This script below draws a combination of squares and text on a Gnome2::Canvas. I want to guarantee that the text will always be visible above the squares, but the script doesn't work as intended.

I'm using Gnome2::Canvas::Item->lower_to_bottom() and ->raise(). There's a white background, which is placed like this:

    $bg->lower_to_bottom();

Then there are some red squares, which are placed like this:

    $square->lower_to_bottom();
    $square->raise(1);

[download]

Finally, there is some text, which is placed like this:

    $text->lower_to_bottom();
    $text->raise(2);

[download]

Clicking on a red square destroys its canvas object, and replaces it with a (new) yellow square, placed in the same way:

    $replaceSquare->lower_to_bottom();
    $replaceSquare->raise(1);

[download]

Unfortunately, the example script doesn't have the desired effect. Initially, four of the five text labels are drawn beneath their (red) squares. The text is only revealed by clicking on the red square.

Can anyone tell me what I'm doing wrong?

#!/usr/bin/perl
package canvas;

use strict;
use diagnostics;
use warnings;

use Gtk2 '-init';
use Glib qw(TRUE FALSE);
use Gnome2::Canvas;

# Canvas size doesn't matter that much, as long as it's a bit bigger t
+han the window
my $size = 600;
my $flipFlag = FALSE;

# Create the window
my $window = Gtk2::Window->new();

$window->set_title('Canvas');
$window->set_position('center');
$window->set_default_size($size, $size);
$window->set_border_width(5);
$window->signal_connect (destroy => sub { Gtk2->main_quit; });

# Add a VBox containing a Gnome2::Canvas
my $vBox = Gtk2::VBox->new(FALSE, 0);

my $canvasFrame = Gtk2::Frame->new(undef);
$canvasFrame->set_border_width(3);

my $canvasScroller = Gtk2::ScrolledWindow->new();
$canvasScroller->set_border_width(3);
$canvasScroller->set_policy('always','always');

my $canvas = Gnome2::Canvas->new();
$canvas->set_scroll_region(0, 0, $size, $size);
$canvas->set_center_scroll_region(1);
$canvas->set_pixels_per_unit(1);
my $canvasRoot = $canvas->root();

$canvasScroller->add($canvas);
$canvasFrame->add($canvasScroller);
$vBox->pack_start($canvasFrame, TRUE, TRUE, 0);
$window->add($vBox);

# Draw a white background
my $bg = Gnome2::Canvas::Item->new (
    $canvasRoot,
    'Gnome2::Canvas::Rect',
    x1 => 0,
    y1 => 0,
    x2 => $size,
    y2 => $size,
    fill_color => '#FFFFFF',
    outline_color => '#FFFFFF',
);

$bg->lower_to_bottom();

# Draw some squares above the background
for (my $count = 0; $count < 5; $count++) {

    my ($square, $posn, $newColour);
    
    $posn = ($count * 100);
    
    $square = Gnome2::Canvas::Item->new(
        $canvasRoot,
        'Gnome2::Canvas::Rect',
        x1 => ($posn + 10),
        y1 => ($posn + 10),
        x2 => ($posn + 60),
        y2 => ($posn + 60),
        outline_color => '#000000',
        fill_color => '#FF0000',
    );

    $square->lower_to_bottom();
    $square->raise(1);

    # Click on a red square? Then destroy it, and replace it with a ye
+llow one!
    $square->signal_connect (event => sub {

        my ($widget, $event) = @_;  

        my $replaceSquare;

        if ($event->type eq 'button-press') {

            $square->destroy();

            $replaceSquare = Gnome2::Canvas::Item->new(
                $canvasRoot,
                'Gnome2::Canvas::Rect',
                x1 => ($posn + 10),
                y1 => ($posn + 10),
                x2 => ($posn + 60),
                y2 => ($posn + 60),
                outline_color => '#000000',
                fill_color => '#FFFF00',
            );

            $replaceSquare->lower_to_bottom();
            $replaceSquare->raise(1);
        }
    });
}

# Draw some blue text above the squares
for (my $count = 0; $count < 5; $count++) {

    my $text = Gnome2::Canvas::Item->new(
        $canvasRoot,
        'Gnome2::Canvas::Text',
        x => (($count * 100) + 25),
        y => (($count * 100) + 25),
        fill_color => '#0000FF',
        font => 'Sans',
        size => 10000,
        anchor => 'GTK_ANCHOR_W',
         text => 'Hello world!', 
    );

    $text->lower_to_bottom();
    $text->raise(2);
}

# Open the window
$window->show_all();
Gtk2->main();

[download]

In reply to Gnome2::Canvas - things on top of other things by Anonymous Monk

Title:
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