From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 28 Feb 2011 15:29:05 +0000 (+0000)
Subject: Add a Layout class to automatically position widgets within a Panel
X-Git-Url: http://git.tdb.fi/?a=commitdiff_plain;h=01eaaef90f4c56cd4669d2f621e3061a938753eb;p=libs%2Fgltk.git

Add a Layout class to automatically position widgets within a Panel
---

diff --git a/source/layout.cpp b/source/layout.cpp
new file mode 100644
index 0000000..3501948
--- /dev/null
+++ b/source/layout.cpp
@@ -0,0 +1,497 @@
+#include <limits>
+#include "container.h"
+#include "layout.h"
+#include "widget.h"
+
+using namespace std;
+
+namespace Msp {
+namespace GLtk {
+
+class Layout::LinearProgram
+{
+public:
+	class Row
+	{
+	private:
+		LinearProgram &linprog;
+		unsigned index;
+
+	public:
+		Row(LinearProgram &, unsigned);
+
+		float &operator[](unsigned);
+		float &back();
+	};
+
+private:
+	struct Column
+	{
+		unsigned basic;
+		std::vector<float> values;
+
+		Column();
+	};
+
+	unsigned n_columns;
+	unsigned n_rows;
+	std::vector<Column> columns;
+	bool solved;
+	bool infeasible;
+
+public:
+	LinearProgram(unsigned);
+
+	Row add_row();
+	Row operator[](unsigned);
+	Row get_object_row();
+	bool solve();
+	float get_variable(unsigned);
+private:
+	unsigned find_minimal_ratio(unsigned);
+	void make_basic_column(unsigned, unsigned);
+	bool pivot();
+};
+
+
+struct Layout::Pointers
+{
+	int Geometry::*pos;
+	unsigned Geometry::*dim;
+	Packing Slot::*packing;
+	unsigned Sides::*low_margin;
+	unsigned Sides::*high_margin;
+	unsigned Layout::*spacing;
+};
+
+Layout::Pointers Layout::pointers[2] =
+{ {
+		&Geometry::x, &Geometry::w,
+		&Slot::horiz_pack,
+		&Sides::left, &Sides::right,
+		&Layout::col_spacing
+	}, {
+		&Geometry::y, &Geometry::h,
+		&Slot::vert_pack,
+		&Sides::bottom, &Sides::top,
+		&Layout::row_spacing
+} };
+
+
+Layout::Layout():
+	container(0),
+	margin(8),
+	row_spacing(5),
+	col_spacing(4)
+{ }
+
+Layout::~Layout()
+{
+	for(list<Slot *>::iterator i=slots.begin(); i!=slots.end(); ++i)
+		delete *i;
+}
+
+void Layout::set_container(Container &c)
+{
+	if(container)
+		throw InvalidState("This layout is already assigned to a Container");
+
+	container = &c;
+}
+
+void Layout::set_margin(const Sides &m)
+{
+	margin = m;
+	if(container)
+		update();
+}
+
+void Layout::add_widget(Widget &wdg)
+{
+	if(!container)
+		throw InvalidState("Can't add Widgets without a Container");
+
+	Slot *slot = create_slot(wdg);
+	for(list<Constraint>::iterator i=slot->constraints.begin(); i!=slot->constraints.end(); ++i)
+		i->target.constraints.push_back(Constraint(complement(i->type), *slot));
+	slot->index = slots.size();
+	slots.push_back(slot);
+	if(container)
+		update();
+}
+
+void Layout::remove_widget(Widget &wdg)
+{
+	for(list<Slot *>::iterator i=slots.begin(); i!=slots.end(); ++i)
+		if(&(*i)->widget==&wdg)
+		{
+			for(list<Slot *>::iterator j=slots.begin(); j!=slots.end(); ++j)
+				if(j!=i)
+				{
+					for(list<Constraint>::iterator k=(*j)->constraints.begin(); k!=(*j)->constraints.end(); )
+					{
+						if(&k->target==*i)
+							(*j)->constraints.erase(k++);
+						else
+							++k;
+					}
+				}
+
+			delete *i;
+			slots.erase(i);
+
+			unsigned n = 0;
+			for(i=slots.begin(); i!=slots.end(); ++i, ++n)
+				(*i)->index = n;
+
+			update();
+			return;
+		}
+}
+
+Layout::Slot *Layout::create_slot(Widget &wdg)
+{
+	return new Slot(*this, wdg);
+}
+
+Layout::Slot &Layout::get_slot_for_widget(Widget &wdg)
+{
+	for(list<Slot *>::iterator i=slots.begin(); i!=slots.end(); ++i)
+		if(&(*i)->widget==&wdg)
+			return **i;
+
