Add GtkConstraintLayout

A layout manager using GtkConstraintSolver to measure and allocate
children.

1 files changed, 31 insertions, 0 deletions

diff --git a/gtk/gtkconstraintsolverprivate.h b/gtk/gtkconstraintsolverprivate.h
index 807b0b08d6..69eed376c7 100644
--- a/gtk/gtkconstraintsolverprivate.h
+++ b/gtk/gtkconstraintsolverprivate.h
@@ -29,6 +29,37 @@ G_BEGIN_DECLS
 
 G_DECLARE_FINAL_TYPE (GtkConstraintSolver, gtk_constraint_solver, GTK, CONSTRAINT_SOLVER, GObject)
 
+/* Symbolic weight thresholds
+ *
+ * Constraint weights live on a continuum, but we use thresholds for simplicity's
+ * sake, so we don't have to necessarily reason in terms of numeric values.
+ *
+ * The public API has a similar approach, where the symbolic constants are negative
+ * values, and positive values are explicit weights. We map those values into
+ * numeric values that the GtkConstraintSolver can plug into the linear equations
+ * tableau.
+ */
+#define GTK_CONSTRAINT_WEIGHT_REQUIRED  (make_weight (1000, 1000, 1000, 1))
+#define GTK_CONSTRAINT_WEIGHT_STRONG    (make_weight (   1,    0,    0, 1))
+#define GTK_CONSTRAINT_WEIGHT_MEDIUM    (make_weight (   0,    1,    0, 1))
+#define GTK_CONSTRAINT_WEIGHT_WEAK      (make_weight (   0,    0,    1, 1))
+
+G_GNUC_PURE
+static inline double
+make_weight (double a,
+             double b,
+             double c,
+             double w)
+{
+  double res = 0;
+
+  res += CLAMP (a * w, 0, 1000) * 1000000;
+  res += CLAMP (b * w, 0, 1000) * 1000;
+  res += CLAMP (c * w, 0, 1000);
+
+  return res;
+}
+
 GtkConstraintSolver *
 gtk_constraint_solver_new (void);