Fix touch event handling for Windows

Filtering touch events depending on Qt::WA_AcceptTouchEvents
is not trivial. I thought about doing so in
QWidgetWindow::handleTouchEvent but the target widget (not
window), which has to be checked, has to be obtained using
the primary touch event's position etc.
Thus that is not part of this commit and will be done in a
followup.

Change-Id: I876ee72acd7fdfbe46da61c6eb3c5891ea319cd8
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>

5 files changed, 29 insertions, 14 deletions

diff --git a/src/plugins/platforms/windows/qwindowscontext.cpp b/src/plugins/platforms/windows/qwindowscontext.cpp
index aaa5573899..28269e8653 100644
--- a/src/plugins/platforms/windows/qwindowscontext.cpp
+++ b/src/plugins/platforms/windows/qwindowscontext.cpp
@@ -171,7 +171,8 @@ QWindowsUser32DLL::QWindowsUser32DLL() :
     setLayeredWindowAttributes(0), updateLayeredWindow(0),
     updateLayeredWindowIndirect(0),
     isHungAppWindow(0),
-    registerTouchWindow(0), getTouchInputInfo(0), closeTouchInputHandle(0)
+    registerTouchWindow(0), unregisterTouchWindow(0),
+    getTouchInputInfo(0), closeTouchInputHandle(0)
 {
 }
 
@@ -192,9 +193,10 @@ bool QWindowsUser32DLL::initTouch()
 {
     QSystemLibrary library(QStringLiteral("user32"));
     registerTouchWindow = (RegisterTouchWindow)(library.resolve("RegisterTouchWindow"));
+    unregisterTouchWindow = (UnregisterTouchWindow)(library.resolve("UnregisterTouchWindow"));
     getTouchInputInfo = (GetTouchInputInfo)(library.resolve("GetTouchInputInfo"));
     closeTouchInputHandle = (CloseTouchInputHandle)(library.resolve("CloseTouchInputHandle"));
-    return registerTouchWindow && getTouchInputInfo && getTouchInputInfo;
+    return registerTouchWindow && unregisterTouchWindow && getTouchInputInfo && getTouchInputInfo;
 }
 
 /*!
diff --git a/src/plugins/platforms/windows/qwindowscontext.h b/src/plugins/platforms/windows/qwindowscontext.h
index 21a846ef97..13e63d19be 100644
--- a/src/plugins/platforms/windows/qwindowscontext.h
+++ b/src/plugins/platforms/windows/qwindowscontext.h
@@ -71,6 +71,7 @@ struct QWindowsUser32DLL
     inline bool initTouch();
 
     typedef BOOL (WINAPI *RegisterTouchWindow)(HWND, ULONG);
+    typedef BOOL (WINAPI *UnregisterTouchWindow)(HWND);
     typedef BOOL (WINAPI *GetTouchInputInfo)(HANDLE, UINT, PVOID, int);
     typedef BOOL (WINAPI *CloseTouchInputHandle)(HANDLE);
     typedef BOOL (WINAPI *SetLayeredWindowAttributes)(HWND, COLORREF, BYTE, DWORD);
@@ -90,6 +91,7 @@ struct QWindowsUser32DLL
 
     // Touch functions from Windows 7 onwards (also for use with Q_CC_MSVC).
     RegisterTouchWindow registerTouchWindow;
+    UnregisterTouchWindow unregisterTouchWindow;
     GetTouchInputInfo getTouchInputInfo;
     CloseTouchInputHandle closeTouchInputHandle;
 };
diff --git a/src/plugins/platforms/windows/qwindowsmousehandler.cpp b/src/plugins/platforms/windows/qwindowsmousehandler.cpp
index d202da1d31..357def57c8 100644
--- a/src/plugins/platforms/windows/qwindowsmousehandler.cpp
+++ b/src/plugins/platforms/windows/qwindowsmousehandler.cpp
@@ -395,34 +395,40 @@ bool QWindowsMouseHandler::translateTouchEvent(QWindow *window, HWND,
     QWindowsContext::user32dll.getTouchInputInfo((HANDLE) msg.lParam, msg.wParam, winTouchInputs.data(), sizeof(TOUCHINPUT));
     for (int i = 0; i < winTouchPointCount; ++i) {
         const TOUCHINPUT &winTouchInput = winTouchInputs[i];
+        int id = m_touchInputIDToTouchPointID.value(winTouchInput.dwID, -1);
+        if (id == -1) {
+            id = m_touchInputIDToTouchPointID.size();
+            m_touchInputIDToTouchPointID.insert(winTouchInput.dwID, id);
+        }
         QTouchPoint touchPoint;
         touchPoint.pressure = 1.0;
-        touchPoint.id = m_touchInputIDToTouchPointID.value(winTouchInput.dwID, -1);
-        if (touchPoint.id == -1) {
-            touchPoint.id = m_touchInputIDToTouchPointID.size();
-            m_touchInputIDToTouchPointID.insert(winTouchInput.dwID, touchPoint.id);
-        }
+        touchPoint.id = id;
+        if (m_lastTouchPositions.contains(id))
+            touchPoint.normalPosition = m_lastTouchPositions.value(id);
 
