Simplify find_box_for_y()

The new routine is iterative and has simpler logic.

Also add some notes about multirows.

1 files changed, 12 insertions, 22 deletions

diff --git a/region-iter.c b/region-iter.c
index 0d0e2a6..b36ca1b 100644
--- a/region-iter.c
+++ b/region-iter.c
@@ -20,10 +20,15 @@
  *     We will need a subroutine row_iter_skip_to_y() that will skip
  *     to the next row with a y2 > y.
  *
+ *     It may be that the existing row_t type should simply be renamed to
+ *     multi_row_t since it's the same API that we'd want.
+ *
  *   - an iterator that will move backwards through a region and then
  *     one that will move backwards through a row would be useful for
  *     scrolling.
  *
+ *   - test suite
+ *
  */
 #include <stdlib.h>
 #include <stdio.h>
@@ -452,32 +457,17 @@ region_iter_get_row (region_iter_t *iter, row_t *row)
 static pixman_box32_t *
 find_box_for_y (pixman_box32_t *begin, pixman_box32_t *end, int y)
 {
-    pixman_box32_t *mid;
-
-    if (end == begin)
-	return end;
-
-    if (end - begin == 1)
+    while (end - begin > 0)
     {
-	if (begin->y2 > y)
-	    return begin;
+	pixman_box32_t *mid = begin + (end - begin) / 2;
+
+	if (mid->y2 > y)
+	    end = mid;
 	else
-	    return end;
+	    begin = mid + 1;
     }
 
-    mid = begin + (end - begin) / 2;
-    if (mid->y2 > y)
-    {
-	/* If no box is found in [begin, mid], the function
-	 * will return @mid, which is then known to be the
-	 * correct answer.
-	 */
-	return find_box_for_y (begin, mid, y);
-    }
-    else
-    {
-	return find_box_for_y (mid, end, y);
-    }
+    return end;
 }
 
 /* Skips forward to the first row whose y2 > @y */