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#include "qsgwindowsrenderloop_p.h"

#include <QtCore/QCoreApplication>

#include <QtGui/QScreen>
#include <QtGui/QGuiApplication>

#include <QtQuick/private/qsgcontext_p.h>
#include <QtQuick/private/qquickwindow_p.h>

#include <QtQuick/QQuickWindow>

#include <private/qqmlprofilerservice_p.h>

QT_BEGIN_NAMESPACE

extern Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha);

// #define QSG_RENDER_LOOP_DEBUG

#ifdef QSG_RENDER_LOOP_DEBUG
static QElapsedTimer qsg_debug_timer;
#  define RLDEBUG(x) printf("(%6d) %s : %4d - %s\n", (int) qsg_debug_timer.elapsed(), __FILE__, __LINE__, x)
#else
#  define RLDEBUG(x)
#endif

#ifndef QSG_NO_RENDER_TIMING
static bool qsg_render_timing = !qgetenv("QSG_RENDER_TIMING").isEmpty();
static QElapsedTimer qsg_render_timer;
#define QSG_RENDER_TIMING_SAMPLE(sampleName) qint64 sampleName = 0; if (qsg_render_timing || QQmlProfilerService::enabled) sampleName = qsg_render_timer.nsecsElapsed()
#else
#define QSG_RENDER_TIMING_SAMPLE(sampleName)
#endif


QSGWindowsRenderLoop::QSGWindowsRenderLoop()
    : m_gl(0)
    , m_sg(QSGContext::createDefaultContext())
    , m_updateTimer(0)
    , m_animationTimer(0)
{
#ifdef QSG_RENDER_LOOP_DEBUG
    qsg_debug_timer.start();
#endif

    m_animationDriver = m_sg->createAnimationDriver(m_sg);
    m_animationDriver->install();

    connect(m_animationDriver, SIGNAL(started()), this, SLOT(started()));
    connect(m_animationDriver, SIGNAL(stopped()), this, SLOT(stopped()));

    m_vsyncDelta = 1000 / QGuiApplication::primaryScreen()->refreshRate();
    if (m_vsyncDelta <= 0)
        m_vsyncDelta = 16;

    RLDEBUG("Windows Render Loop created");

#ifndef QSG_NO_RENDER_TIMIMG
    qsg_render_timer.start();
#endif
}

bool QSGWindowsRenderLoop::interleaveIncubation() const
{
    return m_animationDriver->isRunning() && anyoneShowing();
}

QSGWindowsRenderLoop::WindowData *QSGWindowsRenderLoop::windowData(QQuickWindow *window)
{
    for (int i=0; i<m_windows.size(); ++i) {
        WindowData &wd = m_windows[i];
        if (wd.window == window)
            return &wd;
    }
    return 0;
}

void QSGWindowsRenderLoop::maybePostUpdateTimer()
{
    if (!m_updateTimer) {
        RLDEBUG(" - posting event");
        m_updateTimer = startTimer(m_vsyncDelta / 3);
    }
}

/*
 * If no windows are showing, start ticking animations using a timer,
 * otherwise, start rendering
 */
void QSGWindowsRenderLoop::started()
{
    RLDEBUG("Animations started...");
    if (!anyoneShowing()) {
        if (m_animationTimer == 0) {
            RLDEBUG(" - starting non-visual animation timer");
            m_animationTimer = startTimer(m_vsyncDelta);
        }
    } else {
        maybePostUpdateTimer();
    }
}

void QSGWindowsRenderLoop::stopped()
{
    RLDEBUG("Animations stopped...");
    if (m_animationTimer) {
        RLDEBUG(" - stopping non-visual animation timer");
        killTimer(m_animationTimer);
        m_animationTimer = 0;
    }
}

void QSGWindowsRenderLoop::show(QQuickWindow *window)
{
    RLDEBUG("show");
    if (windowData(window) != 0)
        return;

    // This happens before the platform window is shown, but after
    // it is created. Creating the GL context takes a lot of time
    // (hundreds of milliseconds) and will prevent us from rendering
    // the first frame in time for the initial show on screen.
    // By preparing the GL context here, it is feasible (if the app
    // is quick enough) to have a perfect first frame.
    if (!m_gl) {
        QSG_RENDER_TIMING_SAMPLE(time_start);

        RLDEBUG(" - creating GL context");
        m_gl = new QOpenGLContext();
        m_gl->setFormat(window->requestedFormat());
        m_gl->create();
        QSG_RENDER_TIMING_SAMPLE(time_created);
        RLDEBUG(" - making current");
        m_gl->makeCurrent(window);
        RLDEBUG(" - initializing SG");
        QSG_RENDER_TIMING_SAMPLE(time_current);
        m_sg->initialize(m_gl);

