xcb: Add Xinerama support

This patch makes possible to use Xinerama screens in XCB platform
plugin.

Task-number: QTBUG-48615
Change-Id: Ib4dbfcdfadc46d2875a2fc09e8b852181edfbed2
Reviewed-by: Shawn Rutledge <shawn.rutledge@theqtcompany.com>

6 files changed, 75 insertions, 19 deletions

diff --git a/src/plugins/platforms/xcb/README b/src/plugins/platforms/xcb/README
index 2f666bebfd..15cf4cf241 100644
--- a/src/plugins/platforms/xcb/README
+++ b/src/plugins/platforms/xcb/README
@@ -3,14 +3,14 @@ Requires libxcb >= 1.5.
 PACKAGE DEPENDENCIES
 
 Required packages:
-libxcb1 libxcb1-dev libx11-xcb1 libx11-xcb-dev libxcb-keysyms1 libxcb-keysyms1-dev libxcb-image0 libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm1 libxcb-icccm1-dev libxcb-sync0 libxcb-sync0-dev libxcb-render-util0 libxcb-render-util0-dev libxcb-xfixes0-dev libxrender-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-glx0-dev
+libxcb1 libxcb1-dev libx11-xcb1 libx11-xcb-dev libxcb-keysyms1 libxcb-keysyms1-dev libxcb-image0 libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm1 libxcb-icccm1-dev libxcb-sync0 libxcb-sync0-dev libxcb-render-util0 libxcb-render-util0-dev libxcb-xfixes0-dev libxrender-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-glx0-dev libxcb-xinerama0-dev
 
 On Ubuntu 11.10 icccm1 is replaced by icccm4 and xcb-render-util is not available:
-libxcb1 libxcb1-dev libx11-xcb1 libx11-xcb-dev libxcb-keysyms1 libxcb-keysyms1-dev libxcb-image0 libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm4 libxcb-icccm4-dev libxcb-sync0 libxcb-sync0-dev libxcb-xfixes0-dev libxrender-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-glx0-dev
+libxcb1 libxcb1-dev libx11-xcb1 libx11-xcb-dev libxcb-keysyms1 libxcb-keysyms1-dev libxcb-image0 libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm4 libxcb-icccm4-dev libxcb-sync0 libxcb-sync0-dev libxcb-xfixes0-dev libxrender-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-glx0-dev libxcb-xinerama0-dev
 The packages for xcb-render-util can be installed manually from http://packages.ubuntu.com/natty/libxcb-render-util0 and http://packages.ubuntu.com/natty/libxcb-render-util0-dev
 
 On Ubuntu 12.04 icccm1 is replaced by icccm4 and xcb-render-util can be installed automatically:
-libxcb1 libxcb1-dev libx11-xcb1 libx11-xcb-dev libxcb-keysyms1 libxcb-keysyms1-dev libxcb-image0 libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm4 libxcb-icccm4-dev libxcb-sync0 libxcb-sync0-dev libxcb-xfixes0-dev libxrender-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-render-util0 libxcb-render-util0-dev libxcb-glx0-dev
+libxcb1 libxcb1-dev libx11-xcb1 libx11-xcb-dev libxcb-keysyms1 libxcb-keysyms1-dev libxcb-image0 libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm4 libxcb-icccm4-dev libxcb-sync0 libxcb-sync0-dev libxcb-xfixes0-dev libxrender-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-render-util0 libxcb-render-util0-dev libxcb-glx0-dev libxcb-xinerama0-dev
 
 
 On Fedora, the following packages are required:
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 231fe9af3f..f93cfde4a5 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -60,6 +60,7 @@
 #include <xcb/shm.h>
 #include <xcb/sync.h>
 #include <xcb/xfixes.h>
+#include <xcb/xinerama.h>
 
