/****************************************************************************

**

** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the QtOpenGL module of the Qt Toolkit.

**

** $QT_BEGIN_LICENSE:LGPL$

** No Commercial Usage

** This file contains pre-release code and may not be distributed.

** You may use this file in accordance with the terms and conditions

** contained in the Technology Preview License Agreement accompanying

** this package.

**

** GNU Lesser General Public License Usage

** Alternatively, this file may be used under the terms of the GNU Lesser

** General Public License version 2.1 as published by the Free Software

** Foundation and appearing in the file LICENSE.LGPL included in the

** packaging of this file.  Please review the following information to

** ensure the GNU Lesser General Public License version 2.1 requirements

** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

**

** In addition, as a special exception, Nokia gives you certain additional

** rights.  These rights are described in the Nokia Qt LGPL Exception

** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

**

** If you have questions regarding the use of this file, please contact

** Nokia at qt-info@nokia.com.

**

**

**

**

**

**

**

**

** $QT_END_LICENSE$

**

****************************************************************************/

#include "qtextureglyphcache_gl_p.h"

#include "qpaintengineex_opengl2_p.h"

QT_BEGIN_NAMESPACE

#ifdef Q_WS_WIN

extern Q_GUI_EXPORT bool qt_cleartype_enabled;

#endif

QGLTextureGlyphCache::QGLTextureGlyphCache(QGLContext *context, QFontEngineGlyphCache::Type type, const QTransform &matrix)

    : QTextureGlyphCache(type, matrix)

    , ctx(context)

    , m_width(0)

    , m_height(0)

{

    glGenFramebuffers(1, &m_fbo);

    connect(QGLSignalProxy::instance(), SIGNAL(aboutToDestroyContext(const QGLContext*)),

            SLOT(contextDestroyed(const QGLContext*)));

}

QGLTextureGlyphCache::~QGLTextureGlyphCache()

{

    if (ctx) {

        QGLShareContextScope scope(ctx);

        glDeleteFramebuffers(1, &m_fbo);

        if (m_width || m_height)

            glDeleteTextures(1, &m_texture);

    }

}

void QGLTextureGlyphCache::createTextureData(int width, int height)

{

    glGenTextures(1, &m_texture);

    glBindTexture(GL_TEXTURE_2D, m_texture);

    m_width = width;

    m_height = height;

    QVarLengthArray<uchar> data(width * height);

    for (int i = 0; i < data.size(); ++i)

        data[i] = 0;

    if (m_type == QFontEngineGlyphCache::Raster_RGBMask)

        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, &data[0]);

    else

        glTexImage2D(GL_TEXTURE_2D, 0, GL_ALPHA, width, height, 0, GL_ALPHA, GL_UNSIGNED_BYTE, &data[0]);

    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);

    glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

}

void QGLTextureGlyphCache::resizeTextureData(int width, int height)

{

    // ### the QTextureGlyphCache API needs to be reworked to allow

    // ### resizeTextureData to fail

    int oldWidth = m_width;

    int oldHeight = m_height;

    GLuint oldTexture = m_texture;

    createTextureData(width, height);

    glBindFramebuffer(GL_FRAMEBUFFER_EXT, m_fbo);

    GLuint tmp_texture;

    glGenTextures(1, &tmp_texture);

    glBindTexture(GL_TEXTURE_2D, tmp_texture);

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, oldWidth, oldHeight, 0,

                 GL_RGBA, GL_UNSIGNED_BYTE, NULL);

    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);

    glBindTexture(GL_TEXTURE_2D, 0);

    glFramebufferTexture2D(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,

                           GL_TEXTURE_2D, tmp_texture, 0);

    glActiveTexture(GL_TEXTURE0 + QT_IMAGE_TEXTURE_UNIT);

    glBindTexture(GL_TEXTURE_2D, oldTexture);

    pex->transferMode(BrushDrawingMode);

    glDisable(GL_STENCIL_TEST);

    glDisable(GL_DEPTH_TEST);

    glDisable(GL_SCISSOR_TEST);

    glDisable(GL_BLEND);

    glViewport(0, 0, oldWidth, oldHeight);

    GLfloat* vertexCoordinateArray = pex->staticVertexCoordinateArray;

    vertexCoordinateArray[0] = -1.0f;

    vertexCoordinateArray[1] = -1.0f;

    vertexCoordinateArray[2] =  1.0f;

    vertexCoordinateArray[3] = -1.0f;

    vertexCoordinateArray[4] =  1.0f;

    vertexCoordinateArray[5] =  1.0f;

    vertexCoordinateArray[6] = -1.0f;

    vertexCoordinateArray[7] =  1.0f;

