qglxintegration.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
// Qt-Security score:significant reason:default
 
#include <QDebug>
 
#include "qxcbwindow.h"
#include "qxcbscreen.h"
 
#define register        /* C++17 deprecated register */
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#undef register
#include <GL/glx.h>
 
#if QT_CONFIG(regularexpression)
#  include <QtCore/QRegularExpression>
#endif
#include <QtGui/qguiapplication.h>
#include <QtGui/QOpenGLContext>
#include <QtGui/QOffscreenSurface>
 
#include "qglxintegration.h"
#include <QtGui/private/qglxconvenience_p.h>
 
#include "qxcbglintegration.h"
 
QT_BEGIN_NAMESPACE
 
typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);
typedef const GLubyte *(*glGetStringiProc)(GLenum, GLuint);
 
#ifndef GLX_CONTEXT_CORE_PROFILE_BIT_ARB
#define GLX_CONTEXT_CORE_PROFILE_BIT_ARB 0x00000001
#endif
 
#ifndef GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB
#define GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB 0x00000002
#endif
 
#ifndef GLX_CONTEXT_ES2_PROFILE_BIT_EXT
#define GLX_CONTEXT_ES2_PROFILE_BIT_EXT 0x00000004
#endif
 
#ifndef GLX_CONTEXT_PROFILE_MASK_ARB
#define GLX_CONTEXT_PROFILE_MASK_ARB 0x9126
#endif
 
#ifndef GL_CONTEXT_FLAG_DEBUG_BIT
#define GL_CONTEXT_FLAG_DEBUG_BIT 0x00000002
#endif
 
#ifndef GLX_CONTEXT_ROBUST_ACCESS_BIT_ARB
#define GLX_CONTEXT_ROBUST_ACCESS_BIT_ARB 0x00000004
#endif
 
#ifndef GL_RESET_NOTIFICATION_STRATEGY_ARB
#define GL_RESET_NOTIFICATION_STRATEGY_ARB 0x8256
#endif
 
#ifndef GLX_CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB
#define GLX_CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB 0x8256
#endif
 
#ifndef GL_LOSE_CONTEXT_ON_RESET_ARB
#define GL_LOSE_CONTEXT_ON_RESET_ARB 0x8252
#endif
 
#ifndef GLX_LOSE_CONTEXT_ON_RESET_ARB
#define GLX_LOSE_CONTEXT_ON_RESET_ARB 0x8252
#endif
 
#ifndef GLX_GENERATE_RESET_ON_VIDEO_MEMORY_PURGE_NV
#define GLX_GENERATE_RESET_ON_VIDEO_MEMORY_PURGE_NV 0x20F7
#endif
 
static Window createDummyWindow(Display *dpy, XVisualInfo *visualInfo, int screenNumber, Window rootWin)
{
    Colormap cmap = XCreateColormap(dpy, rootWin, visualInfo->visual, AllocNone);
    XSetWindowAttributes a;
    a.background_pixel = WhitePixel(dpy, screenNumber);
    a.border_pixel = BlackPixel(dpy, screenNumber);
    a.colormap = cmap;
    a.override_redirect = true;
 
    Window window = XCreateWindow(dpy, rootWin,
                                  0, 0, 100, 100,
                                  0, visualInfo->depth, InputOutput, visualInfo->visual,
                                  CWBackPixel|CWBorderPixel|CWColormap|CWOverrideRedirect, &a);
#ifndef QT_NO_DEBUG
    XStoreName(dpy, window, "Qt GLX dummy window");
#endif
    XFreeColormap(dpy, cmap);
    return window;
}
 
static Window createDummyWindow(Display *dpy, GLXFBConfig config, int screenNumber, Window rootWin)
{
    XVisualInfo *visualInfo = glXGetVisualFromFBConfig(dpy, config);
    if (Q_UNLIKELY(!visualInfo))
        qFatal("Could not initialize GLX");
    Window window = createDummyWindow(dpy, visualInfo, screenNumber, rootWin);
    XFree(visualInfo);
    return window;
}
 
