From 27781a4767afdb60a9bea452a910fa4d53d85461 Mon Sep 17 00:00:00 2001
From: Denis Pobedrya <denis.pobedrya@gmail.com>
Date: Mon, 19 Sep 2022 00:01:10 +0300
Subject: [PATCH] Remove touch points on touch up events on Android (#2711)

Fixes #2683

Remove elements from touch point related arrays when touch up and
similar events are processed. This makes GetTouchPointCount() always
report the actual count of touch points, and all positions returned by
GetTouchPosition() correspond to positions of currently happening
touches.
---
 src/rcore.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/rcore.c b/src/rcore.c
index 5605a75f5..1b00b14f1 100644
--- a/src/rcore.c
+++ b/src/rcore.c
@@ -5755,9 +5755,6 @@ static int32_t AndroidInputCallback(struct android_app *app, AInputEvent *event)
     int32_t action = AMotionEvent_getAction(event);
     unsigned int flags = action & AMOTION_EVENT_ACTION_MASK;
 
-    if (flags == AMOTION_EVENT_ACTION_DOWN || flags == AMOTION_EVENT_ACTION_MOVE) CORE.Input.Touch.currentTouchState[MOUSE_BUTTON_LEFT] = 1;
-    else if (flags == AMOTION_EVENT_ACTION_UP) CORE.Input.Touch.currentTouchState[MOUSE_BUTTON_LEFT] = 0;
-
 #if defined(SUPPORT_GESTURES_SYSTEM)        // PLATFORM_ANDROID
     GestureEvent gestureEvent = { 0 };
 
@@ -5779,6 +5776,25 @@ static int32_t AndroidInputCallback(struct android_app *app, AInputEvent *event)
     ProcessGestureEvent(gestureEvent);
 #endif
 
+    int32_t pointerIndex = (action & AMOTION_EVENT_ACTION_POINTER_INDEX_MASK) >> AMOTION_EVENT_ACTION_POINTER_INDEX_SHIFT;
+
+    if (flags == AMOTION_EVENT_ACTION_POINTER_UP || flags == AMOTION_EVENT_ACTION_UP)
+    {
+        // One of the touchpoints is released, remove it from touch point arrays
+        for (int i = pointerIndex; (i < CORE.Input.Touch.pointCount-1) && (i < MAX_TOUCH_POINTS); i++)
+        {
+            CORE.Input.Touch.pointId[i] = CORE.Input.Touch.pointId[i+1];
+            CORE.Input.Touch.position[i] = CORE.Input.Touch.position[i+1];
+        }
+        CORE.Input.Touch.pointCount--;
+    }
+
+    // When all touchpoints are tapped and released really quickly, this event is generated
+    if (flags == AMOTION_EVENT_ACTION_CANCEL) CORE.Input.Touch.pointCount = 0;
+
+    if (CORE.Input.Touch.pointCount > 0) CORE.Input.Touch.currentTouchState[MOUSE_BUTTON_LEFT] = 1;
+    else CORE.Input.Touch.currentTouchState[MOUSE_BUTTON_LEFT] = 0;
+
     return 0;
 }
 #endif