Windows QPA: Fix duplicate Pointer Touch events and missing TouchCancel

translateTouchEvent needs to filter events based on the message type
passed in msg, as Windows sends more than just down/up/update events,
it also sends enter/leave for each touch and occasionally a few more.

One of them is WM_POINTERCAPTURECHANGED which indicates a general loss
of touch input, which needs to be translated to a touch cancel event.

Ignore WM_POINTERENTER/WM_POINTERLEAVE events as they result in sending
duplicate Qt::TouchPointPressed/Qt::TouchPointReleased events otherwise.

Also avoid sending duplicate events for each additional touchpoint:
Windows already bundles all available touchpoints for a touch event
when calling GetPointerFrameTouchInfo, so we get all points at once,
but we'll still receive other events for each additional touchpoint,
resulting in reading the same bundled data again for each one and
sending duplicate events to QWindowSystemInterface.
Use SkipPointerFrameMessages() to avoid receiving the additional
events for the frame we just processed.

Finally, add raw event logging when the platform verbose level is >1.

Change-Id: I55d840285f642a00f6ffcda4a3efd7ae3985310b
Reviewed-by: Andre de la Rocha <andre.rocha@qt.io>

4 files changed, 31 insertions, 1 deletions

diff --git a/src/plugins/platforms/windows/qtwindowsglobal.h b/src/plugins/platforms/windows/qtwindowsglobal.h
index ef22a4451a..985f13bdc5 100644
--- a/src/plugins/platforms/windows/qtwindowsglobal.h
+++ b/src/plugins/platforms/windows/qtwindowsglobal.h
@@ -71,6 +71,7 @@
 #  define WM_POINTERENTER    0x0249
 #  define WM_POINTERLEAVE    0x024A
 #  define WM_POINTERACTIVATE 0x024B
+#  define WM_POINTERCAPTURECHANGED 0x024C
 #  define WM_POINTERWHEEL    0x024E
 #  define WM_POINTERHWHEEL   0x024F
 #endif // WM_POINTERUPDATE
diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index 0df6264bcb..aa85b2edbe 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -201,6 +201,7 @@ void QWindowsUser32DLL::init()
         getPointerTouchInfo = (GetPointerTouchInfo)library.resolve("GetPointerTouchInfo");
         getPointerFrameTouchInfo = (GetPointerFrameTouchInfo)library.resolve("GetPointerFrameTouchInfo");
         getPointerPenInfo = (GetPointerPenInfo)library.resolve("GetPointerPenInfo");
+        skipPointerFrameMessages = (SkipPointerFrameMessages)library.resolve("SkipPointerFrameMessages");
     }
 
     if (QOperatingSystemVersion::current()
@@ -214,7 +215,8 @@ void QWindowsUser32DLL::init()
 bool QWindowsUser32DLL::supportsPointerApi()
 {
     return enableMouseInPointer && getPointerType && getPointerInfo && getPointerDeviceRects
-            && getPointerTouchInfo && getPointerFrameTouchInfo && getPointerPenInfo;
+            && getPointerTouchInfo && getPointerFrameTouchInfo && getPointerPenInfo
+            && skipPointerFrameMessages;
 }
 
 void QWindowsShcoreDLL::init()
diff --git a/src/plugins/platforms/windows/qwindowscontext.h b/src/plugins/platforms/windows/qwindowscontext.h
index 33bd42a669..8102e0bf19 100644
--- a/src/plugins/platforms/windows/qwindowscontext.h
+++ b/src/plugins/platforms/windows/qwindowscontext.h
@@ -93,6 +93,7 @@ struct QWindowsUser32DLL
     typedef BOOL (WINAPI *GetPointerTouchInfo)(UINT32, PVOID);
     typedef BOOL (WINAPI *GetPointerFrameTouchInfo)(UINT32, UINT32 *, PVOID);
     typedef BOOL (WINAPI *GetPointerPenInfo)(UINT32, PVOID);
+    typedef BOOL (WINAPI *SkipPointerFrameMessages)(UINT32);
     typedef BOOL (WINAPI *SetProcessDPIAware)();
     typedef BOOL (WINAPI *AddClipboardFormatListener)(HWND);
     typedef BOOL (WINAPI *RemoveClipboardFormatListener)(HWND);
@@ -110,6 +111,7 @@ struct QWindowsUser32DLL
     GetPointerTouchInfo getPointerTouchInfo = nullptr;
     GetPointerFrameTouchInfo getPointerFrameTouchInfo = nullptr;
     GetPointerPenInfo getPointerPenInfo = nullptr;
+    SkipPointerFrameMessages skipPointerFrameMessages = nullptr;
 
     // Windows Vista onwards
     SetProcessDPIAware setProcessDPIAware = nullptr;
diff --git a/src/plugins/platforms/windows/qwindowspointerhandler.cpp b/src/plugins/platforms/windows/qwindowspointerhandler.cpp
index abd4d56da0..af9048828f 100644
--- a/src/plugins/platforms/windows/qwindowspointerhandler.cpp
+++ b/src/plugins/platforms/windows/qwindowspointerhandler.cpp
@@ -354,6 +354,17 @@ bool QWindowsPointerHandler::translateTouchEvent(QWindow *window, HWND hwnd,
     if (count < 1)
         return false;
 
+    if (msg.message == WM_POINTERCAPTURECHANGED) {
+        QWindowSystemInterface::handleTouchCancelEvent(window, m_touchDevice,
+                                                       QWindowsKeyMapper::queryKeyboardModifiers());
+        m_lastTouchPositions.clear();
+        return true;
+    }
+
+    // Only handle down/up/update, ignore others like WM_POINTERENTER, WM_POINTERLEAVE, etc.
+    if (msg.message > WM_POINTERUP)
+        return false;
+
     const QScreen *screen = window->screen();
     if (!screen)
         screen = QGuiApplication::primaryScreen();
@@ -366,7 +377,18 @@ bool QWindowsPointerHandler::translateTouchEvent(QWindow *window, HWND hwnd,
 
     QList<QWindowSystemInterface::TouchPoint> touchPoints;
 
+    if (QWindowsContext::verbose > 1)
+        qCDebug(lcQpaEvents).noquote().nospace() << showbase
+                << __FUNCTION__
+                << " message=" << hex << msg.message
+                << " count=" << dec << count;
+
     for (quint32 i = 0; i < count; ++i) {
+        if (QWindowsContext::verbose > 1)
+            qCDebug(lcQpaEvents).noquote().nospace() << showbase
+                    << "    TouchPoint id=" << touchInfo[i].pointerInfo.pointerId
+                    << " frame=" << touchInfo[i].pointerInfo.frameId
+                    << " flags=" << hex << touchInfo[i].pointerInfo.pointerFlags;
 
         QWindowSystemInterface::TouchPoint touchPoint;
         touchPoint.id = touchInfo[i].pointerInfo.pointerId;
@@ -398,6 +420,9 @@ bool QWindowsPointerHandler::translateTouchEvent(QWindow *window, HWND hwnd,
             m_lastTouchPositions.insert(touchPoint.id, touchPoint.normalPosition);
         }
         touchPoints.append(touchPoint);
+
+        // Avoid getting repeated messages for this frame if there are multiple pointerIds
+        QWindowsContext::user32dll.skipPointerFrameMessages(touchInfo[i].pointerInfo.pointerId);
     }
 
     QWindowSystemInterface::handleTouchEvent(window, m_touchDevice, touchPoints,