 #ifdef XCB_USE_XLIB
 #include <X11/Xlib.h>
@@ -386,6 +387,7 @@ void QXcbConnection::initializeScreens()
         xcb_screen_t *xcbScreen = it.data;
         QXcbVirtualDesktop *virtualDesktop = new QXcbVirtualDesktop(this, xcbScreen, xcbScreenNumber);
         m_virtualDesktops.append(virtualDesktop);
+        QList<QPlatformScreen *> siblings;
         if (has_randr_extension) {
             xcb_generic_error_t *error = NULL;
             // RRGetScreenResourcesCurrent is fast but it may return nothing if the
@@ -429,7 +431,6 @@ void QXcbConnection::initializeScreens()
                         qWarning("failed to get the primary output of the screen");
                         free(error);
                     } else {
-                        QList<QPlatformScreen *> siblings;
                         for (int i = 0; i < outputCount; i++) {
                             QScopedPointer<xcb_randr_get_output_info_reply_t, QScopedPointerPodDeleter> output(
                                     xcb_randr_get_output_info_reply(xcb_connection(),
@@ -471,12 +472,30 @@ void QXcbConnection::initializeScreens()
                                 }
                             }
                         }
-                        virtualDesktop->setScreens(siblings);
                     }
                 }
             }
+        } else if (has_xinerama_extension) {
+            // Xinerama is available
+            xcb_xinerama_query_screens_cookie_t cookie = xcb_xinerama_query_screens(m_connection);
+            xcb_xinerama_query_screens_reply_t *screens = xcb_xinerama_query_screens_reply(m_connection,
+                                                                                           cookie,
+                                                                                           Q_NULLPTR);
+            if (screens) {
+                xcb_xinerama_screen_info_iterator_t it = xcb_xinerama_query_screens_screen_info_iterator(screens);
+                while (it.rem) {
+                    xcb_xinerama_screen_info_t *screen_info = it.data;
+                    QXcbScreen *screen = new QXcbScreen(this, virtualDesktop,
+                                                        XCB_NONE, Q_NULLPTR,
+                                                        screen_info, it.index);
+                    siblings << screen;
+                    m_screens << screen;
+                    xcb_xinerama_screen_info_next(&it);
+                }
+                free(screens);
+            }
         }
-        if (virtualDesktop->screens().isEmpty()) {
+        if (siblings.isEmpty()) {
             // If there are no XRandR outputs or XRandR extension is missing,
             // then create a fake/legacy screen.
             QXcbScreen *screen = new QXcbScreen(this, virtualDesktop, XCB_NONE, Q_NULLPTR);
@@ -486,8 +505,9 @@ void QXcbConnection::initializeScreens()
                 primaryScreen = screen;
                 primaryScreen->setPrimary(true);
             }
-            virtualDesktop->addScreen(screen);
+            siblings << screen;
         }
+        virtualDesktop->setScreens(siblings);
         xcb_screen_next(&it);
         ++xcbScreenNumber;
     } // for each xcb screen
@@ -529,6 +549,7 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     , xfixes_first_event(0)
     , xrandr_first_event(0)
     , xkb_first_event(0)
+    , has_xinerama_extension(false)
     , has_shape_extension(false)
     , has_randr_extension(false)
     , has_input_shape(false)
@@ -583,7 +604,10 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     m_time = XCB_CURRENT_TIME;
     m_netWmUserTime = XCB_CURRENT_TIME;
 
-    initializeXRandr();
+    if (!qEnvironmentVariableIsSet("QT_XCB_NO_XRANDR"))
+        initializeXRandr();
+    if (!has_randr_extension)
+        initializeXinerama();
     initializeXFixes();
     initializeScreens();
 
@@ -2087,6 +2111,22 @@ void QXcbConnection::initializeXRandr()
     }
 }
 
+void QXcbConnection::initializeXinerama()
+{
+    const xcb_query_extension_reply_t *reply = xcb_get_extension_data(m_connection, &xcb_xinerama_id);
+    if (!reply || !reply->present)
+        return;
+
+    xcb_generic_error_t *error = Q_NULLPTR;
+    xcb_xinerama_is_active_cookie_t xinerama_query_cookie = xcb_xinerama_is_active(m_connection);
+    xcb_xinerama_is_active_reply_t *xinerama_is_active = xcb_xinerama_is_active_reply(m_connection,
+                                                                                      xinerama_query_cookie,
+                                                                                      &error);
+    has_xinerama_extension = xinerama_is_active && !error && xinerama_is_active->state;
+    free(error);
+    free(xinerama_is_active);
+}
+
 void QXcbConnection::initializeXShape()
 {
     const xcb_query_extension_reply_t *xshape_reply = xcb_get_extension_data(m_connection, &xcb_shape_id);
@@ -2174,7 +2214,9 @@ void QXcbConnection::initializeXKB()
 bool QXcbConnection::xi2MouseEvents() const
 {
     static bool mouseViaXI2 = !qEnvironmentVariableIsSet("QT_XCB_NO_XI2_MOUSE");
-    return mouseViaXI2;
+    // Don't use XInput2 when Xinerama extension is enabled,
+    // because it causes problems with multi-monitor setup.
+    return mouseViaXI2 && !has_xinerama_extension;
 }
 
 #if defined(XCB_USE_XINPUT2)
diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index fb7cc137b9..6d26e88fa2 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -515,6 +515,7 @@ private:
     void initializeXFixes();
     void initializeXRender();
     void initializeXRandr();
+    void initializeXinerama();
     void initializeXShape();
     void initializeXKB();
     void handleClientMessageEvent(const xcb_client_message_event_t *event);
@@ -639,6 +640,7 @@ private:
     uint32_t xrandr_first_event;
     uint32_t xkb_first_event;
 
+    bool has_xinerama_extension;
     bool has_shape_extension;
     bool has_randr_extension;
     bool has_input_shape;
diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index f05432ef68..caddd2b2a5 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -155,8 +155,15 @@ void QXcbVirtualDesktop::updateWorkArea()
     }
 }
 
