8176501: Method Shape.getBounds2D() incorrectly includes Bezier contr…

…ol points in bounding box

Reviewed-by: prr

src/java.desktop/share/classes/java/awt/geom/CubicCurve2D.java

@@ -311,23 +311,6 @@ public void setCurve(float x1, float y1,
             this.y2     = y2;
         }
 
-        /**
-         * {@inheritDoc}
-         * @since 1.2
-         */
-        public Rectangle2D getBounds2D() {
-            float left   = Math.min(Math.min(x1, x2),
-                                    Math.min(ctrlx1, ctrlx2));
-            float top    = Math.min(Math.min(y1, y2),
-                                    Math.min(ctrly1, ctrly2));
-            float right  = Math.max(Math.max(x1, x2),
-                                    Math.max(ctrlx1, ctrlx2));
-            float bottom = Math.max(Math.max(y1, y2),
-                                    Math.max(ctrly1, ctrly2));
-            return new Rectangle2D.Float(left, top,
-                                         right - left, bottom - top);
-        }
-
         /**
          * Use serialVersionUID from JDK 1.6 for interoperability.
          */
@@ -558,23 +541,6 @@ public void setCurve(double x1, double y1,
             this.y2     = y2;
         }
 
-        /**
-         * {@inheritDoc}
-         * @since 1.2
-         */
-        public Rectangle2D getBounds2D() {
-            double left   = Math.min(Math.min(x1, x2),
-                                     Math.min(ctrlx1, ctrlx2));
-            double top    = Math.min(Math.min(y1, y2),
-                                     Math.min(ctrly1, ctrly2));
-            double right  = Math.max(Math.max(x1, x2),
-                                     Math.max(ctrlx1, ctrlx2));
-            double bottom = Math.max(Math.max(y1, y2),
-                                     Math.max(ctrly1, ctrly2));
-            return new Rectangle2D.Double(left, top,
-                                          right - left, bottom - top);
-        }
-
         /**
          * Use serialVersionUID from JDK 1.6 for interoperability.
          */
@@ -1509,6 +1475,15 @@ public boolean contains(Rectangle2D r) {
         return contains(r.getX(), r.getY(), r.getWidth(), r.getHeight());
     }
 
+
+    /**
+     * {@inheritDoc}
+     * @since 1.2
+     */
+    public Rectangle2D getBounds2D() {
+        return Path2D.getBounds2D(getPathIterator(null));
+    }
+
     /**
      * {@inheritDoc}
      * @since 1.2

src/java.desktop/share/classes/java/awt/geom/Path2D.java

@@ -802,23 +802,7 @@ public final void transform(AffineTransform at) {
          * @since 1.6
          */
         public final synchronized Rectangle2D getBounds2D() {
-            float x1, y1, x2, y2;
-            int i = numCoords;
-            if (i > 0) {
-                y1 = y2 = floatCoords[--i];
-                x1 = x2 = floatCoords[--i];
-                while (i > 0) {
-                    float y = floatCoords[--i];
-                    float x = floatCoords[--i];
-                    if (x < x1) x1 = x;
-                    if (y < y1) y1 = y;
-                    if (x > x2) x2 = x;
-                    if (y > y2) y2 = y;
-                }
-            } else {
-                x1 = y1 = x2 = y2 = 0.0f;
-            }
-            return new Rectangle2D.Float(x1, y1, x2 - x1, y2 - y1);
+            return getBounds2D(getPathIterator(null));
         }
 
         /**
@@ -1594,23 +1578,7 @@ public final void transform(AffineTransform at) {
          * @since 1.6
          */
         public final synchronized Rectangle2D getBounds2D() {
-            double x1, y1, x2, y2;
-            int i = numCoords;
-            if (i > 0) {
-                y1 = y2 = doubleCoords[--i];
-                x1 = x2 = doubleCoords[--i];
-                while (i > 0) {
-                    double y = doubleCoords[--i];
-                    double x = doubleCoords[--i];
-                    if (x < x1) x1 = x;
-                    if (y < y1) y1 = y;
-                    if (x > x2) x2 = x;
-                    if (y > y2) y2 = y;
-                }
-            } else {
-                x1 = y1 = x2 = y2 = 0.0;
-            }
-            return new Rectangle2D.Double(x1, y1, x2 - x1, y2 - y1);
+            return getBounds2D(getPathIterator(null));
         }
 
