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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 3.0 as published by the Free Software
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** packaging of this file.  Please review the following information to
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#include "private/qpixmapfilter_p.h"
#include "qglpixmapfilter_p.h"
#include "qgraphicssystem_gl_p.h"
#include "qpaintengine_opengl_p.h"

#include "qglpixelbuffer.h"
#include "qglshaderprogram.h"
#include "qgl_p.h"

#include "private/qapplication_p.h"


QT_BEGIN_NAMESPACE


void QGLPixmapFilterBase::bindTexture(const QPixmap &src) const
{
    const_cast<QGLContext *>(QGLContext::currentContext())->d_func()->bindTexture(src, GL_TEXTURE_2D, GL_RGBA, true);
}

void QGLPixmapFilterBase::drawImpl(QPainter *painter, const QPointF &pos, const QPixmap &src, const QRectF& source) const
{
    processGL(painter, pos, src, source);
}

class QGLPixmapColorizeFilter: public QGLPixmapFilter<QPixmapColorizeFilter>
{
public:
    QGLPixmapColorizeFilter();

protected:
    bool processGL(QPainter *painter, const QPointF &pos, const QPixmap &pixmap, const QRectF &srcRect) const;

private:
    mutable QGLShaderProgram m_program;
    int m_colorUniform;
};

class QGLPixmapConvolutionFilter: public QGLPixmapFilter<QPixmapConvolutionFilter>
{
public:
    QGLPixmapConvolutionFilter();
    ~QGLPixmapConvolutionFilter();

protected:
    bool processGL(QPainter *painter, const QPointF &pos, const QPixmap &src, const QRectF &srcRect) const;

private:
    QByteArray generateConvolutionShader() const;

    mutable QGLShaderProgram *m_program;
    mutable int m_scaleUniform;
    mutable int m_matrixUniform;

    mutable int m_kernelWidth;
    mutable int m_kernelHeight;
};

extern QGLWidget *qt_gl_share_widget();

QPixmapFilter *QGLContextPrivate::createPixmapFilter(int type) const
{
    switch (type) {
    case QPixmapFilter::ColorizeFilter:
        return new QGLPixmapColorizeFilter;


    case QPixmapFilter::ConvolutionFilter:
        return new QGLPixmapConvolutionFilter;

    default:
        return 0;
        break;
    }
    return 0;
}

#if !defined(QT_OPENGL_ES_2)
extern void qt_add_rect_to_array(const QRectF &r, q_vertexType *array);
extern void qt_add_texcoords_to_array(qreal x1, qreal y1, qreal x2, qreal y2, q_vertexType *array);
#endif

static void qgl_drawTexture(const QRectF &rect, int tx_width, int tx_height, const QRectF & src)
{
#ifndef QT_OPENGL_ES_2  // XXX: needs to be ported
#ifndef QT_OPENGL_ES
    glPushAttrib(GL_CURRENT_BIT);
#endif
    qreal x1, x2, y1, y2;

    x1 = src.x() / tx_width;
    x2 = x1 + src.width() / tx_width;
    y1 = 1.0 - ((src.y() / tx_height) + (src.height() / tx_height));
    y2 = 1.0 - (src.y() / tx_height);

    q_vertexType vertexArray[4*2];
    q_vertexType texCoordArray[4*2];

    qt_add_rect_to_array(rect, vertexArray);
    qt_add_texcoords_to_array(x1, y2, x2, y1, texCoordArray);

    glVertexPointer(2, q_vertexTypeEnum, 0, vertexArray);
    glTexCoordPointer(2, q_vertexTypeEnum, 0, texCoordArray);

    glEnableClientState(GL_VERTEX_ARRAY);
    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
    glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
    glDisableClientState(GL_VERTEX_ARRAY);

#ifndef QT_OPENGL_ES
    glPopAttrib();
#endif
#endif
}

static const char *qt_gl_colorize_filter =
        "uniform sampler2D texture;"
        "uniform vec3 color;"
        "void main(void)"
        "{"
        "        vec2 coords = gl_TexCoord[0].st;"
        "        vec4 src = texture2D(texture, coords);"
        "        float gray = dot(src.rgb, vec3(0.212671, 0.715160, 0.072169));"
        "        vec3 colorizeed = 1.0-((1.0-gray)*(1.0-color));"
        "        gl_FragColor = vec4(colorizeed, src.a);"
        "}";

