osd: guard against negative sizes

This fixes the broken look of osd with very small width like:

  osd.window-switcher.width: 1

diff --git a/src/osd.c b/src/osd.c
index 0f230024c4ea8829c70c62d6eb604e24ad1397ef..c78d5929003b70864a6a0575160adad24ad0161a 100644 (file)
--- a/src/osd.c
+++ b/src/osd.c
@@ -301,6 +301,12 @@ create_osd_scene(struct output *output, struct wl_array *views)
 
                /* Center workspace indicator on the x axis */
                int x = (w - font_width(&font, workspace_name)) / 2;
+               if (x < 0) {
+                       wlr_log(WLR_ERROR,
+                               "not enough space for workspace name in osd");
+                       goto error;
+               }
+
                struct scaled_font_buffer *font_buffer =
                        scaled_font_buffer_create(output->osd_scene.tree);
                wlr_scene_node_set_position(&font_buffer->scene_buffer->node,
@@ -312,11 +318,17 @@ create_osd_scene(struct output *output, struct wl_array *views)
        }
 
        struct buf buf = BUF_INIT;
+       int nr_fields = wl_list_length(&rc.window_switcher.fields);
 
        /* This is the width of the area available for text fields */
-       int available_width = w - 2 * theme->osd_border_width
+       int field_widths_sum = w - 2 * theme->osd_border_width
                - 2 * theme->osd_window_switcher_padding
-               - 2 * theme->osd_window_switcher_item_active_border_width;
+               - 2 * theme->osd_window_switcher_item_active_border_width
+               - (nr_fields + 1) * theme->osd_window_switcher_item_padding_x;
+       if (field_widths_sum <= 0) {
+               wlr_log(WLR_ERROR, "Not enough spaces for osd contents");
+               goto error;
+       }
 
        /* Draw text for each node */
        struct view **view;
@@ -347,12 +359,9 @@ create_osd_scene(struct output *output, struct wl_array *views)
                struct wlr_scene_tree *item_root =
                        wlr_scene_tree_create(output->osd_scene.tree);
 
-               int nr_fields = wl_list_length(&rc.window_switcher.fields);
                struct window_switcher_field *field;
                wl_list_for_each(field, &rc.window_switcher.fields, link) {
-                       int field_width = (available_width - (nr_fields + 1)
-                               * theme->osd_window_switcher_item_padding_x)
-                               * field->width / 100.0;
+                       int field_width = field_widths_sum * field->width / 100.0;
                        struct wlr_scene_node *node = NULL;
                        int height = -1;
 
@@ -411,6 +420,7 @@ create_osd_scene(struct output *output, struct wl_array *views)
        }
        buf_reset(&buf);
 
+error:;
        /* Center OSD */
        struct wlr_box usable = output_usable_area_in_layout_coords(output);
        wlr_scene_node_set_position(&output->osd_scene.tree->node,