    GLfloat* textureCoordinateArray = pex->staticTextureCoordinateArray;

    textureCoordinateArray[0] = 0.0f;

    textureCoordinateArray[1] = 0.0f;

    textureCoordinateArray[2] = 1.0f;

    textureCoordinateArray[3] = 0.0f;

    textureCoordinateArray[4] = 1.0f;

    textureCoordinateArray[5] = 1.0f;

    textureCoordinateArray[6] = 0.0f;

    textureCoordinateArray[7] = 1.0f;

    pex->setVertexAttributePointer(QT_VERTEX_COORDS_ATTR, vertexCoordinateArray);

    pex->setVertexAttributePointer(QT_TEXTURE_COORDS_ATTR, textureCoordinateArray);

    pex->shaderManager->useBlitProgram();

    pex->shaderManager->blitProgram()->setUniformValue("imageTexture", QT_IMAGE_TEXTURE_UNIT);

    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

    glBindTexture(GL_TEXTURE_2D, m_texture);

#ifdef QT_OPENGL_ES_2

    QDataBuffer<uchar> buffer(4*oldWidth*oldHeight);

    buffer.resize(4*oldWidth*oldHeight);

    glReadPixels(0, 0, oldWidth, oldHeight, GL_RGBA, GL_UNSIGNED_BYTE, buffer.data());

    // do an in-place conversion from GL_RGBA to GL_ALPHA

    for (int i=0; i<oldWidth*oldHeight; ++i)

        buffer.data()[i] = buffer.at(4*i + 3);

    glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, oldWidth, oldHeight,

                    GL_ALPHA, GL_UNSIGNED_BYTE, buffer.data());

#else

    glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, oldWidth, oldHeight);

#endif

    glFramebufferRenderbuffer(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT,

                              GL_RENDERBUFFER_EXT, 0);

    glDeleteTextures(1, &tmp_texture);

    glDeleteTextures(1, &oldTexture);

    glBindFramebuffer(GL_FRAMEBUFFER_EXT, ctx->d_ptr->current_fbo);

    glViewport(0, 0, pex->width, pex->height);

    pex->updateClipScissorTest();

}

void QGLTextureGlyphCache::fillTexture(const Coord &c, glyph_t glyph)

{

    QImage mask = textureMapForGlyph(glyph);

    const int maskWidth = mask.width();

    const int maskHeight = mask.height();

    if (mask.format() == QImage::Format_Mono) {

        mask = mask.convertToFormat(QImage::Format_Indexed8);

        for (int y = 0; y < maskHeight; ++y) {

            uchar *src = (uchar *) mask.scanLine(y);

            for (int x = 0; x < maskWidth; ++x)

                src[x] = -src[x]; // convert 0 and 1 into 0 and 255

        }

    } else if (mask.format() == QImage::Format_RGB32) {

        // Make the alpha component equal to the average of the RGB values.

        // This is needed when drawing sub-pixel antialiased text on translucent targets.

        for (int y = 0; y < maskHeight; ++y) {

            quint32 *src = (quint32 *) mask.scanLine(y);

            for (int x = 0; x < maskWidth; ++x) {

                uchar r = src[x] >> 16;

                uchar g = src[x] >> 8;

                uchar b = src[x];

                quint32 avg = (quint32(r) + quint32(g) + quint32(b) + 1) / 3; // "+1" for rounding.

                src[x] = (src[x] & 0x00ffffff) | (avg << 24);

            }

        }

    }

    glBindTexture(GL_TEXTURE_2D, m_texture);

    if (mask.format() == QImage::Format_RGB32) {

        glTexSubImage2D(GL_TEXTURE_2D, 0, c.x, c.y, maskWidth, maskHeight, GL_BGRA, GL_UNSIGNED_BYTE, mask.bits());

    } else {

#ifdef QT_OPENGL_ES2

        glTexSubImage2D(GL_TEXTURE_2D, 0, c.x, c.y, maskWidth, maskHeight, GL_ALPHA, GL_UNSIGNED_BYTE, mask.bits());

#else

        // glTexSubImage2D() might cause some garbage to appear in the texture if the mask width is

        // not a multiple of four bytes. The bug appeared on a computer with 32-bit Windows Vista

        // and nVidia GeForce 8500GT. GL_UNPACK_ALIGNMENT is set to four bytes, 'mask' has a

        // multiple of four bytes per line, and most of the glyph shows up correctly in the

        // texture, which makes me think that this is a driver bug.

        // One workaround is to make sure the mask width is a multiple of four bytes, for instance

        // by converting it to a format with four bytes per pixel. Another is to copy one line at a

        // time.

        for (int i = 0; i < maskHeight; ++i)

            glTexSubImage2D(GL_TEXTURE_2D, 0, c.x, c.y + i, maskWidth, 1, GL_ALPHA, GL_UNSIGNED_BYTE, mask.scanLine(i));

#endif

    }

}

int QGLTextureGlyphCache::glyphMargin() const

{

#if defined(Q_WS_MAC)

    return 2;

#elif defined (Q_WS_X11)

    return 0;

#else

    return m_type == QFontEngineGlyphCache::Raster_RGBMask ? 2 : 0;

#endif

}

QT_END_NAMESPACE