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thorvg/src/loaders/lottie/tvgLottieModifier.cpp
Mira Grudzinska 78285e1cfd lottie: fix offset 
For long Bezier curves compared to the offset value,
the offsetting algorithm caused deformation. The problem
became evident after adding mask extension, as the simple
shapes defined there are based on Bezier curves rather
than as shapes like a circle/rect/etc, which is the case
for the offset. Now fixed.
2024-10-18 12:09:45 +09:00

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/*
* Copyright (c) 2024 the ThorVG project. All rights reserved.
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#include "tvgLottieModifier.h"
/************************************************************************/
/* Internal Class Implementation */
/************************************************************************/
static void _roundCorner(Array<PathCommand>& cmds, Array<Point>& pts, const Point& prev, const Point& curr, const Point& next, float r)
{
auto lenPrev = length(prev - curr);
auto rPrev = lenPrev > 0.0f ? 0.5f * std::min(lenPrev * 0.5f, r) / lenPrev : 0.0f;
auto lenNext = length(next - curr);
auto rNext = lenNext > 0.0f ? 0.5f * std::min(lenNext * 0.5f, r) / lenNext : 0.0f;
auto dPrev = rPrev * (curr - prev);
auto dNext = rNext * (curr - next);
pts.push(curr - 2.0f * dPrev);
pts.push(curr - dPrev);
pts.push(curr - dNext);
pts.push(curr - 2.0f * dNext);
cmds.push(PathCommand::LineTo);
cmds.push(PathCommand::CubicTo);
}
static bool _zero(const Point& p1, const Point& p2)
{
constexpr float epsilon = 1e-3f;
return fabsf(p1.x / p2.x - 1.0f) < epsilon && fabsf(p1.y / p2.y - 1.0f) < epsilon;
}
static bool _intersect(const Line& line1, const Line& line2, Point& intersection, bool& inside)
{
if (_zero(line1.pt2, line2.pt1)) {
intersection = line1.pt2;
inside = true;
return true;
}
constexpr float epsilon = 1e-3f;
float denom = (line1.pt2.x - line1.pt1.x) * (line2.pt2.y - line2.pt1.y) - (line1.pt2.y - line1.pt1.y) * (line2.pt2.x - line2.pt1.x);
if (fabsf(denom) < epsilon) return false;
float t = ((line2.pt1.x - line1.pt1.x) * (line2.pt2.y - line2.pt1.y) - (line2.pt1.y - line1.pt1.y) * (line2.pt2.x - line2.pt1.x)) / denom;
float u = ((line2.pt1.x - line1.pt1.x) * (line1.pt2.y - line1.pt1.y) - (line2.pt1.y - line1.pt1.y) * (line1.pt2.x - line1.pt1.x)) / denom;
intersection.x = line1.pt1.x + t * (line1.pt2.x - line1.pt1.x);
intersection.y = line1.pt1.y + t * (line1.pt2.y - line1.pt1.y);
inside = t >= -epsilon && t <= 1.0f + epsilon && u >= -epsilon && u <= 1.0f + epsilon;
return true;
}
static Line _offset(const Point& p1, const Point& p2, float offset)
{
auto scaledNormal = normal(p1, p2) * offset;
return {p1 - scaledNormal, p2 - scaledNormal};
}
void LottieOffsetModifier::corner(const Line& line, const Line& nextLine, uint32_t movetoOutIndex, bool nextClose, Array<PathCommand>& outCmds, Array<Point>& outPts) const
{
bool inside{};
Point intersect{};
if (_intersect(line, nextLine, intersect, inside)) {
if (inside) {
if (nextClose) outPts[movetoOutIndex] = intersect;
outPts.push(intersect);