static inline QByteArray getGlString(GLenum param)
{
    if (const GLubyte *s = glGetString(param))
        return QByteArray(reinterpret_cast<const char*>(s));
    return QByteArray();
}
 
static bool hasGlExtension(const QSurfaceFormat &format, const char *ext)
{
    if (format.majorVersion() < 3) {
        auto exts = reinterpret_cast<const char *>(glGetString(GL_EXTENSIONS));
        return exts && strstr(exts, ext);
    } else {
        auto glGetStringi = reinterpret_cast<glGetStringiProc>(
                glXGetProcAddress(reinterpret_cast<const GLubyte*>("glGetStringi")));
        if (glGetStringi) {
            GLint n = 0;
            glGetIntegerv(GL_NUM_EXTENSIONS, &n);
            for (GLint i = 0; i < n; ++i) {
                const char *p = reinterpret_cast<const char *>(glGetStringi(GL_EXTENSIONS, i));
                if (p && !strcmp(p, ext))
                    return true;
            }
        }
        return false;
    }
}
 
static void updateFormatFromContext(QSurfaceFormat &format)
{
    // Update the version, profile, and context bit of the format
    int major = 0, minor = 0;
    QByteArray versionString(getGlString(GL_VERSION));
    if (QPlatformOpenGLContext::parseOpenGLVersion(versionString, major, minor)) {
        format.setMajorVersion(major);
        format.setMinorVersion(minor);
    }
 
    format.setProfile(QSurfaceFormat::NoProfile);
    const bool isStereo = format.testOption(QSurfaceFormat::StereoBuffers);
    format.setOptions(QSurfaceFormat::FormatOptions());
    // Restore flags that come from the VisualInfo/FBConfig.
    if (isStereo)
        format.setOption(QSurfaceFormat::StereoBuffers);
 
    if (format.renderableType() == QSurfaceFormat::OpenGL) {
        if (hasGlExtension(format, "GL_ARB_robustness")) {
            GLint value = 0;
            glGetIntegerv(GL_RESET_NOTIFICATION_STRATEGY_ARB, &value);
            if (value == GL_LOSE_CONTEXT_ON_RESET_ARB)
                format.setOption(QSurfaceFormat::ResetNotification);
        }
 
        if (format.version() < std::pair(3, 0)) {
            format.setOption(QSurfaceFormat::DeprecatedFunctions);
            return;
        }
 
        // Version 3.0 onwards - check if it includes deprecated functionality or is
        // a debug context
        GLint value = 0;
        glGetIntegerv(GL_CONTEXT_FLAGS, &value);
        if (!(value & GL_CONTEXT_FLAG_FORWARD_COMPATIBLE_BIT))
            format.setOption(QSurfaceFormat::DeprecatedFunctions);
        if (value & GL_CONTEXT_FLAG_DEBUG_BIT)
            format.setOption(QSurfaceFormat::DebugContext);
        if (format.version() < std::pair(3, 2))
            return;
 
        // Version 3.2 and newer have a profile
        value = 0;
        glGetIntegerv(GL_CONTEXT_PROFILE_MASK, &value);
 
        if (value & GL_CONTEXT_CORE_PROFILE_BIT)
            format.setProfile(QSurfaceFormat::CoreProfile);
        else if (value & GL_CONTEXT_COMPATIBILITY_PROFILE_BIT)
            format.setProfile(QSurfaceFormat::CompatibilityProfile);
    }
}
 
QGLXContext::QGLXContext(Display *display, QXcbScreen *screen, const QSurfaceFormat &format, QPlatformOpenGLContext *share)
    : QPlatformOpenGLContext()
    , m_display(display)
    , m_format(format)
    , m_ownsContext(true)
{
    if (m_format.renderableType() == QSurfaceFormat::DefaultRenderableType)
        m_format.setRenderableType(QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGL
                                   ? QSurfaceFormat::OpenGL : QSurfaceFormat::OpenGLES);
    if (m_format.renderableType() != QSurfaceFormat::OpenGL && m_format.renderableType() != QSurfaceFormat::OpenGLES)
        return;
 
    if (share)
        m_shareContext = static_cast<const QGLXContext*>(share)->glxContext();
 
