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gecko-dev/dom/svg/SVGPathSegUtils.cpp

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/* -*- 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/. */
#include "SVGPathSegUtils.h"
#include "mozilla/ArrayUtils.h" // MOZ_ARRAY_LENGTH
#include "mozilla/ServoStyleConsts.h" // StylePathCommand
#include "gfx2DGlue.h"
#include "SVGPathDataParser.h"
#include "nsMathUtils.h"
#include "nsTextFormatter.h"
using namespace mozilla::dom::SVGPathSeg_Binding;
using namespace mozilla::gfx;
namespace mozilla {
static const float PATH_SEG_LENGTH_TOLERANCE = 0.0000001f;
static const uint32_t MAX_RECURSION = 10;
/* static */
void SVGPathSegUtils::GetValueAsString(const float* aSeg, nsAString& aValue) {
// Adding new seg type? Is the formatting below acceptable for the new types?
static_assert(
NS_SVG_PATH_SEG_LAST_VALID_TYPE == PATHSEG_CURVETO_QUADRATIC_SMOOTH_REL,
"Update GetValueAsString for the new value.");
static_assert(NS_SVG_PATH_SEG_MAX_ARGS == 7,
"Add another case to the switch below.");
uint32_t type = DecodeType(aSeg[0]);
char16_t typeAsChar = GetPathSegTypeAsLetter(type);
// Special case arcs:
if (IsArcType(type)) {
bool largeArcFlag = aSeg[4] != 0.0f;
bool sweepFlag = aSeg[5] != 0.0f;
nsTextFormatter::ssprintf(aValue, u"%c%g,%g %g %d,%d %g,%g", typeAsChar,
aSeg[1], aSeg[2], aSeg[3], largeArcFlag,
sweepFlag, aSeg[6], aSeg[7]);
} else {
switch (ArgCountForType(type)) {
case 0:
aValue = typeAsChar;
break;
case 1:
nsTextFormatter::ssprintf(aValue, u"%c%g", typeAsChar, aSeg[1]);
break;
case 2:
nsTextFormatter::ssprintf(aValue, u"%c%g,%g", typeAsChar, aSeg[1],
aSeg[2]);
break;
case 4:
nsTextFormatter::ssprintf(aValue, u"%c%g,%g %g,%g", typeAsChar, aSeg[1],
aSeg[2], aSeg[3], aSeg[4]);
break;
case 6:
nsTextFormatter::ssprintf(aValue, u"%c%g,%g %g,%g %g,%g", typeAsChar,
aSeg[1], aSeg[2], aSeg[3], aSeg[4], aSeg[5],
aSeg[6]);
break;
default:
MOZ_ASSERT(false, "Unknown segment type");
aValue = u"<unknown-segment-type>";
return;
}
}
}
static float CalcDistanceBetweenPoints(const Point& aP1, const Point& aP2) {
return NS_hypot(aP2.x - aP1.x, aP2.y - aP1.y);
}
static void SplitQuadraticBezier(const Point* aCurve, Point* aLeft,
Point* aRight) {
aLeft[0].x = aCurve[0].x;
aLeft[0].y = aCurve[0].y;
aRight[2].x = aCurve[2].x;
aRight[2].y = aCurve[2].y;
aLeft[1].x = (aCurve[0].x + aCurve[1].x) / 2;
aLeft[1].y = (aCurve[0].y + aCurve[1].y) / 2;
aRight[1].x = (aCurve[1].x + aCurve[2].x) / 2;
aRight[1].y = (aCurve[1].y + aCurve[2].y) / 2;
aLeft[2].x = aRight[0].x = (aLeft[1].x + aRight[1].x) / 2;
aLeft[2].y = aRight[0].y = (aLeft[1].y + aRight[1].y) / 2;
}
