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258 CHAPTER 12 ■ ADDING IMAGES

Figure 12-1. A broken image icon

Using a Stock ID

In previous examples, you have seen how to create images for buttons and menu items by using

stock IDs. A stock ID is a shortcut that identifies a commonly used image. You can also create

a regular image from a stock ID by using new_from_stock. This static constructor takes the stock

ID plus a size. The size is defined by a GtkIconSize constant. Stock images come in different sizes

so that they can be used for different purposes. Each use has its own size constant, as follows:

• Gtk::ICON_SIZE_MENU: A small image normally used in menus.

• Gtk::ICON_SIZE_SMALL_TOOLBAR: A small version of the icon used for toolbars.

• Gtk::ICON_SIZE_LARGE_TOOLBAR: A larger version of the toolbar icon.

• Gtk::ICON_SIZE_BUTTON: The version normally used for buttons.

• Gtk::ICON_SIZE_DND: The icon size used when an item is dragged.

• Gtk::ICON_SIZE_DIALOG: The version normally used in dialog windows.

Using a Pixel Buffer

Another way to create an image is from data in memory. An image stored in memory can usu￾ally be found in a GdkPixbuf. A pixel buffer (or pixbuf ) is simply a representation of the image

in memory. It cannot be displayed on its own; it is just data. You can put an image into a pixbuf

when an application is started to allow commonly used images to be loaded more quickly.

A pixbuf can be created from a file, just as an image can be created. To create a pixbuf

from a file, call the static constructor new_from_file and pass a file path. Listing 12-1 creates

a pixbuf from a file and then creates an image from the pixbuf using the static constructor

new_from_pixbuf.

Listing 12-1. Loading an Image into a GdkPixbuf and Then a GtkImage

<?php

// Create a window to display the image.

$window = new GtkWindow();

// Close the application cleanly.

$window->connect_simple('destroy', array('Gtk', 'main_quit'));

// Load a pixbuf from a file.

$pb = GdkPixbuf::new_from_file('Crisscott/images/logo.png');

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CHAPTER 12 ■ ADDING IMAGES 259

// Create the image from the pixbuf.

$image = GtkImage::new_from_pixbuf($pb);

// Add the image to the window.

$window->add($image);

// Show the image and the window.

$window->show_all();

// Start the main loop.

Gtk::main();

?>

Using GdkPixbuf and GtkImage, we can now add product images to the Crisscott PIMS

application. Product images should appear in two places: in the product summary area and in

the product editing tool.

Listing 12-2 shows the code added to the Crisscott_Tools_ProductEdit class to allow the

user to add or change a product image. The added lines include a GtkEntry for entering the path

to the image file and the code to display the images. In this example, the creation of the pixbuf

is wrapped in a try/catch block. That is because if the file for the pixbuf is not found, an excep￾tion will be thrown. This allows the application to detect a failure to load an image.

Listing 12-2. Adding Product Images to the Application

<?php

// The added lines from the product summary area.

class Crisscott_Tools_ProductSummary extends GtkTable {

// ...

public function displaySummary(Crisscott_Product $product)

{

// Set the product.

$this->product = $product;

// Set the attribute labels to the values of the product.

$this->productName->set_text($product->name);

$this->productType->set_text($product->type);

// Get the category information.

require_once 'Crisscott/Inventory.php';

$inv = Crisscott_Inventory::singleton();

$cat = $inv->getCategoryById($product->categoryId);

// Set the category name.

$this->productCategory->set_text($cat->name);

// Set the product price.

$this->productPrice->set_text($product->price);

// Remove the current product image.

$this->productImage->remove($this->productImage->get_child());

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260 CHAPTER 12 ■ ADDING IMAGES

// Try to add the product image.

try {

// Create a pixbuf.

$pixbuf = GdkPixbuf::new_from_file($product->imagePath);

// Create an image from the pixbuf.

$this->productImage->add(GtkImage::new_from_pixbuf($pixbuf));

// Show the image.

$this->productImage->show_all();

} catch (Exception $e) {

// Just fail silently.

}

}

// ...

}

class Crisscott_Tools_ProductEdit extends GtkTable {

// ...

private function _layout()

{

// Set up the data entry widgets.

// ...

$this->imageContainer = new GtkFrame();

$this->imagePathEntry = new GtkEntry();

// ...

// Set up the labels.

// ...

$this->imageLabel = new GtkLabel('Image');

// Set the labels' size.

// ...

$this->imageLabel->set_size_request(100, -1);

// ...

// Next align each label within the parent container.

// ...

$this->imageLabel->set_alignment(0, .5);

// Make all of the labels use markup.

// ...

$this->imageLabel->set_use_markup(true);

// ...

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