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thorvg/src/renderer/sw_engine/tvgSwShape.cpp
Mira Grudzinska d45aab043c api: handling values <= 0 in strokeDash() api 
The API allows now values <= 0 for dashes and gaps. Negative values
are treated as zero. The exception is when all provided values
are <= 0, in which case the dash is ignored.
This fixes the issue when dash = 0 was provided for strokes with round
or butt caps - the dot was not drawn, even though it should have been.

docs: the strokeDash API behavior's clarification for odd numbers
of values in dashPattern and refinement of the accepted values.
2025-06-19 12:19:17 +02:00

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/*
* Copyright (c) 2020 - 2025 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 "tvgSwCommon.h"
/************************************************************************/
/* Internal Class Implementation */
/************************************************************************/
static bool _outlineBegin(SwOutline& outline)
{
//Make a contour if lineTo/curveTo without calling close or moveTo beforehand.
if (outline.pts.empty()) return false;
outline.cntrs.push(outline.pts.count - 1);
outline.closed.push(false);
outline.pts.push(outline.pts[outline.cntrs.last()]);
outline.types.push(SW_CURVE_TYPE_POINT);
return false;
}
static bool _outlineEnd(SwOutline& outline)
{
if (outline.pts.empty()) return false;
outline.cntrs.push(outline.pts.count - 1);
outline.closed.push(false);
return false;
}
static bool _outlineMoveTo(SwOutline& outline, const Point* to, const Matrix& transform, bool closed = false)
{
//make it a contour, if the last contour is not closed yet.
if (!closed) _outlineEnd(outline);
outline.pts.push(mathTransform(to, transform));
outline.types.push(SW_CURVE_TYPE_POINT);
return false;
}
static void _outlineLineTo(SwOutline& outline, const Point* to, const Matrix& transform)
{
outline.pts.push(mathTransform(to, transform));
outline.types.push(SW_CURVE_TYPE_POINT);
}
static void _outlineCubicTo(SwOutline& outline, const Point* ctrl1, const Point* ctrl2, const Point* to, const Matrix& transform)
{
outline.pts.push(mathTransform(ctrl1, transform));
outline.types.push(SW_CURVE_TYPE_CUBIC);
outline.pts.push(mathTransform(ctrl2, transform));
outline.types.push(SW_CURVE_TYPE_CUBIC);
outline.pts.push(mathTransform(to, transform));
outline.types.push(SW_CURVE_TYPE_POINT);
}
static bool _outlineClose(SwOutline& outline)
{
uint32_t i;
if (outline.cntrs.count > 0) i = outline.cntrs.last() + 1;
else i = 0;
//Make sure there is at least one point in the current path
if (outline.pts.count == i) return false;
//Close the path
outline.pts.push(outline.pts[i]);
outline.cntrs.push(outline.pts.count - 1);
outline.types.push(SW_CURVE_TYPE_POINT);
outline.closed.push(true);
return true;
}
static void _dashLineTo(SwDashStroke& dash, const Point* to, const Matrix& transform, bool drawPoint)
{
Line cur = {dash.ptCur, *to};
auto len = cur.length();
if (tvg::zero(len)) {
