/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "VectorDrawableUtils.h"
#include "PathParser.h"
#include <math.h>
#include <utils/Log.h>
namespace android {
namespace uirenderer {
class PathResolver {
public:
float currentX = 0;
float currentY = 0;
float ctrlPointX = 0;
float ctrlPointY = 0;
float currentSegmentStartX = 0;
float currentSegmentStartY = 0;
void addCommand(SkPath* outPath, char previousCmd,
char cmd, const std::vector<float>* points, size_t start, size_t end);
};
bool VectorDrawableUtils::canMorph(const PathData& morphFrom, const PathData& morphTo) {
if (morphFrom.verbs.size() != morphTo.verbs.size()) {
return false;
}
for (unsigned int i = 0; i < morphFrom.verbs.size(); i++) {
if (morphFrom.verbs[i] != morphTo.verbs[i]
|| morphFrom.verbSizes[i] != morphTo.verbSizes[i]) {
return false;
}
}
return true;
}
bool VectorDrawableUtils::interpolatePathData(PathData* outData, const PathData& morphFrom,
const PathData& morphTo, float fraction) {
if (!canMorph(morphFrom, morphTo)) {
return false;
}
interpolatePaths(outData, morphFrom, morphTo, fraction);
return true;
}
/**
* Convert an array of PathVerb to Path.
*/
void VectorDrawableUtils::verbsToPath(SkPath* outPath, const PathData& data) {
PathResolver resolver;
char previousCommand = 'm';
size_t start = 0;
outPath->reset();
for (unsigned int i = 0; i < data.verbs.size(); i++) {
size_t verbSize = data.verbSizes[i];
resolver.addCommand(outPath, previousCommand, data.verbs[i], &data.points, start,
start + verbSize);
previousCommand = data.verbs[i];
start += verbSize;
}
}
/**
* The current PathVerb will be interpolated between the
* <code>nodeFrom</code> and <code>nodeTo</code> according to the
* <code>fraction</code>.
*
* @param nodeFrom The start value as a PathVerb.
* @param nodeTo The end value as a PathVerb
* @param fraction The fraction to interpolate.
*/
void VectorDrawableUtils::interpolatePaths(PathData* outData,
const PathData& from, const PathData& to, float fraction) {
outData->points.resize(from.points.size());
outData->verbSizes = from.verbSizes;
outData->verbs = from.verbs;
for (size_t i = 0; i < from.points.size(); i++) {
outData->points[i] = from.points[i] * (1 - fraction) + to.points[i] * fraction;
}
}
/**
* Converts an arc to cubic Bezier segments and records them in p.
*
* @param p The target for the cubic Bezier segments
* @param cx The x coordinate center of the ellipse
* @param cy The y coordinate center of the ellipse
* @param a The radius of the ellipse in the horizontal direction
* @param b The radius of the ellipse in the vertical direction
* @param e1x E(eta1) x coordinate of the starting point of the arc
* @param e1y E(eta2) y coordinate of the starting point of the arc
* @param theta The angle that the ellipse bounding rectangle makes with horizontal plane
* @param start The start angle of the arc on the ellipse
* @param sweep The angle (positive or negative) of the sweep of the arc on the ellipse
*/
static void arcToBezier(SkPath* p,
double cx,
double cy,
double a,
double b,
double e1x,
double e1y,
double theta,
double start,
double sweep) {
// Taken from equations at: http://spaceroots.org/documents/ellipse/node8.html
// and http://www.spaceroots.org/documents/ellipse/node22.html
// Maximum of 45 degrees per cubic Bezier segment
int numSegments = ceil(fabs(sweep * 4 / M_PI));
double eta1 = start;
double cosTheta = cos(theta);
double sinTheta = sin(theta);
double cosEta1 = cos(eta1);
