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#include "qpixmap.h"
#include "qglframebufferobject.h"

#include <private/qpaintengine_raster_p.h>

#include "qpixmapdata_gl_p.h"

#include <private/qgl_p.h>
#include <private/qdrawhelper_p.h>

#include <private/qpaintengineex_opengl2_p.h>

QT_BEGIN_NAMESPACE

extern QGLWidget* qt_gl_share_widget();

class QGLShareContextScope
{
public:
    QGLShareContextScope(const QGLContext *ctx)
        : m_oldContext(0)
    {
        QGLContext *currentContext = const_cast<QGLContext *>(QGLContext::currentContext());
        if (currentContext != ctx && !qgl_share_reg()->checkSharing(ctx, currentContext)) {
            m_oldContext = currentContext;
            m_ctx = const_cast<QGLContext *>(ctx);
            m_ctx->makeCurrent();
        } else {
            m_ctx = currentContext;
        }
    }

    operator QGLContext *()
    {
        return m_ctx;
    }

    QGLContext *operator->()
    {
        return m_ctx;
    }

    ~QGLShareContextScope()
    {
        if (m_oldContext)
            m_oldContext->makeCurrent();
    }

private:
    QGLContext *m_oldContext;
    QGLContext *m_ctx;
};

static int qt_gl_pixmap_serial = 0;

QGLPixmapData::QGLPixmapData(PixelType type)
    : QPixmapData(type, OpenGLClass)
    , m_width(0)
    , m_height(0)
    , m_renderFbo(0)
    , m_textureId(0)
    , m_engine(0)
    , m_ctx(0)
    , m_dirty(false)
    , m_hasFillColor(false)
{
    setSerialNumber(++qt_gl_pixmap_serial);
}

QGLPixmapData::~QGLPixmapData()
{
    QGLWidget *shareWidget = qt_gl_share_widget();
    if (!shareWidget)
        return;
    QGLShareContextScope ctx(shareWidget->context());
    glDeleteTextures(1, &m_textureId);
}

bool QGLPixmapData::isValid() const
{
    return m_width > 0 && m_height > 0;
}

bool QGLPixmapData::isValidContext(const QGLContext *ctx) const
{
    if (ctx == m_ctx)
        return true;

    const QGLContext *share_ctx = qt_gl_share_widget()->context();
    return ctx == share_ctx || qgl_share_reg()->checkSharing(ctx, share_ctx);
}

void QGLPixmapData::resize(int width, int height)
{
    if (width == m_width && height == m_height)
        return;

    m_width = width;
    m_height = height;

    if (m_textureId) {
        QGLShareContextScope ctx(qt_gl_share_widget()->context());
        glDeleteTextures(1, &m_textureId);
        m_textureId = 0;
    }

    m_source = QImage();
    m_dirty = isValid();
    setSerialNumber(++qt_gl_pixmap_serial);
}

void QGLPixmapData::ensureCreated() const
{
    if (!m_dirty)
        return;

    m_dirty = false;

    QGLShareContextScope ctx(qt_gl_share_widget()->context());
    m_ctx = ctx;

    const GLenum format = qt_gl_preferredTextureFormat();
    const GLenum target = GL_TEXTURE_2D;

    if (!m_textureId) {
        glGenTextures(1, &m_textureId);
        glBindTexture(target, m_textureId);
        glTexImage2D(target, 0, GL_RGBA, m_width, m_height, 0,
                GL_RGBA, GL_UNSIGNED_BYTE, 0);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
        glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    }

    if (!m_source.isNull()) {
        const QImage tx = ctx->d_func()->convertToGLFormat(m_source, true, format);

        glBindTexture(target, m_textureId);
        glTexSubImage2D(target, 0, 0, 0, m_width, m_height, format,
                        GL_UNSIGNED_BYTE, tx.bits());

        if (useFramebufferObjects())
            m_source = QImage();
    }
}

QGLFramebufferObject *QGLPixmapData::fbo() const
{
    return m_renderFbo;
}

void QGLPixmapData::fromImage(const QImage &image,
                              Qt::ImageConversionFlags)
{
    if (image.size() == QSize(m_width, m_height))
        setSerialNumber(++qt_gl_pixmap_serial);
    resize(image.width(), image.height());
    m_source = image;
    m_dirty = true;
    m_hasFillColor = false;

    if (m_textureId) {
        QGLShareContextScope ctx(qt_gl_share_widget()->context());
        glDeleteTextures(1, &m_textureId);
        m_textureId = 0;
    }
}

bool QGLPixmapData::scroll(int dx, int dy, const QRect &rect)
{
    Q_UNUSED(dx);
    Q_UNUSED(dy);
    Q_UNUSED(rect);
    return false;
}

void QGLPixmapData::copy(const QPixmapData *data, const QRect &rect)
{
    if (data->classId() != QPixmapData::OpenGLClass) {
        QPixmapData::copy(data, rect);
        return;
    }