_outlineMoveTo(*dash.outline, &dash.ptCur, transform);
//draw the current line fully
} else if (len <= dash.curLen) {
dash.curLen -= len;
if (!dash.curOpGap) {
if (dash.move) {
_outlineMoveTo(*dash.outline, &dash.ptCur, transform);
dash.move = false;
}
_outlineLineTo(*dash.outline, to, transform);
}
//draw the current line partially
} else {
while (len - dash.curLen > DASH_PATTERN_THRESHOLD) {
Line left, right;
if (dash.curLen > 0) {
len -= dash.curLen;
cur.split(dash.curLen, left, right);
if (!dash.curOpGap) {
if (dash.move || dash.pattern[dash.curIdx] - dash.curLen < FLOAT_EPSILON) {
_outlineMoveTo(*dash.outline, &left.pt1, transform);
dash.move = false;
}
_outlineLineTo(*dash.outline, &left.pt2, transform);
}
} else {
if (drawPoint && !dash.curOpGap) {
if (dash.move || dash.pattern[dash.curIdx] < FLOAT_EPSILON) {
_outlineMoveTo(*dash.outline, &cur.pt1, transform);
dash.move = false;
}
_outlineLineTo(*dash.outline, &cur.pt1, transform);
}
right = cur;
}
dash.curIdx = (dash.curIdx + 1) % dash.cnt;
dash.curLen = dash.pattern[dash.curIdx];
dash.curOpGap = !dash.curOpGap;
cur = right;
dash.ptCur = cur.pt1;
dash.move = true;
}
//leftovers
dash.curLen -= len;
if (!dash.curOpGap) {
if (dash.move) {
_outlineMoveTo(*dash.outline, &cur.pt1, transform);
dash.move = false;
}
_outlineLineTo(*dash.outline, &cur.pt2, transform);
}
if (dash.curLen < 1 && TO_SWCOORD(len) > 1) {
//move to next dash
dash.curIdx = (dash.curIdx + 1) % dash.cnt;
dash.curLen = dash.pattern[dash.curIdx];
dash.curOpGap = !dash.curOpGap;
}
}
dash.ptCur = *to;
}
static void _dashCubicTo(SwDashStroke& dash, const Point* ctrl1, const Point* ctrl2, const Point* to, const Matrix& transform, bool drawPoint)
{
Bezier cur = {dash.ptCur, *ctrl1, *ctrl2, *to};
auto len = cur.length();
//draw the current line fully
if (tvg::zero(len)) {
_outlineMoveTo(*dash.outline, &dash.ptCur, transform);
} else if (len <= dash.curLen) {
dash.curLen -= len;
if (!dash.curOpGap) {
if (dash.move) {
_outlineMoveTo(*dash.outline, &dash.ptCur, transform);
dash.move = false;
}
_outlineCubicTo(*dash.outline, ctrl1, ctrl2, to, transform);
}
//draw the current line partially
} else {
while ((len - dash.curLen) > DASH_PATTERN_THRESHOLD) {
Bezier left, right;
if (dash.curLen > 0) {
len -= dash.curLen;
cur.split(dash.curLen, left, right);
if (!dash.curOpGap) {
if (dash.move || dash.pattern[dash.curIdx] - dash.curLen < FLOAT_EPSILON) {
_outlineMoveTo(*dash.outline, &left.start, transform);
dash.move = false;
}
_outlineCubicTo(*dash.outline, &left.ctrl1, &left.ctrl2, &left.end, transform);
}
} else {
if (drawPoint && !dash.curOpGap) {
if (dash.move || dash.pattern[dash.curIdx] < FLOAT_EPSILON) {
_outlineMoveTo(*dash.outline, &cur.start, transform);
dash.move = false;
}
_outlineLineTo(*dash.outline, &cur.start, transform);
}
right = cur;
}
dash.curIdx = (dash.curIdx + 1) % dash.cnt;
dash.curLen = dash.pattern[dash.curIdx];
dash.curOpGap = !dash.curOpGap;
cur = right;
dash.ptCur = right.start;
dash.move = true;
