Question

var bmp = new Bitmap(16, 16);
var gBmp = System.Drawing.Graphics.FromImage(bmp );
Color col = Color.FromArgb(pdmsCol.Red, pdmsCol.Green, pdmsCol.Blue);
gBmp.FillRectangle(new SolidBrush(col), new Rectangle(0, 0, 16, 16));
mColourPopupContainer.Image = bmp;

Using the above code draws a rectangle into my control for given color. This works fine unless the color is Magenta in which case it seems to be drawn transparently. I guess this is something to do with bitmaps treating Magenta as transparent. How to I turn off this behaviour?

mColourPopupContainer is a UserControl (custom color picker).

Answer 1

My current solution is not very nice: Detect when magenta is used and change it to not magenta.

      var col = Color.FromArgb(r, g, b);
      if (r==255 && g==0 && b==255 ) col = Color.FromArgb(r-1, g, b); // Don't use Megenta as it can be treated as transparent