CODEWITHSUNDEEP
cgtkcairo
Josh Wang
Josh Wang

Reputation: 531

Save the contents of a gtk_drawing_area or Cairo pattern to an image on disk

How do you save the contents of a gtk_drawing_area or cairo context to disk?

similar to this (Python) question: Save the contents of a Gtk.DrawingArea or Cairo pattern to an image on disk

but in C.

Upvotes: 1

Views: 396

Answers (1)

andlabs
andlabs

Reputation: 11588

The Python code you linked doesn't seem to do anything different from what a C program would do; you would just need to look up the equivalent C methods, like gdk_pixbuf_savev().

However, because your original question said cairo pattern*, I supposed you deduced that since you write the implementation of the GtkDrawingArea draw signal handler, you could reuse that code to draw to an image. You're correct.

In that case, you would first create an image surface and then a cairo_t from that surface. Pass that to your drawing function, and then you can save the surface to a PNG. Here's an example (from the Pango documentation).

Of course, this assumes your draw handler is written such that it doesn't use either the GtkDrawingArea or the data parameter. If it does, you'll need to split the actual drawing logic out. Either way, hope that helps!

*I'm assuming you meant cairo context or cairo surface. A pattern is just a definition for how a drawing operation draws; saving that to an image is somewhat meaningless. (You can create patterns out of images, yes, but that still doesn't mean much for saving.)

Upvotes: 1

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