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/*
* Copyright (c) 2016, 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 8015070
* @summary Tests for artifacts around the edges of anti-aliased text
* drawn over translucent background color.
*/
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.IOException;
public class AntialiasedTextArtifact {
/* Image dimensions */
private static final int TEST_IMAGE_WIDTH = 2800;
private static final int TEST_IMAGE_HEIGHT = 100;
private static final String TEST_STRING =
"The quick brown fox jumps over the lazy dog. 0123456789.";
/*
* The artifacts appear when text is drawn ontop of translucent
* background. In other words, a background with alpha channel.
* Hence we test the algorithm for image types that contain either
* straight alpha channel or pre-multiplied alpha channel. In
* addition we test the images with other common pixel formats.
*/
private static final int[] TYPES = {BufferedImage.TYPE_INT_ARGB,
BufferedImage.TYPE_INT_ARGB_PRE,
BufferedImage.TYPE_4BYTE_ABGR,
BufferedImage.TYPE_4BYTE_ABGR_PRE,
BufferedImage.TYPE_INT_RGB,
BufferedImage.TYPE_INT_BGR,
BufferedImage.TYPE_3BYTE_BGR};
public static void main(String[] args) throws IOException {
/* Iterate over different image types */
for (int type : TYPES) {
BufferedImage testImg = getBufferedImage(type);
/* Draw anti-aliased string and check for artifacts */
drawAntialiasedString(testImg);
checkArtifact(testImg);
}
}
private static BufferedImage getBufferedImage(int imageType) {
/* Create a Graphics2D object from the given image type */
BufferedImage image = new BufferedImage(TEST_IMAGE_WIDTH,
TEST_IMAGE_HEIGHT,
imageType);
return image;
}
private static void drawAntialiasedString(BufferedImage image) {
/* Create Graphics2D object */
Graphics2D graphics = (Graphics2D) image.getGraphics();
/* Fill the image with translucent color */
graphics.setColor(new Color(127, 127, 127, 127));
graphics.fillRect(0, 0, TEST_IMAGE_WIDTH, TEST_IMAGE_HEIGHT);
/* Drawstring with Antialiasing hint */
graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
Font font = new Font("Verdana" , Font.PLAIN, 60);
graphics.setFont(font);
graphics.setColor(new Color(255, 0, 0));
graphics.drawString(TEST_STRING, 10, 75);
graphics.dispose();
}
private static void checkArtifact(BufferedImage image) throws IOException {
int componentMask = 0xff;
int colorThreshold = 200;
int rowIndex = 0;
int colIndex = 0;
/* Loop through every pixel to check for possible artifact */
for (rowIndex = 0; rowIndex < image.getHeight(); rowIndex++) {
for (colIndex = 0; colIndex < image.getWidth(); colIndex++) {
/*
* API: getRGB(x,y) returns color in INT_ARGB color space.
* Extract individual color components with a simple mask.
*/
int colorValue = image.getRGB(colIndex, rowIndex);
int colorComponent1 = colorValue & componentMask;
int colorComponent2 = (colorValue>>8) & componentMask;
int colorComponent3 = (colorValue>>16) & componentMask;
/*
* Artifacts are predominantly a subjective decision based on
* the quality of the rendered image content. However, in the
* current use-case, the artifacts around the edges of the anti
* aliased text appear like spots of white pixels without any
* relation to the color of foreground text or the background
* translucent shape.
*
* To identify the artifact pixels, each color component from
* the testImage is compared with a constant threshold. The
* component threshold has been set based on observation from
* different experiments on mulitple Java versions.
*/
if (colorComponent1 >= colorThreshold
&& colorComponent2 >= colorThreshold
&& colorComponent3 >= colorThreshold) {
/* Artifact has been noticed. Report error. */
throw new RuntimeException("Test Failed.");
}
}
}
}
}
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