+	throw InvalidParameterValue("Widget is not in the Layout");
+}
+
+Layout::ConstraintType Layout::complement(ConstraintType type)
+{
+	if(type==RIGHT_OF)
+		return LEFT_OF;
+	else if(type==LEFT_OF)
+		return RIGHT_OF;
+	else if(type==ABOVE)
+		return BELOW;
+	else if(type==BELOW)
+		return ABOVE;
+	else
+		return type;
+}
+
+void Layout::add_constraint(Widget &src, ConstraintType type, Widget &tgt)
+{
+	Slot &src_slot = get_slot_for_widget(src);
+	Slot &tgt_slot = get_slot_for_widget(tgt);
+
+	for(list<Constraint>::iterator i=src_slot.constraints.begin(); i!=src_slot.constraints.end(); ++i)
+		if(i->type==type && &i->target==&tgt_slot)
+			return;
+
+	src_slot.constraints.push_back(Constraint(type, tgt_slot));
+	tgt_slot.constraints.push_back(Constraint(complement(type), src_slot));
+
+	update();
+}
+
+void Layout::set_gravity(Widget &wdg, int h, int v)
+{
+	Slot &slot = get_slot_for_widget(wdg);
+
+	slot.horiz_pack.gravity = h;
+	slot.vert_pack.gravity = v;
+
+	update();
+}
+
+void Layout::set_expand(Widget &wdg, bool h, bool v)
+{
+	Slot &slot = get_slot_for_widget(wdg);
+
+	slot.horiz_pack.expand = h;
+	slot.vert_pack.expand = v;
+
+	update();
+}
+
+void Layout::update()
+{
+	for(list<Slot *>::iterator i=slots.begin(); i!=slots.end(); ++i)
+	{
+		(*i)->widget.autosize();
+		(*i)->geom = (*i)->widget.get_geometry();
+	}
+
+	solve_constraints(HORIZONTAL);
+	solve_constraints(VERTICAL);
+
+	for(list<Slot *>::iterator i=slots.begin(); i!=slots.end(); ++i)
+		(*i)->widget.set_geometry((*i)->geom);
+
+}
+
+void Layout::solve_constraints(int dir)
+{
+	Pointers &ptrs = pointers[dir&VERTICAL];
+
+	LinearProgram linprog(slots.size()*5+1);
+	for(list<Slot *>::iterator i=slots.begin(); i!=slots.end(); ++i)
+	{
+		linprog.get_object_row()[(*i)->index*5] = 0.1*((*i)->*(ptrs.packing)).gravity;
+		linprog.get_object_row()[(*i)->index*5+1] = (((*i)->*(ptrs.packing)).expand ? 5 : -1);
+
+		{
+			LinearProgram::Row row = linprog.add_row();
+			row[(*i)->index*5] = 1;
+			row[(*i)->index*5+2] = -1;
+			row.back() = margin.*(ptrs.low_margin);
+		}
+
+		{
+			LinearProgram::Row row = linprog.add_row();
+			row[(*i)->index*5] = 1;
+			row[(*i)->index*5+1] = 1;
+			row[(*i)->index*5+3] = 1;
+			row.back() = container->get_geometry().*(ptrs.dim)-margin.*(ptrs.high_margin);
+		}
+
+		{
+			LinearProgram::Row row = linprog.add_row();
+			row[(*i)->index*5+1] = 1;
+			row[(*i)->index*5+4] = -1;
+			row.back() = (*i)->geom.*(ptrs.dim);
+		}
+
+		for(list<Constraint>::iterator j=(*i)->constraints.begin(); j!=(*i)->constraints.end(); ++j)
+		{
+			if((j->type&1)==dir && j->type!=BELOW && j->type!=LEFT_OF)
+			{
+				LinearProgram::Row row = linprog.add_row();
+				if(j->type&SELF_POS)
+					row[(*i)->index*5] = 1;
+				if(j->type&SELF_DIM)
+					row[(*i)->index*5+1] = 1;
+				if(j->type&TARGET_POS)
+					row[j->target.index*5] = -1;
+				if(j->type&TARGET_DIM)
+					row[j->target.index*5+1] = -1;
+				if(j->type&SPACING)
+					row.back() = this->*(ptrs.spacing);
+			}
+		}
+	}
+
+	if(!linprog.solve())
+		return;
+
+	for(list<Slot *>::iterator i=slots.begin(); i!=slots.end(); ++i)
+	{
+		(*i)->geom.*(ptrs.pos) = linprog.get_variable((*i)->index*5);
+		(*i)->geom.*(ptrs.dim) = linprog.get_variable((*i)->index*5+1);
+	}
+}
+
+
+Layout::Constraint::Constraint(ConstraintType t, Slot &s):
+	type(t),
+	target(s)
+{ }
+
+
+Layout::Packing::Packing():
+	gravity(-1),
+	expand(false)
+{ }
+
+
+Layout::Slot::Slot(Layout &l, Widget &w):
+	layout(l),
+	index(0),
+	widget(w)
+{
+	vert_pack.gravity = 1;
+	widget.signal_autosize_changed.connect(sigc::mem_fun(this, &Slot::autosize_changed));
+}
+
