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#include "qsgatlastexture_p.h"

#include <QtCore/QVarLengthArray>
#include <QtCore/QElapsedTimer>

#include <QtGui/QOpenGLContext>
#include <QtGui/QGuiApplication>
#include <QtGui/QScreen>
#include <QtGui/QSurface>

#include <private/qsgtexture_p.h>

#include <private/qqmlprofilerservice_p.h>

QT_BEGIN_NAMESPACE

#ifndef GL_BGRA
#define GL_BGRA 0x80E1
#endif


#ifndef QSG_NO_RENDER_TIMING
static bool qsg_render_timing = !qgetenv("QSG_RENDER_TIMING").isEmpty();
static QElapsedTimer qsg_renderer_timer;
#endif

namespace QSGAtlasTexture
{

static inline int qsg_powerOfTwo(int v)
{
    v--;
    v |= v >> 1;
    v |= v >> 2;
    v |= v >> 4;
    v |= v >> 8;
    v |= v >> 16;
    ++v;
    return v;
}

static int qsg_envInt(const char *name, int defaultValue)
{
    QByteArray content = qgetenv(name);

    bool ok = false;
    int value = content.toInt(&ok);
    return ok ? value : defaultValue;
}

Manager::Manager()
    : m_atlas(0)
{
    QOpenGLContext *gl = QOpenGLContext::currentContext();
    Q_ASSERT(gl);
    QSurface *surface = gl->surface();
    QSize surfaceSize = surface->size();
    int max;
    glGetIntegerv(GL_MAX_TEXTURE_SIZE, &max);

    int w = qMin(max, qsg_envInt("QSG_ATLAS_WIDTH", qMax(512, qsg_powerOfTwo(surfaceSize.width()))));
    int h = qMin(max, qsg_envInt("QSG_ATLAS_HEIGHT", qMax(512, qsg_powerOfTwo(surfaceSize.height()))));

    m_atlas_size_limit = qsg_envInt("QSG_ATLAS_SIZE_LIMIT", qMax(w, h) / 2);
    m_atlas_size = QSize(w, h);

    if (qEnvironmentVariableIsSet("QSG_INFO"))
        qDebug() << "QSG: texture atlas dimensions:" << w << "x" << h;
}


Manager::~Manager()
{
    Q_ASSERT(m_atlas == 0);
}

void Manager::invalidate()
{
    if (m_atlas) {
        m_atlas->invalidate();
        m_atlas->deleteLater();
        m_atlas = 0;
    }
}

QSGTexture *Manager::create(const QImage &image)
{
    QSGTexture *t = 0;
    if (image.width() < m_atlas_size_limit && image.height() < m_atlas_size_limit) {
        if (!m_atlas)
            m_atlas = new Atlas(m_atlas_size);
        t = m_atlas->create(image);
    }
    return t;
}

Atlas::Atlas(const QSize &size)
    : m_allocator(size)
    , m_texture_id(0)
    , m_size(size)
    , m_filtering(QSGTexture::Linear)
    , m_allocated(false)
{

#ifdef QT_OPENGL_ES
    const char *ext = (const char *) glGetString(GL_EXTENSIONS);
    if (strstr(ext, "GL_EXT_bgra")
            || strstr(ext, "GL_EXT_texture_format_BGRA8888")
            || strstr(ext, "GL_IMG_texture_format_BGRA8888")) {
        m_internalFormat = m_externalFormat = GL_BGRA;
#ifdef Q_OS_IOS
    } else if (strstr(ext, "GL_APPLE_texture_format_BGRA8888")) {
        m_internalFormat = GL_RGBA;
        m_externalFormat = GL_BGRA;
#endif
    } else {
        m_internalFormat = m_externalFormat = GL_RGBA;
    }
#else
    m_internalFormat = GL_RGBA;
    m_externalFormat = GL_BGRA;
#endif

    m_use_bgra_fallback = qEnvironmentVariableIsSet("QSG_ATLAS_USE_BGRA_FALLBACK");
    m_debug_overlay = qEnvironmentVariableIsSet("QSG_ATLAS_OVERLAY");
}

Atlas::~Atlas()
{
    Q_ASSERT(!m_texture_id);
}

void Atlas::invalidate()
{
    Q_ASSERT(QOpenGLContext::currentContext());
    if (m_texture_id) {
        glDeleteTextures(1, &m_texture_id);
        m_texture_id = 0;
    }
}

Texture *Atlas::create(const QImage &image)
{
    // No need to lock, as manager already locked it.
    QRect rect = m_allocator.allocate(QSize(image.width() + 2, image.height() + 2));
    if (rect.width() > 0 && rect.height() > 0) {
        Texture *t = new Texture(this, rect, image);
        m_pending_uploads << t;
        return t;
    }
    return 0;
}


int Atlas::textureId() const
{
    if (!m_texture_id) {
        Q_ASSERT(QOpenGLContext::currentContext());
        glGenTextures(1, &const_cast<Atlas *>(this)->m_texture_id);
    }

    return m_texture_id;
}

static void swizzleBGRAToRGBA(QImage *image)
{
    const int width = image->width();
    const int height = image->height();
    uint *p = (uint *) image->bits();
    int stride = image->bytesPerLine() / 4;
    for (int i = 0; i < height; ++i) {
        for (int x = 0; x < width; ++x)
            p[x] = ((p[x] << 16) & 0xff0000) | ((p[x] >> 16) & 0xff) | (p[x] & 0xff00ff00);
        p += stride;
    }
}

void Atlas::upload(Texture *texture)
{
    const QImage &image = texture->image();
    const QRect &r = texture->atlasSubRect();