} else {
outPts.push(line.pt2);
if (join == StrokeJoin::Round) {
outCmds.push(PathCommand::CubicTo);
outPts.push((line.pt2 + intersect) * 0.5f);
outPts.push((nextLine.pt1 + intersect) * 0.5f);
outPts.push(nextLine.pt1);
} else if (join == StrokeJoin::Miter) {
auto norm = normal(line.pt1, line.pt2);
auto nextNorm = normal(nextLine.pt1, nextLine.pt2);
auto miterDirection = (norm + nextNorm) / length(norm + nextNorm);
outCmds.push(PathCommand::LineTo);
if (1.0f <= miterLimit * fabsf(miterDirection.x * norm.x + miterDirection.y * norm.y)) outPts.push(intersect);
else outPts.push(nextLine.pt1);
} else {
outCmds.push(PathCommand::LineTo);
outPts.push(nextLine.pt1);
}
}
} else outPts.push(line.pt2);
}
void LottieOffsetModifier::line(const PathCommand* inCmds, uint32_t inCmdsCnt, const Point* inPts, uint32_t& currentPt, uint32_t currentCmd, State& state, bool degenerated, Array<PathCommand>& outCmds, Array<Point>& outPts, float offset) const
{
if (tvg::zero(inPts[currentPt - 1] - inPts[currentPt])) {
++currentPt;
return;
}
if (inCmds[currentCmd - 1] != PathCommand::LineTo) state.line = _offset(inPts[currentPt - 1], inPts[currentPt], offset);
if (state.moveto) {
outCmds.push(PathCommand::MoveTo);
state.movetoOutIndex = outPts.count;
outPts.push(state.line.pt1);
state.firstLine = state.line;
state.moveto = false;
}
auto nonDegeneratedCubic = [&](uint32_t cmd, uint32_t pt) {
return inCmds[cmd] == PathCommand::CubicTo && !tvg::zero(inPts[pt] - inPts[pt + 1]) && !tvg::zero(inPts[pt + 2] - inPts[pt + 3]);
};
outCmds.push(PathCommand::LineTo);
if (currentCmd + 1 == inCmdsCnt || inCmds[currentCmd + 1] == PathCommand::MoveTo || nonDegeneratedCubic(currentCmd + 1, currentPt + degenerated)) {
outPts.push(state.line.pt2);
++currentPt;
return;
}
Line nextLine = state.firstLine;
if (inCmds[currentCmd + 1] == PathCommand::LineTo) nextLine = _offset(inPts[currentPt + degenerated], inPts[currentPt + 1 + degenerated], offset);
else if (inCmds[currentCmd + 1] == PathCommand::CubicTo) nextLine = _offset(inPts[currentPt + 1 + degenerated], inPts[currentPt + 2 + degenerated], offset);
else if (inCmds[currentCmd + 1] == PathCommand::Close && !_zero(inPts[currentPt + degenerated], inPts[state.movetoInIndex + degenerated]))
nextLine = _offset(inPts[currentPt + degenerated], inPts[state.movetoInIndex + degenerated], offset);
corner(state.line, nextLine, state.movetoOutIndex, inCmds[currentCmd + 1] == PathCommand::Close, outCmds, outPts);
state.line = nextLine;
++currentPt;
}
/************************************************************************/
/* External Class Implementation */
/************************************************************************/
bool LottieRoundnessModifier::modifyPath(const PathCommand* inCmds, uint32_t inCmdsCnt, const Point* inPts, uint32_t inPtsCnt, Array<PathCommand>& outCmds, Array<Point>& outPts, Matrix* transform) const
{
outCmds.reserve(inCmdsCnt * 2);
outPts.reserve((uint32_t)(inPtsCnt * 1.5));
auto ptsCnt = outPts.count;
uint32_t startIndex = 0;
for (uint32_t iCmds = 0, iPts = 0; iCmds < inCmdsCnt; ++iCmds) {
