source: trunk/src/opengl/qpixmapdata_gl.cpp@ 103

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**
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** This file is part of the QtOpenGL module of the Qt Toolkit.
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#include "qpixmap.h"

#include <private/qpaintengine_raster_p.h>

#include "qpixmapdata_gl_p.h"

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

QT_BEGIN_NAMESPACE

extern QGLWidget* qt_gl_share_widget();

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

    operator QGLContext *()
    {
        return m_ctx;
    }

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

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

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

void qt_gl_convertFromGLImage(QImage *img)
{
    const int w = img->width();
    const int h = img->height();

    if (QSysInfo::ByteOrder == QSysInfo::BigEndian) {
        uint *p = (uint*)img->bits();
        uint *end = p + w*h;

        while (p < end) {
            uint a = *p << 24;
            *p = (*p >> 8) | a;
            p++;
        }

        *img = img->mirrored();
    } else {
        // mirror image
        uint *data = (uint *)img->bits();

        const int mid = h/2;

        for (int y = 0; y < mid; ++y) {
            uint *p = data + y * w;
            uint *end = p + w;
            uint *q = data + (h - y - 1) * w;

            while (p < end)
                qSwap(*p++, *q++);
        }
    }
}


static int qt_gl_pixmap_serial = 0;

QGLPixmapData::QGLPixmapData(PixelType type)
    : QPixmapData(type, OpenGLClass)
    , m_width(0)
    , m_height(0)
    , m_texture(0)
    , m_dirty(false)
{
    setSerialNumber(++qt_gl_pixmap_serial);
}

QGLPixmapData::~QGLPixmapData()
{
    if (m_texture && qt_gl_share_widget()) {
        QGLShareContextScope ctx(qt_gl_share_widget()->context());
        glDeleteTextures(1, &m_texture);
    }
}

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

bool QGLPixmapData::isValidContext(const QGLContext *ctx) const
{
    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;

    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());

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

    if (!m_texture)
        glGenTextures(1, &m_texture);

    glBindTexture(target, m_texture);

    if (m_source.isNull()) {
        glTexImage2D(target, 0, GL_RGBA, m_width, m_height, 0, format, GL_UNSIGNED_BYTE, 0);
    } else {
        const QImage tx = ctx->d_func()->convertToGLFormat(m_source, true, format);

        glBindTexture(target, m_texture);
        glTexImage2D(target, 0, GL_RGBA, m_width, m_height, 0, format,
                GL_UNSIGNED_BYTE, tx.bits());

        m_source = QImage();
    }