/// <summary> Initialize local ressources for all constructors. </summary>
        /// <param name="bmp"> The bitmap associated with this graphic. <see cref="Bitmap"/> </param>
        private void InitializeGraphicRessources(Bitmap bmp)
        {
            IntPtr visual = X11lib.XDefaultVisual(_display, _screenNumber);

            if (visual == IntPtr.Zero)
            {
                throw new OperationCanceledException("Failed to investigate default visual.");
            }

            _width  = bmp.Width;
            _height = bmp.Height;

            // Prepare bitmap conversion.
            int colorPixelBytes = 4;
            int maskLineBytes   = (int)((_width + (int)IMAGE_PADDING - 1) / (int)IMAGE_PADDING);

            _graphicDepth = (int)X11lib.XDefaultDepth(_display, _screenNumber);
            if (_graphicDepth > 16)
            {
                colorPixelBytes = 4;
            }
            else if (_graphicDepth > 8)
            {
                colorPixelBytes = 2;
            }
            else
            {
                colorPixelBytes = 1;
            }

            // ### Allocate bitmap conversion data.
            // The bitmap color data. Use a temporary managed byte array for speed.
            byte[] graphicData = new byte[_height * _width * colorPixelBytes];
            // The bitmap transparency data. Use a temporary managed byte array for speed.
            byte[] maskData = new byte[_height * maskLineBytes];
            // Quick access to current line's color pixel.
            int graphicPixelIndex = 0;
            // Quick access to current line's mask pixel.
            int maskPixelIndex = 0;
            // Reduce slow calls to bmp.GetPixel (x,y).
            Color pixelColor = Color.Black;
            // Determine whether transparency is required.
            bool transparency = false;

            // ### Convert bitmap.
            for (int y = 0; y < _height; y++)
            {
                for (int x = 0; x < _width; x++)
                {
                    graphicPixelIndex = (y * _width + x) << 2;
                    maskPixelIndex    = y * maskLineBytes + (x >> 3);
                    pixelColor        = bmp.GetPixel(x, y);

                    graphicData[graphicPixelIndex + 0] = pixelColor.B;                     // B
                    graphicData[graphicPixelIndex + 1] = pixelColor.G;                     // G
                    graphicData[graphicPixelIndex + 2] = pixelColor.R;                     // R
                    graphicData[graphicPixelIndex + 3] = pixelColor.A;                     // A

                    if (pixelColor.B == 255 && pixelColor.G == 255 && pixelColor.R == 255)
                    {
                        byte summand = (byte)(1 << (x % 8));
                        maskData[maskPixelIndex] = (byte)(maskData[maskPixelIndex] + summand);
                        transparency             = true;
                    }
                }
            }

            // ### Create XImage.
            // The bitmap color data.
            IntPtr graphicDataHandle = Marshal.AllocHGlobal(graphicData.Length);

            // Allocate not movable memory.
            Marshal.Copy(graphicData, 0, graphicDataHandle, graphicData.Length);
            // Client side XImage storage.
            _graphicXImage = X11lib.XCreateImage(_display, visual, (TUint)_graphicDepth,
                                                 X11lib.TImageFormat.ZPixmap, (TInt)0,
                                                 graphicDataHandle, (TUint)_width, (TUint)_height,
                                                 IMAGE_PADDING, ASSUME_CONTIGUOUS);
            if (_graphicXImage == IntPtr.Zero)
            {
                throw new OperationCanceledException("Image creation for graphic failed.");
            }

            if (transparency == true)
            {
                IntPtr maskDataHandle = Marshal.AllocHGlobal(maskData.Length);                                          // The bitmap bitmap transparency data.
                Marshal.Copy(maskData, 0, maskDataHandle, maskData.Length);                                             // Allocate not movable memory.
                // Client side storage.
                _transpXImage = X11lib.XCreateImage(_display, visual, (TUint)_clipDepth, X11lib.TImageFormat.XYBitmap, (TInt)0,
                                                    maskDataHandle, (TUint)_width, (TUint)_height, IMAGE_PADDING, ASSUME_CONTIGUOUS);
                if (_transpXImage == IntPtr.Zero)
                {
                    throw new OperationCanceledException("Image creation for transparency mask failed.");
                }
            }
        }