#ifndef QSG_NO_RENDER_TIMING
        if (qsg_render_timing) {
            qDebug("WindowsRenderLoop: GL=%d ms, makeCurrent=%d ms, SG=%d ms",
                   int((time_created - time_start)/1000000),
                   int((time_current - time_created)/1000000),
                   int((qsg_render_timer.nsecsElapsed() - time_current)/1000000));
        }
        if (QQmlProfilerService::enabled) {
            QQmlProfilerService::sceneGraphFrame(
                        QQmlProfilerService::SceneGraphWindowsRenderShow,
                        time_created - time_start,
                        time_current - time_created,
                        qsg_render_timer.nsecsElapsed() - time_current);
        }
#endif

    }

    WindowData data;
    data.window = window;
    data.pendingUpdate = false;
    m_windows << data;

    RLDEBUG(" - done with show");
}

void QSGWindowsRenderLoop::hide(QQuickWindow *window)
{
    RLDEBUG("hide");

    for (int i=0; i<m_windows.size(); ++i) {
        if (m_windows.at(i).window == window) {
            m_windows.removeAt(i);
            break;
        }
    }

    // The expose event is queued while hide is sent synchronously, so
    // the value might not be updated yet. (plus that the windows plugin
    // sends exposed=true when it goes to hidden, so it is doubly broken)
    // The check is made here, after the removal from m_windows, so
    // anyoneShowing will report the right value.
    if (window->isExposed())
        handleObscurity();

    QQuickWindowPrivate *cd = QQuickWindowPrivate::get(window);
    cd->cleanupNodesOnShutdown();

    // If this is the last tracked window, check for persistent SG and GL and
    // potentially clean up.
    if (m_windows.size() == 0) {
        if (!cd->persistentSceneGraph) {
            m_sg->invalidate();
            if (!cd->persistentGLContext) {
                delete m_gl;
                m_gl = 0;
            }
        }
    }
}

void QSGWindowsRenderLoop::windowDestroyed(QQuickWindow *window)
{
    RLDEBUG("windowDestroyed");
    hide(window);

    // If this is the last tracked window, clean up SG and GL.
    if (m_windows.size() == 0) {
        m_sg->invalidate();
        delete m_gl;
        m_gl = 0;
    }
}

bool QSGWindowsRenderLoop::anyoneShowing() const
{
    foreach (const WindowData &wd, m_windows)
        if (wd.window->isExposed() && wd.window->size().isValid())
            return true;
    return false;
}

void QSGWindowsRenderLoop::exposureChanged(QQuickWindow *window)
{

    if (windowData(window) == 0)
        return;

    if (window->isExposed()) {

        // Stop non-visual animation timer as we now have a window rendering
        if (m_animationTimer && anyoneShowing()) {
            RLDEBUG(" - stopping non-visual animation timer");
            killTimer(m_animationTimer);
            m_animationTimer = 0;
        }

        RLDEBUG("exposureChanged - exposed");
        WindowData *wd = windowData(window);
        wd->pendingUpdate = true;

        // If we have a pending timer and we get an expose, we need to stop it.
        // Otherwise we get two frames and two animation ticks in the same time-interval.
        if (m_updateTimer) {
            RLDEBUG(" - killing pending update timer");
            killTimer(m_updateTimer);
            m_updateTimer = 0;
        }
        render();
    } else {
        handleObscurity();
    }
}

void QSGWindowsRenderLoop::handleObscurity()
{
    RLDEBUG("handleObscurity");
    // Potentially start the non-visual animation timer if nobody is rendering
    if (m_animationDriver->isRunning() && !anyoneShowing() && !m_animationTimer) {
        RLDEBUG(" - starting non-visual animation timer");
        m_animationTimer = startTimer(m_vsyncDelta);
    }
}

QImage QSGWindowsRenderLoop::grab(QQuickWindow *window)
{
    RLDEBUG("grab");
    if (!m_gl)
        return QImage();

    m_gl->makeCurrent(window);

    QQuickWindowPrivate *d = QQuickWindowPrivate::get(window);
    d->polishItems();
    d->syncSceneGraph();
    d->renderSceneGraph(window->size());

    QImage image = qt_gl_read_framebuffer(window->size(), false, false);
    return image;
}

void QSGWindowsRenderLoop::update(QQuickWindow *window)
{
    RLDEBUG("update");
    maybeUpdate(window);
}

void QSGWindowsRenderLoop::maybeUpdate(QQuickWindow *window)
{
    RLDEBUG("maybeUpdate");

