path: root/src/plugins/platforms/xcb/qglxintegration.cpp

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#include <QDebug>
#include <QLibrary>

#include "qxcbwindow.h"
#include "qxcbscreen.h"

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <GL/glx.h>

#include <QtGui/QOpenGLContext>

#include "qglxintegration.h"
#include <QtPlatformSupport/private/qglxconvenience_p.h>

#if defined(Q_OS_LINUX) || defined(Q_OS_BSD4)
#include <dlfcn.h>
#endif

QT_BEGIN_NAMESPACE

typedef GLXContext (*glXCreateContextAttribsARBProc)(Display*, GLXFBConfig, GLXContext, Bool, const int*);

#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_PROFILE_MASK_ARB
#define GLX_CONTEXT_PROFILE_MASK_ARB 0x9126
#endif

static Window createDummyWindow(QXcbScreen *screen, XVisualInfo *visualInfo)
{
    Colormap cmap = XCreateColormap(DISPLAY_FROM_XCB(screen), screen->root(), visualInfo->visual, AllocNone);
    XSetWindowAttributes a;
    a.background_pixel = WhitePixel(DISPLAY_FROM_XCB(screen), screen->screenNumber());
    a.border_pixel = BlackPixel(DISPLAY_FROM_XCB(screen), screen->screenNumber());
    a.colormap = cmap;

    Window window = XCreateWindow(DISPLAY_FROM_XCB(screen), screen->root(),
                                  0, 0, 100, 100,
                                  0, visualInfo->depth, InputOutput, visualInfo->visual,
                                  CWBackPixel|CWBorderPixel|CWColormap, &a);
    XFreeColormap(DISPLAY_FROM_XCB(screen), cmap);
    return window;
}

static Window createDummyWindow(QXcbScreen *screen, GLXFBConfig config)
{
    XVisualInfo *visualInfo = glXGetVisualFromFBConfig(DISPLAY_FROM_XCB(screen), config);
    if (!visualInfo)
        qFatal("Could not initialize GLX");
    Window window = createDummyWindow(screen, visualInfo);
    XFree(visualInfo);
    return window;
}

// Per-window data for active OpenGL contexts.
struct QOpenGLContextData
{
    QOpenGLContextData(Display *display, Window window, GLXContext context)
        : m_display(display),
          m_window(window),
          m_context(context)
    {}

    QOpenGLContextData()
        : m_display(0),
          m_window(0),
          m_context(0)
    {}

    Display *m_display;
    Window m_window;
    GLXContext m_context;
};

static inline QOpenGLContextData currentOpenGLContextData()
{
    QOpenGLContextData result;
    result.m_display = glXGetCurrentDisplay();
    result.m_window = glXGetCurrentDrawable();
    result.m_context = glXGetCurrentContext();
    return result;
}

static inline QOpenGLContextData createDummyWindowOpenGLContextData(QXcbScreen *screen)
{
    QOpenGLContextData result;
    result.m_display = DISPLAY_FROM_XCB(screen);

    QSurfaceFormat format;
    GLXFBConfig config = qglx_findConfig(DISPLAY_FROM_XCB(screen), screen->screenNumber(), format);
    if (config) {
        result.m_context = glXCreateNewContext(DISPLAY_FROM_XCB(screen), config, GLX_RGBA_TYPE, 0, true);
        result.m_window = createDummyWindow(screen, config);
    } else {
        XVisualInfo *visualInfo = qglx_findVisualInfo(DISPLAY_FROM_XCB(screen), screen->screenNumber(), &format);
        if (!visualInfo)
            qFatal("Could not initialize GLX");
        result.m_context = glXCreateContext(DISPLAY_FROM_XCB(screen), visualInfo, 0, true);
        result.m_window = createDummyWindow(screen, visualInfo);
        XFree(visualInfo);
    }

    return result;
}

static inline QByteArray getGlString(GLenum param)
{
    if (const GLubyte *s = glGetString(param))
        return QByteArray(reinterpret_cast<const char*>(s));
    return QByteArray();
}

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);
    }

    const int version = (major << 8) + minor;
    if (version < 0x0300) {
        format.setProfile(QSurfaceFormat::NoProfile);
        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 & GLX_CONTEXT_DEBUG_BIT_ARB)
        format.setOption(QSurfaceFormat::DebugContext);
    if (version < 0x0302)
        return;

    // Version 3.2 and newer have a profile
    value = 0;
    glGetIntegerv(GL_CONTEXT_PROFILE_MASK, &value);
    switch (value) {
    case GLX_CONTEXT_CORE_PROFILE_BIT_ARB:
        format.setProfile(QSurfaceFormat::CoreProfile);
        break;
    case GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB:
        format.setProfile(QSurfaceFormat::CompatibilityProfile);
        break;
    default:
        format.setProfile(QSurfaceFormat::NoProfile);
        break;
    }
}

/*!
    \class QOpenGLTemporaryContext
    \brief A temporary context that can be instantiated on the stack.

    Functions like glGetString() only work if there is a current GL context.