static void SplitCubicBezier(const Point* aCurve, Point* aLeft, Point* aRight) {
Point tmp;
tmp.x = (aCurve[1].x + aCurve[2].x) / 4;
tmp.y = (aCurve[1].y + aCurve[2].y) / 4;
aLeft[0].x = aCurve[0].x;
aLeft[0].y = aCurve[0].y;
aRight[3].x = aCurve[3].x;
aRight[3].y = aCurve[3].y;
aLeft[1].x = (aCurve[0].x + aCurve[1].x) / 2;
aLeft[1].y = (aCurve[0].y + aCurve[1].y) / 2;
aRight[2].x = (aCurve[2].x + aCurve[3].x) / 2;
aRight[2].y = (aCurve[2].y + aCurve[3].y) / 2;
aLeft[2].x = aLeft[1].x / 2 + tmp.x;
aLeft[2].y = aLeft[1].y / 2 + tmp.y;
aRight[1].x = aRight[2].x / 2 + tmp.x;
aRight[1].y = aRight[2].y / 2 + tmp.y;
aLeft[3].x = aRight[0].x = (aLeft[2].x + aRight[1].x) / 2;
aLeft[3].y = aRight[0].y = (aLeft[2].y + aRight[1].y) / 2;
}
static float CalcBezLengthHelper(const Point* aCurve, uint32_t aNumPts,
uint32_t aRecursionCount,
void (*aSplit)(const Point*, Point*, Point*)) {
Point left[4];
Point right[4];
float length = 0, dist;
for (uint32_t i = 0; i < aNumPts - 1; i++) {
length += CalcDistanceBetweenPoints(aCurve[i], aCurve[i + 1]);
}
dist = CalcDistanceBetweenPoints(aCurve[0], aCurve[aNumPts - 1]);
if (length - dist > PATH_SEG_LENGTH_TOLERANCE &&
aRecursionCount < MAX_RECURSION) {
aSplit(aCurve, left, right);
++aRecursionCount;
return CalcBezLengthHelper(left, aNumPts, aRecursionCount, aSplit) +
CalcBezLengthHelper(right, aNumPts, aRecursionCount, aSplit);
}
return length;
}
static inline float CalcLengthOfCubicBezier(const Point& aPos,
const Point& aCP1,
const Point& aCP2,
const Point& aTo) {
Point curve[4] = {aPos, aCP1, aCP2, aTo};
return CalcBezLengthHelper(curve, 4, 0, SplitCubicBezier);
}
static inline float CalcLengthOfQuadraticBezier(const Point& aPos,
const Point& aCP,
const Point& aTo) {
Point curve[3] = {aPos, aCP, aTo};
return CalcBezLengthHelper(curve, 3, 0, SplitQuadraticBezier);
}
static void TraverseClosePath(const float* aArgs,
SVGPathTraversalState& aState) {
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += CalcDistanceBetweenPoints(aState.pos, aState.start);
aState.cp1 = aState.cp2 = aState.start;
}
aState.pos = aState.start;
}
static void TraverseMovetoAbs(const float* aArgs,
SVGPathTraversalState& aState) {
aState.start = aState.pos = Point(aArgs[0], aArgs[1]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
// aState.length is unchanged, since move commands don't affect path length.
aState.cp1 = aState.cp2 = aState.start;
}
}
static void TraverseMovetoRel(const float* aArgs,
SVGPathTraversalState& aState) {
aState.start = aState.pos += Point(aArgs[0], aArgs[1]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
// aState.length is unchanged, since move commands don't affect path length.