    WindowData *wd = windowData(window);
    if (!wd || !anyoneShowing())
        return;

    wd->pendingUpdate = true;
    maybePostUpdateTimer();
}

bool QSGWindowsRenderLoop::event(QEvent *event)
{
    switch (event->type()) {
    case QEvent::Timer: {
        QTimerEvent *te = static_cast<QTimerEvent *>(event);
        if (te->timerId() == m_animationTimer) {
            RLDEBUG("event : animation tick while nothing is showing");
            m_animationDriver->advance();
        } else if (te->timerId() == m_updateTimer) {
            RLDEBUG("event : update");
            killTimer(m_updateTimer);
            m_updateTimer = 0;
            render();
        }
        return true; }
    default:
        break;
    }

    return QObject::event(event);
}

/*
 * Go through all windows we control and render them in turn.
 * Then tick animations if active.
 */
void QSGWindowsRenderLoop::render()
{
    RLDEBUG("render");
    foreach (const WindowData &wd, m_windows) {
        if (wd.pendingUpdate) {
            const_cast<WindowData &>(wd).pendingUpdate = false;
            renderWindow(wd.window);
        }
    }

    if (m_animationDriver->isRunning()) {
        RLDEBUG("advancing animations");
        QSG_RENDER_TIMING_SAMPLE(time_start);
        m_animationDriver->advance();
        RLDEBUG("animations advanced");

#ifndef QSG_NO_RENDER_TIMING
        if (qsg_render_timing) {
            qDebug("WindowsRenderLoop: animations=%d ms",
                   int((qsg_render_timer.nsecsElapsed() - time_start)/1000000));
        }
        if (QQmlProfilerService::Enabled) {
            QQmlProfilerService::sceneGraphFrame(
                        QQmlProfilerService::SceneGraphWindowsAnimations,
                        qsg_render_timer.nsecsElapsed() - time_start);
        }
#endif

        // It is not given that animations triggered another maybeUpdate()
        // and thus another render pass, so to keep things running,
        // make sure there is another frame pending.
        maybePostUpdateTimer();

        emit timeToIncubate();
    }
}

/*
 * Render the contents of this window. First polish, then sync, render
 * then finally swap.
 *
 * Note: This render function does not implement aborting
 * the render call when sync step results in no scene graph changes,
 * like the threaded renderer does.
 */
void QSGWindowsRenderLoop::renderWindow(QQuickWindow *window)
{
    RLDEBUG("renderWindow");
    QQuickWindowPrivate *d = QQuickWindowPrivate::get(window);

    if (!d->isRenderable())
        return;

    if (!m_gl->makeCurrent(window))
        return;

    QSG_RENDER_TIMING_SAMPLE(time_start);

    RLDEBUG(" - polishing");
    d->polishItems();
    QSG_RENDER_TIMING_SAMPLE(time_polished);

    RLDEBUG(" - syncing");
    d->syncSceneGraph();
    QSG_RENDER_TIMING_SAMPLE(time_synced);

    RLDEBUG(" - rendering");
    d->renderSceneGraph(window->size());
    QSG_RENDER_TIMING_SAMPLE(time_rendered);

    RLDEBUG(" - swapping");
    m_gl->swapBuffers(window);
    QSG_RENDER_TIMING_SAMPLE(time_swapped);

    RLDEBUG(" - frameDone");
    d->fireFrameSwapped();

#ifndef QSG_NO_RENDER_TIMING
        if (qsg_render_timing) {
            qDebug("WindowsRenderLoop(t=%d): window=%p, polish=%d ms, sync=%d ms, render=%d ms, swap=%d ms",
                   int(qsg_render_timer.elapsed()),
                   window,
                   int((time_polished - time_start)/1000000),
                   int((time_synced - time_polished)/1000000),
                   int((time_rendered - time_synced)/1000000),
                   int((time_swapped - time_rendered)/1000000));
        }
        if (QQmlProfilerService::enabled) {
            QQmlProfilerService::sceneGraphFrame(
                        QQmlProfilerService::SceneGraphWindowsPolishFrame,
                        time_polished - time_start
                        );

            QQmlProfilerService::sceneGraphFrame(
                        QQmlProfilerService::SceneGraphRenderLoopFrame,
                        time_synced - time_polished,
                        time_rendered - time_synced,
                        time_swapped - time_rendered
                        );
        }
#endif
}

QT_END_NAMESPACE
