475. How to drag and drop between 2 GtkTreeViews - Part 7 - another method of passing along complex drag info?

Problem

This is in response to Wim Stockman's post titled "Problem with serialize and unserialize on treeview DND (drag-and-drop)".

His application encountered some problem when the drag information contains some french accents such as

Solution

  • Store the drag info in some array. In the example below, we use the global array $drag_data.
  • In the drag information $data, store the index to this array.
  • In the 'drag-data-received' signal handlers, retrieve the index, and get the original data direct from the array.
  • Using this method, you can store any complex data structures for the drag info, including structures, arrays of arrays, images, etc.

Note: You might want to refer to Jake's comments why the problem occurs.


Sample Code

Important Note: This only works for PHP-GTK2 compliled with gtk+ v2.10 and above. If you are using an older version, for linux, you may follow the step-by-step instructions to recompile php-gtk2 with gtk+ v2.10. For windows, please refer to How to install php gtk2 on windows? You may also want to take a look here to see some of the new exciting PHP-GTK2 Functionalities.

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<?php
$window = new GtkWindow();
$window->set_title($argv[0]);
$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 7\n".
"Another method of passing along complex drag info");
$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);
$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);
$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);
$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);
$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);
    global $drag_data;
    $drag_data['a123'] = array($id, $desc, $qty, $price); // note 1
    $data->set_text('a123'); // note 2
}

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);

    $data_id = $data->data; // note 3
    echo "data_id = $data_id\n";
    global $drag_data;
    $data2 = $drag_data[$data_id]; // note 4
    print_r($data2);
    $model = $widget->get_model();

    $drop_info = $widget->get_dest_row_at_pos($x, $y);
    if ($drop_info) {
        list($path, $position) = $drop_info;
        if ($position == Gtk::TREE_VIEW_DROP_BEFORE ||
        $position == Gtk::TREE_VIEW_DROP_INTO_OR_BEFORE) {
            $model->insert($path[0], $data2) ;
        } else {
            $model->insert($path[0]+1, $data2) ;
        }
    } else {
        $model->append($data2);
    }

}

?>

Output

As shown above.

 

Explanation

We make use of the code from How to drag and drop between 2 GtkTreeViews - Part 4 - in both directions with insert?

What's new here:

  1. Store the drag info into the array $drag_data['a123']. Note that you can use any index for the array. Here I used 'a123'. You can use any index you like.
  2. Store the index of the array (i.e. 'a123') in the drag information $data.
  3. Retrieve the index.
  4. Retrieve the data.

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