From 23390794cdadaa5d83d1ccc4a61d12ef6c4fdb93 Mon Sep 17 00:00:00 2001
From: Matthias Clasen <mclasen@redhat.com>
Date: Sun, 4 Mar 2012 17:19:16 -0500
Subject: [PATCH] grid: Work harder for tight homogeneous allocation

When doing homogeneous allocation in the presence of
overlapping spanning children, we need to avoid uneven
line allocations, otherwise, the final homogenization
will blow up the size request of the grid.

https://bugzilla.gnome.org/show_bug.cgi?id=671170
---
 gtk/gtkgrid.c | 71 ++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 53 insertions(+), 18 deletions(-)

diff --git a/gtk/gtkgrid.c b/gtk/gtkgrid.c
index 78ae2ffcc7..475d938cc2 100644
--- a/gtk/gtkgrid.c
+++ b/gtk/gtkgrid.c
@@ -772,37 +772,72 @@ gtk_grid_request_spanning (GtkGridRequest *request,
       /* If we need to request more space for this child to fill
        * its requisition, then divide up the needed space amongst the
        * lines it spans, favoring expandable lines if any.
+       *
+       * When doing homogeneous allocation though, try to keep the
+       * line allocations even, since we're going to force them to
+       * be the same anyway, and we don't want to introduce unnecessary
+       * extra space.
        */
       if (span_minimum < minimum)
         {
-          extra = minimum - span_minimum;
-          expand = span_expand;
-          for (i = 0; i < attach->span; i++)
+          if (linedata->homogeneous)
             {
-              line = &lines->lines[attach->pos - lines->min + i];
-              if (force_expand || line->expand)
+              gint total, m;
+
+              total = minimum - (attach->span - 1) * linedata->spacing;
+              m = total / attach->span + (total % attach->span ? 1 : 0);
+              for (i = 0; i < attach->span; i++)
                 {
-                  line_extra = extra / expand;
-                  line->minimum += line_extra;
-                  extra -= line_extra;
-                  expand -= 1;
+                  line = &lines->lines[attach->pos - lines->min + i];
+                  line->minimum = MAX(line->minimum, m);
+                }
+            }
+          else
+            {
+              extra = minimum - span_minimum;
+              expand = span_expand;
+              for (i = 0; i < attach->span; i++)
+                {
+                  line = &lines->lines[attach->pos - lines->min + i];
+                  if (force_expand || line->expand)
+                    {
+                      line_extra = extra / expand;
+                      line->minimum += line_extra;
+                      extra -= line_extra;
+                      expand -= 1;
+                    }
                 }
             }
         }
 
       if (span_natural < natural)
         {
-          extra = natural - span_natural;
-          expand = span_expand;
-          for (i = 0; i < attach->span; i++)
+          if (linedata->homogeneous)
             {
-              line = &lines->lines[attach->pos - lines->min + i];
-              if (force_expand || line->expand)
+              gint total, n;
+
+              total = natural - (attach->span - 1) * linedata->spacing;
+              n = total / attach->span + (total % attach->span ? 1 : 0);
+              for (i = 0; i < attach->span; i++)
                 {
-                  line_extra = extra / expand;
-                  line->natural += line_extra;
-                  extra -= line_extra;
-                  expand -= 1;
+                  line = &lines->lines[attach->pos - lines->min + i];
+                  line->natural = MAX(line->natural, n);
+                }
+            }
+          else
+            {
+              extra = natural - span_natural;
+              expand = span_expand;
+              for (i = 0; i < attach->span; i++)
+                {
+                  line = &lines->lines[attach->pos - lines->min + i];
+                  if (force_expand || line->expand)
+                    {
+                      line_extra = extra / expand;
+                      line->natural += line_extra;
+                      extra -= line_extra;
+                      expand -= 1;
+                    }
                 }
             }
         }