[英]Capture touchDown location of onLongPressGesture in swiftUI?
我正在尝试实现一个自定义上下文菜单,该菜单将在用户触摸的位置长按后出现。 我一直无法找到一种方法来捕获 onLongPressGesture 的触地事件的 XY 位置。
这是我开始的地方
struct ExampleView: View {
@State var showCustomContextMenu = false
@State var longPressLocation = CGPoint.zero
var body: some View {
Rectangle()
.foregroundColor(Color.green)
.frame(width: 100.0, height: 100.0)
.onLongPressGesture {
print("OnLongPressGesture")
self.showCustomContextMenu = true
}
.overlay(
Rectangle()
.foregroundColor(Color.red)
.frame(width: 50.0, height: 50.0)
.position(longPressLocation) // <----- this is what I need to capture.
.opacity( (showCustomContextMenu) ? 1 : 0 )
)
}
}
在查看了这个问题(以及答案中链接的其他 SO 问题)之后,我尝试了以下操作。
如何检测没有移动或持续时间的 SwiftUI touchDown 事件?
struct ExampleView: View {
@State var showCustomContextMenu = false
@State var longPressLocation = CGPoint.zero
var body: some View {
ZStack{
Rectangle()
.foregroundColor(Color.green)
.frame(width: 100.0, height: 100.0)
.onLongPressGesture {
print("OnLongPressGesture")
self.showCustomContextMenu = true
}
.overlay(
Rectangle()
.foregroundColor(Color.red)
.frame(width: 50.0, height: 50.0)
.position(longPressLocation)
.opacity( (showCustomContextMenu) ? 1 : 0 )
)
TapView { point in
self.longPressLocation = point
print("Point: \(point)")
}.background(Color.gray).opacity(0.5)
}
}
}
struct TapView: UIViewRepresentable {
var tappedCallback: ((CGPoint) -> Void)
func makeUIView(context: UIViewRepresentableContext<TapView>) -> TapView.UIViewType {
let v = UIView(frame: .zero)
let gesture = SingleTouchDownGestureRecognizer(target: context.coordinator,
action: #selector(Coordinator.tapped))
v.addGestureRecognizer(gesture)
return v
}
class Coordinator: NSObject {
var tappedCallback: ((CGPoint) -> Void)
init(tappedCallback: @escaping ((CGPoint) -> Void)) {
self.tappedCallback = tappedCallback
}
@objc func tapped(gesture:UITapGestureRecognizer) {
self.tappedCallback(gesture.location(in: gesture.view))
}
}
func makeCoordinator() -> TapView.Coordinator {
return Coordinator(tappedCallback:self.tappedCallback)
}
func updateUIView(_ uiView: UIView,
context: UIViewRepresentableContext<TapView>) {
}
}
class SingleTouchDownGestureRecognizer: UIGestureRecognizer {
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
if self.state == .possible {
self.state = .recognized
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
self.state = .failed
}
override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
self.state = .failed
}
}
这几乎可行,但是,这给我留下的问题是,由于 Rectangle() 和 TapView() 位于 ZStack 中,这取决于我将它们放置在代码中的位置,因此我可以得到touchDown位置或onLongPressGesture,但不能同时获得两者。
我看过但遇到类似问题的其他 SO 问题链接如下
Swift:长按手势识别器 - 检测轻按和长按这可能是我正在寻找的,但我不确定如何使其适应 SwiftUI。
这是一个可能的方法的演示。 它需要两个手势的组合:长按检测长按和拖动检测位置。
使用 Xcode 12 / iOS 14 进行测试。(在以下系统中,可能需要将self.
添加到某些属性使用中)
struct ExampleView: View {
@State var showCustomContextMenu = false
@State var longPressLocation = CGPoint.zero
var body: some View {
Rectangle()
.foregroundColor(Color.green)
.frame(width: 100.0, height: 100.0)
.onTapGesture { showCustomContextMenu = false } // just for demo
.gesture(LongPressGesture(minimumDuration: 1).sequenced(before: DragGesture(minimumDistance: 0, coordinateSpace: .local))
.onEnded { value in
switch value {
case .second(true, let drag):
longPressLocation = drag?.location ?? .zero // capture location !!
showCustomContextMenu = true
default:
break
}
})
.overlay(
Rectangle()
.foregroundColor(Color.red)
.frame(width: 50.0, height: 50.0)
.position(longPressLocation)
.opacity( (showCustomContextMenu) ? 1 : 0 )
.allowsHitTesting(false)
)
}
}
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