Make GLX and EGL dynamic dependencies for xcb

[ChangeLog][QPA][Xcb] GLX and EGL code paths are now dynamically
resolved, making it possible for one build of a plugin to use both code
paths. Default is to use the GLX code path if available. This can be
overwritten by specifying QT_XCB_GL_INTEGRATION=xcb_egl as an
evnironment variable. Enable qt.xcb.glintegration.debug to get debug log
output of what integration is used

Change-Id: Ia9fa95fcca3d901b91dadb8c98a695fea0ae3b1e
Reviewed-by: Laszlo Agocs <laszlo.agocs@theqtcompany.com>

1 files changed, 35 insertions, 144 deletions

diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index ea13502a21..2e429939ba 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -44,6 +44,8 @@
 #include "qxcbnativeinterface.h"
 #include "qxcbintegration.h"
 #include "qxcbsystemtraytracker.h"
+#include "qxcbglintegrationfactory.h"
+#include "qxcbglintegration.h"
 
 #include <QSocketNotifier>
 #include <QAbstractEventDispatcher>
@@ -74,14 +76,6 @@
 #include <xcb/render.h>
 #endif
 
-#if defined(XCB_HAS_XCB_GLX)
-#include <xcb/glx.h>
-#endif
-
-#ifdef XCB_USE_EGL //don't pull in eglext prototypes
-#include <EGL/egl.h>
-#endif
-
 QT_BEGIN_NAMESPACE
 
 Q_LOGGING_CATEGORY(lcQpaXInput, "qt.qpa.input")
@@ -121,39 +115,6 @@ static int ioErrorHandler(Display *dpy)
 }
 #endif
 
-#if defined(XCB_HAS_XCB_GLX) && XCB_GLX_MAJOR_VERSION == 1 && XCB_GLX_MINOR_VERSION < 4
-
-#define XCB_GLX_BUFFER_SWAP_COMPLETE 1
-
-typedef struct xcb_glx_buffer_swap_complete_event_t {
-    uint8_t            response_type;
-    uint8_t            pad0;
-    uint16_t           sequence;
-    uint16_t           event_type;
-    uint8_t            pad1[2];
-    xcb_glx_drawable_t drawable;
-    uint32_t           ust_hi;
-    uint32_t           ust_lo;
-    uint32_t           msc_hi;
-    uint32_t           msc_lo;
-    uint32_t           sbc;
-} xcb_glx_buffer_swap_complete_event_t;
-#endif
-
-#if defined(XCB_USE_XLIB) && defined(XCB_USE_GLX)
-typedef struct {
-    int type;
-    unsigned long serial;       /* # of last request processed by server */
-    Bool send_event;            /* true if this came from a SendEvent request */
-    Display *display;           /* Display the event was read from */
-    Drawable drawable;  /* drawable on which event was requested in event mask */
-    int event_type;
-    int64_t ust;
-    int64_t msc;
-    int64_t sbc;
-} QGLXBufferSwapComplete;
-#endif
-
 QXcbScreen* QXcbConnection::findOrCreateScreen(QList<QXcbScreen *>& newScreens,
     int screenNumber, xcb_screen_t* xcbScreen, xcb_randr_get_output_info_reply_t *output)
 {
@@ -309,11 +270,12 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     , m_primaryScreenNumber(0)
     , m_displayName(displayName ? QByteArray(displayName) : qgetenv("DISPLAY"))
     , m_nativeInterface(nativeInterface)
+#ifdef XCB_USE_XLIB
+    , m_xlib_display(0)
+#endif
     , xfixes_first_event(0)
     , xrandr_first_event(0)
     , xkb_first_event(0)
-    , glx_first_event(0)
-    , has_glx_extension(false)
     , has_shape_extension(false)
     , has_randr_extension(false)
     , has_input_shape(false)
@@ -322,14 +284,10 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     , m_buttons(0)
     , m_focusWindow(0)
     , m_systemTrayTracker(0)
+    , m_glIntegration(Q_NULLPTR)
 {
-#ifdef XCB_USE_EGL
-    EGLNativeDisplayType dpy = EGL_DEFAULT_DISPLAY;
-#elif defined(XCB_USE_XLIB)
-    Display *dpy;
-#endif
 #ifdef XCB_USE_XLIB
-    dpy = XOpenDisplay(m_displayName.constData());
+    Display *dpy = XOpenDisplay(m_displayName.constData());
     if (dpy) {
         m_primaryScreenNumber = DefaultScreen(dpy);
         m_connection = XGetXCBConnection(dpy);
@@ -345,12 +303,6 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     if (!m_connection || xcb_connection_has_error(m_connection))
         qFatal("QXcbConnection: Could not connect to display %s", m_displayName.constData());
 
