8015070: Antialiased text on translucent backgrounds gets bright artifacts
Reviewed-by: flar, prr, jdv
Contributed-by: prahalad.kumar.narayanan@oracle.com
--- a/jdk/src/java.desktop/share/native/libawt/java2d/loops/FourByteAbgr.h Fri May 06 11:30:41 2016 +0100
+++ b/jdk/src/java.desktop/share/native/libawt/java2d/loops/FourByteAbgr.h Fri May 06 11:23:49 2016 +0000
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2000, 2008, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -191,4 +191,11 @@
COMP_PREFIX ## A, COMP_PREFIX ## R, \
COMP_PREFIX ## G, COMP_PREFIX ## B)
+/*
+ * SrcOver ## TYPE ## BlendFactor
+ * Returns appropriate blend value for use in blending calculations.
+ */
+#define SrcOverFourByteAbgrBlendFactor(dF, dA) \
+ (dA)
+
#endif /* FourByteAbgr_h_Included */
--- a/jdk/src/java.desktop/share/native/libawt/java2d/loops/FourByteAbgrPre.h Fri May 06 11:30:41 2016 +0100
+++ b/jdk/src/java.desktop/share/native/libawt/java2d/loops/FourByteAbgrPre.h Fri May 06 11:23:49 2016 +0000
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2000, 2008, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -217,4 +217,11 @@
(pRas)[4*(x)+3] = (jubyte) COMP_PREFIX ## R; \
} while (0)
+/*
+ * SrcOver ## TYPE ## BlendFactor
+ * Returns appropriate blend value for use in blending calculations.
+ */
+#define SrcOverFourByteAbgrPreBlendFactor(dF, dA) \
+ (dF)
+
#endif /* FourByteAbgrPre_h_Included */
--- a/jdk/src/java.desktop/share/native/libawt/java2d/loops/IntArgb.h Fri May 06 11:30:41 2016 +0100
+++ b/jdk/src/java.desktop/share/native/libawt/java2d/loops/IntArgb.h Fri May 06 11:23:49 2016 +0000
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -208,4 +208,11 @@
COMP_PREFIX ## A = (COMP_PREFIX ## A << 8) + COMP_PREFIX ## A; \
} while (0)
+/*
+ * SrcOver ## TYPE ## BlendFactor
+ * Returns appropriate blend value for use in blending calculations.
+ */
+#define SrcOverIntArgbBlendFactor(dF, dA) \
+ (dA)
+
#endif /* IntArgb_h_Included */
--- a/jdk/src/java.desktop/share/native/libawt/java2d/loops/IntArgbBm.h Fri May 06 11:30:41 2016 +0100
+++ b/jdk/src/java.desktop/share/native/libawt/java2d/loops/IntArgbBm.h Fri May 06 11:23:49 2016 +0000
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 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
@@ -206,4 +206,11 @@
COMP_PREFIX ## A = (COMP_PREFIX ## A << 8) + COMP_PREFIX ## A; \
} while (0)
+/*
+ * SrcOver ## TYPE ## BlendFactor
+ * Returns appropriate blend value for use in blending calculations.
+ */
+#define SrcOverIntArgbBmBlendFactor(dF, dA) \
+ (dA)
+
#endif /* IntArgbBm_h_Included */
--- a/jdk/src/java.desktop/share/native/libawt/java2d/loops/IntArgbPre.h Fri May 06 11:30:41 2016 +0100
+++ b/jdk/src/java.desktop/share/native/libawt/java2d/loops/IntArgbPre.h Fri May 06 11:23:49 2016 +0000
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -216,4 +216,11 @@
COMP_PREFIX ## G, \
COMP_PREFIX ## B)
+/*
+ * SrcOver ## TYPE ## BlendFactor
+ * Returns appropriate blend value for use in blending calculations.
+ */
+#define SrcOverIntArgbPreBlendFactor(dF, dA) \
+ (dF)
+
#endif /* IntArgbPre_h_Included */
--- a/jdk/src/java.desktop/share/native/libawt/java2d/loops/LoopMacros.h Fri May 06 11:30:41 2016 +0100
+++ b/jdk/src/java.desktop/share/native/libawt/java2d/loops/LoopMacros.h Fri May 06 11:23:49 2016 +0000
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 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
@@ -1668,31 +1668,83 @@
} \
} while (0);
+/*
+ * Antialiased glyph drawing results in artifacts around the character edges
+ * when text is drawn ontop of translucent background color. The standard
+ * blending equation for two colors:
+ * destColor = srcColor * glyphAlpha + destColor * (1 - glyphAlpha)
+ * works only when srcColor and destColor are opaque. For translucent srcColor
+ * and destColor, the respective alpha components in each color will influence
+ * the visibility of the color and the visibility of the color below it. Hence
+ * the equation for blending is given as:
+ * resA = srcAlpha + dstAlpha * (1 - srcAlpha)
+ * resCol = (srcColor * srcAlpha + destColor * destAlpha * (1- srcAlpha))/resA
+ * In addition, srcAlpha is multiplied with the glyphAlpha- that indicates the
+ * grayscale mask value of the glyph being drawn. The combined result provides
+ * smooth antialiased text on the buffer without any artifacts. Since the
+ * logic is executed for every pixel in a glyph, the implementation is further
+ * optimized to reduce computation and improve execution time.
