forked from mirrors/gecko-dev
2c84305426
D2D has a more efficient path when asked to stroke circles vs. circular paths. This will let us use that. Differential Revision: https://phabricator.services.mozilla.com/D181545
399 lines
15 KiB
C++
399 lines
15 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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 "UserData.h"
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#include <cmath>
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namespace mozilla {
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namespace gfx {
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struct PathOp {
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~PathOp() = default;
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enum OpType {
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OP_MOVETO = 0,
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OP_LINETO,
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OP_BEZIERTO,
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OP_QUADRATICBEZIERTO,
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OP_ARC,
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OP_CLOSE
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};
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OpType mType;
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Point mP1;
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#if (!defined(__GNUC__) || __GNUC__ >= 7) && defined(__clang__)
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PathOp() {}
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union {
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struct {
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Point mP2;
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Point mP3;
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};
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struct {
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float mRadius;
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float mStartAngle;
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float mEndAngle;
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bool mAntiClockwise;
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};
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};
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#else
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PathOp() = default;
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Point mP2;
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Point mP3;
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float mRadius;
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float mStartAngle;
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float mEndAngle;
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bool mAntiClockwise;
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#endif
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};
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const int32_t sPointCount[] = {1, 1, 3, 2, 0, 0};
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// Kappa constant for 90-degree angle
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const Float kKappaFactor = 0.55191497064665766025f;
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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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inline Float ComputeKappaFactor(Float aAngle) {
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return (4.0f / 3.0f) * tanf(aAngle / 4.0f);
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}
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/**
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* Draws a partial arc <= 90 degrees given exact start and end points.
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* Assumes that it is continuing from an already specified start point.
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*/
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template <typename T>
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inline void PartialArcToBezier(T* aSink, const Point& aStartOffset,
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const Point& aEndOffset,
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const Matrix& aTransform,
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Float aKappaFactor = kKappaFactor) {
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Point cp1 =
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aStartOffset + Point(-aStartOffset.y, aStartOffset.x) * aKappaFactor;
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Point cp2 = aEndOffset + Point(aEndOffset.y, -aEndOffset.x) * aKappaFactor;
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aSink->BezierTo(aTransform.TransformPoint(cp1),
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aTransform.TransformPoint(cp2),
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aTransform.TransformPoint(aEndOffset));
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}
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/**
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* Draws an acute arc (<= 90 degrees) given exact start and end points.
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* Specialized version avoiding kappa calculation.
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*/
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template <typename T>
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inline void AcuteArcToBezier(T* aSink, const Point& aOrigin,
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const Size& aRadius, const Point& aStartPoint,
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const Point& aEndPoint,
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Float aKappaFactor = kKappaFactor) {
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aSink->LineTo(aStartPoint);
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if (!aRadius.IsEmpty()) {
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Float kappaX = aKappaFactor * aRadius.width / aRadius.height;
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Float kappaY = aKappaFactor * aRadius.height / aRadius.width;
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Point startOffset = aStartPoint - aOrigin;
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Point endOffset = aEndPoint - aOrigin;
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aSink->BezierTo(
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aStartPoint + Point(-startOffset.y * kappaX, startOffset.x * kappaY),
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aEndPoint + Point(endOffset.y * kappaX, -endOffset.x * kappaY),
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aEndPoint);
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} else if (aEndPoint != aStartPoint) {
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aSink->LineTo(aEndPoint);
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}
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}
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/**
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* Draws an acute arc (<= 90 degrees) given exact start and end points.
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*/
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template <typename T>
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inline void AcuteArcToBezier(T* aSink, const Point& aOrigin,
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const Size& aRadius, const Point& aStartPoint,
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const Point& aEndPoint, Float aStartAngle,
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Float aEndAngle) {
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AcuteArcToBezier(aSink, aOrigin, aRadius, aStartPoint, aEndPoint,
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ComputeKappaFactor(aEndAngle - aStartAngle));
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}
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template <typename T>
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void ArcToBezier(T* aSink, const Point& aOrigin, const Size& aRadius,
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float aStartAngle, float aEndAngle, bool aAntiClockwise,
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float aRotation = 0.0f, const Matrix& aTransform = Matrix()) {
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Float sweepDirection = aAntiClockwise ? -1.0f : 1.0f;
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// Calculate the total arc we're going to sweep.
