How to detect a single mouse down event in SwiftUI on macOS - macos

Question

I want to detect ONE mouse down and ONE mouse up event on my view (a simple Rectangle). Here is the code I already made. Unfortunately I got a lot of 'mouse down' and 'mouse up' on the console. This not what I want. I want just one 'mouse down' when the mouse is pressed on my rectangle and one 'mouse up' when the mouse is released.
var body: some View {
Rectangle()
.onAppear(perform: {
NSEvent.addLocalMonitorForEvents(matching: [.leftMouseDown]) { event in
print ("mouse down")
return event
}
NSEvent.addLocalMonitorForEvents(matching: [.leftMouseUp]) { event in
print ("mouse up")
return event
}
})
}

Answer 1

I found the solution by using a View modifier
//
// ContentView.swift
// OnPressedOnRelease
//
import SwiftUI
struct ContentView: View {
#State private var message: String = "Click on rectangle"
var body: some View {
VStack {
Image(systemName: "magicmouse")
.imageScale(.large)
.foregroundColor(.accentColor)
Text("\(message)")
Rectangle()
.modifier(PressActions(
onPress: {
// Do something on press...
message = "Mouse down"
},
onRelease: {
// Do something on release...
message = "Mouse up"
}
))
}
.padding()
.frame(width: 200, height: 200)
}
}
struct PressActions: ViewModifier {
var onPress: () -> Void
var onRelease: () -> Void
func body(content: Content) -> some View {
content
.simultaneousGesture(
DragGesture(minimumDistance: 0)
.onChanged({ _ in
onPress()
})
.onEnded({ _ in
onRelease()
})
)
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}

Answer 2

I've recently worked with Gestures and a good solution is to do this :
struct ContentView: View {
#State var dragGestureValue: DragGesture.Value?
var body: some View {
Rectangle()
.gesture(pressActionsGesture())
.padding()
}
private func pressActionsGesture() -> some Gesture {
return DragGesture(minimumDistance: 0)
.onChanged {
// If nil, it means its the beginning of the DragGesture
if dragGestureValue == nil {
print("Mouse Down")
}
// Gives DragGesture informations to our #State value
dragGestureValue = $0
}
.onEnded { _ in
print("Mouse Up")
dragGestureValue = nil
}
}
}