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gecko-dev
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gecko-dev/layout/painting/DottedCornerFinder.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 "DottedCornerFinder.h"
#include "mozilla/Move.h"
#include "BorderCache.h"
#include "BorderConsts.h"
namespace mozilla {
using namespace gfx;
static inline Float
Square(Float x)
{
return x * x;
}
static Point
PointRotateCCW90(const Point& aP)
{
return Point(aP.y, -aP.x);
}
struct BestOverlap
{
Float overlap;
size_t count;
BestOverlap()
: overlap(0.0f), count(0)
{}
BestOverlap(Float aOverlap, size_t aCount)
: overlap(aOverlap), count(aCount)
{}
};
static const size_t DottedCornerCacheSize = 256;
nsDataHashtable<FourFloatsHashKey, BestOverlap> DottedCornerCache;
DottedCornerFinder::DottedCornerFinder(const Bezier& aOuterBezier,
const Bezier& aInnerBezier,
Corner aCorner,
Float aBorderRadiusX,
Float aBorderRadiusY,
const Point& aC0, Float aR0,
const Point& aCn, Float aRn,
const Size& aCornerDim)
: mOuterBezier(aOuterBezier),
mInnerBezier(aInnerBezier),
mCorner(aCorner),
mNormalSign((aCorner == C_TL || aCorner == C_BR) ? -1.0f : 1.0f),
mC0(aC0), mCn(aCn),
mR0(aR0), mRn(aRn), mMaxR(std::max(aR0, aRn)),
mCenterCurveOrigin(mC0.x, mCn.y),
mInnerCurveOrigin(mInnerBezier.mPoints[0].x, mInnerBezier.mPoints[3].y),
mBestOverlap(0.0f),
mHasZeroBorderWidth(false), mHasMore(true),
mMaxCount(aCornerDim.width + aCornerDim.height),
mType(OTHER),
mI(0), mCount(0)
{
NS_ASSERTION(mR0 > 0.0f || mRn > 0.0f,
"At least one side should have non-zero radius.");
mInnerWidth = fabs(mInnerBezier.mPoints[0].x - mInnerBezier.mPoints[3].x);
mInnerHeight = fabs(mInnerBezier.mPoints[0].y - mInnerBezier.mPoints[3].y);
DetermineType(aBorderRadiusX, aBorderRadiusY);
Reset();
}
static bool
IsSingleCurve(Float aMinR, Float aMaxR,
Float aMinBorderRadius, Float aMaxBorderRadius)
{
return aMinR > 0.0f &&
aMinBorderRadius > aMaxR * 4.0f &&
aMinBorderRadius / aMaxBorderRadius > 0.5f;
}
void
DottedCornerFinder::DetermineType(Float aBorderRadiusX, Float aBorderRadiusY)
{
// Calculate parameters for the center curve before swap.
Float centerCurveWidth = fabs(mC0.x - mCn.x);
Float centerCurveHeight = fabs(mC0.y - mCn.y);
Point cornerPoint(mCn.x, mC0.y);
bool swapped = false;
if (mR0 < mRn) {
// Always draw from wider side to thinner side.
Swap(mC0, mCn);
Swap(mR0, mRn);
Swap(mInnerBezier.mPoints[0], mInnerBezier.mPoints[3]);
Swap(mInnerBezier.mPoints[1], mInnerBezier.mPoints[2]);
Swap(mOuterBezier.mPoints[0], mOuterBezier.mPoints[3]);
Swap(mOuterBezier.mPoints[1], mOuterBezier.mPoints[2]);
mNormalSign = -mNormalSign;
swapped = true;
}
// See the comment at mType declaration for each condition.
