The blend mode to be used when transparency is in use.

The BlendMode enumeration may take the following values:

• Normal - Normal.
• Multiply - Multiply source and backdrop colors.
• Screen - Multiply complements of souurce and backdrop colors and then complement the output.
• Overlay - Multiplies of screens depending on backdrop.
• Darken - Minimum of source and backdrop.
• Lighten - Maximum of source and backdrop.
• ColorDodge - Brightens the backdrop.
• ColorBurn - Darkens the backdrop.
• HardLight - Like shining a spotlight on the backrop.
• SoftLight - Like shining a light on the backrop.
• Difference - Finds the difference between th colors.
• Exclusion - A lower contrast difference.
• Hue - Hue of source, saturation and luminescence of backdrop.
• Saturation - Saturation of source, hue and luminescence of backdrop.
• Color - Hue and saturation of source, luminescence of backdrop.
• Luminosity - Luminosity of source, hue and saturation of backdrop.