aState.cp1 = aState.cp2 = aState.start;
}
}
static void TraverseLinetoAbs(const float* aArgs,
SVGPathTraversalState& aState) {
Point to(aArgs[0], aArgs[1]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += CalcDistanceBetweenPoints(aState.pos, to);
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseLinetoRel(const float* aArgs,
SVGPathTraversalState& aState) {
Point to = aState.pos + Point(aArgs[0], aArgs[1]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += CalcDistanceBetweenPoints(aState.pos, to);
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseLinetoHorizontalAbs(const float* aArgs,
SVGPathTraversalState& aState) {
Point to(aArgs[0], aState.pos.y);
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += std::fabs(to.x - aState.pos.x);
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseLinetoHorizontalRel(const float* aArgs,
SVGPathTraversalState& aState) {
aState.pos.x += aArgs[0];
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += std::fabs(aArgs[0]);
aState.cp1 = aState.cp2 = aState.pos;
}
}
static void TraverseLinetoVerticalAbs(const float* aArgs,
SVGPathTraversalState& aState) {
Point to(aState.pos.x, aArgs[0]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += std::fabs(to.y - aState.pos.y);
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseLinetoVerticalRel(const float* aArgs,
SVGPathTraversalState& aState) {
aState.pos.y += aArgs[0];
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += std::fabs(aArgs[0]);
aState.cp1 = aState.cp2 = aState.pos;
}
}
static void TraverseCurvetoCubicAbs(const float* aArgs,
SVGPathTraversalState& aState) {
Point to(aArgs[4], aArgs[5]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp1(aArgs[0], aArgs[1]);
Point cp2(aArgs[2], aArgs[3]);
aState.length += (float)CalcLengthOfCubicBezier(aState.pos, cp1, cp2, to);
aState.cp2 = cp2;
aState.cp1 = to;
}
aState.pos = to;
}
static void TraverseCurvetoCubicSmoothAbs(const float* aArgs,
SVGPathTraversalState& aState) {
Point to(aArgs[2], aArgs[3]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp1 = aState.pos - (aState.cp2 - aState.pos);
Point cp2(aArgs[0], aArgs[1]);
aState.length += (float)CalcLengthOfCubicBezier(aState.pos, cp1, cp2, to);
aState.cp2 = cp2;
aState.cp1 = to;
}
aState.pos = to;
}
static void TraverseCurvetoCubicRel(const float* aArgs,
SVGPathTraversalState& aState) {
Point to = aState.pos + Point(aArgs[4], aArgs[5]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp1 = aState.pos + Point(aArgs[0], aArgs[1]);
Point cp2 = aState.pos + Point(aArgs[2], aArgs[3]);
aState.length += (float)CalcLengthOfCubicBezier(aState.pos, cp1, cp2, to);
aState.cp2 = cp2;
aState.cp1 = to;
}
aState.pos = to;
}
static void TraverseCurvetoCubicSmoothRel(const float* aArgs,
SVGPathTraversalState& aState) {
Point to = aState.pos + Point(aArgs[2], aArgs[3]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp1 = aState.pos - (aState.cp2 - aState.pos);
Point cp2 = aState.pos + Point(aArgs[0], aArgs[1]);
aState.length += (float)CalcLengthOfCubicBezier(aState.pos, cp1, cp2, to);
aState.cp2 = cp2;
aState.cp1 = to;
}
aState.pos = to;
}
static void TraverseCurvetoQuadraticAbs(const float* aArgs,
SVGPathTraversalState& aState) {
Point to(aArgs[2], aArgs[3]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp(aArgs[0], aArgs[1]);
aState.length += (float)CalcLengthOfQuadraticBezier(aState.pos, cp, to);
aState.cp1 = cp;
aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseCurvetoQuadraticSmoothAbs(const float* aArgs,
SVGPathTraversalState& aState) {
