubles the width but leaves height intact would be CGAffineTransformMakeScale(2.0, 1.0).

To leverage UIScrollView's scrolling, you then embed your view into a UIScrollView, and set the contentSize and contentOffset properties accordingly from your GestureRecognizer's callback methods.

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