The Tor Browser: comparison gfx/skia/trunk/src/gpu/GrPathUtils.h

--1:000000000000
+:05386bf4222c
+/*
+* Copyright 2011 Google Inc.
+*
+* Use of this source code is governed by a BSD-style license that can be
+* found in the LICENSE file.
+*/
+#ifndef GrPathUtils_DEFINED
+#define GrPathUtils_DEFINED
+#include "GrPoint.h"
+#include "SkRect.h"
+#include "SkPath.h"
+#include "SkTArray.h"
+class SkMatrix;
+/**
+*  Utilities for evaluating paths.
+*/
+namespace GrPathUtils {
+SkScalar scaleToleranceToSrc(SkScalar devTol,
+const SkMatrix& viewM,
+const SkRect& pathBounds);
+/// Since we divide by tol if we're computing exact worst-case bounds,
+/// very small tolerances will be increased to gMinCurveTol.
+int worstCasePointCount(const SkPath&,
+int* subpaths,
+SkScalar tol);
+/// Since we divide by tol if we're computing exact worst-case bounds,
+/// very small tolerances will be increased to gMinCurveTol.
+uint32_t quadraticPointCount(const GrPoint points[], SkScalar tol);
+uint32_t generateQuadraticPoints(const GrPoint& p0,
+const GrPoint& p1,
+const GrPoint& p2,
+SkScalar tolSqd,
+GrPoint** points,
+uint32_t pointsLeft);
+/// Since we divide by tol if we're computing exact worst-case bounds,
+/// very small tolerances will be increased to gMinCurveTol.
+uint32_t cubicPointCount(const GrPoint points[], SkScalar tol);
+uint32_t generateCubicPoints(const GrPoint& p0,
+const GrPoint& p1,
+const GrPoint& p2,
+const GrPoint& p3,
+SkScalar tolSqd,
+GrPoint** points,
+uint32_t pointsLeft);
+// A 2x3 matrix that goes from the 2d space coordinates to UV space where
+// u^2-v = 0 specifies the quad. The matrix is determined by the control
+// points of the quadratic.
+class QuadUVMatrix {
+public:
+QuadUVMatrix() {};
+// Initialize the matrix from the control pts
+QuadUVMatrix(const GrPoint controlPts[3]) { this->set(controlPts); }
+void set(const GrPoint controlPts[3]);
+/**
+* Applies the matrix to vertex positions to compute UV coords. This
+* has been templated so that the compiler can easliy unroll the loop
+* and reorder to avoid stalling for loads. The assumption is that a
+* path renderer will have a small fixed number of vertices that it
+* uploads for each quad.
+*
+* N is the number of vertices.
+* STRIDE is the size of each vertex.
+* UV_OFFSET is the offset of the UV values within each vertex.
+* vertices is a pointer to the first vertex.
+*/
+template <int N, size_t STRIDE, size_t UV_OFFSET>
+void apply(const void* vertices) {
+intptr_t xyPtr = reinterpret_cast<intptr_t>(vertices);
+intptr_t uvPtr = reinterpret_cast<intptr_t>(vertices) + UV_OFFSET;
+float sx = fM[0];
+float kx = fM[1];
+float tx = fM[2];
+float ky = fM[3];
+float sy = fM[4];
+float ty = fM[5];
+for (int i = 0; i < N; ++i) {
+const GrPoint* xy = reinterpret_cast<const GrPoint*>(xyPtr);
+GrPoint* uv = reinterpret_cast<GrPoint*>(uvPtr);
+uv->fX = sx * xy->fX + kx * xy->fY + tx;
+uv->fY = ky * xy->fX + sy * xy->fY + ty;
+xyPtr += STRIDE;
+uvPtr += STRIDE;
+}
+}
+private:
+float fM[6];
+};
+// Input is 3 control points and a weight for a bezier conic. Calculates the
+// three linear functionals (K,L,M) that represent the implicit equation of the
+// conic, K^2 - LM.
+//
+// Output:
+//  K = (klm[0], klm[1], klm[2])
+//  L = (klm[3], klm[4], klm[5])
+//  M = (klm[6], klm[7], klm[8])
+void getConicKLM(const SkPoint p[3], const SkScalar weight, SkScalar klm[9]);
+// Converts a cubic into a sequence of quads. If working in device space
+// use tolScale = 1, otherwise set based on stretchiness of the matrix. The
+// result is sets of 3 points in quads (TODO: share endpoints in returned
