Problem
This is in response to vlada's post titled "Automatic scrolling".
He has inserted some items in a linear list using GtkTreeView, and he would like to the treeview to automatically scroll to the newly inserted item.
In Part 1, we make use of the mathod GtkTreeView::scroll_to_cell()
.
In this Part 2, we achieve the same effect by setting GtkAdjustment of GtkScrolledWindow as shown below:
Solution
- First get the vadjustment of the scrolled window using GtkScrolledwindow::get_vadjustment().
- Then we scroll to the last row by setting the value of the vadjustment to the maximum with GtkAdjustment::value_changed().
Sample Code
1 2 3 4 5 6 7 8 9 10 11 12 13 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 98 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 125 126 127 136 137 138 139 | <?php $window = new GtkWindow(); $window->set_size_request(400, 210); $window->connect_simple('destroy', array('Gtk','main_quit')); $window->add($vbox = new GtkVBox()); // display title $title = new GtkLabel(" Scroll to newly inserted item in linear list\n". "Part 2 - setting GtkAdjustment of GtkScrolledWindow"); $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); $vbox->pack_start($hbox = new GtkHBox(), 0, 0); $button = new GtkButton('Insert New Item'); $hbox->pack_start($button, 0, 0); $button->connect('clicked', 'on_click'); // the 2D table $data = array( array('row0', 'item 42', 2, 3.1), array('row1', 'item 36', 20, 6.21), array('row2', 'item 21', 8, 9.36), array('row3', 'item 10', 11, 12.4), array('row4', 'item 7', 5, 15.5), array('row5', 'item 4', 17, 18.6), array('row6', 'item 3', 20, 21.73)); display_table($vbox, $data); $window->show_all(); Gtk::main(); function display_table($vbox, $data) { // Set up a scroll window global $scrolled_win; $scrolled_win = new GtkScrolledWindow(); $scrolled_win->set_policy( Gtk::POLICY_AUTOMATIC, Gtk::POLICY_AUTOMATIC); $vbox->pack_start($scrolled_win); // Creates the list store global $view, $model; 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); } $selection = $view->get_selection(); $selection->connect('changed', 'on_selection'); } // self-defined function to format the price column function format_col($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'; $cell->set_property('cell-background', $row_color); } // the function that is called when user selects a row function on_selection($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_click($button) { global $model; $n = $model->iter_n_children(NULL); $model->append(array("row$n", "item $n", rand(1,20), sqrt(rand(1,100)))); global $scrolled_win; $adj = $scrolled_win->get_vadjustment(); // note 1 $adj->set_value($adj->upper); // note 2 } ?> |
Output
As shown above.
Explanation
The above code is based on How to scroll to newly inserted item in a linear list using GtkTreeView - Part 1 - using GtkTreeView scroll_to_cell?
What's new here:
- Get the vadjustment.
- Scroll to the last row by setting the vadjustment to the upper boundary (i.e. the maximum value)
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