    GLXFBConfig config = qglx_findConfig(m_display, screen->screenNumber(), m_format);
    m_config = config;
    XVisualInfo *visualInfo = nullptr;
    Window window = 0; // Temporary window used to query OpenGL context
 
    if (config) {
        const QByteArrayList glxExt = QByteArray(glXQueryExtensionsString(m_display, screen->screenNumber())).split(' ');
 
        // Resolve entry point for glXCreateContextAttribsARB
        glXCreateContextAttribsARBProc glXCreateContextAttribsARB = nullptr;
        if (glxExt.contains("GLX_ARB_create_context"))
            glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc) glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");
 
        const bool supportsProfiles = glxExt.contains("GLX_ARB_create_context_profile");
        const bool supportsRobustness = glxExt.contains("GLX_ARB_create_context_robustness");
        const bool supportsVideoMemoryPurge = glxExt.contains("GLX_NV_robustness_video_memory_purge");
 
        // Use glXCreateContextAttribsARB if available
        // Also, GL ES context creation requires GLX_EXT_create_context_es2_profile
        if (glXCreateContextAttribsARB != nullptr
                && (m_format.renderableType() != QSurfaceFormat::OpenGLES || (supportsProfiles && glxExt.contains("GLX_EXT_create_context_es2_profile")))) {
            // Try to create an OpenGL context for each known OpenGL version in descending
            // order from the requested version.
            const int requestedVersion = m_format.majorVersion() * 10 + qMin(m_format.minorVersion(), 9);
 
            QList<int> glVersions;
            if (m_format.renderableType() == QSurfaceFormat::OpenGL) {
                if (requestedVersion > 46)
                    glVersions << requestedVersion;
 
                // Don't bother with versions below 2.0
                glVersions << 46 << 45 << 44 << 43 << 42 << 41 << 40 << 33 << 32 << 31 << 30 << 21 << 20;
            } else if (m_format.renderableType() == QSurfaceFormat::OpenGLES) {
                if (requestedVersion > 32)
                    glVersions << requestedVersion;
 
                // Don't bother with versions below ES 2.0
                glVersions << 32 << 31 << 30 << 20;
                // ES does not support any format option
                m_format.setOptions(QSurfaceFormat::FormatOptions());
            }
            // Robustness must match that of the shared context.
            if (share && share->format().testOption(QSurfaceFormat::ResetNotification))
                m_format.setOption(QSurfaceFormat::ResetNotification);
            Q_ASSERT(glVersions.size() > 0);
 
            for (int i = 0; !m_context && i < glVersions.size(); i++) {
                const int version = glVersions[i];
                if (version > requestedVersion)
                    continue;
 
                const int majorVersion = version / 10;
                const int minorVersion = version % 10;
 
                QList<int> contextAttributes;
                contextAttributes << GLX_CONTEXT_MAJOR_VERSION_ARB << majorVersion
                                  << GLX_CONTEXT_MINOR_VERSION_ARB << minorVersion;
 
 
                if (m_format.renderableType() == QSurfaceFormat::OpenGL) {
                    // If asking for OpenGL 3.2 or newer we should also specify a profile
                    if (version >= 32 && supportsProfiles) {
                        if (m_format.profile() == QSurfaceFormat::CoreProfile)
                            contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
                        else
                            contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB;
                    }
 
                    int flags = 0;
 
                    if (supportsRobustness)
                        flags |= GLX_CONTEXT_ROBUST_ACCESS_BIT_ARB;
 
                    if (m_format.testOption(QSurfaceFormat::DebugContext))
                        flags |= GLX_CONTEXT_DEBUG_BIT_ARB;
 
