/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
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**
** This file is part of the QtOpenGL module of the Qt Toolkit.
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** General Public License version 3 as published by the Free Software
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** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
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** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
** Public license version 3 or any later version approved by the KDE Free
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** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
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****************************************************************************/

#include "qopengltextureglyphcache_p.h"
#include <private/qopenglpaintengine_p.h>
#include "private/qopenglengineshadersource_p.h"
#include <private/qopenglextensions_p.h>
#include <qrgb.h>
#include <private/qdrawhelper_p.h>

QT_BEGIN_NAMESPACE


static int next_qopengltextureglyphcache_serial_number()
{
    static QBasicAtomicInt serial = Q_BASIC_ATOMIC_INITIALIZER(0);
    return 1 + serial.fetchAndAddRelaxed(1);
}

QOpenGLTextureGlyphCache::QOpenGLTextureGlyphCache(QFontEngine::GlyphFormat format, const QTransform &matrix, const QColor &color)
    : QImageTextureGlyphCache(format, matrix, color)
    , m_textureResource(nullptr)
    , pex(nullptr)
    , m_blitProgram(nullptr)
    , m_filterMode(Nearest)
    , m_serialNumber(next_qopengltextureglyphcache_serial_number())
    , m_buffer(QOpenGLBuffer::VertexBuffer)
{
#ifdef QT_GL_TEXTURE_GLYPH_CACHE_DEBUG
    qDebug(" -> QOpenGLTextureGlyphCache() %p for context %p.", this, QOpenGLContext::currentContext());
#endif
    m_vertexCoordinateArray[0] = -1.0f;
    m_vertexCoordinateArray[1] = -1.0f;
    m_vertexCoordinateArray[2] =  1.0f;
    m_vertexCoordinateArray[3] = -1.0f;
    m_vertexCoordinateArray[4] =  1.0f;
    m_vertexCoordinateArray[5] =  1.0f;
    m_vertexCoordinateArray[6] = -1.0f;
    m_vertexCoordinateArray[7] =  1.0f;

    m_textureCoordinateArray[0] = 0.0f;
    m_textureCoordinateArray[1] = 0.0f;
    m_textureCoordinateArray[2] = 1.0f;
    m_textureCoordinateArray[3] = 0.0f;
    m_textureCoordinateArray[4] = 1.0f;
    m_textureCoordinateArray[5] = 1.0f;
    m_textureCoordinateArray[6] = 0.0f;
    m_textureCoordinateArray[7] = 1.0f;
}

QOpenGLTextureGlyphCache::~QOpenGLTextureGlyphCache()
{
#ifdef QT_GL_TEXTURE_GLYPH_CACHE_DEBUG
    qDebug(" -> ~QOpenGLTextureGlyphCache() %p.", this);
#endif
    clear();
}

#if !QT_CONFIG(opengles2)
static inline bool isCoreProfile()
{
    return QOpenGLContext::currentContext()->format().profile() == QSurfaceFormat::CoreProfile;
}
#endif

void QOpenGLTextureGlyphCache::createTextureData(int width, int height)
{
    QOpenGLContext *ctx = const_cast<QOpenGLContext *>(QOpenGLContext::currentContext());
    if (ctx == nullptr) {
        qWarning("QOpenGLTextureGlyphCache::createTextureData: Called with no context");
        return;
    }

    // create in QImageTextureGlyphCache baseclass is meant to be called
    // only to create the initial image and does not preserve the content,
    // so we don't call when this function is called from resize.
    if (ctx->d_func()->workaround_brokenFBOReadBack && image().isNull())
        QImageTextureGlyphCache::createTextureData(width, height);

    // Make the lower glyph texture size 16 x 16.
    if (width < 16)
        width = 16;
    if (height < 16)
        height = 16;

    if (m_textureResource && !m_textureResource->m_texture) {
        delete m_textureResource;
        m_textureResource = nullptr;
    }

    if (!m_textureResource)
        m_textureResource = new QOpenGLGlyphTexture(ctx);

    QOpenGLFunctions *funcs = ctx->functions();
    funcs->glGenTextures(1, &m_textureResource->m_texture);
    funcs->glBindTexture(GL_TEXTURE_2D, m_textureResource->m_texture);

    m_textureResource->m_width = width;
    m_textureResource->m_height = height;

    if (m_format == QFontEngine::Format_A32 || m_format == QFontEngine::Format_ARGB) {
        QVarLengthArray<uchar> data(width * height * 4);
        for (int i = 0; i < data.size(); ++i)
            data[i] = 0;
        funcs->glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, width, height, 0, GL_RGBA, GL_UNSIGNED_BYTE, &data[0]);
    } else {
        QVarLengthArray<uchar> data(width * height);
        for (int i = 0; i < data.size(); ++i)
            data[i] = 0;
#if !QT_CONFIG(opengles2)
        const GLint internalFormat = isCoreProfile() ? GL_R8 : GL_ALPHA;
        const GLenum format = isCoreProfile() ? GL_RED : GL_ALPHA;
#else
        const GLint internalFormat = GL_ALPHA;
        const GLenum format = GL_ALPHA;
#endif
        funcs->glTexImage2D(GL_TEXTURE_2D, 0, internalFormat, width, height, 0, format, GL_UNSIGNED_BYTE, &data[0]);
    }

