patches(iOS): support ignoring indirect touch events

Due to the way prefersPointerLocked works, if the pointer is currently over
a SwiftUI button, it will trigger every time the mouse is clicked. We
swizzle in a new property that allows us to ignore all indirect touch events
when active.

Fixes #4843

Platform/iOS/Display/VMDisplayMetalViewController+Pointer.m

@@ -94,9 +94,6 @@ - (void)mouseDidBecomeCurrent:(NSNotification *)notification API_AVAILABLE(ios(1
         };
     }
     // no handler to the gcmouse scroll event, gestureScroll works fine.
-    dispatch_async(dispatch_get_main_queue(), ^{
-        self.prefersPointerLocked = YES;
-    });
 }
 
 - (void)mouseDidStopBeingCurrent:(NSNotification *)notification API_AVAILABLE(ios(14)) {
@@ -109,9 +106,6 @@ - (void)mouseDidStopBeingCurrent:(NSNotification *)notification API_AVAILABLE(io
     for (int i = 0; i < MIN(4, mouse.mouseInput.auxiliaryButtons.count); i++) {
         mouse.mouseInput.auxiliaryButtons[i].pressedChangedHandler = nil;
     }
-    dispatch_async(dispatch_get_main_queue(), ^{
-        self.prefersPointerLocked = NO;
-    });
 }
 
 #pragma mark - UIPointerInteractionDelegate

Platform/iOS/Display/VMDisplayMetalViewController+Touch.m

@@ -627,11 +627,6 @@ - (BOOL)switchMouseType:(VMMouseType)type {
 - (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
     if (!self.delegate.qemuInputLegacy) {
         for (UITouch *touch in touches) {
-            if (@available(iOS 14, *)) {
-                if (self.prefersPointerLocked && (touch.type == UITouchTypeIndirect || touch.type == UITouchTypeIndirectPointer)) {
-                    continue; // skip indirect touches if we are capturing mouse input
-                }
-            }
             VMMouseType type = [self touchTypeToMouseType:touch.type];
             if ([self switchMouseType:type]) {
                 [self dragCursor:UIGestureRecognizerStateEnded primary:YES secondary:YES middle:YES]; // reset drag

Platform/iOS/Display/VMDisplayMetalViewController.m

@@ -142,6 +142,7 @@ - (void)viewWillTransitionToSize:(CGSize)size withTransitionCoordinator:(id<UIVi
 - (void)enterSuspendedWithIsBusy:(BOOL)busy {
     [super enterSuspendedWithIsBusy:busy];
     self.prefersPointerLocked = NO;
+    self.view.window.isIndirectPointerTouchIgnored = NO;
     if (!busy) {
         if (self.delegate.qemuHasClipboardSharing) {
             [[UTMPasteboard generalPasteboard] releasePollingModeForObject:self];
@@ -152,6 +153,7 @@ - (void)enterSuspendedWithIsBusy:(BOOL)busy {
 - (void)enterLive {
     [super enterLive];
     self.prefersPointerLocked = YES;
+    self.view.window.isIndirectPointerTouchIgnored = YES;
     if (self.delegate.qemuDisplayIsDynamicResolution) {
         [self displayResize:self.view.bounds.size];
     }

Platform/iOS/UTMPatches.swift

@@ -25,6 +25,7 @@ final class UTMPatches {
     static func patchAll() {
         UIViewController.patchViewController()
         UIPress.patchPress()
+        UIWindow.patchWindow()
     }
 }
 
@@ -98,3 +99,44 @@ extension UIPress {
         }
     }
 }
+
+private var IndirectPointerTouchIgnoredHandle: Int = 0
+
+/// Patch to allow ignoring indirect touch when capturing pointer
+extension UIWindow {
+    /// When true, `sendEvent(_:)` will ignore any indirect touch events.
+    @objc var isIndirectPointerTouchIgnored: Bool {
+        set {
+            let number = NSNumber(booleanLiteral: newValue)
+            objc_setAssociatedObject(self, &IndirectPointerTouchIgnoredHandle, number, .OBJC_ASSOCIATION_ASSIGN)
+        }
+
+        get {
+            let number = objc_getAssociatedObject(self, &IndirectPointerTouchIgnoredHandle) as? NSNumber
+            return number?.boolValue ?? false
+        }
+    }
+
+    /// Replacement `sendEvent(_:)` function
+    /// - Parameter event: The event to dispatch.
+    @objc private func xxx_sendEvent(_ event: UIEvent) {
+        if isIndirectPointerTouchIgnored && event.type == .touches {
+            event.touches(for: self)?.forEach { touch in
+                if touch.type == .indirectPointer {
+                    // for some reason, if we just ignore the event, future touch events get messed up
+                    // so as an alternative, we still pass the event through but with a modified coordinate
+                    touch.perform(Selector(("_setLocationInWindow:resetPrevious:")),
+                                  with: CGPoint(x: -1, y: -1),
+                                  with: true)
+                }
+            }
+        }
+        xxx_sendEvent(event)
+    }
+
+    fileprivate static func patchWindow() {
+        patch(#selector(sendEvent),
+              with: #selector(xxx_sendEvent),
+              class: Self.self)
+    }
+}