+void Layout::Slot::autosize_changed()
+{
+	layout.update();
+}
+
+
+Layout::LinearProgram::LinearProgram(unsigned s):
+	n_columns(s),
+	n_rows(1),
+	columns(n_columns),
+	solved(false),
+	infeasible(false)
+{ }
+
+Layout::LinearProgram::Row Layout::LinearProgram::add_row()
+{
+	return Row(*this, n_rows++);
+}
+
+Layout::LinearProgram::Row Layout::LinearProgram::operator[](unsigned r)
+{
+	if(r>=n_rows)
+		throw InvalidParameterValue("Row index out of range");
+
+	return Row(*this, r);
+}
+
+Layout::LinearProgram::Row Layout::LinearProgram::get_object_row()
+{
+	return Row(*this, 0);
+}
+
+float Layout::LinearProgram::get_variable(unsigned i)
+{
+	if(!solved || infeasible)
+		throw InvalidState("Not solved");
+	if(i+1>=n_columns)
+		throw InvalidParameterValue("Variable index out of range");
+
+	unsigned r = columns[i].basic;
+	return columns.back().values[r];
+}
+
+bool Layout::LinearProgram::solve()
+{
+	if(solved || infeasible)
+		return !infeasible;
+
+	// Force all columns fully into existence and relocate objective row to bottom
+	for(vector<Column>::iterator i=columns.begin(); i!=columns.end(); ++i)
+	{
+		float objective = i->values.front();
+		i->values.front() = 0.0f;
+		for(vector<float>::iterator j=i->values.begin(); j!=i->values.end(); ++j)
+			i->values.front() += *j;
+		i->values.resize(n_rows+1, 0.0f);
+		i->values.back() = objective;
+	}
+
+	// Create artificial variables for phase 1
+	columns.resize(n_columns+n_rows-1);
+	columns.back() = columns[n_columns-1];
+	columns[n_columns-1].values.clear();
+	for(unsigned i=1; i<n_rows; ++i)
+	{
+		Column &column = columns[n_columns+i-2];
+		column.basic = i;
+	}
+
+	// Solve the phase 1 problem
+	while(pivot()) ;
+
+	if(columns.back().values.front())
+	{
+		infeasible = true;
+		return false;
+	}
+
+	// Get rid of artificial columns and restore objective row
+	columns.erase(columns.begin()+(n_columns-1), columns.end()-1);
+	for(vector<Column>::iterator i=columns.begin(); i!=columns.end(); ++i)
+		if(!i->basic)
+		{
+			i->values.front() = i->values.back();
+			i->values.pop_back();
+		}
+
+	while(pivot()) ;
+
+	solved = true;
+
+	return true;
+}
+
+unsigned Layout::LinearProgram::find_minimal_ratio(unsigned c)
+{
+	float best = numeric_limits<float>::infinity();
+	unsigned row = 0;
+	/* Intentionally use n_rows since we need to ignore the relocated original
+	objective row in phase 1 */
+	for(unsigned i=1; i<n_rows; ++i)
+		if(columns[c].values[i]>0)
+		{
+			float ratio = columns.back().values[i]/columns[c].values[i];
+			if(ratio<best)
+			{
+				best = ratio;
+				row = i;
+			}
+		}
+	
+	return row;
+}
+
+void Layout::LinearProgram::make_basic_column(unsigned c, unsigned r)
+{
+	for(unsigned i=0; i<columns.size(); ++i)
+		if(i!=c && (columns[i].basic==r || (!columns[i].basic && columns[i].values[r])))
+		{
+			if(columns[i].basic)
+			{
+				columns[i].values.resize(columns.back().values.size(), 0.0f);
+				columns[i].values[columns[i].basic] = 1.0f;
+				columns[i].basic = 0;
+			}
+
+			float scale = columns[i].values[r]/columns[c].values[r];
+			
+			for(unsigned j=0; j<columns[i].values.size(); ++j)
+			{
+				if(j==r)
+					columns[i].values[j] = scale;
+				else
+					columns[i].values[j] -= scale*columns[c].values[j];
+			}
+		}
+
+	columns[c].basic = r;
+	columns[c].values.clear();
+}
+
+bool Layout::LinearProgram::pivot()
+{
+	for(unsigned i=0; i+1<columns.size(); ++i)
+		if(!columns[i].basic && columns[i].values.front()>0)
+			if(unsigned row = find_minimal_ratio(i))
+			{
+				make_basic_column(i, row);
+				return true;
+			}
+
+	return false;
+}
+
+