Point to(aArgs[0], aArgs[1]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp = aState.pos - (aState.cp1 - aState.pos);
aState.length += (float)CalcLengthOfQuadraticBezier(aState.pos, cp, to);
aState.cp1 = cp;
aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseCurvetoQuadraticRel(const float* aArgs,
SVGPathTraversalState& aState) {
Point to = aState.pos + Point(aArgs[2], aArgs[3]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp = aState.pos + Point(aArgs[0], aArgs[1]);
aState.length += (float)CalcLengthOfQuadraticBezier(aState.pos, cp, to);
aState.cp1 = cp;
aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseCurvetoQuadraticSmoothRel(const float* aArgs,
SVGPathTraversalState& aState) {
Point to = aState.pos + Point(aArgs[0], aArgs[1]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp = aState.pos - (aState.cp1 - aState.pos);
aState.length += (float)CalcLengthOfQuadraticBezier(aState.pos, cp, to);
aState.cp1 = cp;
aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseArcAbs(const float* aArgs, SVGPathTraversalState& aState) {
Point to(aArgs[5], aArgs[6]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
float dist = 0;
Point radii(aArgs[0], aArgs[1]);
if (radii.x == 0.0f || radii.y == 0.0f) {
dist = CalcDistanceBetweenPoints(aState.pos, to);
} else {
Point bez[4] = {aState.pos, Point(0, 0), Point(0, 0), Point(0, 0)};
SVGArcConverter converter(aState.pos, to, radii, aArgs[2], aArgs[3] != 0,
aArgs[4] != 0);
while (converter.GetNextSegment(&bez[1], &bez[2], &bez[3])) {
dist += CalcBezLengthHelper(bez, 4, 0, SplitCubicBezier);
bez[0] = bez[3];
}
}
aState.length += dist;
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
}
static void TraverseArcRel(const float* aArgs, SVGPathTraversalState& aState) {
Point to = aState.pos + Point(aArgs[5], aArgs[6]);
if (aState.ShouldUpdateLengthAndControlPoints()) {
float dist = 0;
Point radii(aArgs[0], aArgs[1]);
if (radii.x == 0.0f || radii.y == 0.0f) {
dist = CalcDistanceBetweenPoints(aState.pos, to);
} else {
Point bez[4] = {aState.pos, Point(0, 0), Point(0, 0), Point(0, 0)};
SVGArcConverter converter(aState.pos, to, radii, aArgs[2], aArgs[3] != 0,
aArgs[4] != 0);
while (converter.GetNextSegment(&bez[1], &bez[2], &bez[3])) {
dist += CalcBezLengthHelper(bez, 4, 0, SplitCubicBezier);
bez[0] = bez[3];
}
}
aState.length += dist;
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
}
using TraverseFunc = void (*)(const float*, SVGPathTraversalState&);
static TraverseFunc gTraverseFuncTable[NS_SVG_PATH_SEG_TYPE_COUNT] = {
nullptr, // 0 == PATHSEG_UNKNOWN
TraverseClosePath,
TraverseMovetoAbs,
TraverseMovetoRel,
TraverseLinetoAbs,
TraverseLinetoRel,
TraverseCurvetoCubicAbs,
TraverseCurvetoCubicRel,
TraverseCurvetoQuadraticAbs,
TraverseCurvetoQuadraticRel,
TraverseArcAbs,
TraverseArcRel,
TraverseLinetoHorizontalAbs,
TraverseLinetoHorizontalRel,
TraverseLinetoVerticalAbs,
TraverseLinetoVerticalRel,
TraverseCurvetoCubicSmoothAbs,
TraverseCurvetoCubicSmoothRel,
TraverseCurvetoQuadraticSmoothAbs,
TraverseCurvetoQuadraticSmoothRel};
/* static */
void SVGPathSegUtils::TraversePathSegment(const float* aData,
SVGPathTraversalState& aState) {
static_assert(
MOZ_ARRAY_LENGTH(gTraverseFuncTable) == NS_SVG_PATH_SEG_TYPE_COUNT,
"gTraverseFuncTable is out of date");
uint32_t type = DecodeType(aData[0]);
gTraverseFuncTable[type](aData + 1, aState);
}
// Basically, this is just a variant version of the above TraverseXXX functions.
// We just put those function inside this and use StylePathCommand instead.
// This function and the above ones should be dropped by Bug 1388931.
