Gtk2::Ex::TreeMaker - A high level widget to represent a set of relational records in a hierarchical spreadsheet kinda display. This task is typical to most of the business application user interfaces.

Typically in business applications, users like to view data in a spreadsheet kind of display. (Columns represent timeline(typically) and rows represent measures like sales/inventory/blah/blah).

The data itself is typically stored internally as relational records. For example, here is some sales info (stored internally in a relational database)

	-------------------------------------
	Region, City, Product, Date, Quantity
	-------------------------------------
	Texas, Dallas, Fruits, Dec-2003, 300
	Texas, Dallas, Veggies, Jan-2004, 120
	Texas, Austin, Fruits, Nov-2003, 310
	Texas, Austin, Veggies, Feb-2004, 20
	-------------------------------------

The user will typically want to view the same data in a hierarchical(/spreadsheet) kinda display.

	------------------------------------------------------
	Prod / Date   Nov-2003  Dec-2003  Jan-2004  Feb-2004 
	------------------------------------------------------
	Texas
	  Dallas
		Fruits                  300             
		Veggies                           120 
	  Austin
		Fruits        310
		Veggies                                     20
	------------------------------------------------------

With web-based business apps, similar views are created in the browser using lots of html/jsp coding.

The Gtk2::TreeView is an excellent widget to display a similar presentation of data in a desktop app. But creating a (hierarchical) TreeView from flat relational data can require some recursive function coding. It would be great if all this recursive code could be abstracted out and packaged separately.

This high level widget is designed with that purpose in mind. This module will accept a relational feed of records and automatically convert it into a hierarchical treeview using the Gtk2::TreeView. The process involves invoking some recursive functions to build a TreeModel and populate it. Also, since the spreadsheet itself can be rather long horizontally, the widget also has a FreezePane capability.

Details on the widget including a screenshot can be found at: http://ofey.blogspot.com/2005/02/gtk2extreemaker.html

	use Gtk2 -init;
	use Gtk2::Ex::TreeMaker;

	# Create an array to contain the column_names. These names appear as the header for each column.
	# The first entry should be the title of the left side of the FreezePane.
	my $column_names = [
		'Name',
		'Nov-2003', 'Dec-2003', 'Jan-2004', 'Feb-2004'
	];

	# This api will have to be cleaned soon...
	# All the attributes of the cell in the treeview are specified here
	# The value for these attributes are to be populated from the recordset
	# The assumption is that the attributes are contained in the data record
	# in the same order towards the **end** of the record. (the last few fields)
	# Since we are using CellRendererText in the TreeView, any of the properties
	# of the CellRendererText can be passed using this mechanism
	# In addition to the properties of the CellRendererText, I have also added a
	# custom property called 'hyperlinked'.
	my $data_attributes = [
		{'text' => 'Glib::String'},
		{'editable' => 'Glib::Boolean'},
		{'hyperlinked' => 'Glib::Boolean'}, 
		{'background' => 'Glib::String'}, 
	];

	# Here is the set of relational records to be displayed
	my $recordset = [
		['Texas','Dallas','Fruits','Dec-2003','300',0,1,'red'],
		['Texas','Dallas','Veggies','Jan-2004','120',1,0,'blue'],
		['Texas','Austin','Fruits','Nov-2003','310',1,1,'white'],
		['Texas','Austin','Veggies','Feb-2004','20',0,1,'green']
	];

	# Initialize our new widget
	# The constructor requires two attributes
	# This constitutes of the $column_name and the $data_attributes as described above
	my $treemaker = Gtk2::Ex::TreeMaker->new($column_names, $data_attributes);

	# We will inject our relational recordset into the new widget
	$treemaker->set_data_flat(\@recordset);

	# Build the model
	$treemaker->build_model;

	# Create a root window to display the widget
	my $window = Gtk2::Window->new;
	$window->signal_connect(destroy => sub { Gtk2->main_quit; });

	# Add the widget to the root window
	$window->add($treemaker->get_widget());

	$window->set_default_size(500, 300);
	$window->show_all;
	Gtk2->main;

This is the constructor. Accepts two arguments.

First argument is the column_names list. Each element of the array is a hash. The hash uses 'ColumnName' as the key. For example,

	my $column_names = [
		'Name',
		'Nov-2003', 'Dec-2003', 'Jan-2004', 'Feb-2004'
	];

Second argument is the data_attributes list. Here you specify what attributes each record has. For example,

	my $data_attributes = [
		{'text' => 'Glib::String'},
		{'editable' => 'Glib::Boolean'},
		{'hyperlinked' => 'Glib::Boolean'}, 
		{'background' => 'Glib::String'}, 
	];

All the attributes of the cell in the treeview are specified here. The value for these attributes are to be populated from the recordset. The assumption is that the attributes are contained in the data record in the same order towards the **end** of the record. (the last few fields)

Since we are using Gtk2::CellRendererText in the TreeView, any of the properties of the Gtk2::CellRendererText can be passed using this mechanism In addition to the properties of the CellRendererText, I have also added a custom property called 'hyperlinked'.

This sub is used to inject the relational recordset into the widget. This sub accepts a set of relational records (an array of arrays) as the argument. For example,

	my $recordset = [
		['Texas','Dallas','Fruits','Dec-2003','300',0,1,'red'],
		['Texas','Dallas','Veggies','Jan-2004','120',1,0,'blue'],
		['Texas','Austin','Fruits','Nov-2003','310',1,1,'white'],
		['Texas','Austin','Veggies','Feb-2004','20',0,1,'green']
	];

Currently, four signals are suppoted

* cell-edited

Thrown only for 'editable' cells.

* cell-clicked

Thrown only for 'hyperlinked' cells.

* cell-enter

Thrown only for 'hyperlinked' cells.

* cell-leave

Thrown only for 'hyperlinked' cells.

This is the core recursive method that actually builds the tree.

Returns the widget that you can later attach to a root window or any other container.

This sub maps a TreeCell location into a flat record in the original recordset that was used to create this tree. The location of the TreeCell itself is denoted using two arguments, the Gtk2::TreePath that points to the row and the Column_ID that points to the column.

Using this information, the function then traverses the internal data structure and returns a record (an array object).

Here is a list of stuff that I plan to add to this module.

* Wake Up ! Add some more tests.

Ofey Aikon, <ofey.aikon at gmail dot com>

You tell me. Send me an email !

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Copyright 2004 Ofey Aikon, All Rights Reserved.

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Library General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public License for more details.

You should have received a copy of the GNU Library General Public License along with this library; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307 USA.