From 1c3e743d2a44b461ec0447f0c20a30b202728907 Mon Sep 17 00:00:00 2001
From: Paul Davis <paul@linuxaudiosystems.com>
Date: Fri, 22 May 2020 08:46:04 -0600
Subject: [PATCH] Canvas: continued work on constraint packer

---
 libs/canvas/canvas/constraint_packer.h | 18 +++++++++
 libs/canvas/constraint_packer.cc       | 51 ++++++++++++++++++++++++++
 2 files changed, 69 insertions(+)

diff --git a/libs/canvas/canvas/constraint_packer.h b/libs/canvas/canvas/constraint_packer.h
index 70ef55c91a..1fd42a821e 100644
--- a/libs/canvas/canvas/constraint_packer.h
+++ b/libs/canvas/canvas/constraint_packer.h
@@ -20,11 +20,13 @@
 #define __CANVAS_CONSTRAINT_PACKER_H__
 
 #include "canvas/item.h"
+#include "kiwi/kiwi.h"
 
 namespace ArdourCanvas
 {
 
 class Rectangle;
+class ConstrainedItem;
 
 class LIBCANVAS_API ConstraintPacker : public Item
 {
@@ -32,13 +34,29 @@ public:
 	ConstraintPacker (Canvas *);
 	ConstraintPacker (Item *);
 
+	void add (Item *);
+	void remove (Item *);
+	void constrain (kiwi::Constraint const &);
+
+	void solve ();
+	void apply ();
+
 	void compute_bounding_box () const;
 	void render (Rect const & area, Cairo::RefPtr<Cairo::Context> context) const;
 
+	void size_allocate (Rect const &);
+
   protected:
 	void child_changed ();
 
   private:
+	typedef std::map<Item*,ConstrainedItem*> ConstraintMap;
+	ConstraintMap constraint_map;
+
+	kiwi::Solver _solver;
+	kiwi::Variable width;
+	kiwi::Variable height;
+
 	Rectangle *self;
 	bool collapse_on_hide;
 
diff --git a/libs/canvas/constraint_packer.cc b/libs/canvas/constraint_packer.cc
index dc8b24ea88..a29b65abd3 100644
--- a/libs/canvas/constraint_packer.cc
+++ b/libs/canvas/constraint_packer.cc
@@ -16,16 +16,25 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */
 
+#include "pbd/i18n.h"
+
+
 #include "kiwi/kiwi.h"
 
 #include "canvas/constraint_packer.h"
+#include "canvas/constrained_item.h"
+#include "canvas/item.h"
 #include "canvas/rectangle.h"
 
 using namespace ArdourCanvas;
 
 ConstraintPacker::ConstraintPacker (Canvas* canvas)
 	: Item (canvas)
+	, width (X_("width"))
+	, height (X_("height"))
 {
+	_solver.addEditVariable (width, kiwi::strength::strong);
+	_solver.addEditVariable (height, kiwi::strength::strong);
 }
 
 ConstraintPacker::ConstraintPacker (Item* parent)
@@ -88,3 +97,45 @@ ConstraintPacker::child_changed ()
 	reposition_children ();
 }
 
+void
+ConstraintPacker::constrain (kiwi::Constraint const &c)
+{
+	_solver.addConstraint (c);
+}
+
+void
+ConstraintPacker::size_allocate (Rect const & r)
+{
+	Item::size_allocate (r);
+
+	_solver.suggestValue (width, r.width());
+	_solver.suggestValue (height, r.height());
+
+	solve ();
+}
+
+void
+ConstraintPacker::add (Item* item)
+{
+	Item::add (item);
+	ConstrainedItem* ci = new ConstrainedItem (*item);
+	constraint_map.insert (std::make_pair (item, ci));
+}
+
+void
+ConstraintPacker::remove (Item* item)
+{
+	Item::remove (item);
+	constraint_map.erase (item);
+}
+
+void
+ConstraintPacker::solve ()
+{
+	_solver.updateVariables ();
+
+	for (ConstraintMap::iterator x = constraint_map.begin(); x != constraint_map.end(); ++x) {
+		x->first->constrained (*(x->second));
+	}
+}
+