Fixed incorrect handling of extra mouse buttons in XCB platform plugin.

translateMouseButtons() was only able to correctly handle the left,
right, and mid mouse buttons. Thus, if any buttons outside of those were
pressed, the motion notify event would basically unset the mouse button
mask, leading to a release event being sent instead. Later on, when the
actual release event arrives, that button gets xor'ed into the empty
button mask generating another press, and later another motion event
will generate a release. In the end that means two press-release
sequences are sent for any extra mouse buttons.

Instead of getting the mask of the buttons currently being pressed from
the event, we need to keep track of the mask ourselves.

Task-number: QTBUG-28561
Change-Id: Iaa67e784a13d792deef8fc29dbd5456a5471a861
Reviewed-by: Oliver Wolff <oliver.wolff@digia.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Rick Stockton <rickstockton@reno-computerhelp.com>
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 4c4df137a3..b4f1a278a2 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -257,6 +257,7 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, const char
     , has_shape_extension(false)
     , has_randr_extension(false)
     , has_input_shape(false)
+    , m_buttons(0)
 {
 #ifdef XCB_USE_XLIB
     Display *dpy = XOpenDisplay(m_displayName.constData());
@@ -662,6 +663,73 @@ void QXcbConnection::handleXcbError(xcb_generic_error_t *error)
 #endif
 }
 
+static Qt::MouseButtons translateMouseButtons(int s)
+{
+    Qt::MouseButtons ret = 0;
+    if (s & XCB_BUTTON_MASK_1)
+        ret |= Qt::LeftButton;
+    if (s & XCB_BUTTON_MASK_2)
+        ret |= Qt::MidButton;
+    if (s & XCB_BUTTON_MASK_3)
+        ret |= Qt::RightButton;
+    return ret;
+}
+
+static Qt::MouseButton translateMouseButton(xcb_button_t s)
+{
+    switch (s) {
+    case 1: return Qt::LeftButton;
+    case 2: return Qt::MidButton;
+    case 3: return Qt::RightButton;
+    // Button values 4-7 were already handled as Wheel events, and won't occur here.
+    case 8: return Qt::BackButton;      // Also known as Qt::ExtraButton1
+    case 9: return Qt::ForwardButton;   // Also known as Qt::ExtraButton2
+    case 10: return Qt::ExtraButton3;
+    case 11: return Qt::ExtraButton4;
+    case 12: return Qt::ExtraButton5;
+    case 13: return Qt::ExtraButton6;
+    case 14: return Qt::ExtraButton7;
+    case 15: return Qt::ExtraButton8;
+    case 16: return Qt::ExtraButton9;
+    case 17: return Qt::ExtraButton10;
+    case 18: return Qt::ExtraButton11;
+    case 19: return Qt::ExtraButton12;
+    case 20: return Qt::ExtraButton13;
+    case 21: return Qt::ExtraButton14;
+    case 22: return Qt::ExtraButton15;
+    case 23: return Qt::ExtraButton16;
+    case 24: return Qt::ExtraButton17;
+    case 25: return Qt::ExtraButton18;
+    case 26: return Qt::ExtraButton19;
+    case 27: return Qt::ExtraButton20;
+    case 28: return Qt::ExtraButton21;
+    case 29: return Qt::ExtraButton22;
+    case 30: return Qt::ExtraButton23;
+    case 31: return Qt::ExtraButton24;
+    default: return Qt::NoButton;
+    }
+}
+
+void QXcbConnection::handleButtonPress(xcb_generic_event_t *ev)
+{
+    xcb_button_press_event_t *event = (xcb_button_press_event_t *)ev;
+
+    // the event explicitly contains the state of the three first buttons,
+    // the rest we need to manage ourselves
+    m_buttons = (m_buttons & ~0x7) | translateMouseButtons(event->state);
+    m_buttons |= translateMouseButton(event->detail);
+}
+
+void QXcbConnection::handleButtonRelease(xcb_generic_event_t *ev)
+{
+    xcb_button_release_event_t *event = (xcb_button_release_event_t *)ev;
+
+    // the event explicitly contains the state of the three first buttons,
+    // the rest we need to manage ourselves
+    m_buttons = (m_buttons & ~0x7) | translateMouseButtons(event->state);
+    m_buttons &= ~translateMouseButton(event->detail);
+}
+
 void QXcbConnection::handleXcbEvent(xcb_generic_event_t *event)
 {
 #ifdef Q_XCB_DEBUG
@@ -686,8 +754,10 @@ void QXcbConnection::handleXcbEvent(xcb_generic_event_t *event)
         case XCB_EXPOSE:
             HANDLE_PLATFORM_WINDOW_EVENT(xcb_expose_event_t, window, handleExposeEvent);
         case XCB_BUTTON_PRESS:
+            handleButtonPress(event);
             HANDLE_PLATFORM_WINDOW_EVENT(xcb_button_press_event_t, event, handleButtonPressEvent);
         case XCB_BUTTON_RELEASE:
+            handleButtonRelease(event);
             HANDLE_PLATFORM_WINDOW_EVENT(xcb_button_release_event_t, event, handleButtonReleaseEvent);
         case XCB_MOTION_NOTIFY:
             HANDLE_PLATFORM_WINDOW_EVENT(xcb_motion_notify_event_t, event, handleMotionNotifyEvent);