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Float arcSweepLeft = (aEndAngle - aStartAngle) * sweepDirection;
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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 (arcSweepLeft < 0) {
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// Rerverse sweep is modulo'd into range rather than clamped.
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arcSweepLeft = Float(2.0f * M_PI) + fmodf(arcSweepLeft, Float(2.0f * M_PI));
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// Recalculate the start angle to land closer to end angle.
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aStartAngle = aEndAngle - arcSweepLeft * sweepDirection;
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} else if (arcSweepLeft > Float(2.0f * M_PI)) {
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// Sweeping more than 2 * pi is a full circle.
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arcSweepLeft = Float(2.0f * M_PI);
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}
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Float currentStartAngle = aStartAngle;
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Point currentStartOffset(cosf(aStartAngle), sinf(aStartAngle));
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Matrix transform = Matrix::Scaling(aRadius.width, aRadius.height);
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if (aRotation != 0.0f) {
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transform *= Matrix::Rotation(aRotation);
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}
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transform.PostTranslate(aOrigin);
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transform *= aTransform;
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aSink->LineTo(transform.TransformPoint(currentStartOffset));
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while (arcSweepLeft > 0) {
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Float currentEndAngle =
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currentStartAngle +
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std::min(arcSweepLeft, Float(M_PI / 2.0f)) * sweepDirection;
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Point currentEndOffset(cosf(currentEndAngle), sinf(currentEndAngle));
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PartialArcToBezier(aSink, currentStartOffset, currentEndOffset, transform,
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ComputeKappaFactor(currentEndAngle - currentStartAngle));
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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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arcSweepLeft -= Float(M_PI / 2.0f);
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currentStartAngle = currentEndAngle;
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currentStartOffset = currentEndOffset;
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}
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}
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/* This is basically the ArcToBezier with the parameters for drawing a circle
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* inlined which vastly simplifies it and avoids a bunch of transcedental
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* function calls which should make it faster. */
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template <typename T>
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void EllipseToBezier(T* aSink, const Point& aOrigin, const Size& aRadius) {
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Matrix transform(aRadius.width, 0, 0, aRadius.height, aOrigin.x, aOrigin.y);
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Point currentStartOffset(1, 0);
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aSink->LineTo(transform.TransformPoint(currentStartOffset));
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for (int i = 0; i < 4; i++) {
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// cos(x+pi/2) == -sin(x)
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// sin(x+pi/2) == cos(x)
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Point currentEndOffset(-currentStartOffset.y, currentStartOffset.x);
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PartialArcToBezier(aSink, currentStartOffset, currentEndOffset, transform);
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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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currentStartOffset = currentEndOffset;
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}
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}
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/**
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* Appends a path represending a rectangle to the path being built by
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* aPathBuilder.
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*
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* aRect The rectangle to append.
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* aDrawClockwise If set to true, the path will start at the left of the top
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* left edge and draw clockwise. If set to false the path will
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* start at the right of the top left edge and draw counter-
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* clockwise.
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*/
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GFX2D_API void AppendRectToPath(PathBuilder* aPathBuilder, const Rect& aRect,
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bool aDrawClockwise = true);
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inline already_AddRefed<Path> MakePathForRect(const DrawTarget& aDrawTarget,
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const Rect& aRect,
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bool aDrawClockwise = true) {
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RefPtr<PathBuilder> builder = aDrawTarget.CreatePathBuilder();
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AppendRectToPath(builder, aRect, aDrawClockwise);
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return builder->Finish();
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}
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/**
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* Appends a path represending a rounded rectangle to the path being built by
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* aPathBuilder.
