Use the constructor to create a new empty, drawing area widget.
In the example, we use the "expose-event" to draw a simple checkerboard. A word of caution, this example is not intented to illustrate a real-world use of this widget, because the same effect can be brought in a much easier manner using a GtkImage. What is important to understand is the underlying concept of how the widget works.
Example 52. Simple checkerboard using a GtkDrawingArea
<?php
/* Define some constants */
define("SIZE", 10);
define("SPACING", 2);
/* The drawing area's Expose Event Callback */
function doExpose($widget, $event)
{
/* Red and White colors for the squares */
$color1 = new GdkColor(30000, 0, 30000);
$color2 = new GdkColor(65535, 65535, 65535);
/* A graphics context for the red box */
$gc1 = new GdkGC($widget->window);
$gc1->set_rgb_fg_color($color1);
/* A graphics context for the white box */
$gc2 = new GdkGC($widget->window);
$gc2->set_rgb_fg_color($color2);
/* Values to start painting with */
$xcount = 0;
$x = SPACING;
/* Traverse columns */
while ($x < $widget->allocation->width)
{
$y = SPACING;
$ycount = $xcount % 2;
/* Traverse rows */
while ($y < $widget->allocation->height)
{
/* Even number mean paint red box, else white box */
if ($ycount % 2) {
$gc = $gc1;
} else {
$gc = $gc2;
}
/* Paint a rectangle measuring SIZExSIZE */
$widget->window->draw_rectangle($gc, true, $x, $y, SIZE, SIZE);
/* Next row */
$y += SIZE + SPACING;
++$ycount;
}
/* Next column */
$x += SIZE + SPACING;
++$xcount;
}
/* Job's done, no more painting! */
return true;
}
/* Create the Window and Drawing area objects */
$win = new GtkWindow();
$dra = new GtkDrawingArea();
/* Connect callbacks and start */
$dra->connect('expose-event', 'doExpose');
$win->connect_simple('destroy', array('Gtk', 'main_quit'));
$win->set_title('Drawing Area Demo');
$win->add($dra);
$win->set_size_request(250,250);
$win->show_all();
Gtk::main();
?>
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