Sams Teach Yourself Visual J++ 6 in 21 Days
(Publisher: Macmillan Computer Publishing)
Author(s): Rick Leinecker
ISBN: 0672313510
Publication Date: 11/01/98

The pictureBox properties allow you a lot of control in determining how your pictureBox displays the image and responds to users. Table 12.3 provides an easy reference to each property name, its description, and its default.

Referring to the image property: if you click the button on the right part of the field, it brings up a Selector box with which you can select the image that will be displayed. Now, suppose I have just selected a JPG file. As you can see in Figure 12.6, when you select an image file, it shows up in your control.

Figure 12.6  When you select an image file, it shows up in a control.

In some of the examples, we will change the visible property to False so that we can do our own image drawing and manipulation; but for most of your uses, this will always be set to True.

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Note:  In the name field, you can name your file anything you want. I recommend that you name it something that’s meaningful to your program for easier reference.

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// The pictureBox1 control already contains an image.
Image img = pictureBox1.getImage();

Displaying Images

To draw images, you’ll use the Graphics class’s drawImage() method. There are several variations of this, but the easiest one to use takes three arguments: the first argument as an Image class, the second argument as the x coordinate of the upper-left corner of the image, and the third argument as the y coordinate of the upper-left corner of the image. The following examples show you how to use this easiest form of drawImage() in both an application and an applet:

// Application
protected void onPaint( PaintEvent pe )
{
    // m_Image is an Image class that's already loaded
    int x = 10, y = 10;
    pe.graphics.drawImage( m_Image, x, y );
}
// Applet
public void paint( Graphics g )
{
    // m_Image is an Image class that's already loaded
    int x = 10, y = 10;
    g.drawImage( m_Image, x, y, this );
}

Figure 12.7 (shown after Listing 12.1) shows an application. The application used a pictureBox to load the image of the sailboats, but then the visible property of the pictureBox was set to False. Our first action, then, used the pictureBox’s getImage() method to get the image. Next we used the drawImage() method and the onPaint() method to draw this image ourselves. So rather than rely on pictureBox’s native drawing capabilities, we went ahead and drew the image ourselves. In this case, it was just to show you how to draw an image in an application. However, in the future at times you’ll want more control than a pictureBox offers, and you’ll want to draw the image yourself. The source code for an entire application is given in Listing 12.1.