i3 - improved tiling WM

i3bar: suspend the child when bars are fully obscured

Patch status: needinfo

Patch by Alexander Monakov

To apply this patch, use:
curl http://cr.i3wm.org/patch/701/raw.patch | git am

b/i3bar/include/outputs.h

14 
@@ -40,6 +40,7 @@ struct i3_output {
15 
     char* name;   /* Name of the output */
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     bool active;  /* If the output is active */
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     bool primary; /* If it is the primary output */
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+    bool visible; /* If the bar is visible on this output */
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     int ws;       /* The number of the currently visible ws */
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     rect rect;    /* The rect (relative to the root-win) */
21

b/i3bar/src/xcb.c

26 
@@ -482,6 +482,37 @@ void handle_button(xcb_button_press_event_t *event) {
27 
 }
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 /*
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+ * Handle visibility notifications: when none of the bars are visible, e.g.
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+ * if windows are in full-screen on each output, suspend the child process.
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+ *
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+ */
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+static void handle_visibility_notify(xcb_visibility_notify_event_t *event) {
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+    bool visible = (event->state != XCB_VISIBILITY_FULLY_OBSCURED);
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+    int num_visible = 0;
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+    i3_output *output;
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+
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+    SLIST_FOREACH (output, outputs, slist) {
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+        if (!output->active) {
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+            continue;
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+        }
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+        if (output->bar == event->window) {
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+            if (output->visible == visible) {
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+                return;
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+            }
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+            output->visible = visible;
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+        }
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+        num_visible += output->visible;
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+    }
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+
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+    if (num_visible == 0) {
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+        stop_child();
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+    } else if (num_visible == visible) {
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+        /* Wake the child only when transitioning from 0 to 1 visible bar */
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+        cont_child();
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+    }
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+}
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+
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+/*
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  * Adjusts the size of the tray window and alignment of the tray clients by
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  * configuring their respective x coordinates. To be called when mapping or
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  * unmapping a tray client window.
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@@ -945,6 +976,10 @@ void xcb_chk_cb(struct ev_loop *loop, ev_check *watcher, int revents) {
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         }
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         switch (type) {
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+            case XCB_VISIBILITY_NOTIFY:
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+                /* Visibility change: a bar is [un]obscured by other window */
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+                handle_visibility_notify((xcb_visibility_notify_event_t *)event);
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+                break;
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             case XCB_EXPOSE:
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                 /* Expose-events happen, when the window needs to be redrawn */
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                 redraw_bars();
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@@ -1461,6 +1496,12 @@ void reconfig_windows(bool redraw_bars) {
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              * */
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             values[2] = XCB_EVENT_MASK_EXPOSURE |
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                         XCB_EVENT_MASK_SUBSTRUCTURE_REDIRECT;
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+            if (config.hide_on_modifier == M_DOCK) {
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+                /* If the bar is normally visible, catch visibility change events to suspend
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+                 * the status process when the bar is obscured by full-screened windows.  */
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+                values[2] |= XCB_EVENT_MASK_VISIBILITY_CHANGE;
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+                walk->visible = true;
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+            }
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             if (!config.disable_ws) {
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                 values[2] |= XCB_EVENT_MASK_BUTTON_PRESS;
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             }