                    // A forward-compatible context may be requested for 3.0 and later
                    if (version >= 30 && !m_format.testOption(QSurfaceFormat::DeprecatedFunctions))
                        flags |= GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB;
 
                    if (flags != 0)
                        contextAttributes << GLX_CONTEXT_FLAGS_ARB << flags;
                } else if (m_format.renderableType() == QSurfaceFormat::OpenGLES) {
                    contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_ES2_PROFILE_BIT_EXT;
                }
 
                if (supportsRobustness && m_format.testOption(QSurfaceFormat::ResetNotification)) {
                    QList<int> contextAttributesWithRobustness = contextAttributes;
                    contextAttributesWithRobustness << GLX_CONTEXT_RESET_NOTIFICATION_STRATEGY_ARB << GLX_LOSE_CONTEXT_ON_RESET_ARB;
                    if (supportsVideoMemoryPurge)
                        contextAttributesWithRobustness << GLX_GENERATE_RESET_ON_VIDEO_MEMORY_PURGE_NV << GL_TRUE;
 
                    contextAttributesWithRobustness << None;
                    m_context = glXCreateContextAttribsARB(m_display, config, m_shareContext, true,
                                                           contextAttributesWithRobustness.data());
                    // Context creation against a shared context may fail specifically due to this request, so try
                    // without before dropping sharing.
                }
 
                if (m_context) {
                    m_getGraphicsResetStatus = reinterpret_cast<GLenum (QOPENGLF_APIENTRYP)()>(getProcAddress("glGetGraphicsResetStatusARB"));
                } else {
                    contextAttributes << None;
                    m_context = glXCreateContextAttribsARB(m_display, config, m_shareContext, true, contextAttributes.data());
                    if (!m_context && m_shareContext) {
                        // re-try without a shared glx context
                        m_context = glXCreateContextAttribsARB(m_display, config, nullptr, true, contextAttributes.data());
                        if (m_context)
                            m_shareContext = nullptr;
                    }
                }
            }
        }
 
        // Could not create a context using glXCreateContextAttribsARB, falling back to glXCreateNewContext.
        if (!m_context) {
            // requesting an OpenGL ES context requires glXCreateContextAttribsARB, so bail out
            if (m_format.renderableType() == QSurfaceFormat::OpenGLES)
                return;
 
            m_context = glXCreateNewContext(m_display, config, GLX_RGBA_TYPE, m_shareContext, true);
            if (!m_context && m_shareContext) {
                // re-try without a shared glx context
                m_context = glXCreateNewContext(m_display, config, GLX_RGBA_TYPE, nullptr, true);
                if (m_context)
                    m_shareContext = nullptr;
            }
        }
 
        // Get the basic surface format details
        if (m_context)
            qglx_surfaceFormatFromGLXFBConfig(&m_format, m_display, config);
 
        // Create a temporary window so that we can make the new context current
        window = createDummyWindow(m_display, config, screen->screenNumber(), screen->root());
    } else {
        // requesting an OpenGL ES context requires glXCreateContextAttribsARB, so bail out
        if (m_format.renderableType() == QSurfaceFormat::OpenGLES)
            return;
 
        // Note that m_format gets updated with the used surface format
        visualInfo = qglx_findVisualInfo(m_display, screen->screenNumber(), &m_format);
        if (Q_UNLIKELY(!visualInfo))
            qFatal("Could not initialize GLX");
        m_context = glXCreateContext(m_display, visualInfo, m_shareContext, true);
        if (!m_context && m_shareContext) {
            // re-try without a shared glx context
            m_shareContext = nullptr;
            m_context = glXCreateContext(m_display, visualInfo, nullptr, true);
        }
 
        // Create a temporary window so that we can make the new context current
        window = createDummyWindow(m_display, visualInfo, screen->screenNumber(), screen->root());
        XFree(visualInfo);
    }
 
