From 994e99c94d44b71ef6c9363bac3fc660f400ebc7 Mon Sep 17 00:00:00 2001
From: "Unknown W. Brackets" <checkins@unknownbrackets.org>
Date: Tue, 11 Apr 2017 18:48:40 -0700
Subject: [PATCH] Windows: Fix mismatch on multitouch finger up.

Fixes buttons "sticking".
---
 Windows/TouchInputHandler.cpp | 61 +++++++++++++++++++++--------------
 Windows/TouchInputHandler.h   |  2 ++
 2 files changed, 38 insertions(+), 25 deletions(-)

diff --git a/Windows/TouchInputHandler.cpp b/Windows/TouchInputHandler.cpp
index 766364987c..36b7726b6a 100644
--- a/Windows/TouchInputHandler.cpp
+++ b/Windows/TouchInputHandler.cpp
@@ -33,32 +33,40 @@ TouchInputHandler::~TouchInputHandler()
 {
 }
 
+int TouchInputHandler::ToTouchID(int windowsID, bool allowAllocate) {
+	// Find the id for the touch.  Avoid 0 (mouse.)
+	for (int localId = 1; localId < (int)ARRAY_SIZE(touchIds); ++localId) {
+		if (touchIds[localId] == windowsID) {
+			return localId;
+		}
+	}
+
+	// Allocate a new one, perhaps?
+	if (allowAllocate) {
+		for (int localId = 1; localId < (int)ARRAY_SIZE(touchIds); ++localId) {
+			if (touchIds[localId] == 0) {
+				touchIds[localId] = windowsID;
+				return localId;
+			}
+		}
+
+		// None were free.
+		// TODO: Better to just ignore this touch instead?
+		touchUp(0, 0, 0);
+		return 0;
+	}
+
+	return -1;
+}
+
 void TouchInputHandler::handleTouchEvent(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
 {
-	if (hasTouch()){
+	if (hasTouch()) {
 		UINT inputCount = LOWORD(wParam);
+		HTOUCHINPUT touchInputData = (HTOUCHINPUT) lParam;
 		TOUCHINPUT *inputs = new TOUCHINPUT[inputCount];
-		if (touchInfo((HTOUCHINPUT) lParam,
-			inputCount,
-			inputs,
-			sizeof(TOUCHINPUT))) {
+		if (touchInfo(touchInputData, inputCount, inputs, sizeof(TOUCHINPUT))) {
 			for (UINT i = 0; i < inputCount; i++) {
-				int id = -1;
-
-				// Find or allocate an id for the touch.  Avoid 0 (mouse.)
-				for (int localId = 1; localId < (int)ARRAY_SIZE(touchIds); ++localId) {
-					if (touchIds[localId] == inputs[i].dwID || touchIds[localId] == 0) {
-						touchIds[localId] = inputs[i].dwID;
-						id = localId;
-						break;
-					}
-				}
-				if (id == -1) {
-					id = 0;
-					// TODO: Better to just ignore this touch instead?
-					touchUp(id, 0, 0);
-				}
-
 				POINT point;
 				point.x = (float)(TOUCH_COORD_TO_PIXEL(inputs[i].x));
 				point.y = (float)(TOUCH_COORD_TO_PIXEL(inputs[i].y));
@@ -66,14 +74,17 @@ void TouchInputHandler::handleTouchEvent(HWND hWnd, UINT message, WPARAM wParam,
 					point.x *= g_dpi_scale;
 					point.y *= g_dpi_scale;
 					if (inputs[i].dwFlags & TOUCHEVENTF_DOWN) {
-						touchDown(id, point.x, point.y);
+						touchDown(ToTouchID(inputs[i].dwID), point.x, point.y);
 					}
 					if (inputs[i].dwFlags & TOUCHEVENTF_MOVE) {
-						touchMove(id, point.x, point.y);
+						touchMove(ToTouchID(inputs[i].dwID), point.x, point.y);
 					}
 					if (inputs[i].dwFlags & TOUCHEVENTF_UP) {
-						touchUp(id, point.x, point.y);
-						touchIds[id] = 0;
+						int id = ToTouchID(inputs[i].dwID, false);
+						if (id >= 0) {
+							touchUp(id, point.x, point.y);
+							touchIds[id] = 0;
+						}
 					}
 				}
 			}
diff --git a/Windows/TouchInputHandler.h b/Windows/TouchInputHandler.h
index 3e404b3646..429641d752 100644
--- a/Windows/TouchInputHandler.h
+++ b/Windows/TouchInputHandler.h
@@ -26,6 +26,8 @@ public:
 	bool hasTouch();
 
 private:
+	int ToTouchID(int windowsID, bool allowAllocate = true);
+
 	void disablePressAndHold(HWND hWnd);
 	void touchUp(int id, float x, float y);
 	void touchDown(int id, float x, float y);