// Convert an RGB color value into a pixel using this colormap.
// This assumes that standard colors have already been expanded.
internal XPixel RGBToPixel(Color color)
{
try
{
// Acquire the display lock.
IntPtr display = dpy.Lock();
// Do we already have a cached pixel value for this color?
Object cached = cachedPixels[color];
if (cached != null)
{
return((XPixel)(cached));
}
// Try to allocate the color from the X display server.
XColor xcolor;
int red = color.Red;
int green = color.Green;
int blue = color.Blue;
xcolor.pixel = XPixel.Zero;
xcolor.red = (ushort)(red << 8);
xcolor.green = (ushort)(green << 8);
xcolor.blue = (ushort)(blue << 8);
xcolor.flags =
(sbyte)(XColor.DoRed | XColor.DoGreen | XColor.DoBlue);
xcolor.pad = (sbyte)0;
if (Xlib.XAllocColor(display, colormap, ref xcolor) != 0)
{
// Cache the value for next time.
cachedPixels[color] = xcolor.pixel;
return(xcolor.pixel);
}
// TODO: do a closest color match for the color.
// Last ditch: return black or white depending upon
// the intensity of the color.
if (((color.Red * 54 + color.Green * 183 +
color.Blue * 19) / 256) < 128)
{
return(Xlib.XBlackPixelOfScreen(screen.screen));
}
else
{
return(Xlib.XWhitePixelOfScreen(screen.screen));
}
}
finally
{
dpy.Unlock();
}
}
private ulong GetPixelByName(string name)
{
var screen = Xlib.XDefaultScreen(this.display);
XColor color = new XColor();
if (0 == Xlib.XParseColor(this.display, Xlib.XDefaultColormap(this.display, screen), name, ref color))
{
Log.Error($"Invalid Color {name}");
}
if (0 == Xlib.XAllocColor(this.display, Xlib.XDefaultColormap(this.display, screen), ref color))
{
Log.Error($"Failed to allocate color {name}");
}
return(color.pixel);
}
