Hi, there are a couple of patches pending in Bugzilla that add previews to some of our plug-ins. In particular these are: http://bugzilla.gnome.org/show_bug.cgi?id=140974 http://bugzilla.gnome.org/show_bug.cgi?id=142318 http://bugzilla.gnome.org/show_bug.cgi?id=142587 If you take a look at these bug-reports you will notice that there's quite some confusion on how a preview should best be implemented. I'd like to settle on one way before accepting these patches and I think we need to come to a decision here soon so that more plug-ins can get a preview added for gimp-2.2. There seem to be a couple of options. Let me try to summarize the ones that I see: - Use GtkPreview. GtkPreview is declared deprecated by the GTK+ team and we will want to get rid of it at some point. On the other hand there isn't really a good reason not to use it. The API does it's job w/o and I never understood why it as deprecated in the first place. - Use a drawing area and draw from the expose event. This seems to be asked too much for a plug-in developer and it would duplicate even more code. IMHO not an option. - Use a GdkPixbuf as the pixel buffer and use a GtkImage to display it. The disadvantage is that the GdkPixbuf and GtkImage API are not too well suited for our needs. GdkPixbuf doesn't handle greyscale buffers and GtkImage can only display the full pixbuf. If we wanted to show only a region of the buffer we could work around this using gdk_pixbuf_new_subpixbuf() but IMHO this is becoming too hackish to consider it. - Come up with a full-featured preview widget. We could use the widget that Ernst Lippe wrote but since there hasn't been any effort so far to discuss it's API again and to get it into CVS I am not sure if it makes sense to wait for this to happen. - Come up with a simple preview widget to replace GtkPreview. We could add a simple GimpPreview to libgimpwidgets and try to design the API so that it o easily replaces GtkPreview An API that isn't too different from the GtkPreview API would make it easy to port plug-ins that currently use GtkPreview to the new widget. o allows to be turned into a full-featured preview widget later o performs some very common tasks like the drawing of the checkerboard for the alpha channel So the question here is what functionality should a simple GimpPreview widget provide and how should the API look like? I will try to come up with a more detailed proposal for a simple GimpPreview widget this weekend. Your feedback will help me to find out what we actually need. Sven PS: I've added Federico to the Cc: because he lately expressed interest in adding a preview to Unsharp Mask (w/o knowing about the patch in Bugzilla).
