71 lines
1.9 KiB
Swift
71 lines
1.9 KiB
Swift
//
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// Copyright (c) 2019 Open Whisper Systems. All rights reserved.
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//
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import UIKit
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// This GR:
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//
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// * Tries to fail quickly to avoid conflicts with other GRs, especially pans/swipes.
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// * Captures a bunch of useful "pan state" that makes using this GR much easier
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// than UIPanGestureRecognizer.
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public class ImageEditorPanGestureRecognizer: UIPanGestureRecognizer {
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public weak var referenceView: UIView?
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// Capture the location history of this gesture.
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public var locationHistory = [CGPoint]()
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public var locationFirst: CGPoint? {
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return locationHistory.first
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}
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// MARK: - Touch Handling
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@objc
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public override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
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updateLocationHistory(event: event)
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super.touchesBegan(touches, with: event)
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}
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@objc
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public override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
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updateLocationHistory(event: event)
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super.touchesMoved(touches, with: event)
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}
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@objc
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public override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
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updateLocationHistory(event: event)
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super.touchesEnded(touches, with: event)
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}
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private func updateLocationHistory(event: UIEvent) {
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guard let touches = event.allTouches,
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touches.count > 0 else {
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owsFailDebug("no touches.")
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return
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}
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guard let referenceView = referenceView else {
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owsFailDebug("Missing view")
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return
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}
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// Find the centroid.
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var location = CGPoint.zero
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for touch in touches {
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location = location.plus(touch.location(in: referenceView))
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}
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location = location.times(CGFloat(1) / CGFloat(touches.count))
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locationHistory.append(location)
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}
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public override func reset() {
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super.reset()
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locationHistory.removeAll()
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}
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}
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