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8299255: Unexpected round errors in FreetypeFontScaler

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Reviewed-by: prr, serb
This commit is contained in:
Toshio Nakamura 2022-12-24 14:26:42 +00:00
parent 5e861e3965
commit 26868c1ac4
2 changed files with 74 additions and 5 deletions
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10
src/java.desktop/share/native/libfontmanager/freetypeScaler.c
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2007, 2021, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2007, 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
@ -525,10 +525,10 @@ Java_sun_font_FreetypeFontScaler_createScalerContextNative(
ptsz = 1.0;
}
context->ptsz = (int)(ptsz * 64);
context->transform.xx = FloatToFTFixed((float)dmat[0]/ptsz);
context->transform.yx = -FloatToFTFixed((float)dmat[1]/ptsz);
context->transform.xy = -FloatToFTFixed((float)dmat[2]/ptsz);
context->transform.yy = FloatToFTFixed((float)dmat[3]/ptsz);
context->transform.xx = FloatToFTFixed((float)(dmat[0]/ptsz));
context->transform.yx = -FloatToFTFixed((float)(dmat[1]/ptsz));
context->transform.xy = -FloatToFTFixed((float)(dmat[2]/ptsz));
context->transform.yy = FloatToFTFixed((float)(dmat[3]/ptsz));
context->aaType = aa;
context->fmType = fm;

69
test/jdk/java/awt/FontClass/FontScalerRoundTest.java Normal file
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@ -0,0 +1,69 @@
/*
* Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @bug 8299255
* @summary Verify no round error in Font scaling
*/
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.font.LineMetrics;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
public class FontScalerRoundTest {
public static void main(String[] args) {
final double SCALE = 4096.0;
final double STEP = 0.0001;
final double LIMIT = STEP * 100.0;
BufferedImage img = new BufferedImage(100, 100,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
FontRenderContext frc = g2d.getFontRenderContext();
Font font = new Font(Font.DIALOG, Font.PLAIN, 1);
float h1 = getScaledHeight(font, frc, SCALE);
float h2 = getScaledHeight(font, frc, SCALE + STEP);
float diff = Math.abs(h1 - h2);
if (diff > LIMIT) {
throw new RuntimeException("Font metrix had round error " +
h1 + "," + h2);
}
}
private static float getScaledHeight(Font font,
FontRenderContext frc,
double scale) {
AffineTransform at = new AffineTransform(scale, 0.0, 0.0, scale,
0.0, 0.0);
Font transFont = font.deriveFont(at);
LineMetrics m = transFont.getLineMetrics("0", frc);
return m.getHeight();
}
}