    // Query the OpenGL version and profile
    if (m_context && window) {
        GLXContext prevContext = glXGetCurrentContext();
        GLXDrawable prevDrawable = glXGetCurrentDrawable();
        glXMakeCurrent(m_display, window, m_context);
        updateFormatFromContext(m_format);
 
        // Make our context non-current
        glXMakeCurrent(m_display, prevDrawable, prevContext);
    }
 
    // Destroy our temporary window
    XDestroyWindow(m_display, window);
}
 
QGLXContext::QGLXContext(Display *display, GLXContext context, void *visualInfo, QPlatformOpenGLContext *share)
    : QPlatformOpenGLContext()
    , m_display(display)
{
    // Legacy contexts created using glXCreateContext are created using a
    // XVisualInfo. If the user passed one we should use that.
    XVisualInfo *vinfo = static_cast<XVisualInfo*>(visualInfo);
 
    // Otherwise assume the context was created with an FBConfig using the modern functions
    if (!vinfo) {
        int configId = 0;
        if (glXQueryContext(m_display, context, GLX_FBCONFIG_ID, &configId) != Success) {
            qWarning("QGLXContext: Failed to query config from the provided context");
            return;
        }
 
        int screenNumber = 0;
        if (glXQueryContext(m_display, context, GLX_SCREEN, &screenNumber) != Success) {
            qWarning("QGLXContext: Failed to query screen from the provided context");
            screenNumber = DefaultScreen(m_display);
        }
 
        GLXFBConfig *configs;
        int numConfigs = 0;
        static const int attribs[] = { GLX_FBCONFIG_ID, configId, None };
        configs = glXChooseFBConfig(m_display, screenNumber, attribs, &numConfigs);
        if (!configs) {
            qWarning("QGLXContext: Failed to find config(invalid arguments for glXChooseFBConfig)");
            return;
        } else if (numConfigs < 1) {
            qWarning("QGLXContext: Failed to find config");
            XFree(configs);
            return;
        }
        if (configs && numConfigs > 1) // this is suspicious so warn but let it continue
            qWarning("QGLXContext: Multiple configs for FBConfig ID %d", configId);
 
        m_config = configs[0];
        XFree(configs);
    }
 
    Q_ASSERT(vinfo || m_config);
 
    int screenNumber = DefaultScreen(m_display);
    Window window;
    if (vinfo)
        window = createDummyWindow(m_display, vinfo, screenNumber, RootWindow(m_display, screenNumber));
    else
        window = createDummyWindow(m_display, m_config, screenNumber, RootWindow(m_display, screenNumber));
    if (!window) {
        qWarning("QGLXContext: Failed to create dummy window");
        return;
    }
 
    // Update OpenGL version and buffer sizes in our format.
    GLXContext prevContext = glXGetCurrentContext();
    GLXDrawable prevDrawable = glXGetCurrentDrawable();
    if (!glXMakeCurrent(m_display, window, context)) {
        qWarning("QGLXContext: Failed to make provided context current");
        return;
    }
    m_format = QSurfaceFormat();
    m_format.setRenderableType(QOpenGLContext::openGLModuleType() == QOpenGLContext::LibGL
                               ? QSurfaceFormat::OpenGL : QSurfaceFormat::OpenGLES);
    updateFormatFromContext(m_format);
    if (vinfo)
        qglx_surfaceFormatFromVisualInfo(&m_format, m_display, vinfo);
    else
        qglx_surfaceFormatFromGLXFBConfig(&m_format, m_display, m_config);
    glXMakeCurrent(m_display, prevDrawable, prevContext);
    XDestroyWindow(m_display, window);
 
    if (vinfo)
        XFree(vinfo);
 
    // Success. Store the context. From this point on isValid() is true.
    m_context = context;
 
    if (share)
        m_shareContext = static_cast<const QGLXContext*>(share)->glxContext();
}
 
