How to make transparent buttons in C#

[AmdUser]

I make my own buttons with pictureBox. They should be round and drag only, and is fine to look to.

But I am unable to transparent device to work. I use MakeTrasparent to make a color transparent. The problem is that color is not transparent, but the same as the background color of the form. Is there something wrong, or have I just misunderstood?

Bitmap b = new Bitmap (recorderButtonPic.Image); 
Color t = b.GetPixel (1, 1); 
b.MakeTransparent (t); 
recorderButtonPic.Image = b;

[sergioKomic]

Do not set this property on Bitmap. Just when you make a Bitmap without an Alpha channel, select a color mask.

Use Form.TransparencyKey instead.

[AmdUser]

Is it the way you think:

Bitmap b = new Bitmap (recorderButtonPic.Image); 
b.MakeTransparent (TPC.ActiveForm.TransparencyKey); 
recorderButtonPic.Image = b;

Isn't that the same.

[sergioKomic]

You made a mistake my friend. This will give an error.

TCP.ActiveForm.TransparencyKey = Color.Magenta

Afterwards, you can draw the shape, just set Image property of the Bitmap you have made.

You can change TCP.ActiveForm.TransparencyKey to [Bitmap].GetPixel (0, 0) if you wish.

MakeTransparent is to set a transparent color on a bitmap, that you do not need to do in this case.

[AmdUser]

So is that correct now:

Form.ActiveForm.TransparencyKey = Form.ActiveForm.BackColor;

Unfortunately it gives an exception:

Cross-thread operation not valid: Control '' accessed from a thread other than the thread it was created on.

[sergioKomic]

Choose the form in the editor, and select TransparencyKey property, and select Color.Control instead. If that does not help to put PictureBox.BackColor to Color.Transparent, you must declare a separate class:

class MyTransparentPictureBox : PictureBox 
{
public override CreateParams CreateParams 
{
get {CreateParam param = base.CreateParams; param.ExStyle | = 0x00000020; return param;}
}
}