doubleheadedscrollbarui.java

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import java.awt.Rectangle;
import java.awt.event.MouseEvent;

import javax.swing.JComponent;
import javax.swing.SwingConstants;
import javax.swing.event.MouseInputAdapter;
import javax.swing.plaf.metal.MetalScrollBarUI;
import javax.swing.plaf.metal.MetalScrollButton;


/**
 * DoubleHeadedScrollbarUI provides the look and feel (i.e., output and input)
 * for a DoubleHeadedScrollbar, by adding two draggable buttons to the 
 * ends of the thumb.
 */
public class DoubleHeadedScrollbarUI extends MetalScrollBarUI {

    /**
     * Attach this look-and-feel delegate to its component.
     * Typically creates and adds new subcomponents to c, 
     * attaches listeners, and intializes this delegate.
     *
     * @param c  scrollbar (must be a DoubleHeadedScrollbar) that
     *           this delegate will be handling input and output
     *           for.
     */
    public void installUI(JComponent c) {
        super.installUI(c);

        // here's how to create a left-pointing arrow button:
        // new MetalScrollButton(SwingConstants.WEST, scrollBarWidth, true);
    }
    
    /**
     * Called to set the bounding rectangle of the scroll thumb.
     * We override it here because we need to position buttons
     * on top of the thumb.
     * <p>
     * When the thumb is as big as the scrollbar, this method
     * is called with (0,0,0,0).
     *
     * @param x   left edge of thumb, relative to scrollbar's coordinate system
     * @param y    top edge of thumb, relative to scrollbar's coordinate system
     * @param width   width of thumb in pixels
     * @param height  height of thumb in pixels
     */
    protected void setThumbBounds(int x, int y, int width, int height) {
        super.setThumbBounds(x, y, width, height);

        // your code here
    }
}