Windows: Add command line parameter enabling OS-synthesized mouse events from touch.

Applications launched with -platform windows:mousefromtouch will
receive OS-synthesized mouse events.

Task-number: QTBUG-31386
Change-Id: I1c49486589c4a7fa4fb5525f7a5adca09b1cfb89
Reviewed-by: Joerg Bornemann <joerg.bornemann@digia.com>

3 files changed, 15 insertions, 7 deletions

diff --git a/src/plugins/platforms/windows/qwindowsintegration.cpp b/src/plugins/platforms/windows/qwindowsintegration.cpp
index 754d7a0288..5f1f9cf149 100644
--- a/src/plugins/platforms/windows/qwindowsintegration.cpp
+++ b/src/plugins/platforms/windows/qwindowsintegration.cpp
@@ -342,6 +342,8 @@ static inline unsigned parseOptions(const QStringList &paramList)
             }
         } else if (param == QLatin1String("gl=gdi")) {
             options |= QWindowsIntegration::DisableArb;
+        } else if (param == QLatin1String("mousefromtouch")) {
+            options |= QWindowsIntegration::PassOsMouseEventsSynthesizedFromTouch;
         }
     }
     return options;
@@ -557,13 +559,15 @@ QVariant QWindowsIntegration::styleHint(QPlatformIntegration::StyleHint hint) co
         break;
     case QPlatformIntegration::UseRtlExtensions:
         return QVariant(d->m_context.useRTLExtensions());
-#ifdef Q_OS_WINCE
     case QPlatformIntegration::SynthesizeMouseFromTouchEvents:
+#ifdef Q_OS_WINCE
         // We do not want Qt to synthesize mouse events as Windows also does that.
         // Alternatively, Windows-generated touch mouse events can be identified and
         // ignored by checking GetMessageExtraInfo() for MI_WP_SIGNATURE (0xFF515700).
        return false;
-#endif // Q_OS_WINCE
+#else // Q_OS_WINCE
+        return QVariant(!(d->m_options & PassOsMouseEventsSynthesizedFromTouch));
+#endif // !Q_OS_WINCE
     default:
         break;
     }
diff --git a/src/plugins/platforms/windows/qwindowsintegration.h b/src/plugins/platforms/windows/qwindowsintegration.h
index ca484415be..b3854d673a 100644
--- a/src/plugins/platforms/windows/qwindowsintegration.h
+++ b/src/plugins/platforms/windows/qwindowsintegration.h
@@ -58,7 +58,8 @@ public:
         FontDatabaseNative = 0x2,
         DisableArb = 0x4,
         NoNativeDialogs = 0x8,
-        XpNativeDialogs = 0x10
+        XpNativeDialogs = 0x10,
+        PassOsMouseEventsSynthesizedFromTouch = 0x20 // Pass OS-generated mouse events from touch.
     };
 
     explicit QWindowsIntegration(const QStringList &paramList);
diff --git a/src/plugins/platforms/windows/qwindowsmousehandler.cpp b/src/plugins/platforms/windows/qwindowsmousehandler.cpp
index 43286eadf3..3782b7e020 100644
--- a/src/plugins/platforms/windows/qwindowsmousehandler.cpp
+++ b/src/plugins/platforms/windows/qwindowsmousehandler.cpp
@@ -169,10 +169,13 @@ bool QWindowsMouseHandler::translateMouseEvent(QWindow *window, HWND hwnd,
 
 #ifndef Q_OS_WINCE
     // Check for events synthesized from touch. Lower byte is touch index, 0 means pen.
-    const quint64 extraInfo = GetMessageExtraInfo();
-    const bool fromTouch = (extraInfo & signatureMask) == miWpSignature && (extraInfo & 0xff);
-    if (fromTouch)
-        return false;
+    static const bool passSynthesizedMouseEvents = QWindowsIntegration::instance()->options() & QWindowsIntegration::PassOsMouseEventsSynthesizedFromTouch;
+    if (!passSynthesizedMouseEvents) {
+        const quint64 extraInfo = GetMessageExtraInfo();
+        const bool fromTouch = (extraInfo & signatureMask) == miWpSignature && (extraInfo & 0xff);
+        if (fromTouch)
+            return false;
+    }
 #endif // !Q_OS_WINCE
 
     const QPoint winEventPosition(GET_X_LPARAM(msg.lParam), GET_Y_LPARAM(msg.lParam));