Float minR = std::min(mR0, mRn);
Float minBorderRadius = std::min(aBorderRadiusX, aBorderRadiusY);
Float maxBorderRadius = std::max(aBorderRadiusX, aBorderRadiusY);
if (IsSingleCurve(minR, mMaxR, minBorderRadius, maxBorderRadius)) {
if (mR0 == mRn) {
Float borderLength;
if (minBorderRadius == maxBorderRadius) {
mType = PERFECT;
borderLength = M_PI * centerCurveHeight / 2.0f;
mCenterCurveR = centerCurveWidth;
} else {
mType = SINGLE_CURVE_AND_RADIUS;
borderLength = GetQuarterEllipticArcLength(centerCurveWidth,
centerCurveHeight);
}
Float diameter = mR0 * 2.0f;
size_t count = round(borderLength / diameter);
if (count % 2) {
count++;
}
mCount = count / 2 - 1;
if (mCount > 0) {
mBestOverlap = 1.0f - borderLength / (diameter * count);
}
} else {
mType = SINGLE_CURVE;
}
}
if (mType == SINGLE_CURVE_AND_RADIUS || mType == SINGLE_CURVE) {
Size cornerSize(centerCurveWidth, centerCurveHeight);
GetBezierPointsForCorner(&mCenterBezier, mCorner,
cornerPoint, cornerSize);
if (swapped) {
Swap(mCenterBezier.mPoints[0], mCenterBezier.mPoints[3]);
Swap(mCenterBezier.mPoints[1], mCenterBezier.mPoints[2]);
}
}
if (minR == 0.0f) {
mHasZeroBorderWidth = true;
}
if ((mType == SINGLE_CURVE || mType == OTHER) && !mHasZeroBorderWidth) {
FindBestOverlap(minR, minBorderRadius, maxBorderRadius);
}
}
bool
DottedCornerFinder::HasMore(void) const
{
if (mHasZeroBorderWidth) {
return mI < mMaxCount && mHasMore;
}
return mI < mCount;
}
DottedCornerFinder::Result
DottedCornerFinder::Next(void)
{
mI++;
if (mType == PERFECT) {
Float phi = mI * 4.0f * mR0 * (1 - mBestOverlap) / mCenterCurveR;
if (mCorner == C_TL) {
phi = -M_PI / 2.0f - phi;
} else if (mCorner == C_TR) {
phi = -M_PI / 2.0f + phi;
} else if (mCorner == C_BR) {
phi = M_PI / 2.0f - phi;
} else {
phi = M_PI / 2.0f + phi;
}
Point C(mCenterCurveOrigin.x + mCenterCurveR * cos(phi),
mCenterCurveOrigin.y + mCenterCurveR * sin(phi));
return DottedCornerFinder::Result(C, mR0);
}
// Find unfilled and filled circles.
(void)FindNext(mBestOverlap);
if (mHasMore) {
(void)FindNext(mBestOverlap);
}
return Result(mLastC, mLastR);
}
void
DottedCornerFinder::Reset(void)
{
mLastC = mC0;
mLastR = mR0;
mLastT = 0.0f;
mHasMore = true;
}
void
DottedCornerFinder::FindPointAndRadius(Point& C, Float& r,
const Point& innerTangent,
const Point& normal, Float t)
{
// Find radius for the given tangent point on the inner curve such that the
// circle is also tangent to the outer curve.
NS_ASSERTION(mType == OTHER, "Wrong mType");
Float lower = 0.0f;
Float upper = mMaxR;
const Float DIST_MARGIN = 0.1f;
for (size_t i = 0; i < MAX_LOOP; i++) {
r = (upper + lower) / 2.0f;
C = innerTangent + normal * r;
Point Near = FindBezierNearestPoint(mOuterBezier, C, t);
Float distSquare = (C - Near).LengthSquare();
if (distSquare > Square(r + DIST_MARGIN)) {
lower = r;
} else if (distSquare < Square(r - DIST_MARGIN)) {
upper = r;
} else {
break;
}
}
}
Float
DottedCornerFinder::FindNext(Float overlap)
{
Float lower = mLastT;
Float upper = 1.0f;
Float t;
Point C = mLastC;
Float r = 0.0f;
Float factor = (1.0f - overlap);
Float circlesDist = 0.0f;
Float expectedDist = 0.0f;
const Float DIST_MARGIN = 0.1f;
if (mType == SINGLE_CURVE_AND_RADIUS) {
r = mR0;
expectedDist = (r + mLastR) * factor;
// Find C_i on the center curve.
for (size_t i = 0; i < MAX_LOOP; i++) {
t = (upper + lower) / 2.0f;
C = GetBezierPoint(mCenterBezier, t);
// Check overlap along arc.
circlesDist = GetBezierLength(mCenterBezier, mLastT, t);
if (circlesDist < expectedDist - DIST_MARGIN) {
lower = t;
} else if (circlesDist > expectedDist + DIST_MARGIN) {
upper = t;
} else {
break;
}
}
} else if (mType == SINGLE_CURVE) {
// Find C_i on the center curve, and calculate r_i.
for (size_t i = 0; i < MAX_LOOP; i++) {
t = (upper + lower) / 2.0f;
C = GetBezierPoint(mCenterBezier, t);
Point Diff = GetBezierDifferential(mCenterBezier, t);
Float DiffLength = Diff.Length();
if (DiffLength == 0.0f) {
// Basically this shouldn't happen.
