android.util.PathParser Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of android-all Show documentation
Show all versions of android-all Show documentation
A library jar that provides APIs for Applications written for the Google Android Platform.
/*
* Copyright (C) 2014 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.
*/
package android.util;
import android.graphics.Path;
import android.util.Log;
import java.util.ArrayList;
import java.util.Arrays;
/**
* @hide
*/
public class PathParser {
static final String LOGTAG = PathParser.class.getSimpleName();
/**
* @param pathData The string representing a path, the same as "d" string in svg file.
* @return the generated Path object.
*/
public static Path createPathFromPathData(String pathData) {
Path path = new Path();
PathDataNode[] nodes = createNodesFromPathData(pathData);
if (nodes != null) {
try {
PathDataNode.nodesToPath(nodes, path);
} catch (RuntimeException e) {
throw new RuntimeException("Error in parsing " + pathData, e);
}
return path;
}
return null;
}
/**
* @param pathData The string representing a path, the same as "d" string in svg file.
* @return an array of the PathDataNode.
*/
public static PathDataNode[] createNodesFromPathData(String pathData) {
if (pathData == null) {
return null;
}
int start = 0;
int end = 1;
ArrayList list = new ArrayList();
while (end < pathData.length()) {
end = nextStart(pathData, end);
String s = pathData.substring(start, end).trim();
if (s.length() > 0) {
float[] val = getFloats(s);
addNode(list, s.charAt(0), val);
}
start = end;
end++;
}
if ((end - start) == 1 && start < pathData.length()) {
addNode(list, pathData.charAt(start), new float[0]);
}
return list.toArray(new PathDataNode[list.size()]);
}
/**
* @param source The array of PathDataNode to be duplicated.
* @return a deep copy of the source.
*/
public static PathDataNode[] deepCopyNodes(PathDataNode[] source) {
if (source == null) {
return null;
}
PathDataNode[] copy = new PathParser.PathDataNode[source.length];
for (int i = 0; i < source.length; i ++) {
copy[i] = new PathDataNode(source[i]);
}
return copy;
}
/**
* @param nodesFrom The source path represented in an array of PathDataNode
* @param nodesTo The target path represented in an array of PathDataNode
* @return whether the nodesFrom can morph into nodesTo
*/
public static boolean canMorph(PathDataNode[] nodesFrom, PathDataNode[] nodesTo) {
if (nodesFrom == null || nodesTo == null) {
return false;
}
if (nodesFrom.length != nodesTo.length) {
return false;
}
for (int i = 0; i < nodesFrom.length; i ++) {
if (nodesFrom[i].mType != nodesTo[i].mType
|| nodesFrom[i].mParams.length != nodesTo[i].mParams.length) {
return false;
}
}
return true;
}
/**
* Update the target's data to match the source.
* Before calling this, make sure canMorph(target, source) is true.
*
* @param target The target path represented in an array of PathDataNode
* @param source The source path represented in an array of PathDataNode
*/
public static void updateNodes(PathDataNode[] target, PathDataNode[] source) {
for (int i = 0; i < source.length; i ++) {
target[i].mType = source[i].mType;
for (int j = 0; j < source[i].mParams.length; j ++) {
target[i].mParams[j] = source[i].mParams[j];
}
}
}
private static int nextStart(String s, int end) {
char c;
while (end < s.length()) {
c = s.charAt(end);
// Note that 'e' or 'E' are not valid path commands, but could be
// used for floating point numbers' scientific notation.
// Therefore, when searching for next command, we should ignore 'e'
// and 'E'.
if ((((c - 'A') * (c - 'Z') <= 0) || ((c - 'a') * (c - 'z') <= 0))
&& c != 'e' && c != 'E') {
return end;
}
end++;
}
return end;
}
private static void addNode(ArrayList list, char cmd, float[] val) {
list.add(new PathDataNode(cmd, val));
}
private static class ExtractFloatResult {
// We need to return the position of the next separator and whether the
// next float starts with a '-' or a '.'.
int mEndPosition;
boolean mEndWithNegOrDot;
}
/**
* Parse the floats in the string.
