From: Larry Liang <###@###.###>
This does not look like form output to me.


Hi,

There is a bug in the Container.java class,

Container.class line 349
if ((comp != null) && comp.inside(x - comp.x, y - comp.y)){

the inside() call should be:
comp.inside(x, y)

because it expects coordinates of the parent object, not relative to
the current component. This bug caused deliverEvent() to deliver
events to the wrong component. Thanks.

Larry
// This is an example program to show two bugs in AWT:
// The Container.locate() function and
// the Component.inside() function
//
// Container.locate(x, y) is supposed to return the component where the
// (x, y) coordinate falls. But in the call to comp.inside(), it incorrectly
// subtracted the location x and y value from the (x, y) parameter
// respectively, and causes the component returned by the locate function
// to be incorrect.
//
// Component.inside(x, y) is supposed to return true if the (x, y) point
// is inside the component, and false otherwise. But it fails to check
// if the (x, y) is less than the left edge and top edge. Therefore if
// the x < location().x or y < location().y, it still returns true.
//
// Usage:
// start the applet
// click in any one of the box
// The output should be:
// print the current box number
// print the box number to the right of current box
// iterate through all components of the parent, and
// print the box number of all those that have inside(x,y)
// returning a true value. If the inside function is
// correct, there should only be one box, the current box.
//
// Fix:
// In file "Container.java" line 349, replace:
// if ((comp != null) && comp.inside(x - comp.x, y - comp.y)) {
// with:
// if ((comp != null) && comp.inside(x, y)) {
//
// In file "Component.java" line 804, replace:
// return (x >= 0) && ((x-this.x) < width) && (y >= 0) && ((y-this.y) < height);
// with:
// return ((x-this.x) >= 0) && ((x-this.x) < width) && ((y-this.y) >= 0) && ((y-this.y) < height);
//

import java.awt.*;
import java.applet.*;

public class awtbug extends Applet {
   static int total = 9;

   public awtbug() {
      setLayout(new GridLayout(1, total));
      for(int i = 0; i < total; i++) {
         add(new TestButton(i));
      }
   }
}

class TestButton extends Canvas {
   public TestButton(int num) {
      this.num = num;
   }

   public void paint(Graphics g) {
      g.drawRect(0, 0, size().width - 2, size().height - 2);
      g.drawString(Integer.toString(num), size().width / 2,
                   size().height / 2);
   }

   public boolean mouseDown(Event e, int x, int y) {
      identify();
      Container parent = getParent();
      if(num < awtbug.total - 1) {
         e.translate(location().x, location().y);
         TestButton sibling = (TestButton) parent.locate(e.x+size().width, e.y);
         System.out.print("My right hand button is: ");
         sibling.identify();
      }

      System.out.println("("+e.x+","+e.y+") is in the following boxes:");
      int cnt = parent.countComponents();
      for(int i = 0; i < cnt; i++) {
         TestButton box = (TestButton) parent.getComponent(i);
         if(box.inside(e.x, e.y)) {
            box.identify();
         }
      }

      return(false);
   }

   public void identify() {
      System.out.println("Button " + num);
   }

   int num;
}