1 /*
2 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23 import java.awt.Color;
24 import java.awt.Font;
25 import java.awt.Graphics2D;
26 import java.awt.RenderingHints;
27 import java.awt.image.BufferedImage;
28 import java.io.IOException;
29
30 /**
31 * @test
32 * @bug 8015070
33 * @summary Tests for artifacts around the edges of anti-aliased text
34 * drawn over translucent background color.
35 */
36 public class AntialiasedTextArtifact {
37 /* Image dimensions */
38 private static final int TEST_IMAGE_WIDTH = 2800;
39 private static final int TEST_IMAGE_HEIGHT = 100;
40 private static final String TEST_STRING =
41 "The quick brown fox jumps over the lazy dog. 0123456789.";
42
43 /*
44 * The artifacts appear when text is drawn ontop of translucent
45 * background. In other words, a background with alpha channel.
46 * Hence we test the algorithm for image types that contain either
47 * straight alpha channel or pre-multiplied alpha channel. In
48 * addition we test the images with other common pixel formats.
49 */
50 private static final int[] TYPES = {BufferedImage.TYPE_INT_ARGB,
51 BufferedImage.TYPE_INT_ARGB_PRE,
52 BufferedImage.TYPE_4BYTE_ABGR,
53 BufferedImage.TYPE_4BYTE_ABGR_PRE,
54 BufferedImage.TYPE_INT_RGB,
55 BufferedImage.TYPE_INT_BGR,
56 BufferedImage.TYPE_3BYTE_BGR};
57
58 public static void main(String[] args) throws IOException {
59 /* Iterate over different image types */
60 for (int type : TYPES) {
61 BufferedImage testImg = getBufferedImage(type);
62
63 /* Draw anti-aliased string and check for artifacts */
64 drawAntialiasedString(testImg);
65 checkArtifact(testImg);
66 }
67 }
68
69 private static BufferedImage getBufferedImage(int imageType) {
70 /* Create a Graphics2D object from the given image type */
71 BufferedImage image = new BufferedImage(TEST_IMAGE_WIDTH,
72 TEST_IMAGE_HEIGHT,
73 imageType);
74 return image;
75 }
76
77 private static void drawAntialiasedString(BufferedImage image) {
78 /* Create Graphics2D object */
79 Graphics2D graphics = (Graphics2D) image.getGraphics();
80
81 /* Fill the image with translucent color */
82 graphics.setColor(new Color(127, 127, 127, 127));
83 graphics.fillRect(0, 0, TEST_IMAGE_WIDTH, TEST_IMAGE_HEIGHT);
84
85 /* Drawstring with Antialiasing hint */
86 graphics.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING,
87 RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
88 Font font = new Font("Verdana" , Font.PLAIN, 60);
89 graphics.setFont(font);
90 graphics.setColor(new Color(255, 0, 0));
91 graphics.drawString(TEST_STRING, 10, 75);
92 graphics.dispose();
93 }
94
95 private static void checkArtifact(BufferedImage image) throws IOException {
96 int componentMask = 0xff;
97 int colorThreshold = 200;
98 int rowIndex = 0;
99 int colIndex = 0;
100
101 /* Loop through every pixel to check for possible artifact */
102 for (rowIndex = 0; rowIndex < image.getHeight(); rowIndex++) {
103 for (colIndex = 0; colIndex < image.getWidth(); colIndex++) {
104 /*
105 * API: getRGB(x,y) returns color in INT_ARGB color space.
106 * Extract individual color components with a simple mask.
107 */
108 int colorValue = image.getRGB(colIndex, rowIndex);
109 int colorComponent1 = colorValue & componentMask;
110 int colorComponent2 = (colorValue>>8) & componentMask;
111 int colorComponent3 = (colorValue>>16) & componentMask;
112
113 /*
114 * Artifacts are predominantly a subjective decision based on
115 * the quality of the rendered image content. However, in the
116 * current use-case, the artifacts around the edges of the anti
117 * aliased text appear like spots of white pixels without any
118 * relation to the color of foreground text or the background
119 * translucent shape.
120 *
121 * To identify the artifact pixels, each color component from
122 * the testImage is compared with a constant threshold. The
123 * component threshold has been set based on observation from
124 * different experiments on mulitple Java versions.
125 */
126 if (colorComponent1 >= colorThreshold
127 && colorComponent2 >= colorThreshold
128 && colorComponent3 >= colorThreshold) {
129 /* Artifact has been noticed. Report error. */
130 throw new RuntimeException("Test Failed.");
131 }
132 }
133 }
134 }
135 }