493. How to setup a button in GtkTreeView - Part 1?

Problem

At least for now, there is still no GtkCellRenderer yet to display a native button inside a treeview.

However, since the main functionality of a button is to respond to button clicks, we can simulate a button using gif, png or jpg image files as shown below.

To make the button more realistic, I used two gif images for the button   one more button up, and one for button down.

How to setup a button in GtkTreeView - Part 1?


Solution

  • We make use of the signal button-press-event on the treeview to detect any "clicks" on the image button.
  • We make use of the signal button-release-event on the treeview to detect when the user releases the button.
  • We make use of the technique from How to display gif or jpg images in GtkTreeView - Part 1? to display a gif image in treeview.
  • Note that I've made extensive use of the notation $model[$path][$col_num]. This greatly simplifies the codes instead of using $model->get_value($iter, $col_num) and $model->set($iter, $col_num, $value) (in which case you have to always convert the path to the iter first). If you're not familiar with this, I would strongly encourage you to read this article by Andrei Zmievski titled New GtkTreeModel functionality.

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.

 button_click.gif
 button_click2.gif

1   
 2   
 3   
 4   
 5   
 6   
 7   
 8   
 9   
 10   
 11   
 12   
 13   
 14   
 15   
 16   
 17   
 18   
 19   
 20   
 21   
 22   
 23   
 24   
 25   
 26   
 27   
 28   
 29   
 30   
 31   
 32   
 33   
 34   
 35   
 36   
 37   
 38   
 39   
 40   
 41   
 42   
 43   
 44   
 45   
 46   
 47   
 48   
 49   
 50   
 51   
 52   
 53   
 54   
 55   
 56   
 57   
 58   
 59   
 60   
 61   
 62   
 63   
 64   
 65   
 66   
 67   
 68   
 69   
 70   
 71   
 72   
 73   
 74   
 75   
 76   
 77   
 78   
 79   
 80   
 81   
 82   
 83   
 84   
 85   
 86   
 87   
 88   
 89   
 90   
 91   
 92   
 93   
 94   
 95   
 96   
 97   
 98   
 99   
100   
101   
102   
103   
104   
105   
106   
107   
108   
109   
110   
111   
114   
115   
116   
117   
118   
121   
122   
123   
124   
125   
127   
128   
129   
130   
131   
133   
134   
135   
136   
137   
138   
139   
140   
141   
142   
146   
148   
149   
151   
152   
153   
154   
155   
156   
157   
159   
160   
161   
162   
163   
164   
165   
166   
167   
168   
169   
171   
172   
173   
174   
175   
176   
<?php
$window = new GtkWindow();
$window->set_size_request(400, 200);
$window->connect_simple('destroy', array('Gtk','main_quit'));
$window->add($vbox = new GtkVBox());

// display title
$title = new GtkLabel("Setup a button in GtkTreeView - Part 1");
$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);

// the 2D table
$data = array(
array('row0', 'item 42', 2, 3.1, 0),
array('row1', 'item 36', 20, 6.21, 0),
array('row2', 'item 21', 8, 9.36, 0),
array('row3', 'item 10', 11, 12.4, 0),
array('row4', 'item 7', 5, 15.5, 0),
array('row5', 'item 4', 17, 18.6, 0),
array('row6', 'item 3', 20, 21.73, 0));

display_table($vbox, $data);

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

function display_table($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, GObject::TYPE_LONG);
    } else {
        $model = new GtkListStore(Gtk::TYPE_STRING, Gtk::TYPE_STRING,
                    Gtk::TYPE_LONG, Gtk::TYPE_DOUBLE, Gtk::TYPE_LONG);
    }
    $field_header = array('Row #', 'Description', 'Qty', 'Price', 'Action');
    $field_justification = array(0.0, 0.0, 0.5, 1.0, 0.0);

    // Creates the view to display the list store
    $view = new GtkTreeView($model);
    $scrolled_win->add($view);
    $view->connect('button-press-event', 'on_buttonpress', $model); // note 1
    $view->connect('button-release-event', 'on_buttonrelease', $model); // note 2

    // Creates the columns
    for ($col=0; $col<count($field_header); ++$col) {

        if ($col==4) {
            $cell_renderer = new GtkCellRendererPixbuf(); // note 3
            $column = new GtkTreeViewColumn();
            $column->pack_start($cell_renderer);
            $column->set_title($field_header[$col]);

        } else {

            $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);
            if ($col==1) $column->set_expand(1);
        }

        // 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);
    }

    $selection = $view->get_selection();
    $selection->set_mode(Gtk::SELECTION_NONE);
}

// self-defined function to display alternate row color
function format_col($column, $cell, $model, $iter, $col_num) {
    if ($col_num==4) {
        if ($model[$iter][4]) { // note 4
            $pixbuf = GdkPixbuf::new_from_file("button_click2.gif"); // note 4
        } else {
            $pixbuf = GdkPixbuf::new_from_file("button_click.gif"); // note 4
        }
        $cell->set_property('pixbuf', $pixbuf);
    }
    $path = $model->get_path($iter);
    $row_num = $path[0];
    $row_color = ($row_num%2==1) ? '#dddddd' : '#ffffff';
    $cell->set_property('cell-background', $row_color);
}

function on_buttonpress($view, $event, $model) {
    static $i=0;
    if ($event->button==1 && $event->type==4) {
        ++$i;
        // get the row and column
        $path_array = $view->get_path_at_pos($event->x, $event->y);
        $path = $path_array[0][0];
        $col = $path_array[1];
        $col_title = $col->get_title();
        clear_all_buttons($model);
        if ($col_title!='Action') return true;
        $model[$path][4] = 1;
        echo "$i: You have clicked the button for {$model[$path][0]}: {$model[$path][1]}\n"; // note 5
        return true;
    } else {
        clear_all_buttons($model);
        return false;
    }
}

function on_buttonrelease($view, $event, $model) {
    if ($event->button==1) {
        // get the row and column
        $path_array = $view->get_path_at_pos($event->x, $event->y);
        $path = $path_array[0][0];
        $col = $path_array[1];
        $col_title = $col->get_title();
        if ($col_title!='Action') {
            clear_all_buttons($model);
            return true;
        }
        $model[$path][4] = 0;
        return true;
    } else {
        clear_all_buttons($model);
        return false;
    }
}

function clear_all_buttons($model) { // note 6
    $n = $model->iter_n_children(null);
    for ($i=0; $i<$n; ++$i) {
        $iter = $model->get_iter($i);
        $model[$iter][4] = 0;
    }
}

?>

Output

As shown above.
 

Explanation

  1. Detect button click on the treeview.
  2. Detect button release on the treeview.
  3. Set up the column where the button image will appear. Note that there is no image loaded at this point in time. The respective images are loaded in the custom cell display function.
  4. This is the part that sets the image button depending on the status of the button.
  5. Try clicking the button in very fast sequence, and take note of the output in the command window. You will see that even though the treeview might not reflect that clicks fast enough, all the button clicks are indeed being captured.
  6. This function takes care of the case when the user clicks on a button, holds on to the mouse button, and moves away from the button. Since there is no button-release signal, the button will still be in the 'clicked' state. This function serves to release any previous button clicks that have not been released.

Related Links

Add comment

Security code
Refresh