+Layout::LinearProgram::Row::Row(LinearProgram &lp, unsigned i):
+	linprog(lp),
+	index(i)
+{ }
+
+float &Layout::LinearProgram::Row::operator[](unsigned c)
+{
+	if(c>=linprog.n_columns)
+		throw InvalidParameterValue("Column index out of range");
+
+	Column &column = linprog.columns[c];
+	if(column.values.size()<=index)
+		column.values.resize(index+1);
+
+	return column.values[index];
+}
+
+float &Layout::LinearProgram::Row::back()
+{
+	return (*this)[linprog.n_columns-1];
+}
+
+
+Layout::LinearProgram::Column::Column():
+	basic(0)
+{ }
+
+} // namespace GLtk
+} // namespace Msp
diff --git a/source/layout.h b/source/layout.h
new file mode 100644
index 0000000..540c5ee
--- /dev/null
+++ b/source/layout.h
@@ -0,0 +1,122 @@
+#ifndef MSP_GLTK_LAYOUT_H_
+#define MSP_GLTK_LAYOUT_H_
+
+#include <list>
+#include <set>
+#include <sigc++/trackable.h>
+#include "geometry.h"
+
+namespace Msp {
+namespace GLtk {
+
+class Container;
+class Widget;
+
+class Layout
+{
+private:
+	enum
+	{
+		HORIZONTAL = 0,
+		VERTICAL = 1,
+		SELF_POS = 2,
+		SELF_DIM = 4,
+		TARGET_POS = 8,
+		TARGET_DIM = 16,
+		SPACING = 32
+	};
+
+public:
+	enum ConstraintType
+	{
+		ABOVE = VERTICAL|SELF_POS|TARGET_POS|TARGET_DIM|SPACING,
+		BELOW = VERTICAL|SELF_POS|SELF_DIM|TARGET_POS|SPACING,
+		RIGHT_OF = HORIZONTAL|SELF_POS|TARGET_POS|TARGET_DIM|SPACING,
+		LEFT_OF = HORIZONTAL|SELF_POS|SELF_DIM|TARGET_POS|SPACING,
+		ALIGN_TOP = VERTICAL|SELF_POS|SELF_DIM|TARGET_POS|TARGET_DIM,
+		ALIGN_BOTTOM = VERTICAL|SELF_POS|TARGET_POS,
+		ALIGN_RIGHT = HORIZONTAL|SELF_POS|SELF_DIM|TARGET_POS|TARGET_DIM,
+		ALIGN_LEFT = HORIZONTAL|SELF_POS|TARGET_POS,
+		COPY_WIDTH = HORIZONTAL|SELF_DIM|TARGET_DIM,
+		COPY_HEIGHT = VERTICAL|SELF_DIM|TARGET_DIM
+	};
+
+protected:
+	struct Slot;
+
+	struct Constraint
+	{
+		ConstraintType type;
+		Slot &target;
+
+		Constraint(ConstraintType, Slot &);
+	};
+
+	struct Packing
+	{
+		int gravity;
+		bool expand;
+
+		Packing();
+	};
+
+	struct Slot: public sigc::trackable
+	{
+		Layout &layout;
+		unsigned index;
+		Widget &widget;
+		Geometry geom;
+		std::list<Constraint> constraints;
+		Packing horiz_pack;
+		Packing vert_pack;
+
+		Slot(Layout &, Widget &);
+		virtual ~Slot() { }
+
+		void autosize_changed();
+	};
+
+	class LinearProgram;
+	struct Pointers;
+
+	Container *container;
+	std::list<Slot *> slots;
+	Sides margin;
+	unsigned row_spacing;
+	unsigned col_spacing;
+
+	static Pointers pointers[2];
+
+public:
+	Layout();
+	virtual ~Layout();
+
+	void set_container(Container &);
+	void set_margin(const Sides &);
+	void set_spacing(unsigned);
+	void set_row_spacing(unsigned);
+	void set_column_spacing(unsigned);
+
+	void add_widget(Widget &);
+	void remove_widget(Widget &);
+protected:
+	virtual Slot *create_slot(Widget &);
+	Slot &get_slot_for_widget(Widget &);
+	static ConstraintType complement(ConstraintType);
+public:
+	void add_constraint(Widget &, ConstraintType, Widget &);
+	void set_gravity(Widget &, int, int);
+	void set_expand(Widget &, bool, bool);
+
+	void update();
+
+protected:
+	void find_constraint_group(Slot &, ConstraintType, std::set<Slot *> &);
+	void sort_slots(std::list<Slot *> &, ConstraintType);
+	void solve_constraints(int);
+};
+
+} // namespace GLtk
+} // namespace Msp
+
+#endif
diff --git a/source/panel.cpp b/source/panel.cpp
index 0ecdf10..a1a453a 100644
--- a/source/panel.cpp
+++ b/source/panel.cpp
@@ -13,6 +13,7 @@ Distributed under the LGPL
 #include "hslider.h"
 #include "indicator.h"
 #include "label.h"
+#include "layout.h"
 #include "list.h"
 #include "panel.h"
 #include "part.h"
@@ -26,11 +27,25 @@ namespace Msp {
 namespace GLtk {
 
