[gtk+] grid: Work harder for tight homogeneous allocation

[Matthias Clasen <matthiasc src gnome org>]

commit 47c190a1b732225a9c26bfd492f8c392f5adc931
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Mar 4 17:19:16 2012 -0500

    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 files changed, 53 insertions(+), 18 deletions(-)
---
diff --git a/gtk/gtkgrid.c b/gtk/gtkgrid.c
index 3b75219..fdbdf7c 100644
--- a/gtk/gtkgrid.c
+++ b/gtk/gtkgrid.c
@@ -770,37 +770,72 @@ 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 = &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_extra = extra / expand;
-                  line->minimum += line_extra;
-                  extra -= line_extra;
-                  expand -= 1;
+                  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 = &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_extra = extra / expand;
-                  line->natural += line_extra;
-                  extra -= line_extra;
-                  expand -= 1;
+                  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;
+                    }
                 }
             }
         }