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*
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* aRect The rectangle to append.
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* aCornerRadii Contains the radii of the top-left, top-right, bottom-right
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* and bottom-left corners, in that order.
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* aDrawClockwise If set to true, the path will start at the left of the top
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* left edge and draw clockwise. If set to false the path will
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* start at the right of the top left edge and draw counter-
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* clockwise.
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*/
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GFX2D_API void AppendRoundedRectToPath(
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PathBuilder* aPathBuilder, const Rect& aRect, const RectCornerRadii& aRadii,
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bool aDrawClockwise = true, const Maybe<Matrix>& aTransform = Nothing());
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inline already_AddRefed<Path> MakePathForRoundedRect(
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const DrawTarget& aDrawTarget, const Rect& aRect,
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const RectCornerRadii& aRadii, bool aDrawClockwise = true) {
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RefPtr<PathBuilder> builder = aDrawTarget.CreatePathBuilder();
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AppendRoundedRectToPath(builder, aRect, aRadii, aDrawClockwise);
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return builder->Finish();
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}
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/**
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* Appends a path represending an ellipse to the path being built by
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* aPathBuilder.
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*
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* The ellipse extends aDimensions.width / 2.0 in the horizontal direction
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* from aCenter, and aDimensions.height / 2.0 in the vertical direction.
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*/
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GFX2D_API void AppendEllipseToPath(PathBuilder* aPathBuilder,
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const Point& aCenter,
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const Size& aDimensions);
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inline already_AddRefed<Path> MakePathForEllipse(const DrawTarget& aDrawTarget,
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const Point& aCenter,
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const Size& aDimensions) {
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RefPtr<PathBuilder> builder = aDrawTarget.CreatePathBuilder();
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AppendEllipseToPath(builder, aCenter, aDimensions);
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return builder->Finish();
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}
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inline already_AddRefed<Path> MakePathForCircle(const DrawTarget& aDrawTarget,
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const Point& aCenter,
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float aRadius) {
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RefPtr<PathBuilder> builder = aDrawTarget.CreatePathBuilder();
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builder->Arc(aCenter, aRadius, 0.0f, Float(2.0 * M_PI));
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builder->Close();
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return builder->Finish();
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}
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/**
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* If aDrawTarget's transform only contains a translation, and if this line is
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* a horizontal or vertical line, this function will snap the line's vertices
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* to align with the device pixel grid so that stroking the line with a one
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* pixel wide stroke will result in a crisp line that is not antialiased over
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* two pixels across its width.
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*
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* @return Returns true if this function snaps aRect's vertices, else returns
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* false.
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*/
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GFX2D_API bool SnapLineToDevicePixelsForStroking(Point& aP1, Point& aP2,
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const DrawTarget& aDrawTarget,
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Float aLineWidth);
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/**
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* This function paints each edge of aRect separately, snapping the edges using
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* SnapLineToDevicePixelsForStroking. Stroking the edges as separate paths
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* helps ensure not only that the stroke spans a single row of device pixels if
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* possible, but also that the ends of stroke dashes start and end on device
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* pixels too.
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*/
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GFX2D_API void StrokeSnappedEdgesOfRect(const Rect& aRect,
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DrawTarget& aDrawTarget,
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const ColorPattern& aColor,
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const StrokeOptions& aStrokeOptions);
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/**
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* Return the margin, in device space, by which a stroke can extend beyond the
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* rendered shape.
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* @param aStrokeOptions The stroke options that the stroke is drawn with.
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* @param aTransform The user space to device space transform.
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* @return The stroke margin.
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*/
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GFX2D_API Margin MaxStrokeExtents(const StrokeOptions& aStrokeOptions,
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const Matrix& aTransform);
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extern UserDataKey sDisablePixelSnapping;
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/**
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* If aDrawTarget's transform only contains a translation or, if
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* aAllowScaleOr90DegreeRotate is true, and/or a scale/90 degree rotation, this
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* function will convert aRect to device space and snap it to device pixels.