QGLXContext::~QGLXContext()
{
    if (m_ownsContext)
        glXDestroyContext(m_display, m_context);
}
 
static QXcbScreen *screenForPlatformSurface(QPlatformSurface *surface)
{
    QSurface::SurfaceClass surfaceClass = surface->surface()->surfaceClass();
    if (surfaceClass == QSurface::Window) {
        return static_cast<QXcbScreen *>(static_cast<QXcbWindow *>(surface)->screen());
    } else if (surfaceClass == QSurface::Offscreen) {
        return static_cast<QXcbScreen *>(static_cast<QGLXPbuffer *>(surface)->screen());
    }
    return nullptr;
}
 
bool QGLXContext::makeCurrent(QPlatformSurface *surface)
{
    bool success = false;
    Q_ASSERT(surface->surface()->supportsOpenGL());
 
    GLXDrawable glxDrawable = 0;
    QSurface::SurfaceClass surfaceClass = surface->surface()->surfaceClass();
    if (surfaceClass == QSurface::Window) {
        m_isPBufferCurrent = false;
        QXcbWindow *window = static_cast<QXcbWindow *>(surface);
        glxDrawable = window->xcb_window();
        success = glXMakeCurrent(m_display, glxDrawable, m_context);
        m_lost = false;
        if (m_getGraphicsResetStatus && m_getGraphicsResetStatus() != GL_NO_ERROR) {
            m_lost = true;
            success = false;
            // Drop the surface. Will recreate on the next makeCurrent.
            window->invalidateSurface();
        }
    } else if (surfaceClass == QSurface::Offscreen) {
        m_isPBufferCurrent = true;
        QGLXPbuffer *pbuffer = static_cast<QGLXPbuffer *>(surface);
        glxDrawable = pbuffer->pbuffer();
        success = glXMakeContextCurrent(m_display, glxDrawable, glxDrawable, m_context);
        m_lost = false;
        if (m_getGraphicsResetStatus && m_getGraphicsResetStatus() != GL_NO_ERROR) {
            m_lost = true;
            success = false;
        }
    }
 
    if (success && surfaceClass == QSurface::Window) {
        int interval = surface->format().swapInterval();
        QXcbWindow *window = static_cast<QXcbWindow *>(surface);
        QXcbScreen *screen = screenForPlatformSurface(surface);
        if (interval >= 0 && interval != window->swapInterval() && screen) {
            typedef void (*qt_glXSwapIntervalEXT)(Display *, GLXDrawable, int);
            typedef void (*qt_glXSwapIntervalMESA)(unsigned int);
            static qt_glXSwapIntervalEXT glXSwapIntervalEXT = nullptr;
            static qt_glXSwapIntervalMESA glXSwapIntervalMESA = nullptr;
            static bool resolved = false;
            if (!resolved) {
                resolved = true;
                QList<QByteArray> glxExt = QByteArray(glXQueryExtensionsString(m_display,
                                                                               screen->screenNumber())).split(' ');
                if (glxExt.contains("GLX_EXT_swap_control"))
                    glXSwapIntervalEXT = (qt_glXSwapIntervalEXT) getProcAddress("glXSwapIntervalEXT");
                if (glxExt.contains("GLX_MESA_swap_control"))
                    glXSwapIntervalMESA = (qt_glXSwapIntervalMESA) getProcAddress("glXSwapIntervalMESA");
            }
            if (glXSwapIntervalEXT)
                glXSwapIntervalEXT(m_display, glxDrawable, interval);
            else if (glXSwapIntervalMESA)
                glXSwapIntervalMESA(interval);
            window->setSwapInterval(interval);
        }
    }
 
    return success;
}
 
void QGLXContext::doneCurrent()
{
    if (m_isPBufferCurrent)
        glXMakeContextCurrent(m_display, 0, 0, nullptr);
    else
        glXMakeCurrent(m_display, 0, nullptr);
    m_isPBufferCurrent = false;
}
 
