url-mode: snapshot screen state when entering URL mode

Previously, we automatically exited URL mode whenever we received data
on the PTY. This was done since we don’t know _what_ has changed on
the screen, and we don’t want to display misleading jump labels.

However, this becomes a problem in curses-like applications that
periodically updates part of the screen. For example, a statusbar with
a clock.

This patch changes this behavior; instead of cancelling URL mode when
receiving PTY data, we snapshot the grid when entering URL mode.

When *rendering*, we use the snapshot:ed grid, while PTY updates
modify the “real” grid.

Snapshot:ing the grid means taking a full/deep copy of the current
grid, including sixel images etc.

Finally, it isn’t necessary to “damage” the entire view
when *entering* URL mode, since we’re at that point the renderer is in
sync with the grid. But we *do* need to damage the entire view when
exiting URL mode, since the grid changes on the “real” grid hasn’t
been tracked by the renderer.

render.c

@@ -2675,6 +2675,12 @@ frame_callback(void *data, struct wl_callback *wl_callback, uint32_t callback_da
     term->render.pending.title = false;
     term->render.pending.urls = false;
 
+    struct grid *original_grid = term->grid;
+    if (urls_mode_is_active(term)) {
+        xassert(term->url_grid_snapshot != NULL);
+        term->grid = term->url_grid_snapshot;
+    }
+
     if (csd && term->window->use_csd == CSD_YES) {
         quirk_weston_csd_on(term);
         render_csd(term);
@@ -2697,6 +2703,8 @@ frame_callback(void *data, struct wl_callback *wl_callback, uint32_t callback_da
         if (it->item.kbd_focus == term)
             ime_update_cursor_rect(&it->item, term);
     }
+
+    term->grid = original_grid;
 }
 
 static void
@@ -3127,6 +3135,12 @@ fdm_hook_refresh_pending_terminals(struct fdm *fdm, void *data)
         term->render.refresh.urls = false;
 
         if (term->window->frame_callback == NULL) {
+            struct grid *original_grid = term->grid;
+            if (urls_mode_is_active(term)) {
+                xassert(term->url_grid_snapshot != NULL);
+                term->grid = term->url_grid_snapshot;
+            }
+
             if (csd && term->window->use_csd == CSD_YES) {
                 quirk_weston_csd_on(term);
                 render_csd(term);
@@ -3145,6 +3159,8 @@ fdm_hook_refresh_pending_terminals(struct fdm *fdm, void *data)
                 if (it->item.kbd_focus == term)
                     ime_update_cursor_rect(&it->item, term);
             }
+
+            term->grid = original_grid;
         } else {
             /* Tells the frame callback to render again */
             term->render.pending.grid |= grid;

terminal.c

@@ -227,8 +227,6 @@ fdm_ptmx(struct fdm *fdm, int fd, int events, void *data)
         cursor_blink_rearm_timer(term);
     }
 
-    urls_reset(term);
-
     uint8_t buf[24 * 1024];
     ssize_t count = sizeof(buf);
 

terminal.h

@@ -547,9 +547,11 @@ struct terminal {
         unsigned max_height;    /* Maximum image height, in pixels */
     } sixel;
 
+    /* TODO: wrap in a struct */
     url_list_t urls;
     wchar_t url_keys[5];
     bool urls_show_uri_on_jump_label;
+    struct grid *url_grid_snapshot;
 
 #if defined(FOOT_IME_ENABLED) && FOOT_IME_ENABLED
     struct {

url-mode.c

@@ -637,6 +637,9 @@ urls_render(struct terminal *term)
         tag_cells_for_url(term, &it->item, true);
     }
 
+    /* Snapshot the current grid */
+    term->url_grid_snapshot = grid_snapshot(term->grid);
+
     render_refresh_urls(term);
     render_refresh(term);
 }
@@ -651,8 +654,15 @@ url_destroy(struct url *url)
 void
 urls_reset(struct terminal *term)
 {
-    if (likely(tll_length(term->urls) == 0))
+    if (likely(tll_length(term->urls) == 0)) {
+        xassert(term->url_grid_snapshot == NULL);
         return;
+    }
+
+    grid_free(term->url_grid_snapshot);
+    free(term->url_grid_snapshot);
+    term->url_grid_snapshot = NULL;
+    term->render.last_cursor.row = NULL;
 
     if (term->window != NULL) {
         tll_foreach(term->window->urls, it) {
@@ -669,5 +679,7 @@ urls_reset(struct terminal *term)
 
     term->urls_show_uri_on_jump_label = false;
     memset(term->url_keys, 0, sizeof(term->url_keys));
+
+    term_damage_view(term);
     render_refresh(term);
 }