         /**
@@ -2131,6 +2099,88 @@ public final Rectangle getBounds() {
         return getBounds2D().getBounds();
     }
 
+    /**
+     * Returns a high precision bounding box of the specified PathIterator.
+     * <p>
+     * This method provides a basic facility for implementors of the {@link Shape} interface to
+     * implement support for the {@link Shape#getBounds2D()} method.
+     * </p>
+     *
+     * @param pi the specified {@code PathIterator}
+     * @return an instance of {@code Rectangle2D} that is a high-precision bounding box of the
+     *         {@code PathIterator}.
+     * @see Shape#getBounds2D()
+     */
+    static Rectangle2D getBounds2D(final PathIterator pi) {
+        final double[] coeff = new double[4];
+        final double[] deriv_coeff = new double[3];
+
+        final double[] coords = new double[6];
+
+        // bounds are stored as {leftX, rightX, topY, bottomY}
+        double[] bounds = null;
+        double lastX = 0.0;
+        double lastY = 0.0;
+        double endX = 0.0;
+        double endY = 0.0;
+
+        for (; !pi.isDone(); pi.next()) {
+            final int type = pi.currentSegment(coords);
+            switch (type) {
+                case PathIterator.SEG_MOVETO:
+                    if (bounds == null) {
+                        bounds = new double[] { coords[0], coords[0], coords[1], coords[1] };
+                    }
+                    endX = coords[0];
+                    endY = coords[1];
+                    break;
+                case PathIterator.SEG_LINETO:
+                    endX = coords[0];
+                    endY = coords[1];
+                    break;
+                case PathIterator.SEG_QUADTO:
+                    endX = coords[2];
+                    endY = coords[3];
+                    break;
+                case PathIterator.SEG_CUBICTO:
+                    endX = coords[4];
+                    endY = coords[5];
+                    break;
+                case PathIterator.SEG_CLOSE:
+                default:
+                    continue;
+            }
+
+            if (endX < bounds[0]) bounds[0] = endX;
+            if (endX > bounds[1]) bounds[1] = endX;
+            if (endY < bounds[2]) bounds[2] = endY;
+            if (endY > bounds[3]) bounds[3] = endY;
+
+            switch (type) {
+                case PathIterator.SEG_QUADTO:
+                    Curve.accumulateExtremaBoundsForQuad(bounds, 0, lastX, coords[0], coords[2], coeff, deriv_coeff);
+                    Curve.accumulateExtremaBoundsForQuad(bounds, 2, lastY, coords[1], coords[3], coeff, deriv_coeff);
+                    break;
+                case PathIterator.SEG_CUBICTO:
+                    Curve.accumulateExtremaBoundsForCubic(bounds, 0, lastX, coords[0], coords[2], coords[4], coeff, deriv_coeff);
+                    Curve.accumulateExtremaBoundsForCubic(bounds, 2, lastY, coords[1], coords[3], coords[5], coeff, deriv_coeff);
+                    break;
+                default:
+                    break;
+            }
+
+            lastX = endX;
+            lastY = endY;
+        }
+        if (bounds != null) {
+            return new Rectangle2D.Double(bounds[0], bounds[2], bounds[1] - bounds[0], bounds[3] - bounds[2]);
+        }
+
+        // there's room to debate what should happen here, but historically we return a zeroed
+        // out rectangle here. So for backwards compatibility let's keep doing that:
+        return new Rectangle2D.Double();
+    }
+
     /**
      * Tests if the specified coordinates are inside the closed
      * boundary of the specified {@link PathIterator}.

src/java.desktop/share/classes/java/awt/geom/QuadCurve2D.java

@@ -238,19 +238,6 @@ public void setCurve(float x1, float y1,
             this.y2    = y2;
         }
 