void QGLXContext::swapBuffers(QPlatformSurface *surface)
{
    GLXDrawable glxDrawable = 0;
    if (surface->surface()->surfaceClass() == QSurface::Offscreen)
        glxDrawable = static_cast<QGLXPbuffer *>(surface)->pbuffer();
    else
        glxDrawable = static_cast<QXcbWindow *>(surface)->xcb_window();
    glXSwapBuffers(m_display, glxDrawable);
 
    if (surface->surface()->surfaceClass() == QSurface::Window) {
        QXcbWindow *platformWindow = static_cast<QXcbWindow *>(surface);
        // OpenGL context might be bound to a non-gui thread use QueuedConnection to sync
        // the window from the platformWindow's thread as QXcbWindow is no QObject, an
        // event is sent to QXcbConnection. (this is faster than a metacall)
        if (platformWindow->needsSync())
            platformWindow->postSyncWindowRequest();
    }
}
 
QFunctionPointer QGLXContext::getProcAddress(const char *procName)
{
    return glXGetProcAddress(reinterpret_cast<const GLubyte *>(procName));
}
 
QSurfaceFormat QGLXContext::format() const
{
    return m_format;
}
 
bool QGLXContext::isSharing() const
{
    return m_shareContext != nullptr;
}
 
bool QGLXContext::isValid() const
{
    return m_context != nullptr && !m_lost;
}
 
bool QGLXContext::m_queriedDummyContext = false;
bool QGLXContext::m_supportsThreading = true;
 
 
// If this list grows to any significant size, change it a
// proper string table and make the implementation below use
// binary search.
static const char *qglx_threadedgl_blacklist_renderer[] = {
    "Chromium",                             // QTBUG-32225 (initialization fails)
    nullptr
};
 
static const char *qglx_threadedgl_blacklist_vendor[] = {
    "llvmpipe",                             // QTCREATORBUG-10666
    "nouveau",                              // https://bugs.freedesktop.org/show_bug.cgi?id=91632
    nullptr
};
 
void QGLXContext::queryDummyContext()
{
    if (m_queriedDummyContext)
        return;
    m_queriedDummyContext = true;
 
    static bool skip = qEnvironmentVariableIsSet("QT_OPENGL_NO_SANITY_CHECK");
    if (skip)
        return;
 
    QOpenGLContext *oldContext = QOpenGLContext::currentContext();
    QSurface *oldSurface = nullptr;
    if (oldContext)
        oldSurface = oldContext->surface();
 
    QScopedPointer<QSurface> surface;
    Display *display = glXGetCurrentDisplay();
    if (!display) {
        // FIXME: Since Qt 5.6 we don't need to check whether primary screen is NULL
        if (QScreen *screen = QGuiApplication::primaryScreen()) {
            QXcbScreen *xcbScreen = static_cast<QXcbScreen *>(screen->handle());
            display = static_cast<Display *>(xcbScreen->connection()->xlib_display());
        }
    }
    const char *glxvendor = glXGetClientString(display, GLX_VENDOR);
    if (glxvendor && !strcmp(glxvendor, "ATI")) {
        QWindow *window = new QWindow;
        window->resize(64, 64);
        window->setSurfaceType(QSurface::OpenGLSurface);
        window->create();
        surface.reset(window);
    } else {
        QOffscreenSurface *offSurface = new QOffscreenSurface;
        offSurface->create();
        surface.reset(offSurface);
    }
 
    QOpenGLContext context;
    if (!context.create() || !context.makeCurrent(surface.data())) {
        qWarning("QGLXContext: Failed to create dummy context");
        m_supportsThreading = false;
        return;
    }
 
    m_supportsThreading = true;
 
