CODEWITHSUNDEEP
c#.netwinforms
Zgrkpnr
Zgrkpnr

Reputation: 1231

Are we able to set opacity of the background image of a panel?

As you know it is possible in WPF. But I have a project in Windows Forms but I don't want to struggle to move project into WPF. So is it possible in Windows Forms? (Unlike asked in another question, I don't ask transparency of a panel. I am asking "If I would use a background image", can I make it half transparent.)

Upvotes: 4

Views: 15372

Answers (2)

LarsTech
LarsTech

Reputation: 81610

You need to try two things: set the BackColor to Transparent and convert the image to something that has opacity.

From Change Opacity of Image in C#:

public Image SetImageOpacity(Image image, float opacity) {
  Bitmap bmp = new Bitmap(image.Width, image.Height);
  using (Graphics g = Graphics.FromImage(bmp)) {
    ColorMatrix matrix = new ColorMatrix();
    matrix.Matrix33 = opacity;
    ImageAttributes attributes = new ImageAttributes();
    attributes.SetColorMatrix(matrix, ColorMatrixFlag.Default,
                                      ColorAdjustType.Bitmap);
    g.DrawImage(image, new Rectangle(0, 0, bmp.Width, bmp.Height),
                       0, 0, image.Width, image.Height,
                       GraphicsUnit.Pixel, attributes);
  }
  return bmp;
}

Then you panel properties would look like this:

panel1.BackColor = Color.Transparent;
panel1.BackgroundImage = SetImageOpacity(backImage, 0.25F);

Upvotes: 8

devmb
devmb

Reputation: 805

Opacity can only work on top-level windows. You can't use opacity on a Panel.

If you only want a picture with opacity i think you can draw it by yourself, like the following example. image is an instance of System.Drawing.Image.

using (Graphics g = Graphics.FromImage(image))
{
    Pen pen = new Pen(Color.FromArgb(alpha, 255, 255, 255), image.Width);
    g.DrawLine(pen, -1, -1, image.Width, image.Height);
    g.Save();
}

EDIT: This article maybe give you any further hints.

Upvotes: 1

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