[4599] in java-interest
Disappearing Text
daemon@ATHENA.MIT.EDU (Michael Afergan)
Mon Jan 8 19:03:50 1996
From: mikea@ai.mit.edu (Michael Afergan)
To: java-interest@java.sun.com
Date: Mon, 08 Jan 96 17:21:32 GMT
I am slightly confused as to when the background is cleared with
repaint(). I am trying to create a simple message scroller using the
following code:
g.drawString(""+mes.charAt(c++),200,200);
g.copyArea(20,180,200,40,-20,0);
Obviously there's more to it, but I would think that the above code
would place the next letter of mes (a String) at 200,200, and move the
rectangle defined by (20,180) and (220,220) - which contains the new character
- back 20 units.
I could then place the next character at the end, slide it back, add
another, etc.
Obiously there must be more to the code, but I have encountered a
basic error that prevents any such procedure: When I return to paint(), the
text is no longer there.
To test this phenomenon, I used the following code:
public void paint(Graphics g) {
if (c >= 10)
c = 0;
g.drawString(""+mes.charAt(c),200+5*c,200+5*c);
}
public boolean mouseDown( java.awt.Event evt, int x, int y ) {
repaint();
}
At first I thought this code would cause my message to be printed
diagonally down the applet - one letter each time I clicked it. While each
new character was displayed, previous characters were no longer there.
Am I missing something? Can anyone show me an example of a simple
text scroller?
Thanks,
-- Mike
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