    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    m_filterMode = Nearest;

    if (!m_buffer.isCreated()) {
        m_buffer.create();
        m_buffer.bind();
        static GLfloat buf[sizeof(m_vertexCoordinateArray) + sizeof(m_textureCoordinateArray)];
        memcpy(buf, m_vertexCoordinateArray, sizeof(m_vertexCoordinateArray));
        memcpy(buf + (sizeof(m_vertexCoordinateArray) / sizeof(GLfloat)),
               m_textureCoordinateArray,
               sizeof(m_textureCoordinateArray));
        m_buffer.allocate(buf, sizeof(buf));
        m_buffer.release();
    }

    if (!m_vao.isCreated())
        m_vao.create();
}

void QOpenGLTextureGlyphCache::setupVertexAttribs()
{
    m_buffer.bind();
    m_blitProgram->setAttributeBuffer(int(QT_VERTEX_COORDS_ATTR), GL_FLOAT, 0, 2);
    m_blitProgram->setAttributeBuffer(int(QT_TEXTURE_COORDS_ATTR), GL_FLOAT, sizeof(m_vertexCoordinateArray), 2);
    m_blitProgram->enableAttributeArray(int(QT_VERTEX_COORDS_ATTR));
    m_blitProgram->enableAttributeArray(int(QT_TEXTURE_COORDS_ATTR));
    m_buffer.release();
}

static void load_glyph_image_to_texture(QOpenGLContext *ctx,
                                        QImage &img,
                                        GLuint texture,
                                        int tx, int ty)
{
    QOpenGLFunctions *funcs = ctx->functions();

    const int imgWidth = img.width();
    const int imgHeight = img.height();

    if (img.format() == QImage::Format_Mono) {
        img = img.convertToFormat(QImage::Format_Grayscale8);
    } else if (img.depth() == 32) {
        if (img.format() == QImage::Format_RGB32
            // We need to make the alpha component equal to the average of the RGB values.
            // This is needed when drawing sub-pixel antialiased text on translucent targets.
#if Q_BYTE_ORDER == Q_BIG_ENDIAN
            || img.format() == QImage::Format_ARGB32_Premultiplied
#else
            || (img.format() == QImage::Format_ARGB32_Premultiplied
                && ctx->isOpenGLES())
#endif
            ) {
            for (int y = 0; y < imgHeight; ++y) {
                QRgb *src = (QRgb *) img.scanLine(y);
                for (int x = 0; x < imgWidth; ++x) {
                    int r = qRed(src[x]);
                    int g = qGreen(src[x]);
                    int b = qBlue(src[x]);
                    int avg;
                    if (img.format() == QImage::Format_RGB32)
                        avg = (r + g + b + 1) / 3; // "+1" for rounding.
                    else // Format_ARGB_Premultiplied
                        avg = qAlpha(src[x]);

                    src[x] = qRgba(r, g, b, avg);
                    // swizzle the bits to accommodate for the GL_RGBA upload.
#if Q_BYTE_ORDER != Q_BIG_ENDIAN
                    if (ctx->isOpenGLES())
#endif
                        src[x] = ARGB2RGBA(src[x]);
                }
            }
        }
    }

    funcs->glBindTexture(GL_TEXTURE_2D, texture);
    if (img.depth() == 32) {
#if QT_CONFIG(opengles2)
        GLenum fmt = GL_RGBA;
#else
        GLenum fmt = ctx->isOpenGLES() ? GL_RGBA : GL_BGRA;
#endif // QT_CONFIG(opengles2)

