Trying to add transparent text with TextRenderer.DrawText to a bitmap image

Question

I'm actually trying to add some text to an image in C# with

System.Windows.Forms.TextRenderer.DrawText(Graphics, string, Rectangle, Color, TextFormaFlags)

I prepare my image (which is a png) by loading it in memory, with something similar to

Image image = ImageCache.Get(...);
bitmap = new Bitmap(image);
graphic = Graphics.FromImage(bitmap);

I then draw my text with the above command. The problem is that whatever I use for the color, even something like

System.Drawing.Color.FromArgb(0,255,255,255)

the transparency is not drawn. I tried many settings for

graphics.TextRenderingHint

and different combinations of fonts, transparency level, etc. Is there something I don't understand here? Any hint is appreciated.

Thank you.

Use `Color.Transparent` as `BackColor` or use `Graphics.DrawString`. See: [TextRenderer.DrawText in Bitmap vs OnPaintBackground](http://stackoverflow.com/q/849531/880990) — Olivier Jacot-Descombes, Feb 09 '16 at 20:57
If you want alpha blending effects then you must use Graphics.DrawString(), TextRenderer uses GDI which is limited to RGB. — Hans Passant, Feb 09 '16 at 21:11
@Hans Passant Well, not the answer I wanted to hear, but good to know. If you put it as a formal answer, I'll accept it. — Bene Tleilax, Feb 09 '16 at 21:18
I avoid posting answers that nobody wants to hear. You can post it yourself and accept it. — Hans Passant, Feb 09 '16 at 21:20

score 2 · Accepted Answer · answered Feb 10 '16 at 14:36

As mentionned in the comments : if you try to draw transparent text with

System.Windows.Forms.TextRenderer.DrawText

because you look for the advantages brought by GDI in C#, you just can't. Use

System.Drawing.Graphics.DrawString

instead, even if the result for the word-wrapping is slightly inferior with GDI+.

1 Answers1