double sinEta1 = sin(eta1);
double ep1x = (-a * cosTheta * sinEta1) - (b * sinTheta * cosEta1);
double ep1y = (-a * sinTheta * sinEta1) + (b * cosTheta * cosEta1);
double anglePerSegment = sweep / numSegments;
for (int i = 0; i < numSegments; i++) {
double eta2 = eta1 + anglePerSegment;
double sinEta2 = sin(eta2);
double cosEta2 = cos(eta2);
double e2x = cx + (a * cosTheta * cosEta2) - (b * sinTheta * sinEta2);
double e2y = cy + (a * sinTheta * cosEta2) + (b * cosTheta * sinEta2);
double ep2x = -a * cosTheta * sinEta2 - b * sinTheta * cosEta2;
double ep2y = -a * sinTheta * sinEta2 + b * cosTheta * cosEta2;
double tanDiff2 = tan((eta2 - eta1) / 2);
double alpha =
sin(eta2 - eta1) * (sqrt(4 + (3 * tanDiff2 * tanDiff2)) - 1) / 3;
double q1x = e1x + alpha * ep1x;
double q1y = e1y + alpha * ep1y;
double q2x = e2x - alpha * ep2x;
double q2y = e2y - alpha * ep2y;
p->cubicTo((float) q1x,
(float) q1y,
(float) q2x,
(float) q2y,
(float) e2x,
(float) e2y);
eta1 = eta2;
e1x = e2x;
e1y = e2y;
ep1x = ep2x;
ep1y = ep2y;
}
}
inline double toRadians(float theta) { return theta * M_PI / 180;}
static void drawArc(SkPath* p,
float x0,
float y0,
float x1,
float y1,
float a,
float b,
float theta,
bool isMoreThanHalf,
bool isPositiveArc) {
/* Convert rotation angle from degrees to radians */
double thetaD = toRadians(theta);
/* Pre-compute rotation matrix entries */
double cosTheta = cos(thetaD);
double sinTheta = sin(thetaD);
/* Transform (x0, y0) and (x1, y1) into unit space */
/* using (inverse) rotation, followed by (inverse) scale */
double x0p = (x0 * cosTheta + y0 * sinTheta) / a;
double y0p = (-x0 * sinTheta + y0 * cosTheta) / b;
double x1p = (x1 * cosTheta + y1 * sinTheta) / a;
double y1p = (-x1 * sinTheta + y1 * cosTheta) / b;
/* Compute differences and averages */
double dx = x0p - x1p;
double dy = y0p - y1p;
double xm = (x0p + x1p) / 2;
double ym = (y0p + y1p) / 2;
/* Solve for intersecting unit circles */
double dsq = dx * dx + dy * dy;
if (dsq == 0.0) {
ALOGW("Points are coincident");
return; /* Points are coincident */
}
double disc = 1.0 / dsq - 1.0 / 4.0;
if (disc < 0.0) {
ALOGW("Points are too far apart %f", dsq);
float adjust = (float) (sqrt(dsq) / 1.99999);
drawArc(p, x0, y0, x1, y1, a * adjust,
b * adjust, theta, isMoreThanHalf, isPositiveArc);
return; /* Points are too far apart */
}
double s = sqrt(disc);
double sdx = s * dx;
double sdy = s * dy;
double cx;
double cy;
if (isMoreThanHalf == isPositiveArc) {
cx = xm - sdy;
cy = ym + sdx;
} else {
cx = xm + sdy;
cy = ym - sdx;
}
double eta0 = atan2((y0p - cy), (x0p - cx));
double eta1 = atan2((y1p - cy), (x1p - cx));
double sweep = (eta1 - eta0);
if (isPositiveArc != (sweep >= 0)) {
if (sweep > 0) {
sweep -= 2 * M_PI;
} else {
sweep += 2 * M_PI;
}
}
cx *= a;
cy *= b;
double tcx = cx;
cx = cx * cosTheta - cy * sinTheta;
cy = tcx * sinTheta + cy * cosTheta;
arcToBezier(p, cx, cy, a, b, x0, y0, thetaD, eta0, sweep);
}
// Use the given verb, and points in the range [start, end) to insert a command into the SkPath.
void PathResolver::addCommand(SkPath* outPath, char previousCmd,
char cmd, const std::vector<float>* points, size_t start, size_t end) {
int incr = 2;
float reflectiveCtrlPointX;
float reflectiveCtrlPointY;
switch (cmd) {
case 'z':
case 'Z':
outPath->close();
// Path is closed here, but we need to move the pen to the
// closed position. So we cache the segment's starting position,
// and restore it here.
