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Make sure image will be zoomed from the pinch center #3

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Make sure image will be zoomed from the pinch center #3

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38 changes: 27 additions & 11 deletions Sources/InstaZoom.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ public extension UIImageView {
static var ImagePinchGestureKey: Int8 = 1
static var ImagePanGestureKey: Int8 = 2
static var ImageScaleKey: Int8 = 3
static var PinchCenterKey: Int8 = 4
}

/// The image should zoom on Pinch
Expand Down Expand Up @@ -70,8 +71,17 @@ public extension UIImageView {
objc_setAssociatedObject(self, &AssociatedKeys.ImageScaleKey, newValue, .OBJC_ASSOCIATION_RETAIN)
}
}



/// The center from which the image is pinched
private var pinchCenter: CGPoint {
get {
return objc_getAssociatedObject(self, &AssociatedKeys.PinchCenterKey) as? CGPoint ?? CGPoint(x: bounds.midX, y: bounds.midY)
}
set {
objc_setAssociatedObject(self, &AssociatedKeys.PinchCenterKey, newValue, .OBJC_ASSOCIATION_RETAIN)
}
}

/// Initialize pinch & pan gestures
private func inititialize() {
pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(imagePinched(_:)))
Expand All @@ -84,16 +94,20 @@ public extension UIImageView {
///
/// - Parameter sender: UIPinvhGestureRecognizer
@objc private func imagePinched(_ pinch: UIPinchGestureRecognizer) {
if pinch.scale >= 1.0 {
scale = pinch.scale
transform(withTranslation: .zero)
switch pinch.state {
case .began:
pinchCenter = CGPoint(x: pinch.location(in: self).x - bounds.midX,
y: pinch.location(in: self).y - bounds.midY)
case .changed:
if pinch.scale >= 1.0 {
scale = pinch.scale
transform(withTranslation: .zero)
}
default:
reset()
}

if pinch.state != .ended { return }

reset()
}

/// Perform the panning if needed
///
/// - Parameter sender: UIPanGestureRecognizer
Expand All @@ -114,15 +128,17 @@ public extension UIImageView {
self.transform = .identity
}
}

/// Will transform the image with the appropriate
/// scale or translation.
///
/// Parameter translation: CGPoint
private func transform(withTranslation translation: CGPoint) {
var transform = CATransform3DIdentity
transform = CATransform3DTranslate(transform, pinchCenter.x * (1-scale), pinchCenter.y * (1-scale), 0)
transform = CATransform3DScale(transform, scale, scale, 1.01)
transform = CATransform3DTranslate(transform, translation.x, translation.y, 0)

layer.transform = transform
}
}
Expand Down