051. How to drag and drop between 2 GtkTreeViews - Part 2 - in both directions?

Problem

You have set up drag and drop of items from the treeview on the left to the treeview on the right in Part 1.

Now you would like to allow drag and drop between both treeviews (left-to-right and right-to-left) as shown below:

How to drag and drop between 2 GtkTreeViews - Part 2 - in both directions?


Solution


Sample Code

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<?php
$window = new GtkWindow();
$window->set_size_request(600, 240);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());

// display title
$title = new GtkLabel("Drag and Drop between 2 TreeViews - Part 2 (in both directions)");
$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);
$vbox->pack_start($hbox = new GtkHBox());

// Set up treeview 1
$data1 = array(
    array('row0', 'item 42', 2, 3.1),
    array('row1', 'item 36', 20, 6.21),
    array('row2', 'item 21', 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));
$view1 = display_table ($hbox, $data1);

// setup drag for left side
$view1->drag_source_set(Gdk::BUTTON1_MASK, 
    array( array( 'text/plain', 0, 0)), Gdk::ACTION_COPY|Gdk::ACTION_MOVE); // note 1
$view1->connect('drag-data-get', 'on_drag');

// setup drop for left side
$view1->drag_dest_set(Gtk::DEST_DEFAULT_ALL, 
    array( array( 'text/plain', 0, 0)), Gdk::ACTION_COPY|Gdk::ACTION_MOVE); // note 2
$hbox->pack_start(new GtkLabel('  '), 0, 0);

// Set up treeview 2
$data2 = array(
    array('row7', 'item 127', 105, 115.5),
    array('row8', 'item 124', 117, 118.6),
    array('row9', 'item 123', 120, 121.73));
$view2 = display_table ($hbox, $data2);

// setup drop for right side
$view2->drag_dest_set(Gtk::DEST_DEFAULT_ALL, 
    array( array( 'text/plain', 0, 0)), Gdk::ACTION_COPY|Gdk::ACTION_MOVE);// note 3
$view2->connect('drag-data-received', 'on_drop', $view1);

// setup drag for right side
$view2->drag_source_set(Gdk::BUTTON1_MASK, 
    array( array( 'text/plain', 0, 0)), Gdk::ACTION_COPY|Gdk::ACTION_MOVE); // note 4
$view2->connect('drag-data-get', 'on_drag');

// this is delayed till here because we need the ID of $view2
$view1->connect('drag-data-received', 'on_drop', $view2);

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

// display a 2D table in treeview
function display_table($container, $data) {

    // Set up a scroll window
    $scrolled_win = new GtkScrolledWindow();
    $scrolled_win->set_policy( Gtk::POLICY_AUTOMATIC,
        Gtk::POLICY_AUTOMATIC);
    $container->pack_start($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');
    return $view;
}

// format treeview columns
function format_col($column, $cell, $model, $iter, $col_num) {
    $path = $model->get_path($iter); // get the current path
    $row_num = $path[0]; // get the row number
    if ($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'; // sets the row color for odd and even rows
    $cell->set_property('cell-background', $row_color); // sets the background color
}

// the function that is called when user selects a row
function on_selection($selection) {
    list($model, $iter) = $selection->get_selected();
    if ($iter==null) return;
    $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_drag($widget, $context, $data, $info, $time) {
    $selection = $widget->get_selection();
    list($model, $iter) = $selection->get_selected();
    if ($iter==null) return;
    $id = $model->get_value($iter, 0);
    $desc = $model->get_value($iter, 1);
    $qty = $model->get_value($iter, 2);
    $price = $model->get_value($iter, 3);
    $data->set_text(serialize(array($id, $desc, $qty, $price)));
}

function on_drop($widget, $context, $x, $y, $data, $info, $time, $src_view) {
    // remove from src first
    $src_selection = $src_view->get_selection();
    list($src_model, $src_iter) = $src_selection->get_selected();
    if ($src_iter==null) {
        return;
    }
    $src_model->remove($src_iter);

    $data2 = unserialize($data->data);
    $model = $widget->get_model();
    $model->append($data2);
}

?>

Output

As shown above.

 

Explanation

Please refer to How to drag and drop between 2 GtkTreeViews - Part 1 - left to right? for more detailed explanations on setting up drag and drop for a treeview.

  • Set up drag on the left side.
  • Set up drop on the left side.
  • Set up drag on the right side.
  • Set up drop on the right side.

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