100. How to change window contents on the fly by adding and removing widgets?

Problem

This example serves to show that we can dynamically change the contents of a GtkWindow by selectively removing the unwanted widgets and replacing with new widgets.

The sample code below will first display a 2D array using GtkTable. At the click of a button, the same data will be displayed in a GtkTreeView. Click the button again, it will change back to using GtkTable.

How to change window contents on the fly by adding and removing widgets?


Solution


Sample Code

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<?php
$window = new GtkWindow();
$window->set_size_request(400, 300);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());

// display title
$title = new GtkLabel("Switch between GtkTable and GtkTreeview");
$title->modify_font(new PangoFontDescription("Times New Roman Italic 10"));
$title->modify_fg(Gtk::STATE_NORMAL, GdkColor::parse("#0000ff"));
$title->set_size_request(-1, 40);
$vbox->pack_start($title, 0, 0);

$vbox->pack_start(new GtkLabel(), 0, 0);
$button = new GtkButton('Change to GtkTreeView'); // note 2
$button->connect('clicked', 'on_button'); // note 2
$hbox = new GtkHBox();
$hbox->pack_start(new GtkLabel(''));
$hbox->pack_start($button, 0, 0);
$hbox->pack_start(new GtkLabel(''));
$vbox->pack_start($hbox, 0, 0);
$vbox->pack_start(new GtkLabel(), 0, 0);

// the 2D table
$data = array(
array('row0', 'item 19', 2, 3.1),
array('row1', 'item 16', 20, 6.21),
array('row2', 'item 13', 8, 9.36),
array('row3', 'item 10', 11, 12.4),
array('row4', 'item 7', 5, 15.5),
array('row5', 'item 4', 17, 18.6),
array('row6', 'item 3', 20, 21.73));

display_table_using_gtktable ($vbox, $data); // note 1

$window->show_all();
Gtk::main();

function display_table_using_gtktable($vbox, $a) {
    $vbox->pack_start($hbox = new GtkHBox());
    $hbox->pack_start(new GtkHBox());
    $hbox->pack_start($table = new GtkTable(), 0, 0);
    $hbox->pack_start(new GtkHBox());

    for ($row=0; $row<count($a); ++$row) {
        for ($col=0; $col<count($a[$row]); ++$col) {
            $frame = new GtkFrame(); // note 1
            $eventbox = new GtkEventBox(); // note 2
            $frame->add($eventbox); // note 3
            $eventbox->add(new GtkLabel($a[$row][$col])); // note 4
            if ($row==0) { // note 5
                $eventbox->modify_bg(Gtk::STATE_NORMAL, GdkColor::parse("#FFCC66"));
            } elseif ($row%2==0) { // note 6
                $eventbox->modify_bg(Gtk::STATE_NORMAL, GdkColor::parse("#CCFF99"));
            }
            $table->attach($frame, $col, $col+1, $row, $row+1,
                Gtk::FILL, Gtk::SHRINK, 0, 0);
        }
    }
}

function display_table_using_gtktreeview($vbox, $data) {
    // Set up a scroll window
    $scrolled_win = new GtkScrolledWindow();
    $scrolled_win->set_policy( Gtk::POLICY_AUTOMATIC, Gtk::POLICY_AUTOMATIC);
    $vbox->pack_start($scrolled_win);

    // Creates the list store
    if (defined("GObject::TYPE_STRING")) {
        $model = new GtkListStore(GObject::TYPE_STRING, GObject::TYPE_STRING,
                GObject::TYPE_LONG, GObject::TYPE_DOUBLE);
    } else {
        $model = new GtkListStore(Gtk::TYPE_STRING, Gtk::TYPE_STRING,
                    Gtk::TYPE_LONG, Gtk::TYPE_DOUBLE);
    }
    $field_header = array('Row #', 'Description', 'Qty', 'Price');
    $field_justification = array(0.0, 0.0, 0.5, 1.0);

    // Creates the view to display the list store
    $view = new GtkTreeView($model);
    $scrolled_win->add($view);

    // Creates the columns
    for ($col=0; $col<count($field_header); ++$col) {
        $cell_renderer = new GtkCellRendererText();
        $cell_renderer->set_property("xalign", $field_justification[$col]);
        $column = new GtkTreeViewColumn($field_header[$col], $cell_renderer, 'text', $col);
        $column->set_alignment($field_justification[$col]);
        $column->set_sort_column_id($col);

        // set the header font and color
        $label = new GtkLabel($field_header[$col]);
        $label->modify_font(new PangoFontDescription("Arial Bold"));
        $label->modify_fg(Gtk::STATE_NORMAL, GdkColor::parse("#0000FF"));
        $column->set_widget($label);
        $label->show();

        // setup self-defined function to display alternate row color
        $column->set_cell_data_func($cell_renderer, "format_col", $col);
        $view->append_column($column);
    }

    // pupulates the data
    for ($row=0; $row<count($data); ++$row) {
        $values = array();
        for ($col=0; $col<count($data[$row]); ++$col) {
            $values[] = $data[$row][$col];
        }
        $model->append($values);
    }

    // setup selection
    $selection = $view->get_selection();
    $selection->connect('changed', 'on_selection');
}

// display alternate row color
function format_col($column, $cell, $model, $iter, $col_num) {
    $path = $model->get_path($iter);
    $row_num = $path[0];
    if ($col_num==3) {
        $amt = $model->get_value($iter, 3);
        $cell->set_property('text', '$'.number_format($amt,2));
    }
    $row_color = ($row_num%2==1) ? '#dddddd' : '#ffffff';
    $cell->set_property('cell-background', $row_color);
}

// process user selection
function on_selection($selection) {
    list($model, $iter) = $selection->get_selected();
    $desc = $model->get_value($iter, 1);
    $qty = $model->get_value($iter, 2);
    $price = $model->get_value($iter, 3);
    print "You have selected $desc: $qty ($price)\n";
}

function on_button($button) {
    $button_label = $button->child->get_text(); // get button label

    global $vbox;
    $vbox_widgets = array();
    foreach($vbox->get_children() as $widget) { // note 3
        $vbox_widgets[] = $widget;
    }
    $last_widget = end($vbox_widgets); // note 4
    $vbox->remove($last_widget); // note 4

    global $data;
    if (preg_match("/GtkTreeView/", $button_label)) {
        display_table_using_gtktreeview ($vbox, $data); // note 5
        $button->child->set_text('Change to GtkTable');
    } else {
        display_table_using_gtktable ($vbox, $data); // note 5
        $button->child->set_text('Change to GtkTreeView');
    }
    global $window;
    $window->show_all(); // note 6
}

?>

Output

As shown above.
 

Explanation

We make use of the code in How to display a 2D array in table - Part 5? to display a 2D array using GtkTable, and the code in How to display a 2D array in GtkTreeView - Part 5 - get user selection? to display a 2D array using GtkTreeView.

What's new here:

  1. First display the 2D array in GtkTable.
  2. Set up the button.
  3. Get all the widgets inside $vbox.
  4. Both GtkTable and GtkTreeView happen to be the last widget inside $vbox. Let's get its ID and remove it!
  5. Display the 2D array again using the new format.
  6. Refresh the window contents.

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