quirks: sway does not damage surface beneath sub-surface, when unmapped

When unmapping a sub-surface, Sway <= 1.8 does not damage the surface
beneath the sub-surface.

https://github.com/swaywm/sway/issues/6960

The workaround is to manually damage the main surface. Previously,
this was done when exiting scrollback search, and after the ‘flash’
OSC. But other sub-surfaces, that may also be unmapped, did not.

This patch adds a quirk handler that does this, and calls it when:

* Exiting scrollback search
* Ending the ‘flash’ OSC
* Exiting unicode input mode
* Clearing URL labels
* Removing the scrollback position indicator

Closes #1335

quirks.c

@@ -66,3 +66,28 @@ quirk_weston_csd_off(struct terminal *term)
     for (int i = 0; i < ALEN(term->window->csd.surface); i++)
         quirk_weston_subsurface_desync_off(term->window->csd.surface[i].sub);
 }
+
+static bool
+is_sway(void)
+{
+    static bool is_sway = false;
+    static bool initialized = false;
+
+    if (!initialized) {
+        initialized = true;
+        is_sway = getenv("SWAYSOCK") != NULL;
+        if (is_sway)
+            LOG_WARN("applying wl_surface_damage_buffer() workaround for Sway");
+    }
+
+    return is_sway;
+}
+
+void
+quirk_sway_subsurface_unmap(struct terminal *term)
+{
+    if (!is_sway())
+        return;
+
+    wl_surface_damage_buffer(term->window->surface, 0, 0, INT32_MAX, INT32_MAX);
+}

quirks.h

@@ -21,3 +21,5 @@ void quirk_weston_subsurface_desync_off(struct wl_subsurface *sub);
 /* Shortcuts to call desync_{on,off} on all CSD subsurfaces */
 void quirk_weston_csd_on(struct terminal *term);
 void quirk_weston_csd_off(struct terminal *term);
+
+void quirk_sway_subsurface_unmap(struct terminal *term);

render.c

@@ -1527,6 +1527,10 @@ render_overlay(struct terminal *term)
             wl_surface_commit(overlay->surf);
             term->render.last_overlay_style = OVERLAY_NONE;
             term->render.last_overlay_buf = NULL;
+
+            /* Work around Sway bug - unmapping a sub-surface does not
+             * damage the underlying surface */
+            quirk_sway_subsurface_unmap(term);
         }
         return;
     }
@@ -2374,8 +2378,13 @@ render_scrollback_position(struct terminal *term)
     struct wl_window *win = term->window;
 
     if (term->grid->view == term->grid->offset) {
-        if (win->scrollback_indicator.surf != NULL)
+        if (win->scrollback_indicator.surf != NULL) {
             wayl_win_subsurface_destroy(&win->scrollback_indicator);
+
+            /* Work around Sway bug - unmapping a sub-surface does not damage
+             * the underlying surface */
+            quirk_sway_subsurface_unmap(term);
+        }
         return;
     }
 

search.c

@@ -15,6 +15,7 @@
 #include "input.h"
 #include "key-binding.h"
 #include "misc.h"
+#include "quirks.h"
 #include "render.h"
 #include "selection.h"
 #include "shm.h"
@@ -117,11 +118,6 @@ search_cancel_keep_selection(struct terminal *term)
 
     term_xcursor_update(term);
     render_refresh(term);
-
-    /* Work around Sway bug - unmapping a sub-surface does not damage
-     * the underlying surface */
-    term_damage_margins(term);
-    term_damage_view(term);
 }
 
 void

terminal.c

@@ -406,11 +406,6 @@ fdm_flash(struct fdm *fdm, int fd, int events, void *data)
 
     term->flash.active = false;
     render_refresh(term);
-
-    /* Work around Sway bug - unmapping a sub-surface does not damage
-     * the underlying surface */
-    term_damage_margins(term);
-    term_damage_view(term);
     return true;
 }
 

url-mode.c

@@ -14,6 +14,7 @@
 #include "char32.h"
 #include "grid.h"
 #include "key-binding.h"
+#include "quirks.h"
 #include "render.h"
 #include "selection.h"
 #include "spawn.h"
@@ -859,6 +860,10 @@ urls_reset(struct terminal *term)
         tll_foreach(term->window->urls, it) {
             wayl_win_subsurface_destroy(&it->item.surf);
             tll_remove(term->window->urls, it);
+
+            /* Work around Sway bug - unmapping a sub-surface does not
+             * damage the underlying surface */
+            quirk_sway_subsurface_unmap(term);
         }
     }