/* static */
void SVGPathSegUtils::TraversePathSegment(const StylePathCommand& aCommand,
SVGPathTraversalState& aState) {
switch (aCommand.tag) {
case StylePathCommand::Tag::ClosePath:
TraverseClosePath(nullptr, aState);
break;
case StylePathCommand::Tag::MoveTo: {
const Point& p = aCommand.move_to.point.ConvertsToGfxPoint();
aState.start = aState.pos =
aCommand.move_to.absolute == StyleIsAbsolute::Yes ? p
: aState.pos + p;
if (aState.ShouldUpdateLengthAndControlPoints()) {
// aState.length is unchanged, since move commands don't affect path=
// length.
aState.cp1 = aState.cp2 = aState.start;
}
break;
}
case StylePathCommand::Tag::LineTo: {
Point to = aCommand.line_to.absolute == StyleIsAbsolute::Yes
? aCommand.line_to.point.ConvertsToGfxPoint()
: aState.pos + aCommand.line_to.point.ConvertsToGfxPoint();
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += CalcDistanceBetweenPoints(aState.pos, to);
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
break;
}
case StylePathCommand::Tag::CurveTo: {
const bool isRelative = aCommand.curve_to.absolute == StyleIsAbsolute::No;
Point to = isRelative
? aState.pos + aCommand.curve_to.point.ConvertsToGfxPoint()
: aCommand.curve_to.point.ConvertsToGfxPoint();
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp1 = aCommand.curve_to.control1.ConvertsToGfxPoint();
Point cp2 = aCommand.curve_to.control2.ConvertsToGfxPoint();
if (isRelative) {
cp1 += aState.pos;
cp2 += aState.pos;
}
aState.length +=
(float)CalcLengthOfCubicBezier(aState.pos, cp1, cp2, to);
aState.cp2 = cp2;
aState.cp1 = to;
}
aState.pos = to;
break;
}
case StylePathCommand::Tag::QuadBezierCurveTo: {
const bool isRelative = aCommand.curve_to.absolute == StyleIsAbsolute::No;
Point to =
isRelative
? aState.pos +
aCommand.quad_bezier_curve_to.point.ConvertsToGfxPoint()
: aCommand.quad_bezier_curve_to.point.ConvertsToGfxPoint();
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp =
isRelative
? aState.pos + aCommand.quad_bezier_curve_to.control1
.ConvertsToGfxPoint()
: aCommand.quad_bezier_curve_to.control1.ConvertsToGfxPoint();
aState.length += (float)CalcLengthOfQuadraticBezier(aState.pos, cp, to);
aState.cp1 = cp;
aState.cp2 = to;
}
aState.pos = to;
break;
}
case StylePathCommand::Tag::EllipticalArc: {
Point to =
aCommand.elliptical_arc.absolute == StyleIsAbsolute::Yes
? aCommand.elliptical_arc.point.ConvertsToGfxPoint()
: aState.pos + aCommand.elliptical_arc.point.ConvertsToGfxPoint();
if (aState.ShouldUpdateLengthAndControlPoints()) {
const auto& arc = aCommand.elliptical_arc;
float dist = 0;
Point radii(arc.rx, arc.ry);
if (radii.x == 0.0f || radii.y == 0.0f) {
dist = CalcDistanceBetweenPoints(aState.pos, to);
} else {
Point bez[4] = {aState.pos, Point(0, 0), Point(0, 0), Point(0, 0)};
SVGArcConverter converter(aState.pos, to, radii, arc.angle,
arc.large_arc_flag._0, arc.sweep_flag._0);
while (converter.GetNextSegment(&bez[1], &bez[2], &bez[3])) {
dist += CalcBezLengthHelper(bez, 4, 0, SplitCubicBezier);
bez[0] = bez[3];
}
}
aState.length += dist;
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
break;
}
case StylePathCommand::Tag::HorizontalLineTo: {
Point to(aCommand.horizontal_line_to.absolute == StyleIsAbsolute::Yes
? aCommand.horizontal_line_to.x
: aState.pos.x + aCommand.horizontal_line_to.x,