-#ifdef XCB_USE_EGL
-    EGLDisplay eglDisplay = eglGetDisplay(dpy);
-    m_egl_display = eglDisplay;
-    EGLint major, minor;
-    m_has_egl = eglInitialize(eglDisplay, &major, &minor);
-#endif //XCB_USE_EGL
 
     m_reader = new QXcbEventReader(this);
     m_reader->start();
@@ -363,9 +315,6 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
 #ifdef XCB_USE_RENDER
         &xcb_render_id,
 #endif
-#ifdef XCB_HAS_XCB_GLX
-        &xcb_glx_id,
-#endif
         0
     };
 
@@ -382,7 +331,6 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     initializeXRandr();
     updateScreens();
 
-    initializeGLX();
     initializeXFixes();
     initializeXRender();
     m_xi2Enabled = false;
@@ -405,6 +353,27 @@ QXcbConnection::QXcbConnection(QXcbNativeInterface *nativeInterface, bool canGra
     if (!m_startupId.isNull())
         qunsetenv("DESKTOP_STARTUP_ID");
 
+
+    QStringList glIntegrationNames;
+    glIntegrationNames << QStringLiteral("xcb_glx") << QStringLiteral("xcb_egl");
+    QString glIntegrationName = QString::fromLocal8Bit(qgetenv("QT_XCB_GL_INTEGRATION"));
+    if (glIntegrationName.size()) {
+        glIntegrationNames.removeAll(glIntegrationName);
+        glIntegrationNames.prepend(glIntegrationName);
+    }
+
+    qCDebug(QT_XCB_GLINTEGRATION) << "Choosing xcb gl-integration based on following priority\n" << glIntegrationNames;
+    for (int i = 0; i < glIntegrationNames.size() && !m_glIntegration; i++) {
+        m_glIntegration = QXcbGlIntegrationFactory::create(glIntegrationNames.at(i));
+        if (m_glIntegration && !m_glIntegration->initialize(this)) {
+            qCDebug(QT_XCB_GLINTEGRATION) << "Failed to initialize xcb gl-integration" << glIntegrationNames.at(i);
+            delete m_glIntegration;
+            m_glIntegration = Q_NULLPTR;
+        }
+    }
+    if (!m_glIntegration)
+        qCDebug(QT_XCB_GLINTEGRATION) << "Failed to create xcb gl-integration";
+
     sync();
 
     if (qEnvironmentVariableIsEmpty("QT_IM_MODULE"))
@@ -435,11 +404,6 @@ QXcbConnection::~QXcbConnection()
     while (!m_screens.isEmpty())
         delete m_screens.takeLast();
 
-#ifdef XCB_USE_EGL
-    if (m_has_egl)
-        eglTerminate(m_egl_display);
-#endif //XCB_USE_EGL
-
 #ifdef XCB_USE_XLIB
     XCloseDisplay((Display *)m_xlib_display);
 #else
@@ -990,51 +954,8 @@ void QXcbConnection::handleXcbEvent(xcb_generic_event_t *event)
         }
     }
 
