- min_layer = _layers - ((bottom - _trackview.y_position()) / c);
- max_layer = _layers - ((top - _trackview.y_position()) / c);
+
+ int const mi = _layers - ((bottom - _trackview.y_position()) / c);
+ if (mi < 0) {
+ min_layer = 0;
+ } else {
+ min_layer = mi;
+ }
+
+ int const ma = _layers - ((top - _trackview.y_position()) / c);
+ if (ma > (int) _layers) {
+ max_layer = _layers - 1;
+ } else {
+ max_layer = ma;
+ }
+