8057986: freetype code to get glyph outline does not handle initial control point properly

Reviewed-by: prr, dougfelt
Contributed-by: NBehdad Esfahbod &lt;behdad@google.com&gt;, Igor Kopylov <ikopylov@google.com>

src/share/native/sun/font/freetypeScaler.c

@@ -1201,86 +1201,60 @@ static int allocateSpaceForGP(GPData* gpdata, int npoints, int ncontours) {
         return 1;
 }
 
+static void addSeg(GPData *gp, jbyte type) {
+    gp->pointTypes[gp->numTypes++] = type;
+}
+
+static void addCoords(GPData *gp, FT_Vector *p) {
+    gp->pointCoords[gp->numCoords++] =  F26Dot6ToFloat(p->x);
+    gp->pointCoords[gp->numCoords++] = -F26Dot6ToFloat(p->y);
+}
+
+static int moveTo(FT_Vector *to, GPData *gp) {
+    if (gp->numCoords)
+        addSeg(gp, SEG_CLOSE);
+    addCoords(gp, to);
+    addSeg(gp, SEG_MOVETO);
+    return FT_Err_Ok;
+}
+
+static int lineTo(FT_Vector *to, GPData *gp) {
+    addCoords(gp, to);
+    addSeg(gp, SEG_LINETO);
+    return FT_Err_Ok;
+}
+
+static int conicTo(FT_Vector *control, FT_Vector *to, GPData *gp) {
+    addCoords(gp, control);
+    addCoords(gp, to);
+    addSeg(gp, SEG_QUADTO);
+    return FT_Err_Ok;
+}
+
+static int cubicTo(FT_Vector *control1,
+                   FT_Vector *control2,
+                   FT_Vector *to,
+                   GPData    *gp) {
+    addCoords(gp, control1);
+    addCoords(gp, control2);
+    addCoords(gp, to);
+    addSeg(gp, SEG_CUBICTO);
+    return FT_Err_Ok;
+}
+
 static void addToGP(GPData* gpdata, FT_Outline*outline) {
-    jbyte current_type=SEG_UNKNOWN;
-    int i, j;
-    jfloat x, y;
-
-    j = 0;
-    for(i=0; i<outline->n_points; i++) {
-        x =  F26Dot6ToFloat(outline->points[i].x);
-        y = -F26Dot6ToFloat(outline->points[i].y);
-
-        if (FT_CURVE_TAG(outline->tags[i]) == FT_CURVE_TAG_ON) {
-            /* If bit 0 is unset, the point is "off" the curve,
-             i.e., a Bezier control point, while it is "on" when set. */
-            if (current_type == SEG_UNKNOWN) { /* special case:
-                                                  very first point */
-                /* add segment */
-                gpdata->pointTypes[gpdata->numTypes++] = SEG_MOVETO;
-                current_type = SEG_LINETO;
-            } else {
-                gpdata->pointTypes[gpdata->numTypes++] = current_type;
-                current_type = SEG_LINETO;
-            }
-        } else {
-            if (current_type == SEG_UNKNOWN) { /* special case:
-                                                   very first point */
-                if (FT_CURVE_TAG(outline->tags[i+1]) == FT_CURVE_TAG_ON) {
-                    /* just skip first point. Adhoc heuristic? */
-                    continue;
-                } else {
-                    x = (x + F26Dot6ToFloat(outline->points[i+1].x))/2;
-                    y = (y - F26Dot6ToFloat(outline->points[i+1].y))/2;
-                    gpdata->pointTypes[gpdata->numTypes++] = SEG_MOVETO;
-                    current_type = SEG_LINETO;
-                }
-            } else if (FT_CURVE_TAG(outline->tags[i]) == FT_CURVE_TAG_CUBIC) {
-                /* Bit 1 is meaningful for 'off' points only.
-                   If set, it indicates a third-order Bezier arc control
-                   point; and a second-order control point if unset.  */
-                current_type = SEG_CUBICTO;
-            } else {
-                /* two successive conic "off" points forces the rasterizer
-                   to create (during the scan-line conversion process
-                   exclusively) a virtual "on" point amidst them, at their
-                   exact middle. This greatly facilitates the definition of
-                   successive conic Bezier arcs.  Moreover, it is the way
-                   outlines are described in the TrueType specification. */
-                if (current_type == SEG_QUADTO) {
-                    gpdata->pointCoords[gpdata->numCoords++] =
-                        F26Dot6ToFloat(outline->points[i].x +
-                        outline->points[i-1].x)/2;
-                    gpdata->pointCoords[gpdata->numCoords++] =
-                        - F26Dot6ToFloat(outline->points[i].y +
-                        outline->points[i-1].y)/2;
-                    gpdata->pointTypes[gpdata->numTypes++] = SEG_QUADTO;
-                }
-                current_type = SEG_QUADTO;
-            }
-        }
-        gpdata->pointCoords[gpdata->numCoords++] = x;
-        gpdata->pointCoords[gpdata->numCoords++] = y;
-        if (outline->contours[j] == i) { //end of contour
-            int start = j > 0 ? outline->contours[j-1]+1 : 0;
-            gpdata->pointTypes[gpdata->numTypes++] = current_type;
-            if (current_type == SEG_QUADTO &&
-            FT_CURVE_TAG(outline->tags[start]) != FT_CURVE_TAG_ON) {
-                gpdata->pointCoords[gpdata->numCoords++] =
-                            (F26Dot6ToFloat(outline->points[start].x) + x)/2;
-                gpdata->pointCoords[gpdata->numCoords++] =
-                            (-F26Dot6ToFloat(outline->points[start].y) + y)/2;
-            } else {
-                gpdata->pointCoords[gpdata->numCoords++] =
-                            F26Dot6ToFloat(outline->points[start].x);
-                gpdata->pointCoords[gpdata->numCoords++] =
-                            -F26Dot6ToFloat(outline->points[start].y);
-            }
-            gpdata->pointTypes[gpdata->numTypes++] = SEG_CLOSE;
-            current_type = SEG_UNKNOWN;
-            j++;
-        }
-    }
+    static const FT_Outline_Funcs outline_funcs = {
+        (FT_Outline_MoveToFunc) moveTo,
+        (FT_Outline_LineToFunc) lineTo,
+        (FT_Outline_ConicToFunc) conicTo,
+        (FT_Outline_CubicToFunc) cubicTo,
+        0, /* shift */
+        0, /* delta */
+    };
+
+    FT_Outline_Decompose(outline, &outline_funcs, gpdata);
+    if (gpdata->numCoords)
+        addSeg(gpdata, SEG_CLOSE);
 