}
//leftovers
dash.curLen -= len;
if (!dash.curOpGap) {
if (dash.move) {
_outlineMoveTo(*dash.outline, &cur.start, transform);
dash.move = false;
}
_outlineCubicTo(*dash.outline, &cur.ctrl1, &cur.ctrl2, &cur.end, transform);
}
if (dash.curLen < 0.1f && TO_SWCOORD(len) > 1) {
//move to next dash
dash.curIdx = (dash.curIdx + 1) % dash.cnt;
dash.curLen = dash.pattern[dash.curIdx];
dash.curOpGap = !dash.curOpGap;
}
}
dash.ptCur = *to;
}
static void _dashClose(SwDashStroke& dash, const Matrix& transform, bool drawPoint)
{
_dashLineTo(dash, &dash.ptStart, transform, drawPoint);
}
static void _dashMoveTo(SwDashStroke& dash, uint32_t offIdx, float offset, const Point* pts)
{
dash.curIdx = offIdx % dash.cnt;
dash.curLen = dash.pattern[dash.curIdx] - offset;
dash.curOpGap = offIdx % 2;
dash.ptStart = dash.ptCur = *pts;
dash.move = true;
}
static SwOutline* _genDashOutline(const RenderShape* rshape, const Matrix& transform, SwMpool* mpool, unsigned tid, bool trimmed)
{
PathCommand *cmds, *trimmedCmds = nullptr;
Point *pts, *trimmedPts = nullptr;
uint32_t cmdCnt, ptsCnt;
if (trimmed) {
RenderPath trimmedPath;
if (!rshape->stroke->trim.trim(rshape->path, trimmedPath)) return nullptr;
cmds = trimmedCmds = trimmedPath.cmds.data;
cmdCnt = trimmedPath.cmds.count;
pts = trimmedPts = trimmedPath.pts.data;
ptsCnt = trimmedPath.pts.count;
trimmedPath.cmds.data = nullptr;
trimmedPath.pts.data = nullptr;
} else {
cmds = rshape->path.cmds.data;
cmdCnt = rshape->path.cmds.count;
pts = rshape->path.pts.data;
ptsCnt = rshape->path.pts.count;
}
//No actual shape data
if (cmdCnt == 0 || ptsCnt == 0) return nullptr;
SwDashStroke dash;
dash.pattern = rshape->stroke->dash.pattern;
dash.cnt = rshape->stroke->dash.count;
auto offset = rshape->stroke->dash.offset;
//offset
uint32_t offIdx = 0;
if (!tvg::zero(offset)) {
auto length = rshape->stroke->dash.length;
bool isOdd = dash.cnt % 2;
if (isOdd) length *= 2;
offset = fmodf(offset, length);
if (offset < 0) offset += length;
for (size_t i = 0; i < dash.cnt * (1 + (size_t)isOdd); ++i, ++offIdx) {
auto curPattern = dash.pattern[i % dash.cnt];
if (offset < curPattern) break;
offset -= curPattern;
}
}
dash.outline = mpoolReqDashOutline(mpool, tid);
//must begin with moveTo
if (cmds[0] == PathCommand::MoveTo) {
_dashMoveTo(dash, offIdx, offset, pts);
cmds++;
pts++;
}
auto drawPoint = rshape->stroke->cap != StrokeCap::Butt;
while (--cmdCnt > 0) {
switch (*cmds) {
case PathCommand::Close: {
_dashClose(dash, transform, drawPoint);
break;
}
case PathCommand::MoveTo: {
_dashMoveTo(dash, offIdx, offset, pts);
++pts;
break;
}
case PathCommand::LineTo: {
_dashLineTo(dash, pts, transform, drawPoint);
++pts;
break;
}
case PathCommand::CubicTo: {
_dashCubicTo(dash, pts, pts + 1, pts + 2, transform, drawPoint);
pts += 3;
break;
}
}
++cmds;
}
tvg::free(trimmedCmds);
tvg::free(trimmedPts);
_outlineEnd(*dash.outline);
return dash.outline;
}
static bool _axisAlignedRect(const SwOutline* outline)
{
//Fast Track: axis-aligned rectangle?