QGLPixmapColorizeFilter::QGLPixmapColorizeFilter()
{
    m_program.addShader(QGLShader::FragmentShader, qt_gl_colorize_filter);
    m_program.link();
    m_program.enable();
    m_program.setUniformValue(m_program.uniformLocation("texture"), 0); // GL_TEXTURE_0
    m_colorUniform = m_program.uniformLocation("color");
}

bool QGLPixmapColorizeFilter::processGL(QPainter *, const QPointF &pos, const QPixmap &src, const QRectF &srcRect) const
{
    bindTexture(src);

    QColor col = color();
    m_program.enable();
    m_program.setUniformValue(m_colorUniform, col.redF(), col.greenF(), col.blueF());

    QRectF target = (srcRect.isNull() ? QRectF(src.rect()) : srcRect).translated(pos);
    qgl_drawTexture(target, src.width(), src.height(), srcRect);
    m_program.disable();

    return true;
}

// generates convolution filter code for arbitrary sized kernel
QByteArray QGLPixmapConvolutionFilter::generateConvolutionShader() const {
    QByteArray code;
    code.append("uniform sampler2D texture;\n");
    code.append("uniform vec2 inv_texture_size;\n");
    code.append("uniform float matrix[");
    code.append(QByteArray::number(m_kernelWidth * m_kernelHeight));
    code.append("];\n");
    code.append("vec2 offset[");
    code.append(QByteArray::number(m_kernelWidth*m_kernelHeight));
    code.append("];\n");
    code.append("void main(void) {\n");

    for(int y = 0; y < m_kernelHeight; y++) {
        for(int x = 0; x < m_kernelWidth; x++) {
            code.append("  offset[");
            code.append(QByteArray::number(y * m_kernelWidth + x));
            code.append("] = vec2(inv_texture_size.x * ");
            code.append(QByteArray::number(x-(int)(m_kernelWidth/2)));
            code.append(".0, inv_texture_size.y * ");
            code.append(QByteArray::number((int)(m_kernelHeight/2)-y));
            code.append(".0)");
            code.append(";\n");
        }
    }

    code.append("  int i = 0;\n");
    code.append("  vec2 coords = gl_TexCoord[0].st;\n");
    code.append("  vec4 sum = vec4(0.0);\n");
    code.append("  for (i = 0; i < ");
    code.append(QByteArray::number(m_kernelWidth * m_kernelHeight));
    code.append("; i++) {\n");
    code.append("    vec4 tmp = texture2D(texture,coords+offset[i]);\n");
    code.append("    sum += matrix[i] * tmp;\n");
    code.append("  }\n");
    code.append("  gl_FragColor = sum;\n");
    code.append("}");
    return code;
}

QGLPixmapConvolutionFilter::QGLPixmapConvolutionFilter()
    : m_program(0)
    , m_scaleUniform(0)
    , m_matrixUniform(0)
    , m_kernelWidth(0)
    , m_kernelHeight(0)
{
}

QGLPixmapConvolutionFilter::~QGLPixmapConvolutionFilter()
{
    delete m_program;
}

bool QGLPixmapConvolutionFilter::processGL(QPainter *, const QPointF &pos, const QPixmap &src, const QRectF &srcRect) const
{
    QRectF target = (srcRect.isNull() ? QRectF(src.rect()) : srcRect).translated(pos);

    bindTexture(src);
#ifdef GL_CLAMP
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
    glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
#endif
    if (!m_program || m_kernelWidth != columns() || m_kernelHeight != rows()) {
        delete m_program;

        m_kernelWidth = columns();
        m_kernelHeight = rows();

        QByteArray code = generateConvolutionShader();
        m_program = new QGLShaderProgram();
        m_program->addShader(QGLShader::FragmentShader, code);
        m_program->link();
        m_scaleUniform = m_program->uniformLocation("inv_texture_size");
        m_matrixUniform = m_program->uniformLocation("matrix");
    }

    const qreal *kernel = convolutionKernel();
    GLfloat *conv = new GLfloat[m_kernelWidth * m_kernelHeight];
    for(int i = 0; i < m_kernelWidth * m_kernelHeight; ++i)
        conv[i] = kernel[i];

    const qreal iw = 1.0 / src.width();
    const qreal ih = 1.0 / src.height();
    m_program->enable();
    m_program->setUniformValue(m_scaleUniform, iw, ih);
    m_program->setUniformValueArray(m_matrixUniform, conv, m_kernelWidth * m_kernelHeight, 1);

    qgl_drawTexture(target, src.width(), src.height(), boundingRectFor(srcRect));
    m_program->disable();
    return true;
}

QT_END_NAMESPACE