From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 30 Jun 2013 21:03:38 +0000 (+0300)
Subject: Use a different approach for custom item widgets
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgltk.git;a=commitdiff_plain;h=74934c6f7a6fd0f9e9bf11eeb9f33cf9279bf471

Use a different approach for custom item widgets

Subclassed widgets can't be loaded from datafiles without providing custom
statements.  Dropdown doesn't allow changing the type of the List either.
---

diff --git a/source/dropdown.h b/source/dropdown.h
index eaa29c1..06aefa5 100644
--- a/source/dropdown.h
+++ b/source/dropdown.h
@@ -46,6 +46,9 @@ public:
 	ListData &get_data() { return list.get_data(); }
 	const ListData &get_data() const { return list.get_data(); }
 
+	template<typename T>
+	void set_item_type() { list.set_item_type<T>(); }
+
 	void set_selected_index(int);
 	int get_selected_index() const { return list.get_selected_index(); }
 
diff --git a/source/list.cpp b/source/list.cpp
index 7227f0c..eaab9e0 100644
--- a/source/list.cpp
+++ b/source/list.cpp
@@ -1,3 +1,4 @@
+#include <msp/debug/demangle.h>
 #include <msp/gl/matrix.h>
 #include <msp/gl/meshbuilder.h>
 #include "graphic.h"
@@ -12,6 +13,11 @@ using namespace std;
 namespace Msp {
 namespace GLtk {
 
+incompatible_data::incompatible_data(const type_info &ti):
+	logic_error("expected "+Debug::demangle(ti.name()))
+{ }
+
+
 List::List():
 	data(new BasicListData<string>),
 	own_data(true)
@@ -28,6 +34,7 @@ List::List(ListData &d):
 
 void List::init()
 {
+	item_factory = 0;
 	sel_index = -1;
 	first = 0;
 	max_scroll = 0;
@@ -42,6 +49,7 @@ void List::init()
 
 List::~List()
 {
+	delete item_factory;
 	delete observer;
 	if(own_data)
 		delete data;
@@ -74,6 +82,9 @@ void List::autosize_special(const Part &part, Geometry &ageom)
 
 void List::set_data(ListData &d)
 {
+	if(item_factory)
+		item_factory->set_data(d);
+
 	delete observer;
 	if(own_data)
 		delete data;
@@ -105,7 +116,10 @@ void List::items_changed()
 
 List::Item *List::create_item(unsigned index)
 {
-	return new BasicItem(data->get_string(index));
+	if(item_factory)
+		return item_factory->create_item(index);
+	else
+		return new BasicItem(data->get_string(index));
 }
 
 void List::set_view_size(unsigned s)
diff --git a/source/list.h b/source/list.h
index 14d9eac..351b0a4 100644
--- a/source/list.h
+++ b/source/list.h
@@ -1,6 +1,8 @@
 #ifndef MSP_GLTK_LIST_H_
 #define MSP_GLTK_LIST_H_
 
+#include <stdexcept>
+#include <typeinfo>
 #include <sigc++/signal.h>
 #include "container.h"
 #include "label.h"
@@ -10,6 +12,17 @@
 namespace Msp {
 namespace GLtk {
 
+/**
+Thrown if a list's item type is incompatible with its data.
+*/
+class incompatible_data: public std::logic_error
+{
+public:
+	incompatible_data(const std::type_info &);
+	virtual ~incompatible_data() throw() { }
+};
+
+
 /**
 Shows a list of items, allowing the user to select one.  A slider is included
 to allow scrolling through a long list.
@@ -41,7 +54,7 @@ private:
 		void refresh_item(unsigned);
 	};
 
-protected:
+public:
 	class Item: public Container
 	{
 	public:
@@ -55,7 +68,7 @@ protected:
 		virtual void render_special(const Part &, GL::Renderer &) const;
 	};
 
-public:
+private:
 	class BasicItem: public Item
 	{
 	private:
@@ -68,6 +81,43 @@ public:
 		virtual void on_style_change();
 	};
 
+	class ItemFactory
+	{
+	protected:
+		ItemFactory() { }
+	public:
+		virtual ~ItemFactory() { }
+
+		virtual void set_data(const ListData &) = 0;
+		virtual Item *create_item(unsigned) const = 0;
+	};
+
+	template<typename I>
+	class TypedItemFactory: public ItemFactory
+	{
+	private:
+		typedef typename I::ValueType ValueType;
+
+		const ListDataStore<ValueType> *data;
+
+	public:
+		TypedItemFactory(const ListData &d)
+		{ set_data(d); }
+
+		virtual void set_data(const ListData &d)
+		{
+			if(const ListDataStore<ValueType> *ds = dynamic_cast<const ListDataStore<ValueType> *>(&d))
+				data = ds;
+			else
+				throw incompatible_data(typeid(ValueType));
+		}
+
+		virtual Item *create_item(unsigned i) const
+		{
+			return new I(data->get(i));
+		}
+	};
+
 public:
 	sigc::signal<void, unsigned> signal_item_selected;
 
@@ -75,6 +125,7 @@ private:
 	ListData *data;
 	bool own_data;
 	DataObserver *observer;
+	ItemFactory *item_factory;
 	int sel_index;
 	unsigned first;
 	unsigned max_scroll;
@@ -102,8 +153,17 @@ public:
 	const ListData &get_data() const { return *data; }
 private:
 	void items_changed();
-protected:
-	virtual Item *create_item(unsigned);
+
+public:
+	template<typename I>
+	void set_item_type()
+	{
+		ItemFactory *f = new TypedItemFactory<I>(*data);
+		delete item_factory;
+		item_factory = f;
+	}
+private:
+	Item *create_item(unsigned);
 
 public:
 	void set_view_size(unsigned);