     /* If set to 1, the outline will be filled using the even-odd fill rule */
     if (outline->flags & FT_OUTLINE_EVEN_ODD_FILL) {

test/java/awt/font/GlyphVector/GlyphVectorOutline.java

+/*
+ * Copyright (c) 2014 Google Inc. 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.
+ */
+
+import java.awt.Color;
+import java.awt.Font;
+import java.awt.Graphics2D;
+import java.awt.Image;
+import java.awt.font.FontRenderContext;
+import java.awt.font.GlyphVector;
+import java.awt.font.LineBreakMeasurer;
+import java.awt.font.TextAttribute;
+import java.awt.font.TextLayout;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.text.AttributedString;
+
+import javax.imageio.ImageIO;
+
+/**
+ * Manual test for:
+ * JDK-8057986: freetype code to get glyph outline does not handle initial control point properly
+ *
+ * Manual repro recipe:
+ * (cd test/java/awt/font/GlyphVector/ && javac GlyphVectorOutline.java && wget -q -O/tmp/msgothic.ttc https://browserlinux-jp.googlecode.com/files/msgothic.ttc && java GlyphVectorOutline /tmp/msgothic.ttc /tmp/katakana.png)
+ *
+ * Then examine the two rendered Japanese characters in the png file.
+ *
+ * Renders text to a PNG by
+ * 1. using the native Graphics2D#drawGlyphVector implementation
+ * 2. filling in the result of GlyphVector#getOutline
+ *
+ * Should be the same but is different for some CJK characters
+ * (e.g. Katakana character \u30AF).
+ *
+ * @author ikopylov@google.com (Igor Kopylov)
+ */
+public class GlyphVectorOutline {
+    public static void main(String[] args) throws Exception {
+        if (args.length != 2) {
+            throw new Error("Usage: java GlyphVectorOutline fontfile outputfile");
+        }
+        writeImage(new File(args[0]),
+                   new File(args[1]),
+                   "\u30AF");
+    }
+
+    public static void writeImage(File fontFile, File outputFile, String value) throws Exception {
+        BufferedImage image = new BufferedImage(200, 200, BufferedImage.TYPE_INT_RGB);
+        Graphics2D g = image.createGraphics();
+        g.setColor(Color.WHITE);
+        g.fillRect(0, 0, image.getWidth(), image.getHeight());
+        g.setColor(Color.BLACK);
+
+        Font font = Font.createFont(Font.TRUETYPE_FONT, fontFile);
+        font = font.deriveFont(Font.PLAIN, 72f);
+        FontRenderContext frc = new FontRenderContext(null, false, false);
+        GlyphVector gv = font.createGlyphVector(frc, value);
+        g.drawGlyphVector(gv, 10, 80);
+        g.fill(gv.getOutline(10, 180));
+        ImageIO.write(image, "png", outputFile);
+    }
+
+    private static void drawString(Graphics2D g, Font font, String value, float x, float y) {
+        AttributedString str = new AttributedString(value);
+        str.addAttribute(TextAttribute.FOREGROUND, Color.BLACK);
+        str.addAttribute(TextAttribute.FONT, font);
+        FontRenderContext frc = new FontRenderContext(null, true, true);
+        TextLayout layout = new LineBreakMeasurer(str.getIterator(), frc).nextLayout(Integer.MAX_VALUE);
+        layout.draw(g, x, y);
+    }
+}