currentX = currentSegmentStartX;
currentY = currentSegmentStartY;
ctrlPointX = currentSegmentStartX;
ctrlPointY = currentSegmentStartY;
outPath->moveTo(currentX, currentY);
break;
case 'm':
case 'M':
case 'l':
case 'L':
case 't':
case 'T':
incr = 2;
break;
case 'h':
case 'H':
case 'v':
case 'V':
incr = 1;
break;
case 'c':
case 'C':
incr = 6;
break;
case 's':
case 'S':
case 'q':
case 'Q':
incr = 4;
break;
case 'a':
case 'A':
incr = 7;
break;
}
for (unsigned int k = start; k < end; k += incr) {
switch (cmd) {
case 'm': // moveto - Start a new sub-path (relative)
currentX += points->at(k + 0);
currentY += points->at(k + 1);
if (k > start) {
// According to the spec, if a moveto is followed by multiple
// pairs of coordinates, the subsequent pairs are treated as
// implicit lineto commands.
outPath->rLineTo(points->at(k + 0), points->at(k + 1));
} else {
outPath->rMoveTo(points->at(k + 0), points->at(k + 1));
currentSegmentStartX = currentX;
currentSegmentStartY = currentY;
}
break;
case 'M': // moveto - Start a new sub-path
currentX = points->at(k + 0);
currentY = points->at(k + 1);
if (k > start) {
// According to the spec, if a moveto is followed by multiple
// pairs of coordinates, the subsequent pairs are treated as
// implicit lineto commands.
outPath->lineTo(points->at(k + 0), points->at(k + 1));
} else {
outPath->moveTo(points->at(k + 0), points->at(k + 1));
currentSegmentStartX = currentX;
currentSegmentStartY = currentY;
}
break;
case 'l': // lineto - Draw a line from the current point (relative)
outPath->rLineTo(points->at(k + 0), points->at(k + 1));
currentX += points->at(k + 0);
currentY += points->at(k + 1);
break;
case 'L': // lineto - Draw a line from the current point
outPath->lineTo(points->at(k + 0), points->at(k + 1));
currentX = points->at(k + 0);
currentY = points->at(k + 1);
break;
case 'h': // horizontal lineto - Draws a horizontal line (relative)
outPath->rLineTo(points->at(k + 0), 0);
currentX += points->at(k + 0);
break;
case 'H': // horizontal lineto - Draws a horizontal line
outPath->lineTo(points->at(k + 0), currentY);
currentX = points->at(k + 0);
break;
case 'v': // vertical lineto - Draws a vertical line from the current point (r)
outPath->rLineTo(0, points->at(k + 0));
currentY += points->at(k + 0);
break;
case 'V': // vertical lineto - Draws a vertical line from the current point
outPath->lineTo(currentX, points->at(k + 0));
currentY = points->at(k + 0);
break;
case 'c': // curveto - Draws a cubic Bézier curve (relative)
outPath->rCubicTo(points->at(k + 0), points->at(k + 1), points->at(k + 2), points->at(k + 3),
points->at(k + 4), points->at(k + 5));
ctrlPointX = currentX + points->at(k + 2);
ctrlPointY = currentY + points->at(k + 3);
currentX += points->at(k + 4);
currentY += points->at(k + 5);
break;
case 'C': // curveto - Draws a cubic Bézier curve
outPath->cubicTo(points->at(k + 0), points->at(k + 1), points->at(k + 2), points->at(k + 3),
points->at(k + 4), points->at(k + 5));
currentX = points->at(k + 4);
currentY = points->at(k + 5);
ctrlPointX = points->at(k + 2);
ctrlPointY = points->at(k + 3);
break;
case 's': // smooth curveto - Draws a cubic Bézier curve (reflective cp)
reflectiveCtrlPointX = 0;
reflectiveCtrlPointY = 0;
if (previousCmd == 'c' || previousCmd == 's'
|| previousCmd == 'C' || previousCmd == 'S') {
reflectiveCtrlPointX = currentX - ctrlPointX;
reflectiveCtrlPointY = currentY - ctrlPointY;
}
outPath->rCubicTo(reflectiveCtrlPointX, reflectiveCtrlPointY,
