REGRESSION: paint is not reliably called on resize & has varied clipping applied

Name: gm110360 Date: 04/09/2002


FULL PRODUCT VERSION :
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)

FULL OPERATING SYSTEM VERSION :MS Windows 98


ADDITIONAL OPERATING SYSTEMS :Linux RedHat 7.0



A DESCRIPTION OF THE PROBLEM :
The new graphics handling in 1.4 introduces an
incompatibility with earlier
versions of Java, and inconsistency in the use of paint()
between Microsoft
platforms and Unix.

If a window is resized to enlarge the window, under MS
Windows, only
the newly exposed part of the window is drawn in the paint
method; the
existing area is clipped out of the drawing and remains
unmodified.
Under Unix, the whole window is painted by paint().

If the window is reduced in size, paint is not called at
all, on either
MS or Unix platforms. I am unable to find any documented
way of changing
this behaviour.

The following code demonstrates the problems. Under 1.3 or
earlier, a
rectangle is drawn in the window after any window resize,
with the previous
contents first cleared. Under 1.4, depending on the
platform and the nature
of the resize, pieces of rectangle get drawn, or multiple
rectangles get
drawn, or no rectangles get redrawn.

There no longer seems to be a way to have the whole window
cleared and
redrawn on every window resize on all hardware platforms.



REGRESSION. Last worked in version 1.3.1

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1.Run the example program under Windows or Unix.
2.In several steps, resize the Frame to enlarge it,
observing the rectangles or pieces of rectangle that get
drawn.
3.Resize the window to reduce its size, observing the
absence of output in the Frame and in the originating
window.

EXPECTED VERSUS ACTUAL BEHAVIOR :
The Frame should have been cleared on each resize, and a
single complete rectangle should be drawn after each resize
operation, regardless of whether the window was enlarged or
reduced in size.

This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.*;
import java.awt.event.*;

class Resize extends Frame
{
   public static void main( String arg[] )
   {
      Resize instance = new Resize();
   }

   public Resize()
   {
      super("Try resizing this window");
      Dimension scr = Toolkit.getDefaultToolkit().getScreenSize();
      setSize(scr.width/3,scr.height/4);
      setLocation(scr.width/3,scr.height/3);
      show();
      addKeyListener( new KeyAdapter()
      {
         public void keyTyped(KeyEvent e)
         {
            System.exit(0);
         }
      } );
   }

      /** Redraw the window contents whenever it is exposed. */
   public void paint(Graphics g)
   {
      Dimension sz = getSize();
      System.err.println("Width "+getWidth()+
         ", Height "+getHeight() );
      int height = 4*sz.height/5;
      int width = 4*sz.width/5;
      int x = (sz.width - width)/2; /* center the rectangle */
      int y = (sz.height - height)/2;

      g.drawRect(x,y,width,height);
   }
}
---------- END SOURCE ----------

CUSTOMER WORKAROUND :
Graphics as has traditionally been practiced under Java is
no longer possible.

Release Regression From : 1.3.1_03
The above release value was the last known release where this
bug was known to work. Since then there has been a regression.

(Review ID: 145151)
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