From b233cb640daa15880256d5e5441f22edf37d1cc1 Mon Sep 17 00:00:00 2001
From: bruvzg <7645683+bruvzg@users.noreply.github.com>
Date: Thu, 2 Jul 2020 15:57:19 +0300
Subject: [PATCH] [macOS, 3.2] Implement confined mouse mode.

---
 platform/osx/os_osx.h  |  7 +++++
 platform/osx/os_osx.mm | 60 ++++++++++++++++++++++++++++++++++++++----
 2 files changed, 62 insertions(+), 5 deletions(-)

diff --git a/platform/osx/os_osx.h b/platform/osx/os_osx.h
index fb2485b2305..a0c6373c7c3 100644
--- a/platform/osx/os_osx.h
+++ b/platform/osx/os_osx.h
@@ -65,6 +65,13 @@ public:
 		uint32_t unicode;
 	};
 
+	struct WarpEvent {
+		NSTimeInterval timestamp;
+		NSPoint delta;
+	};
+	List<WarpEvent> warp_events;
+	NSTimeInterval last_warp = 0;
+
 	Vector<KeyEvent> key_event_buffer;
 	int key_event_pos;
 
diff --git a/platform/osx/os_osx.mm b/platform/osx/os_osx.mm
index 54fb302bf3f..f330ec43a8f 100644
--- a/platform/osx/os_osx.mm
+++ b/platform/osx/os_osx.mm
@@ -716,12 +716,58 @@ static void _mouseDownEvent(NSEvent *event, int index, int mask, bool pressed) {
 
 - (void)mouseMoved:(NSEvent *)event {
 
+	NSPoint delta = NSMakePoint([event deltaX], [event deltaY]);
+	NSPoint mpos = [event locationInWindow];
+
+	if (OS_OSX::singleton->mouse_mode == OS::MOUSE_MODE_CONFINED) {
+		// Discard late events
+		if (([event timestamp]) < OS_OSX::singleton->last_warp) {
+			return;
+		}
+
+		// Warp affects next event delta, subtract previous warp deltas
+		List<OS_OSX::WarpEvent>::Element *F = OS_OSX::singleton->warp_events.front();
+		while (F) {
+			if (F->get().timestamp < [event timestamp]) {
+				List<OS_OSX::WarpEvent>::Element *E = F;
+				delta.x -= E->get().delta.x;
+				delta.y -= E->get().delta.y;
+				F = F->next();
+				OS_OSX::singleton->warp_events.erase(E);
+			} else {
+				F = F->next();
+			}
+		}
+
+		// Confine mouse position to the window, and update delta
+		NSRect frame = [OS_OSX::singleton->window_object frame];
+		NSPoint conf_pos = mpos;
+		conf_pos.x = CLAMP(conf_pos.x + delta.x, 0.f, frame.size.width);
+		conf_pos.y = CLAMP(conf_pos.y - delta.y, 0.f, frame.size.height);
+		delta.x = conf_pos.x - mpos.x;
+		delta.y = mpos.y - conf_pos.y;
+		mpos = conf_pos;
+
+		// Move mouse cursor
+		NSRect pointInWindowRect = NSMakeRect(conf_pos.x, conf_pos.y, 0, 0);
+		conf_pos = [[OS_OSX::singleton->window_view window] convertRectToScreen:pointInWindowRect].origin;
+		conf_pos.y = CGDisplayBounds(CGMainDisplayID()).size.height - conf_pos.y;
+		CGWarpMouseCursorPosition(conf_pos);
+
+		// Save warp data
+		OS_OSX::singleton->last_warp = [[NSProcessInfo processInfo] systemUptime];
+		OS_OSX::WarpEvent ev;
+		ev.timestamp = OS_OSX::singleton->last_warp;
+		ev.delta = delta;
+		OS_OSX::singleton->warp_events.push_back(ev);
+	}
+
 	Ref<InputEventMouseMotion> mm;
 	mm.instance();
 
 	mm->set_button_mask(button_mask);
 	const CGFloat backingScaleFactor = [[event window] backingScaleFactor];
-	const Vector2 pos = get_mouse_pos([event locationInWindow], backingScaleFactor);
+	const Vector2 pos = get_mouse_pos(mpos, backingScaleFactor);
 	mm->set_position(pos);
 	mm->set_pressure([event pressure]);
 	if ([event subtype] == NSEventSubtypeTabletPoint) {
@@ -730,9 +776,7 @@ static void _mouseDownEvent(NSEvent *event, int index, int mask, bool pressed) {
 	}
 	mm->set_global_position(pos);
 	mm->set_speed(OS_OSX::singleton->input->get_last_mouse_speed());
-	Vector2 relativeMotion = Vector2();
-	relativeMotion.x = [event deltaX] * OS_OSX::singleton -> _mouse_scale(backingScaleFactor);
-	relativeMotion.y = [event deltaY] * OS_OSX::singleton -> _mouse_scale(backingScaleFactor);
+	const Vector2 relativeMotion = Vector2(delta.x, delta.y) * OS_OSX::singleton->_mouse_scale(backingScaleFactor);
 	mm->set_relative(relativeMotion);
 	get_key_modifier_state([event modifierFlags], mm);
 
@@ -2042,7 +2086,9 @@ void OS_OSX::warp_mouse_position(const Point2 &p_to) {
 		CGEventSourceSetLocalEventsSuppressionInterval(lEventRef, 0.0);
 		CGAssociateMouseAndMouseCursorPosition(false);
 		CGWarpMouseCursorPosition(lMouseWarpPos);
-		CGAssociateMouseAndMouseCursorPosition(true);
+		if (mouse_mode != MOUSE_MODE_CONFINED) {
+			CGAssociateMouseAndMouseCursorPosition(true);
+		}
 	}
 }
 
@@ -3093,11 +3139,15 @@ void OS_OSX::set_mouse_mode(MouseMode p_mode) {
 			CGDisplayHideCursor(kCGDirectMainDisplay);
 		}
 		CGAssociateMouseAndMouseCursorPosition(true);
+	} else if (p_mode == MOUSE_MODE_CONFINED) {
+		CGDisplayShowCursor(kCGDirectMainDisplay);
+		CGAssociateMouseAndMouseCursorPosition(false);
 	} else {
 		CGDisplayShowCursor(kCGDirectMainDisplay);
 		CGAssociateMouseAndMouseCursorPosition(true);
 	}
 
+	warp_events.clear();
 	mouse_mode = p_mode;
 }