+static inline QSizeF sizeInMillimeters(const QSize &size, const QDpi &dpi)
+{
+    return QSizeF(Q_MM_PER_INCH * size.width() / dpi.first,
+                  Q_MM_PER_INCH * size.height() / dpi.second);
+}
+
 QXcbScreen::QXcbScreen(QXcbConnection *connection, QXcbVirtualDesktop *virtualDesktop,
-                       xcb_randr_output_t outputId, xcb_randr_get_output_info_reply_t *output)
+                       xcb_randr_output_t outputId, xcb_randr_get_output_info_reply_t *output,
+                       const xcb_xinerama_screen_info_t *xineramaScreenInfo, int xineramaScreenIdx)
     : QXcbObject(connection)
     , m_virtualDesktop(virtualDesktop)
     , m_output(outputId)
@@ -188,8 +195,14 @@ QXcbScreen::QXcbScreen(QXcbConnection *connection, QXcbVirtualDesktop *virtualDe
             updateRefreshRate(crtc->mode);
             free(crtc);
         }
-    } else {
-        updateGeometry(output ? output->timestamp : 0);
+    } else if (xineramaScreenInfo) {
+        m_geometry = QRect(xineramaScreenInfo->x_org, xineramaScreenInfo->y_org,
+                           xineramaScreenInfo->width, xineramaScreenInfo->height);
+        m_nativeGeometry = m_geometry;
+        m_availableGeometry = m_geometry & m_virtualDesktop->workArea();
+        m_sizeMillimeters = sizeInMillimeters(m_geometry.size(), virtualDpi());
+        if (xineramaScreenIdx > -1)
+            m_outputName += QLatin1Char('-') + QString::number(xineramaScreenIdx);
     }
 
     if (m_geometry.isEmpty()) {
@@ -538,11 +551,8 @@ void QXcbScreen::updateGeometry(const QRect &geom, uint8_t rotation)
     // It can be that physical size is unknown while virtual size
     // is known (probably back-calculated from DPI and resolution),
     // e.g. on VNC or with some hardware.
-    if (m_sizeMillimeters.isEmpty()) {
-        QDpi dpi = virtualDpi();
-        m_sizeMillimeters = QSizeF(Q_MM_PER_INCH * xGeometry.width() / dpi.first,
-                                   Q_MM_PER_INCH * xGeometry.width() / dpi.second);
-    }
+    if (m_sizeMillimeters.isEmpty())
+        m_sizeMillimeters = sizeInMillimeters(xGeometry.size(), virtualDpi());
 
     qreal dpi = xGeometry.width() / physicalSize().width() * qreal(25.4);
     m_pixelDensity = qRound(dpi/96);
diff --git a/src/plugins/platforms/xcb/qxcbscreen.h b/src/plugins/platforms/xcb/qxcbscreen.h
index 79620f40ec..dd7396aca2 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.h
+++ b/src/plugins/platforms/xcb/qxcbscreen.h
@@ -40,6 +40,7 @@
 #include <xcb/xcb.h>
 #include <xcb/randr.h>
 #include <xcb/xfixes.h>
+#include <xcb/xinerama.h>
 
 #include "qxcbobject.h"
 #include "qxcbscreen.h"
@@ -102,7 +103,8 @@ class Q_XCB_EXPORT QXcbScreen : public QXcbObject, public QPlatformScreen
 {
 public:
     QXcbScreen(QXcbConnection *connection, QXcbVirtualDesktop *virtualDesktop,
-               xcb_randr_output_t outputId, xcb_randr_get_output_info_reply_t *outputInfo);
+               xcb_randr_output_t outputId, xcb_randr_get_output_info_reply_t *outputInfo,
+               const xcb_xinerama_screen_info_t *xineramaScreenInfo = Q_NULLPTR, int xineramaScreenIdx = -1);
     ~QXcbScreen();
 
     QString getOutputName(xcb_randr_get_output_info_reply_t *outputInfo);
diff --git a/src/plugins/platforms/xcb/xcb_qpa_lib.pro b/src/plugins/platforms/xcb/xcb_qpa_lib.pro
index 60eb8a02e3..302d87e007 100644
--- a/src/plugins/platforms/xcb/xcb_qpa_lib.pro
+++ b/src/plugins/platforms/xcb/xcb_qpa_lib.pro
@@ -92,7 +92,7 @@ contains(QT_CONFIG, xcb-qt) {
     INCLUDEPATH += $$XCB_DIR/include $$XCB_DIR/sysinclude
     LIBS += -lxcb -L$$OUT_PWD/xcb-static -lxcb-static
 } else {
-    LIBS += -lxcb -lxcb-image -lxcb-icccm -lxcb-sync -lxcb-xfixes -lxcb-shm -lxcb-randr -lxcb-shape -lxcb-keysyms
+    LIBS += -lxcb -lxcb-image -lxcb-icccm -lxcb-sync -lxcb-xfixes -lxcb-shm -lxcb-randr -lxcb-shape -lxcb-keysyms -lxcb-xinerama
     !contains(DEFINES, QT_NO_XKB):LIBS += -lxcb-xkb
 }