-        /**
-         * {@inheritDoc}
-         * @since 1.2
-         */
-        public Rectangle2D getBounds2D() {
-            float left   = Math.min(Math.min(x1, x2), ctrlx);
-            float top    = Math.min(Math.min(y1, y2), ctrly);
-            float right  = Math.max(Math.max(x1, x2), ctrlx);
-            float bottom = Math.max(Math.max(y1, y2), ctrly);
-            return new Rectangle2D.Float(left, top,
-                                         right - left, bottom - top);
-        }
-
         /**
          * Use serialVersionUID from JDK 1.6 for interoperability.
          */
@@ -428,19 +415,6 @@ public void setCurve(double x1, double y1,
             this.y2    = y2;
         }
 
-        /**
-         * {@inheritDoc}
-         * @since 1.2
-         */
-        public Rectangle2D getBounds2D() {
-            double left   = Math.min(Math.min(x1, x2), ctrlx);
-            double top    = Math.min(Math.min(y1, y2), ctrly);
-            double right  = Math.max(Math.max(x1, x2), ctrlx);
-            double bottom = Math.max(Math.max(y1, y2), ctrly);
-            return new Rectangle2D.Double(left, top,
-                                          right - left, bottom - top);
-        }
-
         /**
          * Use serialVersionUID from JDK 1.6 for interoperability.
          */
@@ -1335,6 +1309,14 @@ public boolean contains(Rectangle2D r) {
         return contains(r.getX(), r.getY(), r.getWidth(), r.getHeight());
     }
 
+    /**
+     * {@inheritDoc}
+     * @since 1.2
+     */
+    public Rectangle2D getBounds2D() {
+        return Path2D.getBounds2D(getPathIterator(null));
+    }
+
     /**
      * {@inheritDoc}
      * @since 1.2

src/java.desktop/share/classes/sun/awt/geom/Curve.java

@@ -712,6 +712,126 @@ public static int rectCrossingsForCubic(int crossings,
         return crossings;
     }
 
