The Java TM Tutorial

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Trail: Creating a GUI with JFC/Swing
Lesson: Working with Graphics

## Using Images

> This is an image:

> The next few pages provide the details you'll need to work with images. You'll learn how to load, display, and manipulate them.

> > Wait!: Although the API this section describes is valid for both JDK 1.1 and Java 2 (JDK 1.2), we recommend that you use Swing's built-in icon support instead. If Swing icons aren't sufficient and you're writing a program for Java 2, then consider using the Java 2D API, which is described in the 2D Graphics trail.

> Support for using images is spread across the `java.applet`, `java.awt`, and `java.awt.image` packages. Every image is represented by a `java.awt.Image` object. In addition to the `Image` class, the `java.awt` package provides other basic image support, such as the `Graphics` `drawImage` methods, the `Toolkit` `getImage` methods, and the `MediaTracker` class. In `java.applet`, the `Applet` `getImage` methods make it easy for applets to load images using URLs. Finally, the `java.awt.image` package provides interfaces and classes that let you create, manipulate, and observe images.

### Loading Images

> The AWT makes it easy to load images in either of two formats: GIF and JPEG. The `Applet` and `Toolkit` classes provide `getImage` methods that work for either format. You use them like this:

> >     myImage = getImage(URL); //in a method in an Applet subclass only
> >         or
> >     myImage = Toolkit.getDefaultToolkit().getImage(filenameOrURL);

> The `getImage` methods return immediately, so that you don't have to wait for an image to be loaded before going on to perform other operations in your program. While this improves performance, some programs require more control or information about image loading. You can track image loading status either by using the `MediaTracker` class or by implementing the `imageUpdate` method, which is defined by the `ImageObserver` interface.

> This section will also tell you how to create images on the fly by using the `MemoryImageSource` class.

### Displaying Images

> It's easy to display an image using the `Graphics` object that's passed into your `paintComponent` method. You simply invoke a `drawImage` method on the `Graphics` object. For example:

> >     g.drawImage(myImage, 0, 0, this);

> This section explains the four forms of `drawImage`, two of which scale the image. Like `getImage`, `drawImage` is asynchronous, returning immediately even if the image hasn't been fully loaded or painted yet.

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