This is the Dtk_Preview class.

A Dtk_Preview is a Thumbnail image that may exist in a CAD file.
A Dtk_Preview contains Stream representing picture data This class lets you use Dtk_Preview.

See also: Use Dtk_PreviewPtr class to handle it.

You can get a preview for a Dtk_Component and/or Dtk_Node.
Using Dtk_Component::GetPreview() method retrieves the model preview.
Using Dtk_Node::GetPreview() method retrieves the node preview (for example a drawing type node).

Dtk_PreviewPtr TmpPreview = inComponent->GetPreview();
if (TmpPreview.IsNotNULL())
{
    Dtk_Int32 size = TmpPreview->GetStreamSize();
    char *jpgimage = TmpPreview->GetStream();
    Dtk_string Preview_name = "Preview.jpg";
    FILE *jpg = Preview_name.OpenFile("wb");
    if (jpg)
    {
        fwrite(jpgimage,sizeof(char),size,jpg);
        fclose(jpg);
    }
}