Document.SavePreviewMode Property (Visio)
Determines whether and how a preview picture is saved in a file. Read/write.
The value of the SavePreviewMode property corresponds to the Save preview picture setting on the Summary tab of the Properties dialog box. (Click the File tab, click Info, click Properties, and then click Advanced Properties.) A preview of the first page appears in the Open dialog box. The value of SavePreviewMode can be one of the following VisSavePreviewMode constants. Selecting the Save preview mode checkbox is equivalent to setting the SavePreviewMode property to visSavePreviewDraft1st, which is the default.
No preview picture.
The first page; includes only Visio shapes. Does not include embedded objects, text, or gradient fills.
The first page; includes all objects.