ImageList with Transparent image for treeview

  • Thread starter Thread starter SQACSharp
  • Start date Start date
S

SQACSharp

Hi,

I'm trying to do a simple thing since at least 5 hours :(

At runtime I add several icon to an imageList and use it later to fill
a treeview.

When adding the icon to the ImageList the transparency is lost and a
blue background is displayed instead.

Here is some code to explain my problem :

//IconHandle is already set to a valid HICON; the Icon of a wordpad
mainWindow by example
....
Icon AppIcon = new Icon(IconHandle );
Bitmap Bmp = new Bitmap(AppIcon.Width, AppIcon.Height);
Graphics g = Graphics.FromImage(Bmp);
g.DrawImage(Bmp,new Point(0,0)); //This ensure transparency
g.Dispose();
pictureBox1.Image = Bmp; // The image is correctly displayed in a
picturebox
MyImageList.Images.Add(Bmp);
pictureBox2.Image = MyImageList.Images[MyImageList.Images.Count-1];
// The image is INCORRECTLY displayed with a "random" color instead of
the transparency color

Question :
How can I add an image to an imageList and keep the transparency. I
already try almost everyting possible with no luck.

Thanks
 
Setting the imageList to 32bit solve the problem. But this sounds like
a bad idea since the system may not be configured to 32bit. Look like
I will have to track the system config to correctly set the image list
ColorDepth. At least it work now :)
 
Setting the imageList to 32bit solve the problem. But this sounds like
a bad idea since the system may not be configured to 32bit. Look like
I will have to track the system config to correctly set the image list
ColorDepth. At least it work now :)
Click to expand...

In general, the .NET drawing API should work well enough regardless of the
actual current video setting. And if you expect for your transparency to
be preserved, you have to be using a bitmap format that includes
transparency information (e.g. 32-bit ARGB).

You can easily test whether this fails to work under different video
settings; just try your program after you've changed the video settings to
24-bit, 16-bit, etc. The quality of the output may be reduced, but the
transparency should otherwise work fine.

Pete
 
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