+// array)
+// When we approximate a cubic {a,b,c,d} with a quadratic we may have to
+// ensure that the new control point lies between the lines ab and cd. The
+// convex path renderer requires this. It starts with a path where all the
+// control points taken together form a convex polygon. It relies on this
+// property and the quadratic approximation of cubics step cannot alter it.
+// Setting constrainWithinTangents to true enforces this property. When this
+// is true the cubic must be simple and dir must specify the orientation of
+// the cubic. Otherwise, dir is ignored.
+void convertCubicToQuads(const GrPoint p[4],
+SkScalar tolScale,
+bool constrainWithinTangents,
+SkPath::Direction dir,
+SkTArray<SkPoint, true>* quads);
+// Chops the cubic bezier passed in by src, at the double point (intersection point)
+// if the curve is a cubic loop. If it is a loop, there will be two parametric values for
+// the double point: ls and ms. We chop the cubic at these values if they are between 0 and 1.
+// Return value:
+// Value of 3: ls and ms are both between (0,1), and dst will contain the three cubics,
+//             dst[0..3], dst[3..6], and dst[6..9] if dst is not NULL
+// Value of 2: Only one of ls and ms are between (0,1), and dst will contain the two cubics,
+//             dst[0..3] and dst[3..6] if dst is not NULL
+// Value of 1: Neither ls or ms are between (0,1), and dst will contain the one original cubic,
+//             dst[0..3] if dst is not NULL
+//
+// Optional KLM Calculation:
+// The function can also return the KLM linear functionals for the chopped cubic implicit form
+// of K^3 - LM.
+// It will calculate a single set of KLM values that can be shared by all sub cubics, except
+// for the subsection that is "the loop" the K and L values need to be negated.
+// Output:
+// klm:     Holds the values for the linear functionals as:
+//          K = (klm[0], klm[1], klm[2])
+//          L = (klm[3], klm[4], klm[5])
+//          M = (klm[6], klm[7], klm[8])
+// klm_rev: These values are flags for the corresponding sub cubic saying whether or not
+//          the K and L values need to be flipped. A value of -1.f means flip K and L and
+//          a value of 1.f means do nothing.
+//          *****DO NOT FLIP M, JUST K AND L*****
+//
+// Notice that the klm lines are calculated in the same space as the input control points.
+// If you transform the points the lines will also need to be transformed. This can be done
+// by mapping the lines with the inverse-transpose of the matrix used to map the points.
+int chopCubicAtLoopIntersection(const SkPoint src[4], SkPoint dst[10] = NULL,
+SkScalar klm[9] = NULL, SkScalar klm_rev[3] = NULL);
+// Input is p which holds the 4 control points of a non-rational cubic Bezier curve.
+// Output is the coefficients of the three linear functionals K, L, & M which
+// represent the implicit form of the cubic as f(x,y,w) = K^3 - LM. The w term
+// will always be 1. The output is stored in the array klm, where the values are:
+// K = (klm[0], klm[1], klm[2])
+// L = (klm[3], klm[4], klm[5])
+// M = (klm[6], klm[7], klm[8])
+//
+// Notice that the klm lines are calculated in the same space as the input control points.
+// If you transform the points the lines will also need to be transformed. This can be done
+// by mapping the lines with the inverse-transpose of the matrix used to map the points.
+void getCubicKLM(const SkPoint p[4], SkScalar klm[9]);
+};
+#endif

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comparison: gfx/skia/trunk/src/gpu/GrPathUtils.h

gfx/skia/trunk/src/gpu/GrPathUtils.h