 Panel::Panel():
+	layout(0),
 	pointer_focus(0),
 	pointer_grabbed(false),
 	input_focus(0)
 { }
 
+Panel::~Panel()
+{
+	delete layout;
+	layout = 0;
+}
+
+void Panel::set_layout(Layout *l)
+{
+	l->set_container(*this);
+	delete layout;
+	layout = l;
+}
+
 Panel::Child *Panel::create_child(Widget *wdg)
 {
 	return new Child(*this, wdg);
@@ -134,6 +149,19 @@ void Panel::key_release(unsigned key, unsigned mod)
 void Panel::focus_out()
 {
 	set_input_focus(0);
+	Widget::focus_out();
+}
+
+void Panel::on_child_added(Widget &wdg)
+{
+	if(layout)
+		layout->add_widget(wdg);
+}
+
+void Panel::on_child_removed(Widget &wdg)
+{
+	if(layout)
+		layout->remove_widget(wdg);
 }
 
 void Panel::set_pointer_focus(Widget *wdg)
@@ -230,6 +258,13 @@ void Panel::Child::visibility_changed(bool v)
 	}
 }
 
+void Panel::Child::autosize_changed()
+{
+	Panel &panel = static_cast<Panel &>(container);
+	if(panel.layout)
+		panel.layout->update();
+}
+
 void Panel::Child::request_focus()
 {
 	Panel &panel = static_cast<Panel &>(container);
diff --git a/source/panel.h b/source/panel.h
index 54e75ef..a5483c4 100644
--- a/source/panel.h
+++ b/source/panel.h
@@ -13,6 +13,8 @@ Distributed under the LGPL
 namespace Msp {
 namespace GLtk {
 
+class Layout;
+
 /**
 Panels are containers for other widgets.  Panel styles should have a special
 part "children" to render the child widgets.  All properties of this part are
@@ -45,12 +47,14 @@ protected:
 		virtual ~Child();
 
 		void visibility_changed(bool);
+		void autosize_changed();
 		void request_focus();
 		void grab_pointer();
 		void ungrab_pointer();
 		void raise();
 	};
 
+	Layout *layout;
 	Widget *pointer_focus;
 	bool pointer_grabbed;
 	Widget *input_focus;
@@ -59,9 +63,12 @@ protected:
 	Panel &operator=(const Panel &);
 public:
 	Panel();
+	virtual ~Panel();
 
 	virtual const char *get_class() const { return "panel"; }
 
+	void set_layout(Layout *);
+
 protected:
 	virtual Child *create_child(Widget *);
 
@@ -81,8 +88,10 @@ public:
 	virtual void key_press(unsigned, unsigned, wchar_t);
 	virtual void key_release(unsigned, unsigned);
 	virtual void focus_out();
-
 protected:
+	virtual void on_child_added(Widget &);
+	virtual void on_child_removed(Widget &);
+
 	void set_pointer_focus(Widget *);
 	void set_input_focus(Widget *);
 };