+ */
#define GlyphListAABlend4ByteArgb(DST, GLYPH_PIXELS, PIXEL_INDEX, DST_PTR, \
FG_PIXEL, PREFIX, SRC_PREFIX) \
- do { \
- DeclareAlphaVarFor4ByteArgb(dstA) \
- DeclareCompVarsFor4ByteArgb(dst) \
+ do { \
+ DeclareAlphaVarFor4ByteArgb(resA) \
+ DeclareCompVarsFor4ByteArgb(res) \
jint mixValSrc = GLYPH_PIXELS[PIXEL_INDEX]; \
if (mixValSrc) { \
- if (mixValSrc < 255) { \
- jint mixValDst = 255 - mixValSrc; \
- Load ## DST ## To4ByteArgb(DST_PTR, pix, PIXEL_INDEX, \
- dstA, dstR, dstG, dstB); \
- dstA = MUL8(dstA, mixValDst) + \
- MUL8(SRC_PREFIX ## A, mixValSrc); \
- MultMultAddAndStore4ByteArgbComps(dst, mixValDst, dst, \
- mixValSrc, SRC_PREFIX); \
- if (!(DST ## IsOpaque) && \
- !(DST ## IsPremultiplied) && dstA && dstA < 255) { \
- DivideAndStore4ByteArgbComps(dst, dst, dstA); \
+ if (mixValSrc != 0xff) { \
+ PromoteByteAlphaFor4ByteArgb(mixValSrc); \
+ resA = MultiplyAlphaFor4ByteArgb(mixValSrc, SRC_PREFIX ## A); \
+ } else { \
+ resA = SRC_PREFIX ## A; \
+ } \
+ if (resA != MaxValFor4ByteArgb) { \
+ DeclareAndInvertAlphaVarFor4ByteArgb(dstF, resA) \
+ DeclareAndClearAlphaVarFor4ByteArgb(dstA) \
+ DeclareCompVarsFor4ByteArgb(dst) \
+ DeclareCompVarsFor4ByteArgb(tmp) \
+ MultiplyAndStore4ByteArgbComps(res, resA, SRC_PREFIX); \
+ if (!(DST ## IsPremultiplied)) { \
+ Load ## DST ## To4ByteArgb(DST_PTR, pix, PIXEL_INDEX, \
+ dstA, dstR, dstG, dstB); \
+ Store4ByteArgbCompsUsingOp(tmp, =, dst); \
+ } else { \
+ Declare ## DST ## AlphaLoadData(DstPix) \
+ jint pixelOffset = PIXEL_INDEX * (DST ## PixelStride); \
+ DST ## DataType *pixelAddress = PtrAddBytes(DST_PTR, \
+ pixelOffset); \
+ LoadAlphaFrom ## DST ## For4ByteArgb(pixelAddress, \
+ DstPix, \
+ dst); \
+ Postload4ByteArgbFrom ## DST(pixelAddress, \
+ DstPix, \
+ tmp); \
} \
- Store ## DST ## From4ByteArgbComps(DST_PTR, pix, \
- PIXEL_INDEX, dst); \
+ if (dstA) { \
+ DeclareAlphaVarFor4ByteArgb(blendF) \
+ dstA = MultiplyAlphaFor4ByteArgb(dstF, dstA); \
+ resA += dstA; \
+ blendF = SrcOver ## DST ## BlendFactor(dstF, dstA); \
+ if (blendF != MaxValFor4ByteArgb) { \
+ MultiplyAndStore4ByteArgbComps(tmp, \
+ blendF, \
+ tmp); \
+ } \
+ Store4ByteArgbCompsUsingOp(res, +=, tmp); \
+ } \
} else { \
Store ## DST ## PixelData(DST_PTR, PIXEL_INDEX, \
FG_PIXEL, PREFIX); \
+ break; \
} \
+ if (!(DST ## IsOpaque) && \
+ !(DST ## IsPremultiplied) && resA && \
+ resA < MaxValFor4ByteArgb) \
+ { \
+ DivideAndStore4ByteArgbComps(res, res, resA); \
+ } \
+ Store ## DST ## From4ByteArgbComps(DST_PTR, pix, \
+ PIXEL_INDEX, res); \
} \
} while (0);
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/jdk/test/java/awt/Graphics2D/DrawString/AntialiasedTextArtifact.java Fri May 06 11:23:49 2016 +0000
@@ -0,0 +1,136 @@
+/*
+ * 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.");
+ }
+ }
+ }
+ }
+}