qopenglcompositorbackingstore.cpp

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// Copyright (C) 2017 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
 
#include <QtGui/QOpenGLContext>
#include <QtGui/QWindow>
#include <QtGui/QPainter>
#include <qpa/qplatformbackingstore.h>
#include <private/qwindow_p.h>
#include <rhi/qrhi.h>
 
#include "qopenglcompositorbackingstore_p.h"
#include "qopenglcompositor_p.h"
 
#ifndef GL_UNPACK_ROW_LENGTH
#define GL_UNPACK_ROW_LENGTH              0x0CF2
#endif
 
QT_BEGIN_NAMESPACE
 
QOpenGLCompositorBackingStore::QOpenGLCompositorBackingStore(QWindow *window)
    : QPlatformBackingStore(window),
      m_window(window),
      m_bsTexture(0),
      m_bsTextureWrapper(nullptr),
      m_bsTextureContext(0),
      m_textures(new QPlatformTextureList),
      m_lockedWidgetTextures(0),
      m_rhi(nullptr)
{
}
 
QOpenGLCompositorBackingStore::~QOpenGLCompositorBackingStore()
{
    if (m_bsTexture && m_rhi) {
        delete m_bsTextureWrapper;
        // Contexts are sharing resources, won't matter which one is
        // current here, use the rhi's shortcut.
        m_rhi->makeThreadLocalNativeContextCurrent();
        glDeleteTextures(1, &m_bsTexture);
    }
 
    delete m_textures; // this does not actually own any GL resources
}
 
QPaintDevice *QOpenGLCompositorBackingStore::paintDevice()
{
    return &m_image;
}
 
void QOpenGLCompositorBackingStore::updateTexture()
{
    if (!m_bsTexture) {
        m_bsTextureContext = QOpenGLContext::currentContext();
        Q_ASSERT(m_bsTextureContext);
        glGenTextures(1, &m_bsTexture);
        glBindTexture(GL_TEXTURE_2D, m_bsTexture);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, m_image.width(), m_image.height(), 0, GL_RGBA, GL_UNSIGNED_BYTE, 0);
    } else {
        glBindTexture(GL_TEXTURE_2D, m_bsTexture);
    }
 
    if (!m_dirty.isNull()) {
        QRegion fixed;
        QRect imageRect = m_image.rect();
 
        QOpenGLContext *ctx = QOpenGLContext::currentContext();
        if (!ctx->isOpenGLES() || ctx->format().majorVersion() >= 3) {
            for (const QRect &rect : m_dirty) {
                QRect r = imageRect & rect;
                glPixelStorei(GL_UNPACK_ROW_LENGTH, m_image.width());
                glTexSubImage2D(GL_TEXTURE_2D, 0, r.x(), r.y(), r.width(), r.height(), GL_RGBA, GL_UNSIGNED_BYTE,
                                m_image.constScanLine(r.y()) + r.x() * 4);
                glPixelStorei(GL_UNPACK_ROW_LENGTH, 0);
            }
        } else {
            for (const QRect &rect : m_dirty) {
                // intersect with image rect to be sure
                QRect r = imageRect & rect;
 
                // if the rect is wide enough it's cheaper to just
                // extend it instead of doing an image copy
                if (r.width() >= imageRect.width() / 2) {
                    r.setX(0);
                    r.setWidth(imageRect.width());
                }
 
                fixed |= r;
            }
            for (const QRect &rect : fixed) {
                // if the sub-rect is full-width we can pass the image data directly to
                // OpenGL instead of copying, since there's no gap between scanlines
                if (rect.width() == imageRect.width()) {
                    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
                                    m_image.constScanLine(rect.y()));
                } else {
                    glTexSubImage2D(GL_TEXTURE_2D, 0, rect.x(), rect.y(), rect.width(), rect.height(), GL_RGBA, GL_UNSIGNED_BYTE,
                                    m_image.copy(rect).constBits());
                }
            }
        }
 
        m_dirty = QRegion();
    }
 
    if (!m_bsTextureWrapper) {
        m_bsTextureWrapper = m_rhi->newTexture(QRhiTexture::RGBA8, m_image.size());
        m_bsTextureWrapper->createFrom({m_bsTexture, 0});
    }
}
 
void QOpenGLCompositorBackingStore::flush(QWindow *flushedWindow, const QRegion &region, const QPoint &offset)
{
    // Called for ordinary raster windows.
 