    if (const char *renderer = (const char *) glGetString(GL_RENDERER)) {
        for (int i = 0; qglx_threadedgl_blacklist_renderer[i]; ++i) {
            if (strstr(renderer, qglx_threadedgl_blacklist_renderer[i]) != nullptr) {
                qCDebug(lcQpaGl).nospace() << "Multithreaded OpenGL disabled: "
                                             "blacklisted renderer \""
                                          << qglx_threadedgl_blacklist_renderer[i]
                                          << "\"";
                m_supportsThreading = false;
                break;
            }
        }
    }
    if (const char *vendor = (const char *) glGetString(GL_VENDOR)) {
        for (int i = 0; qglx_threadedgl_blacklist_vendor[i]; ++i) {
            if (strstr(vendor, qglx_threadedgl_blacklist_vendor[i]) != nullptr) {
                qCDebug(lcQpaGl).nospace() << "Multithreaded OpenGL disabled: "
                                              "blacklisted vendor \""
                                           << qglx_threadedgl_blacklist_vendor[i]
                                           << "\"";
                m_supportsThreading = false;
                break;
            }
        }
    }
 
    if (glxvendor && m_supportsThreading) {
        // Blacklist Mesa drivers due to QTCREATORBUG-10875 (crash in creator),
        // QTBUG-34492 (flickering in fullscreen) and QTBUG-38221
        const char *mesaVersionStr = nullptr;
        if (strstr(glxvendor, "Mesa Project") != nullptr) {
            mesaVersionStr = (const char *) glGetString(GL_VERSION);
            m_supportsThreading = false;
        }
 
        if (mesaVersionStr) {
            // The issue was fixed in Xcb 1.11, but we can't check for that
            // at runtime, so instead assume it fixed with recent Mesa versions
            // released several years after the Xcb fix.
#if QT_CONFIG(regularexpression)
            QRegularExpression versionTest(QStringLiteral("Mesa (\\d+)"));
            QRegularExpressionMatch result = versionTest.match(QString::fromLatin1(mesaVersionStr));
            int versionNr = 0;
            if (result.hasMatch())
                versionNr = result.captured(1).toInt();
            if (versionNr >= 17) {
                // White-listed
                m_supportsThreading = true;
            }
#endif
        }
        if (!m_supportsThreading) {
            qCDebug(lcQpaGl).nospace() << "Multithreaded OpenGL disabled: "
                                          "blacklisted vendor \"Mesa Project\"";
        }
    }
 
    static bool nomultithread = qEnvironmentVariableIsSet("QT_XCB_NO_THREADED_OPENGL");
    if (nomultithread)
        m_supportsThreading = false;
 
    context.doneCurrent();
    if (oldContext && oldSurface)
        oldContext->makeCurrent(oldSurface);
 
    if (!m_supportsThreading) {
        qCDebug(lcQpaGl) << "Force-enable multithreaded OpenGL by setting "
                           "environment variable QT_OPENGL_NO_SANITY_CHECK";
    }
}
 
bool QGLXContext::supportsThreading()
{
    queryDummyContext();
    return m_supportsThreading;
}
 
QGLXPbuffer::QGLXPbuffer(QOffscreenSurface *offscreenSurface)
    : QPlatformOffscreenSurface(offscreenSurface)
    , m_screen(static_cast<QXcbScreen *>(offscreenSurface->screen()->handle()))
    , m_format(m_screen->surfaceFormatFor(offscreenSurface->requestedFormat()))
    , m_display(static_cast<Display *>(m_screen->connection()->xlib_display()))
    , m_pbuffer(0)
{
    GLXFBConfig config = qglx_findConfig(m_display, m_screen->screenNumber(), m_format);
 
    if (config) {
        const int attributes[] = {
            GLX_PBUFFER_WIDTH, offscreenSurface->size().width(),
            GLX_PBUFFER_HEIGHT, offscreenSurface->size().height(),
            GLX_LARGEST_PBUFFER, False,
            GLX_PRESERVED_CONTENTS, False,
            None
        };
 
        m_pbuffer = glXCreatePbuffer(m_display, config, attributes);
 
        if (m_pbuffer)
            qglx_surfaceFormatFromGLXFBConfig(&m_format, m_display, config);
    }
}
 
QGLXPbuffer::~QGLXPbuffer()
{
    if (m_pbuffer)
        glXDestroyPbuffer(m_display, m_pbuffer);
}
 
 
QT_END_NAMESPACE