    QImage tmp(r.width(), r.height(), QImage::Format_ARGB32_Premultiplied);
    {
        QPainter p(&tmp);
        p.setCompositionMode(QPainter::CompositionMode_Source);

        int w = r.width();
        int h = r.height();
        int iw = image.width();
        int ih = image.height();

        p.drawImage(1, 1, image);
        p.drawImage(1, 0, image, 0, 0, iw, 1);
        p.drawImage(1, h - 1, image, 0, ih - 1, iw, 1);
        p.drawImage(0, 1, image, 0, 0, 1, ih);
        p.drawImage(w - 1, 1, image, iw - 1, 0, 1, ih);
        p.drawImage(0, 0, image, 0, 0, 1, 1);
        p.drawImage(0, h - 1, image, 0, ih - 1, 1, 1);
        p.drawImage(w - 1, 0, image, iw - 1, 0, 1, 1);
        p.drawImage(w - 1, h - 1, image, iw - 1, ih - 1, 1, 1);
        if (m_debug_overlay) {
            p.setCompositionMode(QPainter::CompositionMode_SourceAtop);
            p.fillRect(0, 0, iw, ih, QBrush(QColor::fromRgbF(1, 0, 1, 0.5)));
        }
    }

    if (m_externalFormat == GL_RGBA)
        swizzleBGRAToRGBA(&tmp);
    glTexSubImage2D(GL_TEXTURE_2D, 0, r.x(), r.y(), r.width(), r.height(), m_externalFormat, GL_UNSIGNED_BYTE, tmp.constBits());
}

void Atlas::uploadBgra(Texture *texture)
{
    const QRect &r = texture->atlasSubRect();
    QImage image = texture->image();

    if (image.format() != QImage::Format_ARGB32_Premultiplied
            || image.format() != QImage::Format_RGB32) {
        image = image.convertToFormat(QImage::Format_ARGB32_Premultiplied);
    }

    if (m_debug_overlay) {
        QPainter p(&image);
        p.setCompositionMode(QPainter::CompositionMode_SourceAtop);
        p.fillRect(0, 0, image.width(), image.height(), QBrush(QColor::fromRgbF(0, 1, 1, 0.5)));
    }

    QVarLengthArray<quint32, 512> tmpBits(qMax(image.width() + 2, image.height() + 2));
    int iw = image.width();
    int ih = image.height();
    int bpl = image.bytesPerLine() / 4;
    const quint32 *src = (const quint32 *) image.constBits();
    quint32 *dst = tmpBits.data();

    // top row, padding corners
    dst[0] = src[0];
    memcpy(dst + 1, src, iw * sizeof(quint32));
    dst[1 + iw] = src[iw-1];
    glTexSubImage2D(GL_TEXTURE_2D, 0, r.x(), r.y(), iw + 2, 1, m_externalFormat, GL_UNSIGNED_BYTE, dst);

    // bottom row, padded corners
    const quint32 *lastRow = src + bpl * (ih - 1);
    dst[0] = lastRow[0];
    memcpy(dst + 1, lastRow, iw * sizeof(quint32));
    dst[1 + iw] = lastRow[iw-1];
    glTexSubImage2D(GL_TEXTURE_2D, 0, r.x(), r.y() + ih + 1, iw + 2, 1, m_externalFormat, GL_UNSIGNED_BYTE, dst);

    // left column
    for (int i=0; i<ih; ++i)
        dst[i] = src[i * bpl];
    glTexSubImage2D(GL_TEXTURE_2D, 0, r.x(), r.y() + 1, 1, ih, m_externalFormat, GL_UNSIGNED_BYTE, dst);

    // right column
    for (int i=0; i<ih; ++i)
        dst[i] = src[i * bpl + iw - 1];
    glTexSubImage2D(GL_TEXTURE_2D, 0, r.x() + iw + 1, r.y() + 1, 1, ih, m_externalFormat, GL_UNSIGNED_BYTE, dst);

    // Inner part of the image....
    glTexSubImage2D(GL_TEXTURE_2D, 0, r.x() + 1, r.y() + 1, r.width() - 2, r.height() - 2, m_externalFormat, GL_UNSIGNED_BYTE, src);