    Q_UNUSED(region);
    Q_UNUSED(offset);
 
    if (!rhi(flushedWindow)) {
        QPlatformBackingStoreRhiConfig rhiConfig;
        rhiConfig.setApi(QPlatformBackingStoreRhiConfig::OpenGL);
        rhiConfig.setEnabled(true);
        createRhi(flushedWindow, rhiConfig);
    }
 
    static QPlatformTextureList emptyTextureList;
    bool translucentBackground = m_image.hasAlphaChannel();
    rhiFlush(flushedWindow, flushedWindow->devicePixelRatio(),
        region, offset, &emptyTextureList, translucentBackground);
}
 
QPlatformBackingStore::FlushResult QOpenGLCompositorBackingStore::rhiFlush(QWindow *window,
                                                                           qreal sourceDevicePixelRatio,
                                                                           const QRegion &region,
                                                                           const QPoint &offset,
                                                                           QPlatformTextureList *textures,
                                                                           bool translucentBackground)
{
    // QOpenGLWidget/QQuickWidget content provided as textures. The raster content goes on top.
 
    Q_UNUSED(region);
    Q_UNUSED(offset);
    Q_UNUSED(translucentBackground);
    Q_UNUSED(sourceDevicePixelRatio);
 
    m_rhi = rhi(window);
    Q_ASSERT(m_rhi);
 
    QOpenGLCompositor *compositor = QOpenGLCompositor::instance();
    QOpenGLContext *dstCtx = compositor->context();
    if (!dstCtx)
        return FlushFailed;
 
    QWindow *dstWin = compositor->targetWindow();
    if (!dstWin)
        return FlushFailed;
 
    if (!dstCtx->makeCurrent(dstWin))
        return FlushFailed;
 
    QWindowPrivate::get(window)->lastComposeTime.start();
 
    m_textures->clear();
    for (int i = 0; i < textures->count(); ++i) {
        m_textures->appendTexture(textures->source(i), textures->texture(i), textures->geometry(i),
                                  textures->clipRect(i), textures->flags(i));
    }
 
    updateTexture();
    m_textures->appendTexture(nullptr, m_bsTextureWrapper, window->geometry());
 
    textures->lock(true);
    m_lockedWidgetTextures = textures;
 
    compositor->update();
 
    return FlushSuccess;
}
 
void QOpenGLCompositorBackingStore::notifyComposited()
{
    if (m_lockedWidgetTextures) {
        QPlatformTextureList *textureList = m_lockedWidgetTextures;
        m_lockedWidgetTextures = 0; // may reenter so null before unlocking
        textureList->lock(false);
    }
}
 
void QOpenGLCompositorBackingStore::beginPaint(const QRegion &region)
{
    m_dirty |= region;
 
    if (m_image.hasAlphaChannel()) {
        QPainter p(&m_image);
        p.setCompositionMode(QPainter::CompositionMode_Source);
        for (const QRect &r : region)
            p.fillRect(r, Qt::transparent);
    }
}
 
void QOpenGLCompositorBackingStore::resize(const QSize &size, const QRegion &staticContents)
{
    Q_UNUSED(staticContents);
 
    QOpenGLCompositor *compositor = QOpenGLCompositor::instance();
    QOpenGLContext *dstCtx = compositor->context();
    if (!dstCtx)
        return;
    QWindow *dstWin = compositor->targetWindow();
    if (!dstWin)
        return;
 
    m_image = QImage(size, QImage::Format_RGBA8888);
 
    m_window->create();
 
    dstCtx->makeCurrent(dstWin);
    if (m_bsTexture) {
        delete m_bsTextureWrapper;
        m_bsTextureWrapper = nullptr;
        glDeleteTextures(1, &m_bsTexture);
        m_bsTexture = 0;
        m_bsTextureContext = nullptr;
    }
}
 
QImage QOpenGLCompositorBackingStore::toImage() const
{
    return m_image;
}
 
QT_END_NAMESPACE