With the composite we theoretically back off the LCD text anyway, so
modulo
pipe selection bugs both hints ought to end up in the grayscale path
which is
showing the poor rendering - on some builds.
I'm not sure of the details of why its so poor or if in fact its
semi-reasonable for that
composite but it doesn't occur in current JDK 7 builds - not since b17 -
when back in those early days of JDK 7 (Summer 2007), I fixed
6263951: Java does not use fast AA text loops when regular AA hint is set
That is presumably what cures this garbage although I'm not sure we
should be using
the regular loops in this case, ie its not so much fixed as incorrectly
masked.
As for why its not happening in OpenJDK, in either case, if you are
talking about 6 open,
or the current jdk 7 source, since openjdk6 forked off jdk7 b23, it
inherited the fix.
Anyway, here's a (full) program that for me on jdk6u22 and jdk7 b115
looks exactly
as bad as you report and you'll notice its not really text rendering at
all. Just filling
a path.
import javax.swing.*;
import java.awt.*;
import java.awt.font.*;
import static java.awt.RenderingHints.*;
public class SRC_EA extends Component {
public static void main(String[] args) {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add("Center", new SRC_EA());
f.pack();
f.setVisible(true);
}
public Dimension getPreferredSize() {
return new Dimension(100,100);
}
public void paint(Graphics g) {
Font f = new Font("Dialog", Font.PLAIN, 12);
g.setFont(f);
g.setColor(Color.white);
g.fillRect(0,0,400,300);
g.setColor(Color.black);
Graphics2D g2 = (Graphics2D)g;
g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC,
0.01f));
g2.setRenderingHint(KEY_ANTIALIASING, VALUE_ANTIALIAS_ON);
FontRenderContext frc = g2.getFontRenderContext();
GlyphVector gv = f.createGlyphVector(frc, "ABCDEFGHIJKL");
Shape s = gv.getOutline(20,20);
g2.fill(s);
}
}
-phil.
On 10/27/2010 2:06 PM, Denis Lila wrote:
Hi Clemens.
It's interesting to note that this doesn't happen on OpenJDK, and
on closed java the subpixel hint is not necessary to reproduce this.
Simply using VALUE_ANTIALIAS_ON and the SRC composite is enough.
Regards,
Denis.
----- "Clemens Eisserer"<linuxhi...@gmail.com> wrote:
Hi,
While playing arround with the SRC composition rule I found what
seems
to be a bug.
When rendering text with an AlphaComposite(SRC, EA) I get garbage
when
enabling subpixel antialising:
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC,
0.01f));
g2d.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
RenderingHints.VALUE_TEXT_ANTIALIAS_LCD_VBGR);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setColor(Color.black);
g2d.drawString("This text is painted with black color", 50,
50);
If I comment out the KEY_ANTIALIASING hint, which shouldn't have any
effect on text rendering, extra alpha is ignored but the text is
rendered correctly.
Should I file a but?
Thanks, Clemens
