selection: on_row_in_view() -> on_rows_in_view(), and now takes a range

This allows us to check the selection once when scrolling, instead of
once for each scrolled in line.

selection.c

@@ -30,17 +30,37 @@ selection_enabled(const struct terminal *term)
 }
 
 bool
-selection_on_row_in_view(const struct terminal *term, int row_no)
+selection_on_rows_in_view(const struct terminal *term, int row_start, int row_end)
 {
+    LOG_DBG("selection: %d-%d, range: %d-%d (view=%d)",
+            term->selection.start.row, term->selection.end.row,
+            row_start, row_end, term->grid->view);
+
     if (term->selection.start.row == -1 || term->selection.end.row == -1)
         return false;
 
     const struct coord *start = &term->selection.start;
     const struct coord *end = &term->selection.end;
-    assert(start->row <= end->row);
 
-    row_no += term->grid->view;
+    if (start->row > end->row) {
-    return row_no >= start->row && row_no <= end->row;
+        const struct coord *tmp = start;
+        start = end;
+        end = tmp;
+    }
+
+    row_start += term->grid->view;
+    row_end += term->grid->view;
+
+    if (row_start <= start->row && row_end >= end->row) {
+        /* Row range completely encompases the selection */
+        return true;
+    }
+
+    else if (row_start >= start->row || row_end <= end->row)
+        return true;
+
+    else
+        return false;
 }
 
 static void

selection.h

@@ -16,7 +16,7 @@ void selection_finalize(struct terminal *term, uint32_t serial);
 void selection_cancel(struct terminal *term);
 void selection_extend(struct terminal *term, int col, int row, uint32_t serial);
 
-bool selection_on_row_in_view(const struct terminal *term, int row_no);
+bool selection_on_rows_in_view(const struct terminal *term, int start, int end);
 
 void selection_mark_word(struct terminal *term, int col, int row,
                          bool spaces_only, uint32_t serial);

terminal.c

@@ -1750,13 +1750,14 @@ term_scroll_partial(struct terminal *term, struct scroll_region region, int rows
     for (int i = term->rows - 1; i >= region.end; i--)
         grid_swap_row(term->grid, i - rows, i, false);
 
+    const int begin_scrolled_in = max(region.end - rows, region.start);
+
     /* Erase scrolled in lines */
-    for (int r = max(region.end - rows, region.start); r < region.end; r++) {
+    for (int r = begin_scrolled_in; r < region.end; r++)
         erase_line(term, grid_row_and_alloc(term->grid, r));
-        //sixel_delete_at_row(term, r);
+
-        if (selection_on_row_in_view(term, r))
+    if (selection_on_rows_in_view(term, begin_scrolled_in, region.end - 1))
-            selection_cancel(term);
+        selection_cancel(term);
-    }
 
     sixel_delete_in_range(term, max(region.end - rows, region.start), region.end - 1);
     term_damage_scroll(term, DAMAGE_SCROLL, region, rows);
@@ -1803,13 +1804,14 @@ term_scroll_reverse_partial(struct terminal *term,
     for (int i = 0 + rows; i < region.start + rows; i++)
         grid_swap_row(term->grid, i, i - rows, false);
 
+    const int end_scrolled_in = min(region.start + rows, region.end);
+
     /* Erase scrolled in lines */
-    for (int r = region.start; r < min(region.start + rows, region.end); r++) {
+    for (int r = region.start; r < end_scrolled_in; r++)
         erase_line(term, grid_row_and_alloc(term->grid, r));
-        //sixel_delete_at_row(term, r);
+
-        if (selection_on_row_in_view(term, r))
+    if (selection_on_rows_in_view(term, region.start, end_scrolled_in - 1))
-            selection_cancel(term);
+        selection_cancel(term);
-    }
 
     sixel_delete_in_range(term, region.start, min(region.start + rows, region.end) - 1);
     term_damage_scroll(term, DAMAGE_SCROLL_REVERSE, region, rows);