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* This function returns true if aRect is modified, otherwise it returns false.
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*
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* Note that the snapping is such that filling the rect using a DrawTarget
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* which has the identity matrix as its transform will result in crisp edges.
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* (That is, aRect will have integer values, aligning its edges between pixel
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* boundaries.) If on the other hand you stroking the rect with an odd valued
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* stroke width then the edges of the stroke will be antialiased (assuming an
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* AntialiasMode that does antialiasing).
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*
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* Empty snaps are those which result in a rectangle of 0 area. If they are
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* disallowed, an axis is left unsnapped if the rounding process results in a
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* length of 0.
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*/
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inline bool UserToDevicePixelSnapped(Rect& aRect, const DrawTarget& aDrawTarget,
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bool aAllowScaleOr90DegreeRotate = false,
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bool aAllowEmptySnaps = true) {
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if (aDrawTarget.GetUserData(&sDisablePixelSnapping)) {
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return false;
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}
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Matrix mat = aDrawTarget.GetTransform();
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const Float epsilon = 0.0000001f;
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#define WITHIN_E(a, b) (fabs((a) - (b)) < epsilon)
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if (!aAllowScaleOr90DegreeRotate &&
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(!WITHIN_E(mat._11, 1.f) || !WITHIN_E(mat._22, 1.f) ||
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!WITHIN_E(mat._12, 0.f) || !WITHIN_E(mat._21, 0.f))) {
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// We have non-translation, but only translation is allowed.
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return false;
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}
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#undef WITHIN_E
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Point p1 = mat.TransformPoint(aRect.TopLeft());
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Point p2 = mat.TransformPoint(aRect.TopRight());
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Point p3 = mat.TransformPoint(aRect.BottomRight());
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// Check that the rectangle is axis-aligned. For an axis-aligned rectangle,
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// two opposite corners define the entire rectangle. So check if
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// the axis-aligned rectangle with opposite corners p1 and p3
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// define an axis-aligned rectangle whose other corners are p2 and p4.
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// We actually only need to check one of p2 and p4, since an affine
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// transform maps parallelograms to parallelograms.
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if (p2 == Point(p1.x, p3.y) || p2 == Point(p3.x, p1.y)) {
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Point p1r = p1;
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Point p3r = p3;
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p1r.Round();
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p3r.Round();
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if (aAllowEmptySnaps || p1r.x != p3r.x) {
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p1.x = p1r.x;
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p3.x = p3r.x;
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}
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if (aAllowEmptySnaps || p1r.y != p3r.y) {
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p1.y = p1r.y;
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p3.y = p3r.y;
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}
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aRect.MoveTo(Point(std::min(p1.x, p3.x), std::min(p1.y, p3.y)));
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aRect.SizeTo(Size(std::max(p1.x, p3.x) - aRect.X(),
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std::max(p1.y, p3.y) - aRect.Y()));
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return true;
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}
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return false;
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}
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/**
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* This function has the same behavior as UserToDevicePixelSnapped except that
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* aRect is not transformed to device space.
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*/
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inline bool MaybeSnapToDevicePixels(Rect& aRect, const DrawTarget& aDrawTarget,
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bool aAllowScaleOr90DegreeRotate = false,
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bool aAllowEmptySnaps = true) {
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if (UserToDevicePixelSnapped(aRect, aDrawTarget, aAllowScaleOr90DegreeRotate,
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aAllowEmptySnaps)) {
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// Since UserToDevicePixelSnapped returned true we know there is no
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// rotation/skew in 'mat', so we can just use TransformBounds() here.
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Matrix mat = aDrawTarget.GetTransform();
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mat.Invert();
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aRect = mat.TransformBounds(aRect);
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return true;
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}
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return false;
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}
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} // namespace gfx
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} // namespace mozilla
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#endif /* MOZILLA_GFX_PATHHELPERS_H_ */
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