// If differential is 0, we cannot calculate tangent circle,
// skip this point.
t = (t + upper) / 2.0f;
continue;
}
Point normal = PointRotateCCW90(Diff / DiffLength) * (-mNormalSign);
r = CalculateDistanceToEllipticArc(C, normal, mInnerCurveOrigin,
mInnerWidth, mInnerHeight);
// Check overlap along arc.
circlesDist = GetBezierLength(mCenterBezier, mLastT, t);
expectedDist = (r + mLastR) * factor;
if (circlesDist < expectedDist - DIST_MARGIN) {
lower = t;
} else if (circlesDist > expectedDist + DIST_MARGIN) {
upper = t;
} else {
break;
}
}
} else {
Float distSquareMax = Square(mMaxR * 3.0f);
Float circlesDistSquare = 0.0f;
// Find C_i and r_i.
for (size_t i = 0; i < MAX_LOOP; i++) {
t = (upper + lower) / 2.0f;
Point innerTangent = GetBezierPoint(mInnerBezier, t);
if ((innerTangent - mLastC).LengthSquare() > distSquareMax) {
// It's clear that this tangent point is too far, skip it.
upper = t;
continue;
}
Point Diff = GetBezierDifferential(mInnerBezier, t);
Float DiffLength = Diff.Length();
if (DiffLength == 0.0f) {
// Basically this shouldn't happen.
// If differential is 0, we cannot calculate tangent circle,
// skip this point.
t = (t + upper) / 2.0f;
continue;
}
Point normal = PointRotateCCW90(Diff / DiffLength) * mNormalSign;
FindPointAndRadius(C, r, innerTangent, normal, t);
// Check overlap with direct distance.
circlesDistSquare = (C - mLastC).LengthSquare();
expectedDist = (r + mLastR) * factor;
if (circlesDistSquare < Square(expectedDist - DIST_MARGIN)) {
lower = t;
} else if (circlesDistSquare > Square(expectedDist + DIST_MARGIN)) {
upper = t;
} else {
break;
}
}
circlesDist = sqrt(circlesDistSquare);
}
if (mHasZeroBorderWidth) {
// When calculating circle around r=0, it may result in wrong radius that
// is bigger than previous circle. Detect it and stop calculating.
const Float R_MARGIN = 0.1f;
if (mLastR < R_MARGIN && r > mLastR) {
mHasMore = false;
mLastR = 0.0f;
return 0.0f;
}
}
mLastT = t;
mLastC = C;
mLastR = r;
if (mHasZeroBorderWidth) {
const Float T_MARGIN = 0.001f;
if (mLastT >= 1.0f - T_MARGIN ||
(mLastC - mCn).LengthSquare() < Square(mLastR)) {
mHasMore = false;
}
}
if (expectedDist == 0.0f) {
return 0.0f;
}
return 1.0f - circlesDist * factor / expectedDist;
}
void
DottedCornerFinder::FindBestOverlap(Float aMinR, Float aMinBorderRadius,
Float aMaxBorderRadius)
{
// If overlap is not calculateable, find it with binary search,
// such that there exists i that C_i == C_n with the given overlap.
FourFloats key(aMinR, mMaxR,
aMinBorderRadius, aMaxBorderRadius);
BestOverlap best;
if (DottedCornerCache.Get(key, &best)) {
mCount = best.count;
mBestOverlap = best.overlap;
return;
}
Float lower = 0.0f;
Float upper = 0.5f;
// Start from lower bound to find the minimum number of circles.
Float overlap = 0.0f;
mBestOverlap = overlap;
size_t targetCount = 0;
const Float OVERLAP_MARGIN = 0.1f;
for (size_t j = 0; j < MAX_LOOP; j++) {
Reset();
size_t count;
Float actualOverlap;
if (!GetCountAndLastOverlap(overlap, &count, &actualOverlap)) {
if (j == 0) {
mCount = mMaxCount;
break;
}
}
if (j == 0) {
if (count < 3 || (count == 3 && actualOverlap > 0.5f)) {
// |count == 3 && actualOverlap > 0.5f| means there could be
// a circle but it is too near from both ends.