    // can be optimized to do a framebuffer blit or similar ...
    QPixmapData::copy(data, rect);
}

void QGLPixmapData::fill(const QColor &color)
{
    if (!isValid())
        return;

    if (useFramebufferObjects()) {
        m_source = QImage();
        m_hasFillColor = true;
        m_fillColor = color;
    } else if (!m_source.isNull()) {
        m_source.fill(PREMUL(color.rgba()));
    } else {
        // ## TODO: improve performance here
        QImage img(m_width, m_height, QImage::Format_ARGB32_Premultiplied);
        img.fill(PREMUL(color.rgba()));

        fromImage(img, 0);
    }
}

bool QGLPixmapData::hasAlphaChannel() const
{
    return true;
}

QImage QGLPixmapData::toImage() const
{
    if (!isValid())
        return QImage();

    if (m_renderFbo) {
        copyBackFromRenderFbo(true);
    } else if (!m_source.isNull()) {
        return m_source;
    } else if (m_dirty || m_hasFillColor) {
        QImage img(m_width, m_height, QImage::Format_ARGB32_Premultiplied);
        if (m_hasFillColor)
            img.fill(PREMUL(m_fillColor.rgba()));
        return img;
    } else {
        ensureCreated();
    }

    QGLShareContextScope ctx(qt_gl_share_widget()->context());
    extern QImage qt_gl_read_texture(const QSize &size, bool alpha_format, bool include_alpha);
    glBindTexture(GL_TEXTURE_2D, m_textureId);
    return qt_gl_read_texture(QSize(m_width, m_height), true, true);
}

struct TextureBuffer
{
    QGLFramebufferObject *fbo;
    QGL2PaintEngineEx *engine;
};

static QVector<TextureBuffer> textureBufferStack;
static int currentTextureBuffer = 0;

void QGLPixmapData::copyBackFromRenderFbo(bool keepCurrentFboBound) const
{
    if (!isValid())
        return;

    m_hasFillColor = false;

    const QGLContext *share_ctx = qt_gl_share_widget()->context();
    QGLShareContextScope ctx(share_ctx);

    ensureCreated();

    if (!ctx->d_ptr->fbo)
        glGenFramebuffers(1, &ctx->d_ptr->fbo);

    glBindFramebuffer(GL_FRAMEBUFFER_EXT, ctx->d_ptr->fbo);
    glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,
        GL_TEXTURE_2D, m_textureId, 0);

    const int x0 = 0;
    const int x1 = m_width;
    const int y0 = 0;
    const int y1 = m_height;

    glBindFramebuffer(GL_READ_FRAMEBUFFER_EXT, m_renderFbo->handle());

    glDisable(GL_SCISSOR_TEST);

    glBlitFramebufferEXT(x0, y0, x1, y1,
            x0, y0, x1, y1,
            GL_COLOR_BUFFER_BIT,
            GL_NEAREST);

    if (keepCurrentFboBound)
        glBindFramebuffer(GL_FRAMEBUFFER_EXT, ctx->d_ptr->current_fbo);
}

void QGLPixmapData::swapBuffers()
{
    if (!isValid())
        return;

    copyBackFromRenderFbo(false);
    m_renderFbo->release();

    --currentTextureBuffer;

    m_renderFbo = 0;
    m_engine = 0;
}

void QGLPixmapData::makeCurrent()
{
    if (isValid() && m_renderFbo)
        m_renderFbo->bind();
}

void QGLPixmapData::doneCurrent()
{
    if (isValid() && m_renderFbo)
        m_renderFbo->release();
}

static TextureBuffer createTextureBuffer(const QSize &size, QGL2PaintEngineEx *engine = 0)
{
    TextureBuffer buffer;
    QGLFramebufferObjectFormat fmt;
    fmt.setAttachment(QGLFramebufferObject::CombinedDepthStencil);
    fmt.setSamples(4);

    buffer.fbo = new QGLFramebufferObject(size, fmt);
    buffer.engine = engine ? engine : new QGL2PaintEngineEx;

    return buffer;
}

bool QGLPixmapData::useFramebufferObjects()
{
    return QGLFramebufferObject::hasOpenGLFramebufferObjects()
           && QGLFramebufferObject::hasOpenGLFramebufferBlit();
}