}

bool Atlas::bind(QSGTexture::Filtering filtering)
{
    bool forceUpdate = false;
    if (!m_allocated) {
        m_allocated = true;

        while (glGetError() != GL_NO_ERROR) ;

        glGenTextures(1, &m_texture_id);
        glBindTexture(GL_TEXTURE_2D, m_texture_id);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
#if !defined(QT_OPENGL_ES_2)
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
#endif
        glTexImage2D(GL_TEXTURE_2D, 0, m_internalFormat, m_size.width(), m_size.height(), 0, m_externalFormat, GL_UNSIGNED_BYTE, 0);

#if 0
        QImage pink(m_size.width(), m_size.height(), QImage::Format_ARGB32_Premultiplied);
        pink.fill(0);
        QPainter p(&pink);
        QLinearGradient redGrad(0, 0, m_size.width(), 0);
        redGrad.setColorAt(0, Qt::black);
        redGrad.setColorAt(1, Qt::red);
        p.fillRect(0, 0, m_size.width(), m_size.height(), redGrad);
        p.setCompositionMode(QPainter::CompositionMode_Plus);
        QLinearGradient blueGrad(0, 0, 0, m_size.height());
        blueGrad.setColorAt(0, Qt::black);
        blueGrad.setColorAt(1, Qt::blue);
        p.fillRect(0, 0, m_size.width(), m_size.height(), blueGrad);
        p.end();

        glTexImage2D(GL_TEXTURE_2D, 0, m_internalFormat, m_size.width(), m_size.height(), 0, m_externalFormat, GL_UNSIGNED_BYTE, pink.constBits());
#endif

        GLenum errorCode = glGetError();
        if (errorCode == GL_OUT_OF_MEMORY) {
            qDebug("QSGTextureAtlas: texture atlas allocation failed, out of memory");
            glDeleteTextures(1, &m_texture_id);
            m_texture_id = 0;
        } else if (errorCode != GL_NO_ERROR) {
            qDebug("QSGTextureAtlas: texture atlas allocation failed, code=%x", errorCode);
            glDeleteTextures(1, &m_texture_id);
            m_texture_id = 0;
        }
        forceUpdate = true;
    } else {
        glBindTexture(GL_TEXTURE_2D, m_texture_id);
    }

    if (m_texture_id == 0)
        return false;

    // Upload all pending images..
    for (int i=0; i<m_pending_uploads.size(); ++i) {

#ifndef QSG_NO_RENDER_TIMING
        bool profileFrames = qsg_render_timing || QQmlProfilerService::enabled;
        if (profileFrames)
            qsg_renderer_timer.start();
#endif

        if (m_externalFormat == GL_BGRA &&
                !m_use_bgra_fallback) {
            uploadBgra(m_pending_uploads.at(i));
        } else {
            upload(m_pending_uploads.at(i));
        }

#ifndef QSG_NO_RENDER_TIMING
        if (qsg_render_timing) {
            printf("   - AtlasTexture(%dx%d), uploaded in %d ms\n",
                   m_pending_uploads.at(i)->image().width(),
                   m_pending_uploads.at(i)->image().height(),
                   (int) (qsg_renderer_timer.elapsed()));
        }

        if (QQmlProfilerService::enabled) {
            QQmlProfilerService::sceneGraphFrame(
                        QQmlProfilerService::SceneGraphTexturePrepare,
                        0,  // bind (not relevant)
                        0,  // convert (not relevant)
                        0,  // swizzle (not relevant)
                        qsg_renderer_timer.nsecsElapsed(), // (upload all of the above)
                        0); // mipmap (not used ever...)
        }
#endif
    }

    if (filtering != m_filtering) {
        GLenum f = filtering == QSGTexture::Nearest ? GL_NEAREST : GL_LINEAR;
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, f);
        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, f);
        m_filtering = filtering;
    }

    m_pending_uploads.clear();

    return forceUpdate;
}

void Atlas::remove(Texture *t)
{
    QRect atlasRect = t->atlasSubRect();
    m_allocator.deallocate(atlasRect);
    m_pending_uploads.removeOne(t);
}



Texture::Texture(Atlas *atlas, const QRect &textureRect, const QImage &image)
    : QSGTexture()
    , m_allocated_rect(textureRect)
    , m_image(image)
    , m_atlas(atlas)
    , m_nonatlas_texture(0)
{
    m_allocated_rect_without_padding = m_allocated_rect.adjusted(1, 1, -1, -1);
    float w = atlas->size().width();
    float h = atlas->size().height();

    m_texture_coords_rect = QRectF(m_allocated_rect_without_padding.x() / w,
                                   m_allocated_rect_without_padding.y() / h,
                                   m_allocated_rect_without_padding.width() / w,
                                   m_allocated_rect_without_padding.height() / h);
}

Texture::~Texture()
{
    m_atlas->remove(this);
    if (m_nonatlas_texture)
        delete m_nonatlas_texture;
}

void Texture::bind()
{
    m_atlas->bind(filtering());
}

QSGTexture *Texture::removedFromAtlas() const
{
    if (!m_nonatlas_texture) {
        m_nonatlas_texture = new QSGPlainTexture();
        m_nonatlas_texture->setImage(m_image);
    }
    return m_nonatlas_texture;
}

}

QT_END_NAMESPACE
