Gnome extension development, how to draw a border like when pressing Alt+esc

mr-sour · August 18, 2020, 5:33pm

So I have decided to make a gnome extension that draws a border around all open windows as if border-width: 0px 1px 1px 1px; was set in gtk.css. While that sounds quite boring the plan is to evolve it into a plugin that would allow Qubes os to render colored VM borders.

After going though a bunch of extensions and gnome code I got to the point where I got something working but running get_allocation_box() on the window actors returns a box inconsistently larger then the window so that probably not what I want I’m wondering wheres the code for alt+esc in gnome or what should I be calling to get the height/width of window as you see it on the screen and not the actor object.

Code is here. it’s pretty hacked together, just a experiment at this point.

github.com

mr-sour/gnome-colored-borders/blob/e11048dd6a7ee1323a04148d61591394f98c084c/extension.js#L36

      
        
            actor.continue_paint(paintContext);
            
            
if (!this._pipeline) {
                let color = new Cogl.Color();
                color.init_from_4ub(0xff, 0, 0, 0xc4);
            
            
    this._pipeline = new Cogl.Pipeline(coglContext);
                this._pipeline.set_color(color);
            }
            
            
let alloc = actor.get_allocation_box();
            let width = 4;
            
            
// clockwise order
            framebuffer.draw_rectangle(this._pipeline,
                0, 0, alloc.get_width(), width);
            framebuffer.draw_rectangle(this._pipeline,
                alloc.get_width() - width, width,
                alloc.get_width(), alloc.get_height());
            framebuffer.draw_rectangle(this._pipeline,
                0, alloc.get_height(),

what it looks like

mr-sour · August 18, 2020, 7:51pm

I think I see my issue. I’m looking at the clutter api and not mutter. I’m going to use actor.get_meta_window() to get the window and play around with the stuff in there to get the coordinates I need.

fmuellner · August 19, 2020, 10:37am

In case you haven’t found it yet, this is the code of the AltEsc outline.

What you want is MetaWindow’s get_frame_rect() method, which gives you the extents of the visible window (without shadows or invisible borders).

mr-sour · August 28, 2020, 5:55pm

Thanks, That was what I ended up using. I have since decided to evolve it to try and add a GTK css provider to the windows so I can take advantage of GTK’s css classes much like how the GTK inspector works. https://gitlab.gnome.org/GNOME/gtk/-/blob/master/gtk/inspector/css-editor.c#L267

system · September 11, 2020, 5:57pm

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