framedbarmeter.java

书籍"Java_面向事件编程"的附带光盘代码

import objectdraw.*;
import java.awt.*;

// A FramedBarMeter displays a variable length rectangle on a
// background framed by a distinct border.
public class FramedBarMeter extends FramedDisplay {
    
    // Space between the frame and the bar
    private static final double INSET = BORDER + 2;
    
    // The bar itself
    private FilledRect bar;
    
    // Maximum width bar that will fit
    private double maxWidth;
    
    // Create frame and bar filling a fraction of the display
    public FramedBarMeter( double fraction,
                           double x, double y,
                           double width, double height,
                           DrawingCanvas canvas ) {
        
        super( x, y, width, height, canvas );
        
        maxWidth = width - 2*INSET;
        bar = new FilledRect( x + INSET,  y + INSET,
                              maxWidth*fraction, height - 2*INSET,
                              canvas );
        bar.setColor(Color.blue);
    }
    
    // Change the fraction of the display filled by the bar
    public void setFraction( double fraction) {
        bar.setWidth( maxWidth*fraction );
    }
}