if (outline->pts.count != 5) return false;
if (outline->types[2] == SW_CURVE_TYPE_CUBIC) return false;
auto pt1 = outline->pts.data + 0;
auto pt2 = outline->pts.data + 1;
auto pt3 = outline->pts.data + 2;
auto pt4 = outline->pts.data + 3;
auto a = SwPoint{pt1->x, pt3->y};
auto b = SwPoint{pt3->x, pt1->y};
if ((*pt2 == a && *pt4 == b) || (*pt2 == b && *pt4 == a)) return true;
return false;
}
static SwOutline* _genOutline(SwShape* shape, const RenderShape* rshape, const Matrix& transform, SwMpool* mpool, unsigned tid, bool hasComposite, bool trimmed = false)
{
PathCommand *cmds, *trimmedCmds = nullptr;
Point *pts, *trimmedPts = nullptr;
uint32_t cmdCnt, ptsCnt;
if (trimmed) {
RenderPath trimmedPath;
if (!rshape->stroke->trim.trim(rshape->path, trimmedPath)) return nullptr;
cmds = trimmedCmds = trimmedPath.cmds.data;
cmdCnt = trimmedPath.cmds.count;
pts = trimmedPts = trimmedPath.pts.data;
ptsCnt = trimmedPath.pts.count;
trimmedPath.cmds.data = nullptr;
trimmedPath.pts.data = nullptr;
} else {
cmds = rshape->path.cmds.data;
cmdCnt = rshape->path.cmds.count;
pts = rshape->path.pts.data;
ptsCnt = rshape->path.pts.count;
}
//No actual shape data
if (cmdCnt == 0 || ptsCnt == 0) return nullptr;
auto outline = mpoolReqOutline(mpool, tid);
auto closed = false;
//Generate Outlines
while (cmdCnt-- > 0) {
switch (*cmds) {
case PathCommand::Close: {
if (!closed) closed = _outlineClose(*outline);
break;
}
case PathCommand::MoveTo: {
closed = _outlineMoveTo(*outline, pts, transform, closed);
++pts;
break;
}
case PathCommand::LineTo: {
if (closed) closed = _outlineBegin(*outline);
_outlineLineTo(*outline, pts, transform);
++pts;
break;
}
case PathCommand::CubicTo: {
if (closed) closed = _outlineBegin(*outline);
_outlineCubicTo(*outline, pts, pts + 1, pts + 2, transform);
pts += 3;
break;
}
}
++cmds;
}
if (!closed) _outlineEnd(*outline);
outline->fillRule = rshape->rule;
tvg::free(trimmedCmds);
tvg::free(trimmedPts);
shape->fastTrack = (!hasComposite && _axisAlignedRect(outline));
return outline;
}
/************************************************************************/
/* External Class Implementation */
/************************************************************************/
bool shapePrepare(SwShape* shape, const RenderShape* rshape, const Matrix& transform, const RenderRegion& clipBox, RenderRegion& renderBox, SwMpool* mpool, unsigned tid, bool hasComposite)
{
if (auto out = _genOutline(shape, rshape, transform, mpool, tid, hasComposite, rshape->trimpath())) shape->outline = out;
else return false;
if (!mathUpdateOutlineBBox(shape->outline, clipBox, renderBox, shape->fastTrack)) return false;
shape->bbox = renderBox;
return true;
}
bool shapePrepared(const SwShape* shape)
{
return shape->rle ? true : false;
}
bool shapeGenRle(SwShape* shape, TVG_UNUSED const RenderShape* rshape, bool antiAlias)
{
//Case A: Fast Track Rectangle Drawing
if (shape->fastTrack) return true;
//Case B: Normal Shape RLE Drawing
if ((shape->rle = rleRender(shape->rle, shape->outline, shape->bbox, antiAlias))) return true;
return false;
}
void shapeDelOutline(SwShape* shape, SwMpool* mpool, uint32_t tid)
{
mpoolRetOutline(mpool, tid);
shape->outline = nullptr;
}
void shapeReset(SwShape* shape)
{
rleReset(shape->rle);
shape->fastTrack = false;
shape->bbox.reset();
}
void shapeFree(SwShape* shape)