    \internal
    \ingroup qt-lighthouse-xcb
*/
class QOpenGLTemporaryContext
{
    Q_DISABLE_COPY(QOpenGLTemporaryContext)
public:
    QOpenGLTemporaryContext(QXcbScreen *screen);
    ~QOpenGLTemporaryContext();

private:
    const QOpenGLContextData m_previous;
    const QOpenGLContextData m_current;
};

QOpenGLTemporaryContext::QOpenGLTemporaryContext(QXcbScreen *screen)
    : m_previous(currentOpenGLContextData()),
      m_current(createDummyWindowOpenGLContextData(screen))
{
    // Make our temporary context current on our temporary window
    glXMakeCurrent(m_current.m_display, m_current.m_window, m_current.m_context);
}

QOpenGLTemporaryContext::~QOpenGLTemporaryContext()
{
    // Restore the previous context if possible, otherwise just release our temporary context
    if (m_previous.m_display)
        glXMakeCurrent(m_previous.m_display, m_previous.m_window, m_previous.m_context);
    else
        glXMakeCurrent(m_current.m_display, 0, 0);

    // Destroy our temporary window
    XDestroyWindow(m_current.m_display, m_current.m_window);

    // Finally destroy our temporary context itself
    glXDestroyContext(m_current.m_display, m_current.m_context);
}

QOpenGLDefaultContextInfo::QOpenGLDefaultContextInfo()
    : vendor(getGlString(GL_VENDOR)),
      renderer(getGlString(GL_RENDERER))
{
    updateFormatFromContext(format);
}

QOpenGLDefaultContextInfo *QOpenGLDefaultContextInfo::create(QXcbScreen *screen)
{
    // We need a current context for getGLString() to work. To have
    // the QOpenGLDefaultContextInfo contain the latest supported
    // context version, we rely upon the QOpenGLTemporaryContext to
    // correctly obtain a context with the latest version
    QScopedPointer<QOpenGLTemporaryContext> temporaryContext(new QOpenGLTemporaryContext(screen));
    QOpenGLDefaultContextInfo *result = new QOpenGLDefaultContextInfo;
    return result;
}


QGLXContext::QGLXContext(QXcbScreen *screen, const QSurfaceFormat &format, QPlatformOpenGLContext *share, QOpenGLDefaultContextInfo *defaultContextInfo)
    : QPlatformOpenGLContext()
    , m_screen(screen)
    , m_context(0)
    , m_format(format)
{
    m_shareContext = 0;
    if (share)
        m_shareContext = static_cast<const QGLXContext*>(share)->glxContext();

    GLXFBConfig config = qglx_findConfig(DISPLAY_FROM_XCB(screen),screen->screenNumber(),format);
    XVisualInfo *visualInfo = 0;
    Window window = 0; // Temporary window used to query OpenGL context

    if (config) {
        // Resolve entry point for glXCreateContextAttribsARB
        glXCreateContextAttribsARBProc glXCreateContextAttribsARB = 0;
        glXCreateContextAttribsARB = (glXCreateContextAttribsARBProc) glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");

        QList<QByteArray> glxExt = QByteArray(glXQueryExtensionsString(DISPLAY_FROM_XCB(m_screen), m_screen->screenNumber())).split(' ');

        // Use glXCreateContextAttribsARB if is available
        if (glxExt.contains("GLX_ARB_create_context") && glXCreateContextAttribsARB != 0) {
            // We limit the requested version by the version of the static context as
            // glXCreateContextAttribsARB fails and returns NULL if the requested context
            // version is not supported. This means that we will get the closest supported
            // context format that that which was requested and is supported by the driver
            const int maxSupportedVersion = (defaultContextInfo->format.majorVersion() << 8)
                                          + defaultContextInfo->format.minorVersion();
            const int requestedVersion = qMin((format.majorVersion() << 8) + format.minorVersion(),
                                               maxSupportedVersion);
            const int majorVersion = requestedVersion >> 8;
            const int minorVersion = requestedVersion & 0xFF;

            QVector<int> contextAttributes;
            contextAttributes << GLX_CONTEXT_MAJOR_VERSION_ARB << majorVersion
                              << GLX_CONTEXT_MINOR_VERSION_ARB << minorVersion;

            // If asking for OpenGL 3.2 or newer we should also specify a profile
            if (m_format.majorVersion() > 3 || (m_format.majorVersion() == 3 && m_format.minorVersion() > 1)) {
                if (m_format.profile() == QSurfaceFormat::CoreProfile) {
                    contextAttributes << GLX_CONTEXT_FLAGS_ARB << GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB
                                      << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_CORE_PROFILE_BIT_ARB;
                } else {
                    contextAttributes << GLX_CONTEXT_PROFILE_MASK_ARB << GLX_CONTEXT_COMPATIBILITY_PROFILE_BIT_ARB;
                }
            }

            contextAttributes << None;

            m_context = glXCreateContextAttribsARB(DISPLAY_FROM_XCB(screen), config, m_shareContext, true, contextAttributes.data());
            if (!m_context && m_shareContext) {
                // re-try without a shared glx context
                m_context = glXCreateContextAttribsARB(DISPLAY_FROM_XCB(screen), config, 0, true, contextAttributes.data());
                if (m_context)
                    m_shareContext = 0;
            }
        }

