如何使用UIPanGestureRecognizer捕获正在平移的方向？
如何使用UIPanGestureRecognizer捕获正在平移的方向？
提问于 2011-03-04 06:38:27
好的，我一直在寻找捕捉多点触控手势的几乎每一个选项，我终于回到了UIPanGestureRecognizer。
我想要的功能真的很简单。我已经设置了一个两个手指的平移手势，我希望能够根据我移动的像素数来拖曳一些图像。我已经做好了所有的工作，但我希望能够捕捉到，如果平移手势颠倒。
有没有一种我看不到的内置方法来检测手势上的后退？我是否必须存储我的原始起始点，然后跟踪结束点，然后查看它们在那之后移动到哪里，如果它小于初始结束点，然后相应地反转？我可以看到这是有效的，但我希望有一个更优雅的解决方案！！
谢谢
编辑：
下面是识别器设置为触发的方法。这有点像黑客，但它是有效的：
-(void) throttle:(UIGestureRecognizer *) recognize{
throttleCounter ++;
if(throttleCounter == 6){
throttleCounter = 0;
[self nextPic:nil];
}
UIPanGestureRecognizer *panGesture = (UIPanGestureRecognizer *) recognize;
UIView *view = recognize.view;
if(panGesture.state == UIGestureRecognizerStateBegan){
CGPoint translation = [panGesture translationInView:view.superview];
NSLog(@"X: %f, Y:%f", translation.x, translation.y);
}else if(panGesture.state == UIGestureRecognizerStateEnded){
CGPoint translation = [panGesture translationInView:view.superview];
NSLog(@"X: %f, Y:%f", translation.x, translation.y);
}
}我刚刚开始尝试跟踪values...to之间的差异，尝试并辨别它们的取景方式
回答 3
Stack Overflow用户
回答已采纳
发布于 2011-03-04 06:47:56
在UIPanGestureRecognizer上，你可以使用-velocityInView:来获得手势被识别时手指的速度。
例如，如果你想在平底锅右边做一件事，在平底锅左边做一件事，你可以这样做：
- (void)handleGesture:(UIPanGestureRecognizer *)gestureRecognizer
{
CGPoint velocity = [gestureRecognizer velocityInView:yourView];
if(velocity.x > 0)
{
NSLog(@"gesture went right");
}
else
{
NSLog(@"gesture went left");
}
}如果你真的想要检测反转，就像在中，你想比较一个新的速度和一个旧的速度，看看它是不是在相反的方向-无论是哪个方向-你可以这样做：
// assuming lastGestureVelocity is a class variable...
- (void)handleGesture:(UIPanGestureRecognizer *)gestureRecognizer
{
CGPoint velocity = [gestureRecognizer velocityInView:yourView];
if(velocity.x*lastGestureVelocity.x + velocity.y*lastGestureVelocity.y > 0)
{
NSLog(@"gesture went in the same direction");
}
else
{
NSLog(@"gesture went in the opposite direction");
}
lastGestureVelocity = velocity;
}乘法和加法看起来可能有点奇怪。这实际上是一个点积，但请放心，如果手势在同一方向，它将是一个正数，如果它们正好在直角上，它将下降到0，如果它们在相反的方向，它将变成负数。
Stack Overflow用户
发布于 2016-05-04 06:22:14
在手势识别器开始之前，这里有一个很容易检测到的：
public override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
guard let panRecognizer = gestureRecognizer as? UIPanGestureRecognizer else {
return super.gestureRecognizerShouldBegin(gestureRecognizer)
}
// Ensure it's a horizontal drag
let velocity = panRecognizer.velocity(in: self)
if abs(velocity.y) > abs(velocity.x) {
return false
}
return true
}如果只想垂直拖动，可以切换x和y。
Stack Overflow用户
发布于 2017-04-13 21:28:39
Serghei Catraniuc的这段代码对我来说效果更好。https://github.com/serp1412/LazyTransitions
func addPanGestureRecognizers() {
let panGesture = UIPanGestureRecognizer(target: self, action: #selector(respondToSwipeGesture(gesture:)))
self.view.addGestureRecognizer(panGesture)
}
func respondToSwipeGesture(gesture: UIGestureRecognizer){
if let swipeGesture = gesture as? UIPanGestureRecognizer{
switch gesture.state {
case .began:
print("began")
case .ended:
print("ended")
switch swipeGesture.direction{
case .rightToLeft:
print("rightToLeft")
case .leftToRight:
print("leftToRight")
case .topToBottom:
print("topToBottom")
case .bottomToTop:
print("bottomToTop")
default:
print("default")
}
default: break
}
}
}//扩展
import Foundation
import UIKit
public enum UIPanGestureRecognizerDirection {
case undefined
case bottomToTop
case topToBottom
case rightToLeft
case leftToRight
}
public enum TransitionOrientation {
case unknown
case topToBottom
case bottomToTop
case leftToRight
case rightToLeft
}
extension UIPanGestureRecognizer {
public var direction: UIPanGestureRecognizerDirection {
let velocity = self.velocity(in: view)
let isVertical = fabs(velocity.y) > fabs(velocity.x)
var direction: UIPanGestureRecognizerDirection
if isVertical {
direction = velocity.y > 0 ? .topToBottom : .bottomToTop
} else {
direction = velocity.x > 0 ? .leftToRight : .rightToLeft
}
return direction
}
public func isQuickSwipe(for orientation: TransitionOrientation) -> Bool {
let velocity = self.velocity(in: view)
return isQuickSwipeForVelocity(velocity, for: orientation)
}
private func isQuickSwipeForVelocity(_ velocity: CGPoint, for orientation: TransitionOrientation) -> Bool {
switch orientation {
case .unknown : return false
case .topToBottom : return velocity.y > 1000
case .bottomToTop : return velocity.y < -1000
case .leftToRight : return velocity.x > 1000
case .rightToLeft : return velocity.x < -1000
}
}
}
extension UIPanGestureRecognizer {
typealias GestureHandlingTuple = (gesture: UIPanGestureRecognizer? , handle: (UIPanGestureRecognizer) -> ())
fileprivate static var handlers = [GestureHandlingTuple]()
public convenience init(gestureHandle: @escaping (UIPanGestureRecognizer) -> ()) {
self.init()
UIPanGestureRecognizer.cleanup()
set(gestureHandle: gestureHandle)
}
public func set(gestureHandle: @escaping (UIPanGestureRecognizer) -> ()) {
weak var weakSelf = self
let tuple = (weakSelf, gestureHandle)
UIPanGestureRecognizer.handlers.append(tuple)
addTarget(self, action: #selector(handleGesture))
}
fileprivate static func cleanup() {
handlers = handlers.filter { $0.0?.view != nil }
}
@objc private func handleGesture(_ gesture: UIPanGestureRecognizer) {
let handleTuples = UIPanGestureRecognizer.handlers.filter{ $0.gesture === self }
handleTuples.forEach { $0.handle(gesture)}
}
}
extension UIPanGestureRecognizerDirection {
public var orientation: TransitionOrientation {
switch self {
case .rightToLeft: return .rightToLeft
case .leftToRight: return .leftToRight
case .bottomToTop: return .bottomToTop
case .topToBottom: return .topToBottom
default: return .unknown
}
}
}
extension UIPanGestureRecognizerDirection {
public var isHorizontal: Bool {
switch self {
case .rightToLeft, .leftToRight:
return true
default:
return false
}
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/5187502
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