thank you all, I now like this mailing list officially. I had it working before with Marteen's help but now it seems like I got an idea for some extra features :) 2011/7/25 richard boaz <ivor.boaz@xxxxxxxxx>: > hi, > i do this same sort of thing in my stuff, but written before cairo was. i > plan on converting all my drawing to cairo one day, thus must eventually > solve this problem myself. so i took your original sample/example and > expanded on it to demonstrate pixmap backing stores and how to use/reference > them when wanting to "undo" things relating to drawing areas. > attached is the same sample, but with the following mods/additions: > > configure and expose events added to handle drawing area > Draw and Undo buttons added > drawing on the canvas can only happen when clicking the Draw button first > (doable multiple times) > Undo button will loop back (undo) over each drawing command initiated by the > event-motion signal > Resize will clear all saved pixmaps and clear the canvas > > but i deliver this with a huge caveat: i do not like the solution, something > about the design is wrong (i can "feel" it). so, this reference is intended > for demonstration purposes only! i will eventually come back to this and > find the proper architecture, but don't have time at the moment. > it does, however, "work", so it's not completely worthless; the best answer > is in there somewhere. > and just for the record, there really is many, many ways to solve this > problem; you must strive to find the most appropriate solution that > satisfies all the specific requirements of your particular problem, and > sometimes this simply comes down to solving it over and over until the best > solution becomes obvious. > cheers, > richard > > 2011/7/24 Carlos López Camey <c.lopez@xxxxxxxxx> >> >> Hello again, >> >> Let's say I'd like to save a GtkDrawingArea 'screenshot' to a file. >> I'm able to do >> >> cairo_t *cr = gtkDrawingAreaWidget->window; >> cairo_surface_t *screenshot = cairo_get_target(cr); >> cairo_surface_write_to_png(screenshot,"screenshot.png"); >> >> but what this code does is save a screenshot for the *entire window*, >> including other widgets in it (e.g. toolbar). I can't get a cairo >> context for a GtkDrawingArea since it's not GdkDrawable, and it's not >> possible to have child GtkWindow. I've seen >> gtk_widget_set_has_window() but it didn't work, I think because it >> says "This function should only be called by widget implementations". >> Is there a work-around? >> >> What I'm really trying to do: Save my drawing area surface everytime >> it's modified (drawn on it), so I can later do "undos" and set the >> surface source to a previous one. >> >> Thanks, >> Carlos >> _______________________________________________ >> gtk-list mailing list >> gtk-list@xxxxxxxxx >> http://mail.gnome.org/mailman/listinfo/gtk-list > > _______________________________________________ gtk-list mailing list gtk-list@xxxxxxxxx http://mail.gnome.org/mailman/listinfo/gtk-list