         QPointF screenPos = QPointF(qreal(winTouchInput.x) / qreal(100.), qreal(winTouchInput.y) / qreal(100.));
         if (winTouchInput.dwMask & TOUCHINPUTMASKF_CONTACTAREA)
             touchPoint.area.setSize(QSizeF(qreal(winTouchInput.cxContact) / qreal(100.),
                                            qreal(winTouchInput.cyContact) / qreal(100.)));
         touchPoint.area.moveCenter(screenPos);
+        QPointF normalPosition = QPointF(screenPos.x() / screenGeometry.width(),
+                                         screenPos.y() / screenGeometry.height());
+        const bool stationaryTouchPoint = (normalPosition == touchPoint.normalPosition);
+        touchPoint.normalPosition = normalPosition;
 
         if (winTouchInput.dwFlags & TOUCHEVENTF_DOWN) {
             touchPoint.state = Qt::TouchPointPressed;
+            m_lastTouchPositions.insert(id, touchPoint.normalPosition);
         } else if (winTouchInput.dwFlags & TOUCHEVENTF_UP) {
             touchPoint.state = Qt::TouchPointReleased;
+            m_lastTouchPositions.remove(id);
         } else {
-            // TODO: Previous code checked"
-            // screenPos == touchPoint.normalPosition -> Qt::TouchPointStationary, but
-            // but touchPoint.normalPosition was never initialized?
-            touchPoint.state = touchPoint.state;
+            touchPoint.state = (stationaryTouchPoint
+                     ? Qt::TouchPointStationary
+                     : Qt::TouchPointMoved);
+            m_lastTouchPositions.insert(id, touchPoint.normalPosition);
         }
 
-        touchPoint.normalPosition = QPointF(screenPos.x() / screenGeometry.width(),
-                                 screenPos.y() / screenGeometry.height());
-
         allStates |= touchPoint.state;
 
         touchPoints.append(touchPoint);
diff --git a/src/plugins/platforms/windows/qwindowsmousehandler.h b/src/plugins/platforms/windows/qwindowsmousehandler.h
index 965deb4e0f..c652f869f1 100644
--- a/src/plugins/platforms/windows/qwindowsmousehandler.h
+++ b/src/plugins/platforms/windows/qwindowsmousehandler.h
@@ -80,6 +80,7 @@ private:
     QPointer<QWindow> m_windowUnderMouse;
     QPointer<QWindow> m_trackedWindow;
     QHash<DWORD, int> m_touchInputIDToTouchPointID;
+    QHash<int, QPointF> m_lastTouchPositions;
     QTouchDevice *m_touchDevice;
     bool m_leftButtonDown;
     QWindow *m_previousCaptureWindow;
diff --git a/src/plugins/platforms/windows/qwindowswindow.cpp b/src/plugins/platforms/windows/qwindowswindow.cpp
index 123607cd79..1f6253438f 100644
--- a/src/plugins/platforms/windows/qwindowswindow.cpp
+++ b/src/plugins/platforms/windows/qwindowswindow.cpp
@@ -728,11 +728,15 @@ QWindowsWindow::QWindowsWindow(QWindow *aWindow, const WindowData &data) :
             break;
         }
     }
+    if (QWindowsContext::instance()->systemInfo() & QWindowsContext::SI_SupportsTouch)
+        QWindowsContext::user32dll.registerTouchWindow(m_data.hwnd, 0);
     setWindowState(aWindow->windowState());
 }
 
 QWindowsWindow::~QWindowsWindow()
 {
+    if (QWindowsContext::instance()->systemInfo() & QWindowsContext::SI_SupportsTouch)
+        QWindowsContext::user32dll.unregisterTouchWindow(m_data.hwnd);
     destroyWindow();
     destroyIcon();
 }