#if Q_BYTE_ORDER == Q_BIG_ENDIAN
        fmt = GL_RGBA;
#endif
        funcs->glTexSubImage2D(GL_TEXTURE_2D, 0, tx, ty, imgWidth, imgHeight, fmt, GL_UNSIGNED_BYTE, img.constBits());
    } else {
        // The scanlines in image are 32-bit aligned, even for mono or 8-bit formats. This
        // is good because it matches the default of 4 bytes for GL_UNPACK_ALIGNMENT.
#if !QT_CONFIG(opengles2)
        const GLenum format = isCoreProfile() ? GL_RED : GL_ALPHA;
#else
        const GLenum format = GL_ALPHA;
#endif
        funcs->glTexSubImage2D(GL_TEXTURE_2D, 0, tx, ty, imgWidth, imgHeight, format, GL_UNSIGNED_BYTE, img.constBits());
    }
}

static void load_glyph_image_region_to_texture(QOpenGLContext *ctx,
                                               const QImage &srcImg,
                                               int x, int y,
                                               int w, int h,
                                               GLuint texture,
                                               int tx, int ty)
{
    Q_ASSERT(x + w <= srcImg.width() && y + h <= srcImg.height());

    QImage img;
    if (x != 0 || y != 0 || w != srcImg.width() || h != srcImg.height())
        img = srcImg.copy(x, y, w, h);
    else
        img = srcImg;

    load_glyph_image_to_texture(ctx, img, texture, tx, ty);
}

void QOpenGLTextureGlyphCache::resizeTextureData(int width, int height)
{
    QOpenGLContext *ctx = QOpenGLContext::currentContext();
    if (ctx == nullptr) {
        qWarning("QOpenGLTextureGlyphCache::resizeTextureData: Called with no context");
        return;
    }

    QOpenGLFunctions *funcs = ctx->functions();
    GLint oldFbo;
    funcs->glGetIntegerv(GL_FRAMEBUFFER_BINDING, &oldFbo);

    int oldWidth = m_textureResource->m_width;
    int oldHeight = m_textureResource->m_height;

    // Make the lower glyph texture size 16 x 16.
    if (width < 16)
        width = 16;
    if (height < 16)
        height = 16;

    GLuint oldTexture = m_textureResource->m_texture;
    createTextureData(width, height);

    if (ctx->d_func()->workaround_brokenFBOReadBack) {
        QImageTextureGlyphCache::resizeTextureData(width, height);
        load_glyph_image_region_to_texture(ctx, image(), 0, 0, qMin(oldWidth, width), qMin(oldHeight, height),
                                           m_textureResource->m_texture, 0, 0);
        return;
    }

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

    funcs->glBindFramebuffer(GL_FRAMEBUFFER, m_textureResource->m_fbo);

    GLuint tmp_texture;
    funcs->glGenTextures(1, &tmp_texture);
    funcs->glBindTexture(GL_TEXTURE_2D, tmp_texture);
    funcs->glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, oldWidth, oldHeight, 0,
                        GL_RGBA, GL_UNSIGNED_BYTE, nullptr);
    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
    funcs->glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
    m_filterMode = Nearest;
    funcs->glBindTexture(GL_TEXTURE_2D, 0);
    funcs->glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                  GL_TEXTURE_2D, tmp_texture, 0);

    funcs->glActiveTexture(GL_TEXTURE0 + QT_IMAGE_TEXTURE_UNIT);
    funcs->glBindTexture(GL_TEXTURE_2D, oldTexture);

    if (pex != nullptr)
        pex->transferMode(BrushDrawingMode);

    funcs->glDisable(GL_STENCIL_TEST);
    funcs->glDisable(GL_DEPTH_TEST);
    funcs->glDisable(GL_SCISSOR_TEST);
    funcs->glDisable(GL_BLEND);

    funcs->glViewport(0, 0, oldWidth, oldHeight);

    QOpenGLShaderProgram *blitProgram = nullptr;
    if (pex == nullptr) {
        if (m_blitProgram == nullptr) {
            m_blitProgram = new QOpenGLShaderProgram;
            const bool isCoreProfile = ctx->format().profile() == QSurfaceFormat::CoreProfile;

            {
                QString source;
#ifdef Q_OS_WASM
                source.append(QLatin1String(isCoreProfile ? qopenglslUntransformedPositionVertexShader_core : qopenglslUntransformedPositionVertexShader));
                source.append(QLatin1String(isCoreProfile ? qopenglslMainWithTexCoordsVertexShader_core : qopenglslMainWithTexCoordsVertexShader));
#else
                source.append(QLatin1String(isCoreProfile ? qopenglslMainWithTexCoordsVertexShader_core : qopenglslMainWithTexCoordsVertexShader));
                source.append(QLatin1String(isCoreProfile ? qopenglslUntransformedPositionVertexShader_core : qopenglslUntransformedPositionVertexShader));
#endif
                m_blitProgram->addCacheableShaderFromSourceCode(QOpenGLShader::Vertex, source);
            }