//
// if actualOverlap == 0.0
// 1 2 3
// +-------+-------+-------+-------+
// | ##### | ***** | ##### | ##### |
// |#######|*******|#######|#######|
// |###+###|***+***|###+###|###+###|
// |# C_0 #|* C_1 *|# C_2 #|# C_n #|
// | ##### | ***** | ##### | ##### |
// +-------+-------+-------+-------+
// |
// V
// +-------+---+-------+---+-------+
// | ##### | | ##### | | ##### |
// |#######| |#######| |#######|
// |###+###| |###+###| |###+###| Find the best overlap to place
// |# C_0 #| |# C_1 #| |# C_n #| C_1 at the middle of them
// | ##### | | ##### | | ##### |
// +-------+---+-------+---|-------+
//
// if actualOverlap == 0.5
// 1 2 3
// +-------+-------+-------+---+
// | ##### | ***** | ##### |## |
// |#######|*******|##### C_n #|
// |###+###|***+***|###+###+###|
// |# C_0 #|* C_1 *|# C_2 #|###|
// | ##### | ***** | ##### |## |
// +-------+-------+-------+---+
// |
// V
// +-------+-+-------+-+-------+
// | ##### | | ##### | | ##### |
// |#######| |#######| |#######|
// |###+###| |###+###| |###+###| Even if we place C_1 at the middle
// |# C_0 #| |# C_1 #| |# C_n #| of them, it's too near from them
// | ##### | | ##### | | ##### |
// +-------+-+-------+-|-------+
// |
// V
// +-------+-----------+-------+
// | ##### | | ##### |
// |#######| |#######|
// |###+###| |###+###| Do not draw any circle
// |# C_0 #| |# C_n #|
// | ##### | | ##### |
// +-------+-----------+-------+
mCount = 0;
break;
}
// targetCount should be 2n, as we're searching C_1 to C_n.
//
// targetCount = 4
// mCount = 1
// 1 2 3 4
// +-------+-------+-------+-------+-------+
// | ##### | ***** | ##### | ***** | ##### |
// |#######|*******|#######|*******|#######|
// |###+###|***+***|###+###|***+***|###+###|
// |# C_0 #|* C_1 *|# C_2 #|* C_3 *|# C_n #|
// | ##### | ***** | ##### | ***** | ##### |
// +-------+-------+-------+-------+-------+
// 1
//
// targetCount = 6
// mCount = 2
// 1 2 3 4 5 6
// +-------+-------+-------+-------+-------+-------+-------+
// | ##### | ***** | ##### | ***** | ##### | ***** | ##### |
// |#######|*******|#######|*******|#######|*******|#######|
// |###+###|***+***|###+###|***+***|###+###|***+***|###+###|
// |# C_0 #|* C_1 *|# C_2 #|* C_3 *|# C_4 #|* C_5 *|# C_n #|
// | ##### | ***** | ##### | ***** | ##### | ***** | ##### |
// +-------+-------+-------+-------+-------+-------+-------+
// 1 2
if (count % 2) {
targetCount = count + 1;
} else {
targetCount = count;
}
mCount = targetCount / 2 - 1;
}
if (count == targetCount) {
mBestOverlap = overlap;
if (fabs(actualOverlap - overlap) < OVERLAP_MARGIN) {
break;
}
// We started from upper bound, no need to update range when j == 0.
if (j > 0) {
if (actualOverlap > overlap) {
lower = overlap;
} else {
upper = overlap;
}
}
} else {
// |j == 0 && count != targetCount| means that |targetCount = count + 1|,
// and we started from upper bound, no need to update range when j == 0.
if (j > 0) {
if (count > targetCount) {
upper = overlap;
} else {
lower = overlap;
}
}
}
overlap = (upper + lower) / 2.0f;
}
if (DottedCornerCache.Count() > DottedCornerCacheSize) {
DottedCornerCache.Clear();
}
DottedCornerCache.Put(key, BestOverlap(mBestOverlap, mCount));
}
bool
DottedCornerFinder::GetCountAndLastOverlap(Float aOverlap,
size_t* aCount,
Float* aActualOverlap)
{
// Return the number of circles and the last circles' overlap for the
// given overlap.
Reset();
const Float T_MARGIN = 0.001f;
const Float DIST_MARGIN = 0.1f;
const Float DIST_MARGIN_SQUARE = Square(DIST_MARGIN);
for (size_t i = 0; i < mMaxCount; i++) {
Float actualOverlap = FindNext(aOverlap);
if (mLastT >= 1.0f - T_MARGIN ||
(mLastC - mCn).LengthSquare() < DIST_MARGIN_SQUARE) {
*aCount = i + 1;
*aActualOverlap = actualOverlap;
return true;
}
}
return false;
}
} // namespace mozilla
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