+    /**
+     * Accumulate the quadratic extrema into the pre-existing bounding array.
+     * <p>
+     * This method focuses on one dimension at a time, so to get both the x and y
+     * dimensions you'll need to call this method twice.
+     * </p>
+     * <p>
+     * Whenever we have to examine cubic or quadratic extrema that change our bounding
+     * box: we run the risk of machine error that may produce a box that is slightly
+     * too small. But the contract of {@link Shape#getBounds2D()} says we should err
+     * on the side of being too large. So to address this: we'll apply a margin based
+     * on the upper limit of numerical error caused by the polynomial evaluation (horner
+     * scheme).
+     * </p>
+     *
+     * @param bounds the bounds to update, which are expressed as: { minX, maxX }
+     * @param boundsOffset the index in boundsof the minimum value
+     * @param x1 the starting value of the bezier curve where t = 0.0
+     * @param ctrlX the control value of the bezier curve
+     * @param x2 the ending value of the bezier curve where t = 1.0
+     * @param coeff an array of at least 3 elements that will be overwritten and reused
+     * @param deriv_coeff an array of at least 2 elements that will be overwritten and reused
+     */
+    public static void accumulateExtremaBoundsForQuad(double[] bounds, int boundsOffset, double x1, double ctrlX, double x2, double[] coeff, double[] deriv_coeff) {
+        if (ctrlX < bounds[boundsOffset] ||
+                ctrlX > bounds[boundsOffset + 1]) {
+
+            final double dx21 = ctrlX - x1;
+            coeff[2] = (x2 - ctrlX) - dx21;  // A = P3 - P0 - 2 P2
+            coeff[1] = 2.0 * dx21;           // B = 2 (P2 - P1)
+            coeff[0] = x1;                   // C = P1
+
+            deriv_coeff[0] = coeff[1];
+            deriv_coeff[1] = 2.0 * coeff[2];
+
+            final double t = -deriv_coeff[0] / deriv_coeff[1];
+            if (t > 0.0 && t < 1.0) {
+                final double v = coeff[0] + t * (coeff[1] + t * coeff[2]);
+
+                // error condition = sum ( abs (coeff) ):
+                final double margin = Math.ulp(Math.abs(coeff[0])
+                        + Math.abs(coeff[1]) + Math.abs(coeff[2]));
+
+                if (v - margin < bounds[boundsOffset]) {
+                    bounds[boundsOffset] = v - margin;
+                }
+                if (v + margin > bounds[boundsOffset + 1]) {
+                    bounds[boundsOffset + 1] = v + margin;
+                }
+            }
+        }
+    }
+
+    /**
+     * Accumulate the cubic extrema into the pre-existing bounding array.
+     * <p>
+     * This method focuses on one dimension at a time, so to get both the x and y
+     * dimensions you'll need to call this method twice.
+     * </p>
+     * <p>
+     * Whenever we have to examine cubic or quadratic extrema that change our bounding
+     * box: we run the risk of machine error that may produce a box that is slightly
+     * too small. But the contract of {@link Shape#getBounds2D()} says we should err
+     * on the side of being too large. So to address this: we'll apply a margin based
+     * on the upper limit of numerical error caused by the polynomial evaluation (horner
+     * scheme).
+     * </p>
+     *
+     * @param bounds the bounds to update, which are expressed as: { minX, maxX }
+     * @param boundsOffset the index in boundsof the minimum value
+     * @param x1 the starting value of the bezier curve where t = 0.0
+     * @param ctrlX1 the first control value of the bezier curve
+     * @param ctrlX1 the second control value of the bezier curve
+     * @param x2 the ending value of the bezier curve where t = 1.0
+     * @param coeff an array of at least 3 elements that will be overwritten and reused
+     * @param deriv_coeff an array of at least 2 elements that will be overwritten and reused
+     */
+    public static void accumulateExtremaBoundsForCubic(double[] bounds, int boundsOffset, double x1, double ctrlX1, double ctrlX2, double x2, double[] coeff, double[] deriv_coeff) {
+        if (ctrlX1 < bounds[boundsOffset] ||
+                ctrlX1 > bounds[boundsOffset + 1] ||
+                ctrlX2 < bounds[boundsOffset] ||
+                ctrlX2 > bounds[boundsOffset + 1]) {
+            final double dx32 = 3.0 * (ctrlX2 - ctrlX1);
+            final double dx21 = 3.0 * (ctrlX1 - x1);
+            coeff[3] = (x2 - x1) - dx32;  // A = P3 - P0 - 3 (P2 - P1) = (P3 - P0) + 3 (P1 - P2)
+            coeff[2] = (dx32 - dx21);         // B = 3 (P2 - P1) - 3(P1 - P0) = 3 (P2 + P0) - 6 P1
+            coeff[1] = dx21;                  // C = 3 (P1 - P0)
+            coeff[0] = x1;                 // D = P0
+
+            deriv_coeff[0] = coeff[1];
+            deriv_coeff[1] = 2.0 * coeff[2];
+            deriv_coeff[2] = 3.0 * coeff[3];
+
+            // reuse this array, give it a new name for readability:
+            final double[] tExtrema = deriv_coeff;
+
+            // solveQuadratic should be improved to get correct t extrema (1 ulp):
+            final int tExtremaCount = QuadCurve2D.solveQuadratic(deriv_coeff, tExtrema);
+            if (tExtremaCount > 0) {
+                // error condition = sum ( abs (coeff) ):
+                final double margin = Math.ulp(Math.abs(coeff[0])
+                        + Math.abs(coeff[1]) + Math.abs(coeff[2])
+                        + Math.abs(coeff[3]));
+
+                for (int i = 0; i < tExtremaCount; i++) {
+                    final double t = tExtrema[i];
+                    if (t > 0.0 && t < 1.0) {
+                        final double v = coeff[0] + t * (coeff[1] + t * (coeff[2] + t * coeff[3]));
+                        if (v - margin < bounds[boundsOffset]) {
+                            bounds[boundsOffset] = v - margin;
+                        }
+                        if (v + margin > bounds[boundsOffset + 1]) {
+                            bounds[boundsOffset + 1] = v + margin;
+                        }
+                    }
+                }
+            }
+        }
+    }
+
     public Curve(int direction) {
         this.direction = direction;
     }