points->at(k + 0), points->at(k + 1),
points->at(k + 2), points->at(k + 3));
ctrlPointX = currentX + points->at(k + 0);
ctrlPointY = currentY + points->at(k + 1);
currentX += points->at(k + 2);
currentY += points->at(k + 3);
break;
case 'S': // shorthand/smooth curveto Draws a cubic Bézier curve(reflective cp)
reflectiveCtrlPointX = currentX;
reflectiveCtrlPointY = currentY;
if (previousCmd == 'c' || previousCmd == 's'
|| previousCmd == 'C' || previousCmd == 'S') {
reflectiveCtrlPointX = 2 * currentX - ctrlPointX;
reflectiveCtrlPointY = 2 * currentY - ctrlPointY;
}
outPath->cubicTo(reflectiveCtrlPointX, reflectiveCtrlPointY,
points->at(k + 0), points->at(k + 1), points->at(k + 2), points->at(k + 3));
ctrlPointX = points->at(k + 0);
ctrlPointY = points->at(k + 1);
currentX = points->at(k + 2);
currentY = points->at(k + 3);
break;
case 'q': // Draws a quadratic Bézier (relative)
outPath->rQuadTo(points->at(k + 0), points->at(k + 1), points->at(k + 2), points->at(k + 3));
ctrlPointX = currentX + points->at(k + 0);
ctrlPointY = currentY + points->at(k + 1);
currentX += points->at(k + 2);
currentY += points->at(k + 3);
break;
case 'Q': // Draws a quadratic Bézier
outPath->quadTo(points->at(k + 0), points->at(k + 1), points->at(k + 2), points->at(k + 3));
ctrlPointX = points->at(k + 0);
ctrlPointY = points->at(k + 1);
currentX = points->at(k + 2);
currentY = points->at(k + 3);
break;
case 't': // Draws a quadratic Bézier curve(reflective control point)(relative)
reflectiveCtrlPointX = 0;
reflectiveCtrlPointY = 0;
if (previousCmd == 'q' || previousCmd == 't'
|| previousCmd == 'Q' || previousCmd == 'T') {
reflectiveCtrlPointX = currentX - ctrlPointX;
reflectiveCtrlPointY = currentY - ctrlPointY;
}
outPath->rQuadTo(reflectiveCtrlPointX, reflectiveCtrlPointY,
points->at(k + 0), points->at(k + 1));
ctrlPointX = currentX + reflectiveCtrlPointX;
ctrlPointY = currentY + reflectiveCtrlPointY;
currentX += points->at(k + 0);
currentY += points->at(k + 1);
break;
case 'T': // Draws a quadratic Bézier curve (reflective control point)
reflectiveCtrlPointX = currentX;
reflectiveCtrlPointY = currentY;
if (previousCmd == 'q' || previousCmd == 't'
|| previousCmd == 'Q' || previousCmd == 'T') {
reflectiveCtrlPointX = 2 * currentX - ctrlPointX;
reflectiveCtrlPointY = 2 * currentY - ctrlPointY;
}
outPath->quadTo(reflectiveCtrlPointX, reflectiveCtrlPointY,
points->at(k + 0), points->at(k + 1));
ctrlPointX = reflectiveCtrlPointX;
ctrlPointY = reflectiveCtrlPointY;
currentX = points->at(k + 0);
currentY = points->at(k + 1);
break;
case 'a': // Draws an elliptical arc
// (rx ry x-axis-rotation large-arc-flag sweep-flag x y)
drawArc(outPath,
currentX,
currentY,
points->at(k + 5) + currentX,
points->at(k + 6) + currentY,
points->at(k + 0),
points->at(k + 1),
points->at(k + 2),
points->at(k + 3) != 0,
points->at(k + 4) != 0);
currentX += points->at(k + 5);
currentY += points->at(k + 6);
ctrlPointX = currentX;
ctrlPointY = currentY;
break;
case 'A': // Draws an elliptical arc
drawArc(outPath,
currentX,
currentY,
points->at(k + 5),
points->at(k + 6),
points->at(k + 0),
points->at(k + 1),
points->at(k + 2),
points->at(k + 3) != 0,
points->at(k + 4) != 0);
currentX = points->at(k + 5);
currentY = points->at(k + 6);
ctrlPointX = currentX;
ctrlPointY = currentY;
break;
default:
LOG_ALWAYS_FATAL("Unsupported command: %c", cmd);
break;
}
previousCmd = cmd;
}
}
} // namespace uirenderer
} // namespace android