aState.pos.y);
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += std::fabs(to.x - aState.pos.x);
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
break;
}
case StylePathCommand::Tag::VerticalLineTo: {
Point to(aState.pos.x,
aCommand.vertical_line_to.absolute == StyleIsAbsolute::Yes
? aCommand.vertical_line_to.y
: aState.pos.y + aCommand.vertical_line_to.y);
if (aState.ShouldUpdateLengthAndControlPoints()) {
aState.length += std::fabs(to.y - aState.pos.y);
aState.cp1 = aState.cp2 = to;
}
aState.pos = to;
break;
}
case StylePathCommand::Tag::SmoothCurveTo: {
const bool isRelative =
aCommand.smooth_curve_to.absolute == StyleIsAbsolute::No;
Point to =
isRelative
? aState.pos + aCommand.smooth_curve_to.point.ConvertsToGfxPoint()
: aCommand.smooth_curve_to.point.ConvertsToGfxPoint();
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp1 = aState.pos - (aState.cp2 - aState.pos);
Point cp2 =
isRelative
? aState.pos +
aCommand.smooth_curve_to.control2.ConvertsToGfxPoint()
: aCommand.smooth_curve_to.control2.ConvertsToGfxPoint();
aState.length +=
(float)CalcLengthOfCubicBezier(aState.pos, cp1, cp2, to);
aState.cp2 = cp2;
aState.cp1 = to;
}
aState.pos = to;
break;
}
case StylePathCommand::Tag::SmoothQuadBezierCurveTo: {
Point to = aCommand.smooth_curve_to.absolute == StyleIsAbsolute::Yes
? aCommand.smooth_curve_to.point.ConvertsToGfxPoint()
: aState.pos +
aCommand.smooth_curve_to.point.ConvertsToGfxPoint();
if (aState.ShouldUpdateLengthAndControlPoints()) {
Point cp = aState.pos - (aState.cp1 - aState.pos);
aState.length += (float)CalcLengthOfQuadraticBezier(aState.pos, cp, to);
aState.cp1 = cp;
aState.cp2 = to;
}
aState.pos = to;
break;
}
case StylePathCommand::Tag::Unknown:
MOZ_ASSERT_UNREACHABLE("Unacceptable path segment type");
}
}
// Possible directions of an edge that doesn't immediately disqualify the path
// as a rectangle.
enum class EdgeDir {
LEFT,
RIGHT,
UP,
DOWN,
// NONE represents (almost) zero-length edges, they should be ignored.
NONE,
};
Maybe<EdgeDir> GetDirection(Point v) {
if (!std::isfinite(v.x.value) || !std::isfinite(v.y.value)) {
return Nothing();
}
bool x = fabs(v.x) > 0.001;
bool y = fabs(v.y) > 0.001;
if (x && y) {
return Nothing();
}
if (!x && !y) {
return Some(EdgeDir::NONE);
}
if (x) {
return Some(v.x > 0.0 ? EdgeDir::RIGHT : EdgeDir::LEFT);
}
return Some(v.y > 0.0 ? EdgeDir::DOWN : EdgeDir::UP);
}
EdgeDir OppositeDirection(EdgeDir dir) {
switch (dir) {
case EdgeDir::LEFT:
return EdgeDir::RIGHT;
case EdgeDir::RIGHT:
return EdgeDir::LEFT;
case EdgeDir::UP:
return EdgeDir::DOWN;
case EdgeDir::DOWN:
return EdgeDir::UP;
default:
return EdgeDir::NONE;
}
}
struct IsRectHelper {
Point min;
Point max;
EdgeDir currentDir;
// Index of the next corner.
uint32_t idx;
EdgeDir dirs[4];
bool Edge(Point from, Point to) {
auto edge = to - from;
auto maybeDir = GetDirection(edge);
if (maybeDir.isNothing()) {
return false;
}
EdgeDir dir = maybeDir.value();
if (dir == EdgeDir::NONE) {
// zero-length edges aren't an issue.
return true;
}
if (dir != currentDir) {
// The edge forms a corner with the previous edge.
if (idx >= 4) {
// We are at the 5th corner, can't be a rectangle.
return false;
}
if (dir == OppositeDirection(currentDir)) {
// Can turn left or right but not a full 180 degrees.