switch (inCmds[iCmds]) {
case PathCommand::MoveTo: {
startIndex = outPts.count;
outCmds.push(PathCommand::MoveTo);
outPts.push(inPts[iPts++]);
break;
}
case PathCommand::CubicTo: {
auto& prev = inPts[iPts - 1];
auto& curr = inPts[iPts + 2];
if (iCmds < inCmdsCnt - 1 &&
tvg::zero(inPts[iPts - 1] - inPts[iPts]) &&
tvg::zero(inPts[iPts + 1] - inPts[iPts + 2])) {
if (inCmds[iCmds + 1] == PathCommand::CubicTo &&
tvg::zero(inPts[iPts + 2] - inPts[iPts + 3]) &&
tvg::zero(inPts[iPts + 4] - inPts[iPts + 5])) {
_roundCorner(outCmds, outPts, prev, curr, inPts[iPts + 5], r);
iPts += 3;
break;
} else if (inCmds[iCmds + 1] == PathCommand::Close) {
_roundCorner(outCmds, outPts, prev, curr, inPts[2], r);
outPts[startIndex] = outPts.last();
iPts += 3;
break;
}
}
outCmds.push(PathCommand::CubicTo);
outPts.push(inPts[iPts++]);
outPts.push(inPts[iPts++]);
outPts.push(inPts[iPts++]);
break;
}
case PathCommand::Close: {
outCmds.push(PathCommand::Close);
break;
}
default: break;
}
}
if (transform) {
for (auto i = ptsCnt; i < outPts.count; ++i) {
outPts[i] *= *transform;
}
}
return true;
}
bool LottieRoundnessModifier::modifyPolystar(TVG_UNUSED const Array<PathCommand>& inCmds, const Array<Point>& inPts, Array<PathCommand>& outCmds, Array<Point>& outPts, float outerRoundness, bool hasRoundness) const
{
static constexpr auto ROUNDED_POLYSTAR_MAGIC_NUMBER = 0.47829f;
auto len = length(inPts[1] - inPts[2]);
auto r = len > 0.0f ? ROUNDED_POLYSTAR_MAGIC_NUMBER * std::min(len * 0.5f, this->r) / len : 0.0f;
if (hasRoundness) {
outCmds.grow((uint32_t)(1.5 * inCmds.count));
outPts.grow((uint32_t)(4.5 * inCmds.count));
int start = 3 * tvg::zero(outerRoundness);
outCmds.push(PathCommand::MoveTo);
outPts.push(inPts[start]);
for (uint32_t i = 1 + start; i < inPts.count; i += 6) {
auto& prev = inPts[i];
auto& curr = inPts[i + 2];
auto& next = (i < inPts.count - start) ? inPts[i + 4] : inPts[2];
auto& nextCtrl = (i < inPts.count - start) ? inPts[i + 5] : inPts[3];
auto dNext = r * (curr - next);
auto dPrev = r * (curr - prev);
auto p0 = curr - 2.0f * dPrev;
auto p1 = curr - dPrev;
auto p2 = curr - dNext;
auto p3 = curr - 2.0f * dNext;
outCmds.push(PathCommand::CubicTo);
outPts.push(prev); outPts.push(p0); outPts.push(p0);
outCmds.push(PathCommand::CubicTo);
outPts.push(p1); outPts.push(p2); outPts.push(p3);
outCmds.push(PathCommand::CubicTo);
outPts.push(p3); outPts.push(next); outPts.push(nextCtrl);
}
} else {
outCmds.grow(2 * inCmds.count);
outPts.grow(4 * inCmds.count);
auto dPrev = r * (inPts[1] - inPts[0]);
auto p = inPts[0] + 2.0f * dPrev;
outCmds.push(PathCommand::MoveTo);
outPts.push(p);
for (uint32_t i = 1; i < inPts.count; ++i) {
auto& curr = inPts[i];
auto& next = (i == inPts.count - 1) ? inPts[1] : inPts[i + 1];
auto dNext = r * (curr - next);
auto p0 = curr - 2.0f * dPrev;
auto p1 = curr - dPrev;
auto p2 = curr - dNext;
auto p3 = curr - 2.0f * dNext;
outCmds.push(PathCommand::LineTo);
outPts.push(p0);
outCmds.push(PathCommand::CubicTo);
outPts.push(p1); outPts.push(p2); outPts.push(p3);
dPrev = -1.0f * dNext;
}
}
outCmds.push(PathCommand::Close);
return true;
}