        // Could not create a context using glXCreateContextAttribsARB, falling back to glXCreateNewContext.
        if (!m_context) {
            m_context = glXCreateNewContext(DISPLAY_FROM_XCB(screen), config, GLX_RGBA_TYPE, m_shareContext, true);
            if (!m_context && m_shareContext) {
                // re-try without a shared glx context
                m_context = glXCreateNewContext(DISPLAY_FROM_XCB(screen), config, GLX_RGBA_TYPE, 0, true);
                if (m_context)
                    m_shareContext = 0;
            }
        }

        // Get the basic surface format details
        if (m_context)
            m_format = qglx_surfaceFormatFromGLXFBConfig(DISPLAY_FROM_XCB(screen), config, m_context);

        // Create a temporary window so that we can make the new context current
        window = createDummyWindow(screen, config);
    } else {
        // Note that m_format gets updated with the used surface format
        visualInfo = qglx_findVisualInfo(DISPLAY_FROM_XCB(screen), screen->screenNumber(), &m_format);
        if (!visualInfo)
            qFatal("Could not initialize GLX");
        m_context = glXCreateContext(DISPLAY_FROM_XCB(screen), visualInfo, m_shareContext, true);
        if (!m_context && m_shareContext) {
            // re-try without a shared glx context
            m_shareContext = 0;
            m_context = glXCreateContext(DISPLAY_FROM_XCB(screen), visualInfo, 0, true);
        }

        // Create a temporary window so that we can make the new context current
        window = createDummyWindow(screen, visualInfo);
        XFree(visualInfo);
    }

    // Query the OpenGL version and profile
    if (m_context && window) {
        glXMakeCurrent(DISPLAY_FROM_XCB(screen), window, m_context);
        updateFormatFromContext(m_format);

        // Make our context non-current
        glXMakeCurrent(DISPLAY_FROM_XCB(screen), 0, 0);
    }

    // Destroy our temporary window
    XDestroyWindow(DISPLAY_FROM_XCB(screen), window);
}

QGLXContext::~QGLXContext()
{
    glXDestroyContext(DISPLAY_FROM_XCB(m_screen), m_context);
}

bool QGLXContext::makeCurrent(QPlatformSurface *surface)
{
    Q_ASSERT(surface->surface()->surfaceType() == QSurface::OpenGLSurface);

    GLXDrawable glxDrawable = static_cast<QXcbWindow *>(surface)->xcb_window();

    return glXMakeCurrent(DISPLAY_FROM_XCB(m_screen), glxDrawable, m_context);
}

void QGLXContext::doneCurrent()
{
    glXMakeCurrent(DISPLAY_FROM_XCB(m_screen), 0, 0);
}

void QGLXContext::swapBuffers(QPlatformSurface *surface)
{
    GLXDrawable glxDrawable = static_cast<QXcbWindow *>(surface)->xcb_window();
    glXSwapBuffers(DISPLAY_FROM_XCB(m_screen), glxDrawable);
}

void (*QGLXContext::getProcAddress(const QByteArray &procName)) ()
{
    typedef void *(*qt_glXGetProcAddressARB)(const GLubyte *);
    static qt_glXGetProcAddressARB glXGetProcAddressARB = 0;
    static bool resolved = false;

    if (resolved && !glXGetProcAddressARB)
        return 0;
    if (!glXGetProcAddressARB) {
        QList<QByteArray> glxExt = QByteArray(glXGetClientString(DISPLAY_FROM_XCB(m_screen), GLX_EXTENSIONS)).split(' ');
        if (glxExt.contains("GLX_ARB_get_proc_address")) {
#if defined(Q_OS_LINUX) || defined(Q_OS_BSD4)
            void *handle = dlopen(NULL, RTLD_LAZY);
            if (handle) {
                glXGetProcAddressARB = (qt_glXGetProcAddressARB) dlsym(handle, "glXGetProcAddressARB");
                dlclose(handle);
            }
            if (!glXGetProcAddressARB)
#endif
            {
                extern const QString qt_gl_library_name();
//                QLibrary lib(qt_gl_library_name());
                QLibrary lib(QLatin1String("GL"));
                glXGetProcAddressARB = (qt_glXGetProcAddressARB) lib.resolve("glXGetProcAddressARB");
            }
        }
        resolved = true;
    }
    if (!glXGetProcAddressARB)
        return 0;
    return (void (*)())glXGetProcAddressARB(reinterpret_cast<const GLubyte *>(procName.constData()));
}

QSurfaceFormat QGLXContext::format() const
{
    return m_format;
}

bool QGLXContext::isSharing() const
{
    return m_shareContext != 0;
}

bool QGLXContext::isValid() const
{
    return m_context != 0;
}

QT_END_NAMESPACE