boxlayout: Compute opposite size properly

For size -1 in the opposite orientation, GtkBoxLayout used to measure
the children based on their min size in the box's orientation instead of
-1. That wasn't really intended, but was a side effect of how the sizing
code did (not) distribute extra size above the minimum size.

This is clearly not what we want.
What we want is measuring the orientation as is for size -1. Then we
want to just take the maximum of all children and use that.

A reftest is incldued that ensures a vbox wraps a label just like an
hbox does.

4 files changed, 86 insertions, 4 deletions

diff --git a/gtk/gtkboxlayout.c b/gtk/gtkboxlayout.c
index f080748830..99feca37e5 100644
--- a/gtk/gtkboxlayout.c
+++ b/gtk/gtkboxlayout.c
@@ -256,13 +256,48 @@ gtk_box_layout_compute_size (GtkBoxLayout *self,
 static void
 gtk_box_layout_compute_opposite_size (GtkBoxLayout *self,
                                       GtkWidget    *widget,
-                                      int           for_size,
                                       int          *minimum,
                                       int          *natural,
                                       int          *min_baseline,
                                       int          *nat_baseline)
 {
   GtkWidget *child;
+  int largest_min = 0, largest_nat = 0;
+
+  for (child = gtk_widget_get_first_child (widget);
+       child != NULL;
+       child = gtk_widget_get_next_sibling (child))
+    {
+      int child_min = 0;
+      int child_nat = 0;
+
+      if (!gtk_widget_should_layout (child))
+        continue;
+
+      gtk_widget_measure (child,
+                          OPPOSITE_ORIENTATION (self->orientation),
+                          -1,
+                          &child_min, &child_nat,
+                          NULL, NULL);
+
+      largest_min = MAX (largest_min, child_min);
+      largest_nat = MAX (largest_nat, child_nat);
+    }
+
+  *minimum = largest_min;
+  *natural = largest_nat;
+}
+
+static void
+gtk_box_layout_compute_opposite_size_for_size (GtkBoxLayout *self,
+                                               GtkWidget    *widget,
+                                               int           for_size,
+                                               int          *minimum,
+                                               int          *natural,
+                                               int          *min_baseline,
+                                               int          *nat_baseline)
+{
+  GtkWidget *child;
   int nvis_children;
   int nexpand_children;
   int computed_minimum = 0, computed_natural = 0;
@@ -437,9 +472,18 @@ gtk_box_layout_measure (GtkLayoutManager *layout_manager,
 
   if (self->orientation != orientation)
     {
-      gtk_box_layout_compute_opposite_size (self, widget, for_size,
-                                            minimum, natural,
-                                            min_baseline, nat_baseline);
+      if (for_size < 0)
+        {
+          gtk_box_layout_compute_opposite_size (self, widget,
+                                                minimum, natural,
+                                                min_baseline, nat_baseline);
+        }
+      else
+        {
+          gtk_box_layout_compute_opposite_size_for_size (self, widget, for_size,
+                                                         minimum, natural,
+                                                         min_baseline, nat_baseline);
+        }
     }
   else
     {
diff --git a/testsuite/reftests/meson.build b/testsuite/reftests/meson.build
index b033760ed7..692a427438 100644
--- a/testsuite/reftests/meson.build
+++ b/testsuite/reftests/meson.build
@@ -498,6 +498,8 @@ testdata = [
   'unresolvable.css',
   'unresolvable.ref.ui',
   'unresolvable.ui',
+  'vbox-with-max-width-chars-label.ref.ui',
+  'vbox-with-max-width-chars-label.ui',
   'window-border-width.ref.ui',
   'window-border-width.ui',
   'window-default-size.ref.ui',
diff --git a/testsuite/reftests/vbox-with-max-width-chars-label.ref.ui b/testsuite/reftests/vbox-with-max-width-chars-label.ref.ui
new file mode 100644
index 0000000000..aa732c608d
--- /dev/null
+++ b/testsuite/reftests/vbox-with-max-width-chars-label.ref.ui
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkWindow">
+    <property name="decorated">0</property>
+    <child>
+      <object class="GtkBox">
+        <property name="orientation">horizontal</property>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Hello World</property>
+            <property name="wrap">1</property>
+            <property name="max-width-chars">1</property>
+          </object>
+        </child>
+      </object>
+    </child>
+  </object>
+</interface>
diff --git a/testsuite/reftests/vbox-with-max-width-chars-label.ui b/testsuite/reftests/vbox-with-max-width-chars-label.ui
new file mode 100644
index 0000000000..3a7d52e4a4
--- /dev/null
+++ b/testsuite/reftests/vbox-with-max-width-chars-label.ui
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<interface>
+  <object class="GtkWindow">
+    <property name="decorated">0</property>
+    <child>
+      <object class="GtkBox">
+        <property name="orientation">vertical</property>
+        <child>
+          <object class="GtkLabel">
+            <property name="label">Hello World</property>
+            <property name="wrap">1</property>
+            <property name="max-width-chars">1</property>
+          </object>
+        </child>
+      </object>
+    </child>
+  </object>
+</interface>