-#ifdef XCB_USE_XLIB
-    if (!handled) {
-        // Check if a custom XEvent constructor was registered in xlib for this event type, and call it discarding the constructed XEvent if any.
-        // XESetWireToEvent might be used by libraries to intercept messages from the X server e.g. the OpenGL lib waiting for DRI2 events.
-        Display *xdisplay = (Display *)m_xlib_display;
-        XLockDisplay(xdisplay);
-        bool locked = true;
-        Bool (*proc)(Display*, XEvent*, xEvent*) = XESetWireToEvent(xdisplay, response_type, 0);
-        if (proc) {
-            XESetWireToEvent(xdisplay, response_type, proc);
-            XEvent dummy;
-            event->sequence = LastKnownRequestProcessed(m_xlib_display);
-            if (proc(xdisplay, &dummy, (xEvent*)event)) {
-#if defined(XCB_USE_GLX) && defined(XCB_HAS_XCB_GLX)
-                // DRI2 clients don't receive GLXBufferSwapComplete events on the wire.
-                // Instead the GLX event is synthesized from the DRI2BufferSwapComplete event
-                // by DRI2WireToEvent(). For an application to be able to see the event
-                // we have to convert it to an xcb_glx_buffer_swap_complete_event_t and
-                // pass it to the native event filter.
-                const uint swap_complete = glx_first_event + XCB_GLX_BUFFER_SWAP_COMPLETE;
-                if (dispatcher && has_glx_extension && uint(dummy.type) == swap_complete && response_type != swap_complete) {
-                    QGLXBufferSwapComplete *xev = reinterpret_cast<QGLXBufferSwapComplete *>(&dummy);
-                    xcb_glx_buffer_swap_complete_event_t ev;
-                    memset(&ev, 0, sizeof(xcb_glx_buffer_swap_complete_event_t));
-                    ev.response_type = xev->type;
-                    ev.sequence = xev->serial;
-                    ev.event_type = xev->event_type;
-                    ev.drawable = xev->drawable;
-                    ev.ust_hi = xev->ust >> 32;
-                    ev.ust_lo = xev->ust & 0xffffffff;
-                    ev.msc_hi = xev->msc >> 32;
-                    ev.msc_lo = xev->msc & 0xffffffff;
-                    ev.sbc = xev->sbc & 0xffffffff;
-                    // Unlock the display before calling the native event filter
-                    XUnlockDisplay(xdisplay);
-                    locked = false;
-                    handled = dispatcher->filterNativeEvent(m_nativeInterface->genericEventFilterType(), &ev, &result);
-                }
-#endif
-            }
-        }
-        if (locked)
-            XUnlockDisplay(xdisplay);
-    }
-#endif
+    if (!handled)
+        handled = m_glIntegration->handleXcbEvent(event, response_type);
 
     if (handled)
         printXcbEvent("Handled XCB event", event);
@@ -1232,6 +1153,11 @@ xcb_window_t QXcbConnection::rootWindow()
     return primaryScreen()->root();
 }
 
+void *QXcbConnection::xlib_display() const
+{
+    return m_xlib_display;
+}
+
 void QXcbConnection::processXcbEvents()
 {
     int connection_error = xcb_connection_has_error(xcb_connection());
@@ -1674,34 +1600,6 @@ void QXcbConnection::initializeXRender()
 #endif
 }
 
-void QXcbConnection::initializeGLX()
-{
-#ifdef XCB_HAS_XCB_GLX
-    const xcb_query_extension_reply_t *reply = xcb_get_extension_data(m_connection, &xcb_glx_id);
-    if (!reply || !reply->present)
-        return;
-
-    has_glx_extension = true;
-    glx_first_event = reply->first_event;
-
-    xcb_generic_error_t *error = 0;
-    xcb_glx_query_version_cookie_t xglx_query_cookie = xcb_glx_query_version(m_connection,
-                                                                             XCB_GLX_MAJOR_VERSION,
-                                                                             XCB_GLX_MINOR_VERSION);
-    xcb_glx_query_version_reply_t *xglx_query = xcb_glx_query_version_reply(m_connection,
-                                                                            xglx_query_cookie, &error);
-    if (!xglx_query || error) {
-        qWarning("QXcbConnection: Failed to initialize GLX");
-        free(error);
-        has_glx_extension = false;
-    }
-    free(xglx_query);
-#else
-    // no way to check, assume GLX is present
-    has_glx_extension = true;
-#endif
-}
-
 void QXcbConnection::initializeXRandr()
 {
     const xcb_query_extension_reply_t *reply = xcb_get_extension_data(m_connection, &xcb_randr_id);
@@ -1811,13 +1709,6 @@ void QXcbConnection::initializeXKB()
 #endif
 }
 
-#if defined(XCB_USE_EGL)
-bool QXcbConnection::hasEgl() const
-{
-    return m_has_egl;
-}
-#endif // defined(XCB_USE_EGL)
-
 #if defined(XCB_USE_XINPUT2)
 static int xi2ValuatorOffset(unsigned char *maskPtr, int maskLen, int number)
 {