Add skia to the repository.

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@16 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 163 insertions, 0 deletions

diff --git a/skia/sgl/SkGeometry.h b/skia/sgl/SkGeometry.h
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+/* libs/graphics/sgl/SkGeometry.h
+**
+** Copyright 2006, Google Inc.
+**
+** Licensed under the Apache License, Version 2.0 (the "License"); 
+** you may not use this file except in compliance with the License. 
+** You may obtain a copy of the License at 
+**
+**     http://www.apache.org/licenses/LICENSE-2.0 
+**
+** Unless required by applicable law or agreed to in writing, software 
+** distributed under the License is distributed on an "AS IS" BASIS, 
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
+** See the License for the specific language governing permissions and 
+** limitations under the License.
+*/
+
+#ifndef SkGeometry_DEFINED
+#define SkGeometry_DEFINED
+
+#include "SkMatrix.h"
+
+/** Given a quadratic equation Ax^2 + Bx + C = 0, return 0, 1, 2 roots for the
+    equation.
+*/
+int SkFindUnitQuadRoots(SkScalar A, SkScalar B, SkScalar C, SkScalar roots[2]);
+
+///////////////////////////////////////////////////////////////////////////////
+
+/** Set pt to the point on the src quadratic specified by t. t must be
+    0 <= t <= 1.0
+*/
+void SkEvalQuadAt(const SkPoint src[3], SkScalar t, SkPoint* pt, SkVector* tangent = NULL);
+void SkEvalQuadAtHalf(const SkPoint src[3], SkPoint* pt, SkVector* tangent = NULL);
+
+/** Given a src quadratic bezier, chop it at the specified t value,
+    where 0 < t < 1, and return the two new quadratics in dst:
+    dst[0..2] and dst[2..4]
+*/
+void SkChopQuadAt(const SkPoint src[3], SkPoint dst[5], SkScalar t);
+
+/** Given a src quadratic bezier, chop it at the specified t == 1/2,
+    The new quads are returned in dst[0..2] and dst[2..4]
+*/
+void SkChopQuadAtHalf(const SkPoint src[3], SkPoint dst[5]);
+
+/** Given the 3 coefficients for a quadratic bezier (either X or Y values), look
+    for extrema, and return the number of t-values that are found that represent
+    these extrema. If the quadratic has no extrema betwee (0..1) exclusive, the
+    function returns 0.
+    Returned count      tValues[]
+    0                   ignored
+    1                   0 < tValues[0] < 1
+*/
+int SkFindQuadExtrema(SkScalar a, SkScalar b, SkScalar c, SkScalar tValues[1]);
+
+/** Given 3 points on a quadratic bezier, chop it into 1, 2 beziers such that
+    the resulting beziers are monotonic in Y. This is called by the scan converter.
+    Depending on what is returned, dst[] is treated as follows
+    1   dst[0..2] is the original quad
+    2   dst[0..2] and dst[2..4] are the two new quads
+    If dst == null, it is ignored and only the count is returned.
+*/
+int SkChopQuadAtYExtrema(const SkPoint src[3], SkPoint dst[5]);
+
+/** Given 3 points on a quadratic bezier, divide it into 2 quadratics
+    if the point of maximum curvature exists on the quad segment.
+    Depending on what is returned, dst[] is treated as follows
+    1   dst[0..2] is the original quad
+    2   dst[0..2] and dst[2..4] are the two new quads
+    If dst == null, it is ignored and only the count is returned.
+*/
+int SkChopQuadAtMaxCurvature(const SkPoint src[3], SkPoint dst[5]);
+
+////////////////////////////////////////////////////////////////////////////////////////
+
+/** Convert from parametric from (pts) to polynomial coefficients
+    coeff[0]*T^3 + coeff[1]*T^2 + coeff[2]*T + coeff[3]
+*/
+void SkGetCubicCoeff(const SkPoint pts[4], SkScalar cx[4], SkScalar cy[4]);
+
+/** Set pt to the point on the src cubic specified by t. t must be
+    0 <= t <= 1.0
+*/
+void SkEvalCubicAt(const SkPoint src[4], SkScalar t, SkPoint* locOrNull, SkVector* tangentOrNull, SkVector* curvatureOrNull);
+
+/** Given a src cubic bezier, chop it at the specified t value,
+    where 0 < t < 1, and return the two new cubics in dst:
+    dst[0..3] and dst[3..6]
+*/
+void SkChopCubicAt(const SkPoint src[4], SkPoint dst[7], SkScalar t);
+void SkChopCubicAt(const SkPoint src[4], SkPoint dst[7], const SkScalar t[], int t_count);
+
+/** Given a src cubic bezier, chop it at the specified t == 1/2,
+    The new cubics are returned in dst[0..3] and dst[3..6]
+*/
+void SkChopCubicAtHalf(const SkPoint src[4], SkPoint dst[7]);
+
+/** Given the 4 coefficients for a cubic bezier (either X or Y values), look
+    for extrema, and return the number of t-values that are found that represent
+    these extrema. If the cubic has no extrema betwee (0..1) exclusive, the
+    function returns 0.
+    Returned count      tValues[]
+    0                   ignored
+    1                   0 < tValues[0] < 1
+    2                   0 < tValues[0] < tValues[1] < 1
+*/
+int SkFindCubicExtrema(SkScalar a, SkScalar b, SkScalar c, SkScalar d, SkScalar tValues[2]);
+
+/** Given 4 points on a cubic bezier, chop it into 1, 2, 3 beziers such that
+    the resulting beziers are monotonic in Y. This is called by the scan converter.
+    Depending on what is returned, dst[] is treated as follows
+    1   dst[0..3] is the original cubic
+    2   dst[0..3] and dst[3..6] are the two new cubics
+    3   dst[0..3], dst[3..6], dst[6..9] are the three new cubics
+    If dst == null, it is ignored and only the count is returned.
+*/
+int SkChopCubicAtYExtrema(const SkPoint src[4], SkPoint dst[10]);
+
+/** Given a cubic bezier, return 0, 1, or 2 t-values that represent the
+    inflection points.
+*/
+int SkFindCubicInflections(const SkPoint src[4], SkScalar tValues[2]);
+
+/** Return 1 for no chop, or 2 for having chopped the cubic at its
+    inflection point.
+*/
+int SkChopCubicAtInflections(const SkPoint src[4], SkPoint dst[10]);
+
+int SkFindCubicMaxCurvature(const SkPoint src[4], SkScalar tValues[3]);
+int SkChopCubicAtMaxCurvature(const SkPoint src[4], SkPoint dst[13], SkScalar tValues[3] = NULL);
+
+///////////////////////////////////////////////////////////////////////////////////////////
+
+enum SkRotationDirection {
+    kCW_SkRotationDirection,
+    kCCW_SkRotationDirection
+};
+
+/** Maximum number of points needed in the quadPoints[] parameter for
+    SkBuildQuadArc()
+*/
+#define kSkBuildQuadArcStorage  17
+
+/** Given 2 unit vectors and a rotation direction, fill out the specified
+    array of points with quadratic segments. Return is the number of points
+    written to, which will be { 0, 3, 5, 7, ... kSkBuildQuadArcStorage }
+
+    matrix, if not null, is appled to the points before they are returned.
+*/
+int SkBuildQuadArc(const SkVector& unitStart, const SkVector& unitStop, SkRotationDirection,
+                   const SkMatrix* matrix, SkPoint quadPoints[]);
+
+//////////////////////////////////////////////////////////////////////////////
+
+#ifdef SK_DEBUG
+    class SkGeometry {
+    public:
+        static void UnitTest();
+    };
+#endif
+
+#endif