70002714 Save a drawing as transparent PNG image

Summary

I would like to export a drawing as a PNG image where the background of VDF is transparent. How can I do it?

Solution

You need to render the contents of the drawing you want to a bitmap then set the transparent color or colors and save it to disk, like:

 
private void button1_Click(object sender, EventArgs e)
{
    doc.Open(@"C:\test\test.vdml"); // open a sample file.
    doc.Redraw(true);
    Bitmap bmp = new Bitmap(400,400); // set the image size
    doc.ActiveLayOut.RenderToBitmap(bmp); // render it to the bitmap
    Color backColor = doc.ActiveLayOut.BkColorEx; 
    if (doc.ActiveLayOut.BkColorEx == Color.Empty)
    {
        backColor = doc.Palette.Background; 
    } // get the color of the VDF Background

   try
   {
       Bitmap myBitmap = bmp; 

       // Make backColor transparent for myBitmap.
       myBitmap.MakeTransparent(backColor);
            //  OPTIONALLY, you may make any other  color transparent 
            //  myBitmap.MakeTransparent(MyRedColo);
            //  myBitmap.MakeTransparent(MyGreenColor);
      // Save myBitmap to file.
      myBitmap.Save(@"C:\test\test.png");
   }
   catch
   {
       //check
       //must do something
   }
}

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