bool LottieRoundnessModifier::modifyRect(const Point& size, float& r) const
{
r = std::min(this->r, std::max(size.x, size.y) * 0.5f);
return true;
}
bool LottieOffsetModifier::modifyPath(const PathCommand* inCmds, uint32_t inCmdsCnt, const Point* inPts, uint32_t inPtsCnt, Array<PathCommand>& outCmds, Array<Point>& outPts, bool clockwise) const
{
outCmds.reserve(inCmdsCnt * 2);
outPts.reserve(inPtsCnt * (join == StrokeJoin::Round ? 4 : 2));
Array<Bezier> stack{5};
State state;
auto offset = clockwise ? this->offset : -this->offset;
auto threshold = 1.0f / fabsf(offset) + 1.0f;
for (uint32_t iCmd = 0, iPt = 0; iCmd < inCmdsCnt; ++iCmd) {
if (inCmds[iCmd] == PathCommand::MoveTo) {
state.moveto = true;
state.movetoInIndex = iPt++;
} else if (inCmds[iCmd] == PathCommand::LineTo) {
line(inCmds, inCmdsCnt, inPts, iPt, iCmd, state, false, outCmds, outPts, offset);
} else if (inCmds[iCmd] == PathCommand::CubicTo) {
//cubic degenerated to a line
if (tvg::zero(inPts[iPt - 1] - inPts[iPt]) || tvg::zero(inPts[iPt + 1] - inPts[iPt + 2])) {
++iPt;
line(inCmds, inCmdsCnt, inPts, iPt, iCmd, state, true, outCmds, outPts, offset);
++iPt;
continue;
}
stack.push({inPts[iPt - 1], inPts[iPt], inPts[iPt + 1], inPts[iPt + 2]});
while (!stack.empty()) {
auto& bezier = stack.last();
auto len = tvg::length(bezier.start - bezier.ctrl1) + tvg::length(bezier.ctrl1 - bezier.ctrl2) + tvg::length(bezier.ctrl2 - bezier.end);
if (len > threshold * bezier.length()) {
Bezier next;
bezier.split(0.5f, next);
stack.push(next);
continue;
}
stack.pop();
auto line1 = _offset(bezier.start, bezier.ctrl1, offset);
auto line2 = _offset(bezier.ctrl1, bezier.ctrl2, offset);
auto line3 = _offset(bezier.ctrl2, bezier.end, offset);
if (state.moveto) {
outCmds.push(PathCommand::MoveTo);
state.movetoOutIndex = outPts.count;
outPts.push(line1.pt1);
state.firstLine = line1;
state.moveto = false;
}
bool inside{};
Point intersect{};
_intersect(line1, line2, intersect, inside);
outPts.push(intersect);
_intersect(line2, line3, intersect, inside);
outPts.push(intersect);
outPts.push(line3.pt2);
outCmds.push(PathCommand::CubicTo);
}
iPt += 3;
}
else {
if (!_zero(inPts[iPt - 1], inPts[state.movetoInIndex])) {
outCmds.push(PathCommand::LineTo);
corner(state.line, state.firstLine, state.movetoOutIndex, true, outCmds, outPts);
}
outCmds.push(PathCommand::Close);
}
}
return true;
}
bool LottieOffsetModifier::modifyPolystar(const Array<PathCommand>& inCmds, const Array<Point>& inPts, Array<PathCommand>& outCmds, Array<Point>& outPts, bool clockwise) const {
return modifyPath(inCmds.data, inCmds.count, inPts.data, inPts.count, outCmds, outPts, clockwise);
}
bool LottieOffsetModifier::modifyRect(const PathCommand* inCmds, uint32_t inCmdsCnt, const Point* inPts, uint32_t inPtsCnt, Array<PathCommand>& outCmds, Array<Point>& outPts, bool clockwise) const
{
return modifyPath(inCmds, inCmdsCnt, inPts, inPtsCnt, outCmds, outPts, clockwise);
}
bool LottieOffsetModifier::modifyEllipse(float& rx, float& ry) const
{
rx += offset;
ry += offset;
return true;
}
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