wmf files not conveting correctly

[Guest]

Hi,

I am trying to convert a group of wmf files to gif files. Easy you'd think?

I'm using the following code:

Image img = Image.FromFile (this.tbxFilename.Text);
string filename = this.tbxFilename.Text.Replace ("wmf", "gif");
img.Save (filename, ImageFormat.Gif);

When I look at the gif, the background of it is black, where as in the wmf
it is white (or rather transparent).

I tried setting the trasparency via using a bitmap and that didn't work
(also black is one of the colours on the wmv so I didn't want to loose that
colour).

So how can I do this and are there any third party dlls that will work?

Look at http://www.bitbetter.com/samples/Hiking.wmf for an example, as the
background goes black if you try the code.

Any ideas?

Ian

 

[Kevin Spencer]

You have to set the transparent color of the GIF, as well as the pallette.
The Image class will create a default pallette for the GIF, but you need to
access the pallette to know what color to make transparent.

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
Ambiguity has a certain quality to it.

 

[Guest]

Hi,

the images I'm trying to convert have a transparent border, then have a
drawing in black, pinky beige and white on it.

I tried using GetPixel, and it falsely reported an RGB of (0,0,0) for the
border. I.E. black, which is what it comes out in the converted picture. The
trouble is I need black in the finished image and atm both it and the
transparent areas merge into one. Messing with the palette will make no
difference here I think.

I don't mind if the transparent area of the image comes out as transparent
or white, but appearing as black is definitely wrong.

Thanks for your suggestion though, but I can't try anything suggested till
monday now as I am at home.

Regards,

Ian

 

[Kevin Spencer]

My pleasure. It is important to understand how GIF images do transparency. A
GIF does not support transparency in the same way as many other image
formats. It is an indexed palletted 24-bit (RGB) format, and can only
support one tranparent color, that is, one color that is identified as being
used for a transparent color. In addition, it only supports full
transparency for that one color.

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
Ambiguity has a certain quality to it.