Sanity check gaps on the outside of the workspace

Avoid gaps that are too large around the workspace that you end up
without any usable space for children.

Fixes #4308

1 files changed, 19 insertions, 0 deletions

diff --git a/sway/tree/workspace.c b/sway/tree/workspace.c
index aca35529..d6819c61 100644
--- a/sway/tree/workspace.c
+++ b/sway/tree/workspace.c
@@ -706,6 +706,25 @@ void workspace_add_gaps(struct sway_workspace *ws) {
         ws->current_gaps.bottom = fmax(0, ws->current_gaps.bottom + ws->gaps_inner);
         ws->current_gaps.left = fmax(0, ws->current_gaps.left + ws->gaps_inner);
 
+        // Now that we have the total gaps calculated we may need to clamp them in
+        // case they've made the available area too small
+        if (ws->width - ws->current_gaps.left - ws->current_gaps.right < MIN_SANE_W
+                        && ws->current_gaps.left + ws->current_gaps.right > 0) {
+                int total_gap = fmax(0, ws->width - MIN_SANE_W);
+                double left_gap_frac = ((double)ws->current_gaps.left /
+                        ((double)ws->current_gaps.left + (double)ws->current_gaps.right));
+                ws->current_gaps.left = left_gap_frac * total_gap;
+                ws->current_gaps.right = total_gap - ws->current_gaps.left;
+        }
+        if (ws->height - ws->current_gaps.top - ws->current_gaps.bottom < MIN_SANE_H
+                        && ws->current_gaps.top + ws->current_gaps.bottom > 0) {
+                int total_gap = fmax(0, ws->height - MIN_SANE_H);
+                double top_gap_frac = ((double) ws->current_gaps.top /
+                        ((double)ws->current_gaps.top + (double)ws->current_gaps.bottom));
+                ws->current_gaps.top = top_gap_frac * total_gap;
+                ws->current_gaps.bottom = total_gap - ws->current_gaps.top;
+        }
+
         ws->x += ws->current_gaps.left;
         ws->y += ws->current_gaps.top;
         ws->width -= ws->current_gaps.left + ws->current_gaps.right;