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Problem Suppose you have displayed two lists of thumbnail images using GtkIconView, and you would like to allow users to drag and drop images between the two views.
If you've tried the sample code in Part 3, you will find that it has one potential problem. If the user tries to drag an image and drop it in the same view, the program does not respond correctly.
In this Part 4, we will fix this (i.e. preventing users from dragging and dropping to same view) as shown below:
Solution
- We need to pass along additional info to the signal handler so that it knows from where it is dragged from.
- If it's from the same side (e.g. left to left, or right to right), we just ignore them.
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.
Sample Code The following image files are required by the sample code below. Please save a copy of the image files and put them in the same directory where you store the sample code.
 | square_red.jpg |
 | square_yellow.jpg |
 | square_green.jpg |
 | square_blue.jpg |
 | square_blue2.jpg |
 | square_blue3.jpg |
 | ball_red.png |
 | ball_yellow.png |
 | ball_blue3.png |
 | ball_blue3a.png |
 | ball_green3.png |
 | ball_green4.png |
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| <?php
$window = new GtkWindow();
$window->set_title($argv[0]);
$window->set_size_request(600, 400);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());
// display title
$title = new GtkLabel("Drag and drop between two thumbnail images using GtkIconView\n".
" Part 3 - both directions (with insert)");
$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); // add a small gap
// Set up the two views
$hpane = new GtkHPaned();
$vbox->pack_start($hpane);
// the thumbnail image lists
// 0 = left
// 1 = right
$imagelist[0] = array('square_red.jpg', 'square_yellow.jpg', 'square_green.jpg',
'square_blue.jpg', 'square_blue2.jpg', 'square_blue3.jpg');
$imagelist[1] = array('ball_red.png', 'ball_yellow.png',
'ball_blue3.png', 'ball_blue3a.png',
'ball_green3.png', 'ball_green4.png',);
$left_vbox = setup_iconview(0, 'left');
$right_vbox = setup_iconview(1, 'right');
// setup drag and drop for left to right
$view[0]->drag_source_set(Gdk::BUTTON1_MASK, array( array( 'text/plain', 0, 0)),
Gdk::ACTION_COPY|Gdk::ACTION_MOVE);
$view[0]->connect('drag-data-get', 'on_drag', 'left'); // note 1
$view[1]->drag_dest_set(Gtk::DEST_DEFAULT_ALL,
array( array( 'text/plain', 0, 0)), Gdk::ACTION_COPY|Gdk::ACTION_MOVE);
$view[1]->connect('drag-data-received', 'on_drop', $view[0], 'right'); // note 1
// setup drag and drop for right to left
$view[1]->drag_source_set(Gdk::BUTTON1_MASK, array( array( 'text/plain', 0, 0)),
Gdk::ACTION_COPY|Gdk::ACTION_MOVE);
$view[1]->connect('drag-data-get', 'on_drag', 'right'); // note 1
$view[0]->drag_dest_set(Gtk::DEST_DEFAULT_ALL,
array( array( 'text/plain', 0, 0)), Gdk::ACTION_COPY|Gdk::ACTION_MOVE);
$view[0]->connect('drag-data-received', 'on_drop', $view[1], 'left'); // note 1
$hpane->add1($left_vbox);
$hpane->add2($right_vbox);
$view[0]->set_size_request(300, -1);
$window->show_all();
Gtk::main();
function setup_iconview($id, $label) {
global $imagelist, $model, $modelfilter, $view;
$model[$id] = new GtkListStore(GdkPixbuf::gtype, Gtk::TYPE_STRING);
foreach($imagelist[$id] as $img) {
$pixbuf = GdkPixbuf::new_from_file($img);
$model[$id]->append(array($pixbuf, $img));
}
$view[$id] = new GtkIconView($model[$id]);
$view[$id]->set_pixbuf_column(0); // col 0 of the model
$view[$id]->set_text_column(1); // col 1 of the model
$view[$id]->set_selection_mode(Gtk::SELECTION_MULTIPLE);
$view[$id]->set_columns(0);
$view[$id]->set_item_width(120);
$vbox = new GtkVBox();
$scrolled_win = new GtkScrolledWindow();
$scrolled_win->set_policy( Gtk::POLICY_AUTOMATIC,
Gtk::POLICY_AUTOMATIC);
$vbox->pack_start($scrolled_win);
$scrolled_win->add($view[$id]);
return $vbox;
}
// process drag
function on_drag($widget, $context, $data, $info, $time, $from_view) {
$selection = $widget->get_selected_items();
if (count($selection)==0) return; // return if there's no selection
$data->set_text(serialize(array($from_view, $selection))); // note 2
}
// process drop
function on_drop($widget, $context, $x, $y, $data, $info, $time, $src_view, $to_view) {
$data = unserialize($data->data);
$from_view = $data[0];
$selection = $data[1];
if ($from_view == $to_view) { // note 3
return true;
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Explanation The above sample code is based on Part 2.
What's new here:
- Note how we pass along additional info along with the signal so that the signal handler will be able to know from which side the image is dragged from.
- Note how we pass along the variable
$from_view together with the dragged info.
- Check if it's from the same side. If yes, just ignore the drag.
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