mirror of
https://gitlab.winehq.org/wine/wine-gecko.git
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88 lines
3.1 KiB
C++
88 lines
3.1 KiB
C++
/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#ifndef MOZILLA_GFX_PATHHELPERS_H_
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#define MOZILLA_GFX_PATHHELPERS_H_
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#include "2D.h"
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#include "mozilla/Constants.h"
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namespace mozilla {
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namespace gfx {
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template <typename T>
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void ArcToBezier(T* aSink, const Point &aOrigin, float aRadius, float aStartAngle,
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float aEndAngle, bool aAntiClockwise)
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{
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Point startPoint(aOrigin.x + cos(aStartAngle) * aRadius,
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aOrigin.y + sin(aStartAngle) * aRadius);
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aSink->LineTo(startPoint);
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// Clockwise we always sweep from the smaller to the larger angle, ccw
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// it's vice versa.
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if (!aAntiClockwise && (aEndAngle < aStartAngle)) {
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Float correction = Float(ceil((aStartAngle - aEndAngle) / (2.0f * M_PI)));
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aEndAngle += float(correction * 2.0f * M_PI);
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} else if (aAntiClockwise && (aStartAngle < aEndAngle)) {
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Float correction = (Float)ceil((aEndAngle - aStartAngle) / (2.0f * M_PI));
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aStartAngle += float(correction * 2.0f * M_PI);
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}
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// Sweeping more than 2 * pi is a full circle.
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if (!aAntiClockwise && (aEndAngle - aStartAngle > 2 * M_PI)) {
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aEndAngle = float(aStartAngle + 2.0f * M_PI);
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} else if (aAntiClockwise && (aStartAngle - aEndAngle > 2.0f * M_PI)) {
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aEndAngle = float(aStartAngle - 2.0f * M_PI);
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}
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// Calculate the total arc we're going to sweep.
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Float arcSweepLeft = fabs(aEndAngle - aStartAngle);
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Float sweepDirection = aAntiClockwise ? -1.0f : 1.0f;
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Float currentStartAngle = aStartAngle;
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while (arcSweepLeft > 0) {
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// We guarantee here the current point is the start point of the next
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// curve segment.
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Float currentEndAngle;
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if (arcSweepLeft > M_PI / 2.0f) {
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currentEndAngle = Float(currentStartAngle + M_PI / 2.0f * sweepDirection);
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} else {
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currentEndAngle = currentStartAngle + arcSweepLeft * sweepDirection;
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}
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Point currentStartPoint(aOrigin.x + cos(currentStartAngle) * aRadius,
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aOrigin.y + sin(currentStartAngle) * aRadius);
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Point currentEndPoint(aOrigin.x + cos(currentEndAngle) * aRadius,
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aOrigin.y + sin(currentEndAngle) * aRadius);
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// Calculate kappa constant for partial curve. The sign of angle in the
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// tangent will actually ensure this is negative for a counter clockwise
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// sweep, so changing signs later isn't needed.
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Float kappa = (4.0f / 3.0f) * tan((currentEndAngle - currentStartAngle) / 4.0f) * aRadius;
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Point tangentStart(-sin(currentStartAngle), cos(currentStartAngle));
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Point cp1 = currentStartPoint;
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cp1 += tangentStart * kappa;
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Point revTangentEnd(sin(currentEndAngle), -cos(currentEndAngle));
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Point cp2 = currentEndPoint;
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cp2 += revTangentEnd * kappa;
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aSink->BezierTo(cp1, cp2, currentEndPoint);
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arcSweepLeft -= Float(M_PI / 2.0f);
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currentStartAngle = currentEndAngle;
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}
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}
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}
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}
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#endif /* MOZILLA_GFX_PATHHELPERS_H_ */
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