GtkBox: Add baseline alignment for horizontal boxes

Report a baseline based height and baseline whenever there
are children with ALIGN_BASELINE.

Assign baseline to childen in size_allocate. Either the one inherited
from the parent if set, or otherwise calculate one based on any
ALIGN_BASELINE children.

1 files changed, 22 insertions, 0 deletions

diff --git a/gtk/gtkenums.h b/gtk/gtkenums.h
index 9df69a89d5..82f5a0a010 100644
--- a/gtk/gtkenums.h
+++ b/gtk/gtkenums.h
@@ -132,6 +132,28 @@ typedef enum
 } GtkAttachOptions;
 
 /**
+ * GtkBaselinePosition:
+ * @GTK_BASELINE_POSITION_TOP: Align the baseline at the top
+ * @GTK_BASELINE_POSITION_CENTER: Center the baseline
+ * @GTK_BASELINE_POSITION_BOTTOM: Align the baseline at the bottom
+ *
+ * Whenever a container has some form of natural row it may align
+ * children in that row along a common typographical baseline. If
+ * the amount of verical space in the row is taller than the total
+ * requested height of the baseline-aligned children then it can use a
+ * #GtkBaselinePosition to select where to put the baseline inside the
+ * extra availible space.
+ *
+ * Since: 3.10
+ */
+typedef enum
+{
+  GTK_BASELINE_POSITION_TOP,
+  GTK_BASELINE_POSITION_CENTER,
+  GTK_BASELINE_POSITION_BOTTOM
+} GtkBaselinePosition;
+
+/**
  * GtkButtonBoxStyle:
  * @GTK_BUTTONBOX_DEFAULT_STYLE: Default packing.
  * @GTK_BUTTONBOX_SPREAD: Buttons are evenly spread across the box.