{
rleFree(shape->rle);
shape->rle = nullptr;
shapeDelFill(shape);
if (shape->stroke) {
rleFree(shape->strokeRle);
shape->strokeRle = nullptr;
strokeFree(shape->stroke);
shape->stroke = nullptr;
}
}
void shapeDelStroke(SwShape* shape)
{
if (!shape->stroke) return;
rleFree(shape->strokeRle);
shape->strokeRle = nullptr;
strokeFree(shape->stroke);
shape->stroke = nullptr;
}
void shapeResetStroke(SwShape* shape, const RenderShape* rshape, const Matrix& transform)
{
if (!shape->stroke) shape->stroke = tvg::calloc<SwStroke*>(1, sizeof(SwStroke));
auto stroke = shape->stroke;
if (!stroke) return;
strokeReset(stroke, rshape, transform);
rleReset(shape->strokeRle);
}
bool shapeGenStrokeRle(SwShape* shape, const RenderShape* rshape, const Matrix& transform, const RenderRegion& clipBox, RenderRegion& renderBox, SwMpool* mpool, unsigned tid)
{
SwOutline* shapeOutline = nullptr;
SwOutline* strokeOutline = nullptr;
auto dashStroking = false;
auto ret = true;
//Dash style with/without trimming
if (rshape->stroke->dash.length > DASH_PATTERN_THRESHOLD) {
//check if the length of the drawn dashes is negligibly small => if yes, then it's a valid shape without a stroke
if (rshape->stroke->cap == StrokeCap::Butt) {
auto len = 0.0f;
for (uint32_t i = 0; i < rshape->stroke->dash.count; i += 2) len += rshape->stroke->dash.pattern[i];
if (len < DASH_PATTERN_THRESHOLD) {
ret = true;
goto clear;
}
}
shapeOutline = _genDashOutline(rshape, transform, mpool, tid, rshape->trimpath());
if (!shapeOutline) return false;
dashStroking = true;
//Trimming & Normal style
} else {
if (!shape->outline) {
if (auto out = _genOutline(shape, rshape, transform, mpool, tid, false, rshape->trimpath())) shape->outline = out;
else return false;
}
shapeOutline = shape->outline;
}
if (!strokeParseOutline(shape->stroke, *shapeOutline)) {
ret = false;
goto clear;
}
strokeOutline = strokeExportOutline(shape->stroke, mpool, tid);
if (!mathUpdateOutlineBBox(strokeOutline, clipBox, renderBox, false)) {
ret = false;
goto clear;
}
shape->strokeRle = rleRender(shape->strokeRle, strokeOutline, renderBox, true);
clear:
if (dashStroking) mpoolRetDashOutline(mpool, tid);
mpoolRetStrokeOutline(mpool, tid);
return ret;
}
bool shapeGenFillColors(SwShape* shape, const Fill* fill, const Matrix& transform, SwSurface* surface, uint8_t opacity, bool ctable)
{
return fillGenColorTable(shape->fill, fill, transform, surface, opacity, ctable);
}
bool shapeGenStrokeFillColors(SwShape* shape, const Fill* fill, const Matrix& transform, SwSurface* surface, uint8_t opacity, bool ctable)
{
return fillGenColorTable(shape->stroke->fill, fill, transform, surface, opacity, ctable);
}
void shapeResetFill(SwShape* shape)
{
if (!shape->fill) {
shape->fill = tvg::calloc<SwFill*>(1, sizeof(SwFill));
if (!shape->fill) return;
}
fillReset(shape->fill);
}
void shapeResetStrokeFill(SwShape* shape)
{
if (!shape->stroke->fill) {
shape->stroke->fill = tvg::calloc<SwFill*>(1, sizeof(SwFill));
if (!shape->stroke->fill) return;
}
fillReset(shape->stroke->fill);
}
void shapeDelFill(SwShape* shape)
{
if (!shape->fill) return;
fillFree(shape->fill);
shape->fill = nullptr;
}
void shapeDelStrokeFill(SwShape* shape)
{
if (!shape->stroke->fill) return;
fillFree(shape->stroke->fill);
shape->stroke->fill = nullptr;
}
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