Method copyToImage

src/SFML/Graphics/Texture.cpp:451–547

///////////////////////////////////////////////////////

////////////////////////////////////////////////////////////
Image Texture::copyToImage() const
{
    // Easy case: empty texture
    if (!m_texture)
        return {};

    const TransientContextLock lock;

    // Make sure that the current texture binding will be preserved
    const priv::TextureSaver save;

    // Create an array of pixels
    std::vector<std::uint8_t> pixels(m_size.x * m_size.y * 4);

#ifdef SFML_OPENGL_ES

    // OpenGL ES doesn't have the glGetTexImage function, the only way to read
    // from a texture is to bind it to a FBO and use glReadPixels
    GLuint frameBuffer = 0;
    glCheck(GLEXT_glGenFramebuffers(1, &frameBuffer));
    if (frameBuffer)
    {
        GLint previousFrameBuffer = 0;
        glCheck(glGetIntegerv(GLEXT_GL_FRAMEBUFFER_BINDING, &previousFrameBuffer));

        glCheck(GLEXT_glBindFramebuffer(GLEXT_GL_FRAMEBUFFER, frameBuffer));
        glCheck(GLEXT_glFramebufferTexture2D(GLEXT_GL_FRAMEBUFFER, GLEXT_GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, m_texture, 0));
        glCheck(glReadPixels(0,
                             0,
                             static_cast<GLsizei>(m_size.x),
                             static_cast<GLsizei>(m_size.y),
                             GL_RGBA,
                             GL_UNSIGNED_BYTE,
                             pixels.data()));
        glCheck(GLEXT_glDeleteFramebuffers(1, &frameBuffer));

        glCheck(GLEXT_glBindFramebuffer(GLEXT_GL_FRAMEBUFFER, static_cast<GLuint>(previousFrameBuffer)));

        if (m_pixelsFlipped)
        {
            // Flip the texture vertically
            const auto stride             = static_cast<std::ptrdiff_t>(m_size.x * 4);
            auto       currentRowIterator = pixels.begin();
            auto       nextRowIterator    = pixels.begin() + stride;
            auto       reverseRowIterator = pixels.begin() + (stride * static_cast<std::ptrdiff_t>(m_size.y - 1));
            for (unsigned int i = 0; i < m_size.y / 2; ++i)
            {
                std::swap_ranges(currentRowIterator, nextRowIterator, reverseRowIterator);
                currentRowIterator = nextRowIterator;
                nextRowIterator += stride;
                reverseRowIterator -= stride;
            }
        }
    }

#else

    if ((m_size == m_actualSize) && !m_pixelsFlipped)