Accessing and Modifying the Attributes of Window Components

 

Each window component maintains a database of its attributes.  After a component has been added to the application window, the programmer can access or modify its attributes by calling the appropriate methods. These methods typically have the forms 

widget.getAttributeName()

widget.setAttributeName(newValue)

As you have seen in the hello world example, a label has a text font and a foreground color that can be modified in this manner.  A label also can show either text or an image, depending on the setting of these attributes.  The next program, which displays an image and a caption, shows how to set the image, font, and color attributes of labels.

 

import javax.swing.*;

import BreezySwing.*;

import java.awt.Color;

import java.awt.Font;

 

public class ImageDemo extends GBFrame{

 

    public ImageDemo(Icon image){

        JLabel imageLabel = addLabel ("", 1,1,1,1);

        imageLabel.setIcon (image);

        JLabel captionLabel = addLabel ("Smokey the Cat", 2,1,1,1);

        captionLabel.setFont (new Font ("Verdana", Font.ITALIC, 24));

        captionLabel.setForeground (Color.blue);

    }

 

    // Create and display the window when the app launches

    public static void main(String[] args){

        Icon image = new ImageIcon ("smokey.jpg");

        JFrame frm = new ImageDemo (image);

        // Set the window's dimensions, leaving room for the title bar and caption

        frm.setSize (image.getIconWidth(), image.getIconHeight() + 50);

        frm.setVisible (true);

    }

}

 

Note that the main method of this program loads the image from a file before the window is created, and passes this image as an argument to the window's constructor. The main method then uses the width and height of the image to set the width and height of the window. Here is the window produced by the program: