[pygobject] demo: Add TreeModel interface implementation demonstration

[Simon Feltman <sfeltman src gnome org>]

commit 8c838b683220bcbf2091bba97b91ddb56b275aed
Author: Simon Feltman <sfeltman src gnome org>
Date:   Tue Jan 14 23:46:44 2014 -0800

    demo: Add TreeModel interface implementation demonstration
    
    Add demo which shows how to implement the Gtk.TreeModel interfaces virtual
    methods.

 demos/gtk-demo/demos/TreeView/treemodel_large.py |  143 ++++++++++++++++++++++
 1 files changed, 143 insertions(+), 0 deletions(-)
---
diff --git a/demos/gtk-demo/demos/TreeView/treemodel_large.py 
b/demos/gtk-demo/demos/TreeView/treemodel_large.py
new file mode 100644
index 0000000..b129521
--- /dev/null
+++ b/demos/gtk-demo/demos/TreeView/treemodel_large.py
@@ -0,0 +1,143 @@
+# -*- Mode: Python; py-indent-offset: 4 -*-
+# pygobject - Python bindings for the GObject library
+# Copyright (C) 2014 Simon Feltman
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser 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
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, see <http://www.gnu.org/licenses/>.
+
+title = "Tree Model with Large Data"
+description = """
+Implementation of the Gtk.TreeModel interface to create a custom model.
+The demo uses a fake data store (it is not backed by a Python list) and is for
+the purpose of showing how to override the TreeModel interfaces virtual methods.
+"""
+
+from gi.repository import GObject
+from gi.repository import GLib
+from gi.repository import Gtk
+
+
+class Model(GObject.Object, Gtk.TreeModel):
+    columns_types = (str, str)
+    item_count = 100000
+    item_data = 'abcdefghijklmnopqrstuvwxyz'
+
+    def __init__(self):
+        super(Model, self).__init__()
+
+    def do_get_flags(self):
+        return Gtk.TreeModelFlags.LIST_ONLY
+
+    def do_get_n_columns(self):
+        return len(self.columns_types)
+
+    def do_get_column_type(self, n):
+        return self.columns_types[n]
+
+    def do_get_iter(self, path):
+        # Return False and an empty iter when out of range
+        index = path.get_indices()[0]
+        if index < 0 or index >= self.item_count:
+            return False, None
+
+        it = Gtk.TreeIter()
+        it.user_data = index
+        return True, it
+
+    def do_get_path(self, it):
+        return Gtk.TreePath([it.user_data])
+
+    def do_get_value(self, it, column):
+        if column == 0:
+            return str(it.user_data)
+        elif column == 1:
+            return self.item_data
+
+    def do_iter_next(self, it):
+        # Return False if there is not a next item
+        next = it.user_data + 1
+        if next >= self.item_count:
+            return False
+
+        # Set the iters data and return True
+        it.user_data = next
+        return True
+
+    def do_iter_previous(self, it):
+        prev = it.user_data - 1
+        if prev < 0:
+            return False
+
+        it.user_data = prev
+        return True
+
+    def do_iter_children(self, parent):
+        # If parent is None return the first item
+        if parent is None:
+            it = Gtk.TreeIter()
+            it.user_data = 0
+            return True, it
+        return False, None
+
+    def do_iter_has_child(self, it):
+        return it is None
+
+    def do_iter_n_children(self, it):
+        # If iter is None, return the number of top level nodes
+        if it is None:
+            return self.item_count
+        return 0
+
+    def do_iter_nth_child(self, parent, n):
+        if parent is not None or n >= self.item_count:
+            return False, None
+        elif parent is None:
+            # If parent is None, return the nth iter
+            it = Gtk.TreeIter()
+            it.user_data = n
+            return True, it
+
+    def do_iter_parent(self, child):
+        return False, None
+
+
+def main(demoapp=None):
+    model = Model()
+    # Use fixed-height-mode to get better model load and display performance.
+    view = Gtk.TreeView(fixed_height_mode=True, headers_visible=False)
+    column = Gtk.TreeViewColumn()
+    column.props.sizing = Gtk.TreeViewColumnSizing.FIXED
+
+    renderer1 = Gtk.CellRendererText()
+    renderer2 = Gtk.CellRendererText()
+    column.pack_start(renderer1, expand=True)
+    column.pack_start(renderer2, expand=True)
+    column.add_attribute(renderer1, 'text', 0)
+    column.add_attribute(renderer2, 'text', 1)
+    view.append_column(column)
+
+    scrolled = Gtk.ScrolledWindow()
+    scrolled.add(view)
+
+    window = Gtk.Window(title=title)
+    window.set_size_request(480, 640)
+    window.add(scrolled)
+    window.show_all()
+    GLib.timeout_add(10, lambda *args: view.set_model(model))
+    return window
+
+
+if __name__ == "__main__":
+    window = main()
+    window.connect('destroy', Gtk.main_quit)
+    Gtk.main()