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Diffstat (limited to 'gfx/2d/BezierUtils.h')
| -rw-r--r-- | gfx/2d/BezierUtils.h | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/gfx/2d/BezierUtils.h b/gfx/2d/BezierUtils.h new file mode 100644 index 0000000000..3ffcd70214 --- /dev/null +++ b/gfx/2d/BezierUtils.h @@ -0,0 +1,186 @@ +/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim: set ts=8 sts=2 et sw=2 tw=80: */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef mozilla_BezierUtils_h_ +#define mozilla_BezierUtils_h_ + +#include "mozilla/gfx/Point.h" +#include "mozilla/gfx/Types.h" + +namespace mozilla { +namespace gfx { + +// Control points for bezier curve +// +// mPoints[2] +// +-----___---+ mPoints[3] +// __-- +// _-- +// / +// / +// mPoints[1] + | +// | | +// || +// || +// | +// | +// | +// | +// mPoints[0] + +struct Bezier { + Point mPoints[4]; +}; + +// Calculate a point or it's differential of a bezier curve formed by +// aBezier and parameter t. +// +// GetBezierPoint = P(t) +// GetBezierDifferential = P'(t) +// GetBezierDifferential2 = P''(t) +// +// mPoints[2] +// +-----___---+ mPoints[3] +// __-- P(1) +// _-- +// + +// / P(t) +// mPoints[1] + | +// | | +// || +// || +// | +// | +// | +// | +// mPoints[0] + P(0) +Point GetBezierPoint(const Bezier& aBezier, Float t); +Point GetBezierDifferential(const Bezier& aBezier, Float t); +Point GetBezierDifferential2(const Bezier& aBezier, Float t); + +// Calculate length of a simple bezier curve formed by aBezier and range [a, b]. +Float GetBezierLength(const Bezier& aBezier, Float a, Float b); + +// Split bezier curve formed by aBezier into [0,t1], [t1,t2], [t2,1] parts, and +// stores control points for [t1,t2] to aSubBezier. +// +// ___---+ +// __+- P(1) +// _-- P(t2) +// - +// / <-- aSubBezier +// | +// | +// + +// | P(t1) +// | +// | +// | +// | +// + P(0) +void GetSubBezier(Bezier* aSubBezier, const Bezier& aBezier, Float t1, + Float t2); + +// Find a nearest point on bezier curve formed by aBezier to a point aTarget. +// aInitialT is a hint to find the parameter t for the nearest point. +// If aT is non-null, parameter for the nearest point is stored to *aT. +// This function expects a bezier curve to be an approximation of elliptic arc. +// Otherwise it will return wrong point. +// +// aTarget +// + ___---+ +// __-- +// _-- +// + +// / nearest point = P(t = *aT) +// | +// | +// | +// + P(aInitialT) +// | +// | +// | +// | +// + +Point FindBezierNearestPoint(const Bezier& aBezier, const Point& aTarget, + Float aInitialT, Float* aT = nullptr); + +// Calculate control points for a bezier curve that is an approximation of +// an elliptic arc. +// +// aCornerSize.width +// |<----------------->| +// | | +// aCornerPoint| mPoints[2] | +// -------------+-------+-----___---+ mPoints[3] +// ^ | __-- +// | | _-- +// | | - +// | | / +// aCornerSize.height | mPoints[1] + | +// | | | +// | || +// | || +// | | +// | | +// | | +// v mPoints[0] | +// -------------+ +void GetBezierPointsForCorner(Bezier* aBezier, mozilla::Corner aCorner, + const Point& aCornerPoint, + const Size& aCornerSize); + +// Calculate the approximate length of a quarter elliptic arc formed by radii +// (a, b). +// +// a +// |<----------------->| +// | | +// ---+-------------___---+ +// ^ | __-- +// | | _-- +// | | - +// | | / +// b | | | +// | | | +// | || +// | || +// | | +// | | +// | | +// v | +// ---+ +Float GetQuarterEllipticArcLength(Float a, Float b); + +// Calculate the distance between an elliptic arc formed by (origin, width, +// height), and a point P, along a line formed by |P + n * normal|. +// P should be outside of the ellipse, and the line should cross with the +// ellipse twice at n > 0 points. +// +// width +// |<----------------->| +// origin | | +// -----------+-------------___---+ +// ^ normal | __-- +// | P +->__ | _-- +// | --__ - +// | | --+ +// height | | | +// | | | +// | || +// | || +// | | +// | | +// | | +// v | +// -----------+ +Float CalculateDistanceToEllipticArc(const Point& P, const Point& normal, + const Point& origin, Float width, + Float height); + +} // namespace gfx +} // namespace mozilla + +#endif /* mozilla_BezierUtils_h_ */ |