QPaintEngine* QGLPixmapData::paintEngine() const
{
    if (!isValid())
        return 0;

    if (m_engine)
        return m_engine;

    if (useFramebufferObjects()) {
        extern QGLWidget* qt_gl_share_widget();

        if (!QGLContext::currentContext())
            qt_gl_share_widget()->makeCurrent();
        QGLShareContextScope ctx(qt_gl_share_widget()->context());

        if (textureBufferStack.size() <= currentTextureBuffer) {
            textureBufferStack << createTextureBuffer(size());
        } else {
            QSize sz = textureBufferStack.at(currentTextureBuffer).fbo->size();
            if (sz.width() < m_width || sz.height() < m_height) {
                if (sz.width() < m_width)
                    sz.setWidth(qMax(m_width, qRound(sz.width() * 1.5)));
                if (sz.height() < m_height)
                    sz.setHeight(qMax(m_height, qRound(sz.height() * 1.5)));

                // wasting too much space?
                if (sz.width() * sz.height() > m_width * m_height * 2.5)
                    sz = QSize(m_width, m_height);

                delete textureBufferStack.at(currentTextureBuffer).fbo;
                textureBufferStack[currentTextureBuffer] =
                    createTextureBuffer(sz, textureBufferStack.at(currentTextureBuffer).engine);
                qDebug() << "Creating new pixmap texture buffer:" << sz;
            }
        }

        if (textureBufferStack.at(currentTextureBuffer).fbo->isValid()) {
            m_renderFbo = textureBufferStack.at(currentTextureBuffer).fbo;
            m_engine = textureBufferStack.at(currentTextureBuffer).engine;

            ++currentTextureBuffer;

            return m_engine;
        }

        qWarning() << "Failed to create pixmap texture buffer of size " << size() << ", falling back to raster paint engine";
    }

    m_dirty = true;
    if (m_source.size() != size())
        m_source = QImage(size(), QImage::Format_ARGB32_Premultiplied);
    if (m_hasFillColor) {
        m_source.fill(PREMUL(m_fillColor.rgba()));
        m_hasFillColor = false;
    }
    return m_source.paintEngine();
}

GLuint QGLPixmapData::bind(bool copyBack) const
{
    if (m_renderFbo && copyBack) {
        copyBackFromRenderFbo(true);
    } else {
        if (m_hasFillColor) {
            m_dirty = true;
            m_source = QImage(m_width, m_height, QImage::Format_ARGB32_Premultiplied);
            m_source.fill(PREMUL(m_fillColor.rgba()));
            m_hasFillColor = false;
        }
        ensureCreated();
    }

    GLuint id = m_textureId;
    glBindTexture(GL_TEXTURE_2D, id);
    return id;
}

GLuint QGLPixmapData::textureId() const
{
    ensureCreated();
    return m_textureId;
}

extern int qt_defaultDpiX();
extern int qt_defaultDpiY();

int QGLPixmapData::metric(QPaintDevice::PaintDeviceMetric metric) const
{
    switch (metric) {
    case QPaintDevice::PdmWidth:
        return m_width;
    case QPaintDevice::PdmHeight:
        return m_height;
    case QPaintDevice::PdmNumColors:
        return 0;
    case QPaintDevice::PdmDepth:
        return pixelType() == QPixmapData::PixmapType ? 32 : 1;
    case QPaintDevice::PdmWidthMM:
        return qRound(m_width * 25.4 / qt_defaultDpiX());
    case QPaintDevice::PdmHeightMM:
        return qRound(m_height * 25.4 / qt_defaultDpiY());
    case QPaintDevice::PdmDpiX:
    case QPaintDevice::PdmPhysicalDpiX:
        return qt_defaultDpiX();
    case QPaintDevice::PdmDpiY:
    case QPaintDevice::PdmPhysicalDpiY:
        return qt_defaultDpiY();
    default:
        qWarning("QGLPixmapData::metric(): Invalid metric");
        return 0;
    }
}

QT_END_NAMESPACE