Hello,
A question for 2D experts..... I'm working for a JavaTV project over at cup01,
and currently writing some test codes for 2D graphics.
There seems to be a problem in doing DST_OVER in jdk 1.2 without using
BufferedImage. When we try to do alphablending DST_OVER onscreen or with
traditional Image class, then a graphics primitive with DST_OVER composite does
not display at all! SRC_OVER worked fine in every case.
This is a problem as there is no BufferedImage implementation in our JavaTV 2D
code. Is there any document/workaround for it?
Below are the three paint methods. The first one displays the oval, the others
do not. Also modifying Composite.java at
http://java.sun.com/docs/books/tutorial/2d/display/compositing.html
reproduced the bug.
Thank you for any help you can give me,
regards,
Chihiro
________________________
Chihiro Saito
[EMAIL PROTECTED]
408-517-6847 (x66847)
________________________
Case 1: Using BufferedImage, works
public void paint( Graphics g ) {
Graphics2D g2 = (Graphics2D) g;
Dimension d = getSize();
BufferedImage buffImg = new BufferedImage( d.width, d.height, Buffered
Image.TYPE_INT_ARGB);
Graphics2D gbi = buffImg.createGraphics();
gbi.setColor( java.awt.Color.darkGray );
gbi.fillRect( 30, 30, d.width/2, d.height/2);
gbi.setComposite(
AlphaComposite.getInstance( AlphaComposite.DST_OVER, 0.5f));
gbi.setColor( java.awt.Color.pink );
gbi.fillOval( 100, 100, d.width/2, d.height/2);
g2.drawImage(buffImg, null, 0, 0);
}
Case 2: Using Image, the oval does not show up
public void paint( Graphics g ) {
Graphics2D g2 = (Graphics2D) g;
Dimension d = getSize();
Image buffImg = createImage(d.width, d.height);
Graphics2D gbi = (Graphics2D) buffImg.getGraphics();
gbi.setColor( java.awt.Color.darkGray );
gbi.fillRect( 30, 30, d.width/2, d.height/2);
gbi.setComposite(
AlphaComposite.getInstance( AlphaComposite.DST_OVER, 0.5f));
gbi.setColor( java.awt.Color.pink );
gbi.fillOval( 100, 100, d.width/2, d.height/2);
g2.drawImage(buffImg, 0, 0, this);
}
Case 3: Painting directly onscreen, the oval does not show up
public void paint( Graphics g ) {
Graphics2D g2 = (Graphics2D) g;
Dimension d = getSize();
g2.setColor( java.awt.Color.darkGray );
g2.fillRect( 30, 30, d.width/2, d.height/2);
g2.setComposite(
AlphaComposite.getInstance( AlphaComposite.DST_OVER, 0.5f));
g2.setColor( java.awt.Color.pink );
g2.fillOval( 100, 100, d.width/2, d.height/2);
}
________________________
Chihiro Saito
[EMAIL PROTECTED]
408-517-6847 (x66847)
________________________
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