            {
                QString source;
#ifdef Q_OS_WASM
                source.append(QLatin1String(isCoreProfile ? qopenglslImageSrcFragmentShader_core : qopenglslImageSrcFragmentShader));
                source.append(QLatin1String(isCoreProfile ? qopenglslMainFragmentShader_core : qopenglslMainFragmentShader));
#else
                source.append(QLatin1String(isCoreProfile ? qopenglslMainFragmentShader_core : qopenglslMainFragmentShader));
                source.append(QLatin1String(isCoreProfile ? qopenglslImageSrcFragmentShader_core : qopenglslImageSrcFragmentShader));
#endif
                m_blitProgram->addCacheableShaderFromSourceCode(QOpenGLShader::Fragment, source);
            }

            m_blitProgram->bindAttributeLocation("vertexCoordsArray", QT_VERTEX_COORDS_ATTR);
            m_blitProgram->bindAttributeLocation("textureCoordArray", QT_TEXTURE_COORDS_ATTR);

            m_blitProgram->link();

            if (m_vao.isCreated()) {
                m_vao.bind();
                setupVertexAttribs();
            }
        }

        if (m_vao.isCreated())
            m_vao.bind();
        else
            setupVertexAttribs();

        m_blitProgram->bind();
        blitProgram = m_blitProgram;

    } else {
        pex->uploadData(QT_VERTEX_COORDS_ATTR, m_vertexCoordinateArray, 8);
        pex->uploadData(QT_TEXTURE_COORDS_ATTR, m_textureCoordinateArray, 8);

        pex->shaderManager->useBlitProgram();
        blitProgram = pex->shaderManager->blitProgram();
    }

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

    funcs->glDrawArrays(GL_TRIANGLE_FAN, 0, 4);

    funcs->glBindTexture(GL_TEXTURE_2D, m_textureResource->m_texture);

    funcs->glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 0, 0, oldWidth, oldHeight);

    funcs->glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
                                     GL_RENDERBUFFER, 0);
    funcs->glDeleteTextures(1, &tmp_texture);
    funcs->glDeleteTextures(1, &oldTexture);

    funcs->glBindFramebuffer(GL_FRAMEBUFFER, (GLuint)oldFbo);

    if (pex != nullptr) {
        funcs->glViewport(0, 0, pex->width, pex->height);
        pex->updateClipScissorTest();
    } else {
        if (m_vao.isCreated()) {
            m_vao.release();
        } else {
            m_blitProgram->disableAttributeArray(int(QT_VERTEX_COORDS_ATTR));
            m_blitProgram->disableAttributeArray(int(QT_TEXTURE_COORDS_ATTR));
        }
    }
}

void QOpenGLTextureGlyphCache::fillTexture(const Coord &c, glyph_t glyph, QFixed subPixelPosition)
{
    QOpenGLContext *ctx = QOpenGLContext::currentContext();
    if (ctx == nullptr) {
        qWarning("QOpenGLTextureGlyphCache::fillTexture: Called with no context");
        return;
    }

    if (ctx->d_func()->workaround_brokenFBOReadBack) {
        QImageTextureGlyphCache::fillTexture(c, glyph, subPixelPosition);
        load_glyph_image_region_to_texture(ctx, image(), c.x, c.y, c.w, c.h, m_textureResource->m_texture, c.x, c.y);
        return;
    }

    QImage mask = textureMapForGlyph(glyph, subPixelPosition);
    load_glyph_image_to_texture(ctx, mask, m_textureResource->m_texture, c.x, c.y);
}

int QOpenGLTextureGlyphCache::glyphPadding() const
{
    return 1;
}

int QOpenGLTextureGlyphCache::maxTextureWidth() const
{
    QOpenGLContext *ctx = const_cast<QOpenGLContext *>(QOpenGLContext::currentContext());
    if (ctx == nullptr)
        return QImageTextureGlyphCache::maxTextureWidth();
    else
        return ctx->d_func()->maxTextureSize();
}

int QOpenGLTextureGlyphCache::maxTextureHeight() const
{
    QOpenGLContext *ctx = const_cast<QOpenGLContext *>(QOpenGLContext::currentContext());
    if (ctx == nullptr)
        return QImageTextureGlyphCache::maxTextureHeight();

    if (ctx->d_func()->workaround_brokenTexSubImage)
        return qMin(1024, ctx->d_func()->maxTextureSize());
    else
        return ctx->d_func()->maxTextureSize();
}

void QOpenGLTextureGlyphCache::clear()
{
    if (m_textureResource)
        m_textureResource->free();
    m_textureResource = nullptr;

    delete m_blitProgram;
    m_blitProgram = nullptr;

    m_w = 0;
    m_h = 0;
    m_cx = 0;
    m_cy = 0;
    m_currentRowHeight = 0;
    coords.clear();
}

QT_END_NAMESPACE
