/// <summary>
/// Copy this GraphicsSurface color buffer into a buffer.
/// </summary>
/// <param name="ctx">
/// A <see cref="GraphicsContext"/> which is bound to this GraphicsSurface.
/// </param>
/// <param name="rBuffer">
/// A <see cref="ReadBufferMode"/> that specify the read buffer where the colors are read from.
/// </param>
/// <param name="x">
/// A <see cref="Int32"/> that specify the x coordinate of the lower left corder of the rectangle area to read.
/// </param>
/// <param name="y">
/// A <see cref="Int32"/> that specify the y coordinate of the lower left corder of the rectangle area to read.
/// </param>
/// <param name="texture">
/// A <see cref="Texture"/> that will hold the buffer data.
/// </param>
/// <param name="level">
/// The level of the texture <paramref name="texture"/> to be written.
/// </param>
/// <returns>
/// It returns an <see cref="Image"/> representing the current read buffer <paramref name="rBuffer"/>.
/// </returns>
protected void CopyBuffer(GraphicsContext ctx, ReadBufferMode rBuffer, uint x, uint y, ref Texture texture, uint level)
{
if (texture == null)
{
throw new ArgumentNullException("texture");
}
if (texture.Exists(ctx) == false)
{
throw new ArgumentException("not exists", "texture");
}
if ((x + texture.Width > Width) || (y + texture.Height > Height))
{
throw new ArgumentException("specified region lies outside the GraphicsSurface");
}
// Bind for reading
BindRead(ctx);
// Set for reading
Gl.ReadBuffer(rBuffer);
// Copy pixels from read buffer to texture
Gl.CopyTexImage2D(texture.TextureTarget, (int)level, Pixel.GetGlInternalFormat(texture.PixelLayout, ctx), (int)x, (int)y, (int)texture.Width, (int)texture.Height, 0);
// Unbind from reading
UnbindRead(ctx);
// Reset read configuration
Gl.ReadBuffer(Gl.NONE);
}