return false;
}
dirs[idx] = dir;
idx += 1;
currentDir = dir;
}
min.x = fmin(min.x, to.x);
min.y = fmin(min.y, to.y);
max.x = fmax(max.x, to.x);
max.y = fmax(max.y, to.y);
return true;
}
bool EndSubpath() {
if (idx != 4) {
return false;
}
if (dirs[0] != OppositeDirection(dirs[2]) ||
dirs[1] != OppositeDirection(dirs[3])) {
return false;
}
return true;
}
};
bool ApproxEqual(gfx::Point a, gfx::Point b) {
auto v = b - a;
return fabs(v.x) < 0.001 && fabs(v.y) < 0.001;
}
Maybe<gfx::Rect> SVGPathToAxisAlignedRect(Span<const StylePathCommand> aPath) {
Point pathStart(0.0, 0.0);
Point segStart(0.0, 0.0);
IsRectHelper helper = {
Point(0.0, 0.0),
Point(0.0, 0.0),
EdgeDir::NONE,
0,
{EdgeDir::NONE, EdgeDir::NONE, EdgeDir::NONE, EdgeDir::NONE},
};
for (const StylePathCommand& cmd : aPath) {
switch (cmd.tag) {
case StylePathCommand::Tag::MoveTo: {
Point to = cmd.move_to.point.ConvertsToGfxPoint();
if (helper.idx != 0) {
// This is overly strict since empty moveto sequences such as "M 10 12
// M 3 2 M 0 0" render nothing, but I expect it won't make us miss a
// lot of rect-shaped paths in practice and lets us avoidhandling
// special caps for empty sub-paths like "M 0 0 L 0 0" and "M 1 2 Z".
return Nothing();
}
if (!ApproxEqual(pathStart, segStart)) {
// If we were only interested in filling we could auto-close here
// by calling helper.Edge like in the ClosePath case and detect some
// unclosed paths as rectangles.
//
// For example:
// - "M 1 0 L 0 0 L 0 1 L 1 1 L 1 0" are both rects for filling and
// stroking.
// - "M 1 0 L 0 0 L 0 1 L 1 1" fills a rect but the stroke is shaped
// like a C.
return Nothing();
}
if (helper.idx != 0 && !helper.EndSubpath()) {
return Nothing();
}
if (cmd.move_to.absolute == StyleIsAbsolute::No) {
to = segStart + to;
}
pathStart = to;
segStart = to;
if (helper.idx == 0) {
helper.min = to;
helper.max = to;
}
break;
}
case StylePathCommand::Tag::ClosePath: {
if (!helper.Edge(segStart, pathStart)) {
return Nothing();
}
if (!helper.EndSubpath()) {
return Nothing();
}
pathStart = segStart;
break;
}
case StylePathCommand::Tag::LineTo: {
Point to = cmd.line_to.point.ConvertsToGfxPoint();
if (cmd.line_to.absolute == StyleIsAbsolute::No) {
to = segStart + to;
}
if (!helper.Edge(segStart, to)) {
return Nothing();
}
segStart = to;
break;
}
case StylePathCommand::Tag::HorizontalLineTo: {
Point to = gfx::Point(cmd.horizontal_line_to.x, segStart.y);
if (cmd.horizontal_line_to.absolute == StyleIsAbsolute::No) {
to.x += segStart.x;
}
if (!helper.Edge(segStart, to)) {
return Nothing();
}
segStart = to;
break;
}
case StylePathCommand::Tag::VerticalLineTo: {
Point to = gfx::Point(segStart.x, cmd.vertical_line_to.y);
if (cmd.horizontal_line_to.absolute == StyleIsAbsolute::No) {
to.y += segStart.y;
}
if (!helper.Edge(segStart, to)) {
return Nothing();
}
segStart = to;
break;
}
default:
return Nothing();
}
}
if (!ApproxEqual(pathStart, segStart)) {
// Same situation as with moveto regarding stroking not fullly closed path
// even though the fill is a rectangle.
return Nothing();
}
if (!helper.EndSubpath()) {
return Nothing();
}
auto size = (helper.max - helper.min);
return Some(Rect(helper.min, Size(size.x, size.y)));
}
} // namespace mozilla
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