* This is an optimized version of parseFloat(s.split(",|\\s"));
*
* @param s the string containing a command and list of floats
* @return array of floats
*/
private static float[] getFloats(String s) {
if (s.charAt(0) == 'z' || s.charAt(0) == 'Z') {
return new float[0];
}
try {
float[] results = new float[s.length()];
int count = 0;
int startPosition = 1;
int endPosition = 0;
ExtractFloatResult result = new ExtractFloatResult();
int totalLength = s.length();
// The startPosition should always be the first character of the
// current number, and endPosition is the character after the current
// number.
while (startPosition < totalLength) {
extract(s, startPosition, result);
endPosition = result.mEndPosition;
if (startPosition < endPosition) {
results[count++] = Float.parseFloat(
s.substring(startPosition, endPosition));
}
if (result.mEndWithNegOrDot) {
// Keep the '-' or '.' sign with next number.
startPosition = endPosition;
} else {
startPosition = endPosition + 1;
}
}
return Arrays.copyOf(results, count);
} catch (NumberFormatException e) {
throw new RuntimeException("error in parsing \"" + s + "\"", e);
}
}
/**
* Calculate the position of the next comma or space or negative sign
* @param s the string to search
* @param start the position to start searching
* @param result the result of the extraction, including the position of the
* the starting position of next number, whether it is ending with a '-'.
*/
private static void extract(String s, int start, ExtractFloatResult result) {
// Now looking for ' ', ',', '.' or '-' from the start.
int currentIndex = start;
boolean foundSeparator = false;
result.mEndWithNegOrDot = false;
boolean secondDot = false;
boolean isExponential = false;
for (; currentIndex < s.length(); currentIndex++) {
boolean isPrevExponential = isExponential;
isExponential = false;
char currentChar = s.charAt(currentIndex);
switch (currentChar) {
case ' ':
case ',':
foundSeparator = true;
break;
case '-':
// The negative sign following a 'e' or 'E' is not a separator.
if (currentIndex != start && !isPrevExponential) {
foundSeparator = true;
result.mEndWithNegOrDot = true;
}
break;
case '.':
if (!secondDot) {
secondDot = true;
} else {
// This is the second dot, and it is considered as a separator.
foundSeparator = true;
result.mEndWithNegOrDot = true;
}
break;
case 'e':
case 'E':
isExponential = true;
break;
}
if (foundSeparator) {
break;
}
}
// When there is nothing found, then we put the end position to the end
// of the string.
result.mEndPosition = currentIndex;
}
/**
* Each PathDataNode represents one command in the "d" attribute of the svg
* file.
* An array of PathDataNode can represent the whole "d" attribute.
*/
public static class PathDataNode {
private char mType;
private float[] mParams;
private PathDataNode(char type, float[] params) {
mType = type;
mParams = params;
}
private PathDataNode(PathDataNode n) {
mType = n.mType;
mParams = Arrays.copyOf(n.mParams, n.mParams.length);
}
/**
* Convert an array of PathDataNode to Path.
*
* @param node The source array of PathDataNode.
* @param path The target Path object.
*/
public static void nodesToPath(PathDataNode[] node, Path path) {
float[] current = new float[6];
char previousCommand = 'm';
for (int i = 0; i < node.length; i++) {
addCommand(path, current, previousCommand, node[i].mType, node[i].mParams);
previousCommand = node[i].mType;
}
}
/**
* The current PathDataNode will be interpolated between the
* nodeFrom and nodeTo according to the
* fraction.
*
* @param nodeFrom The start value as a PathDataNode.
* @param nodeTo The end value as a PathDataNode
* @param fraction The fraction to interpolate.
*/
public void interpolatePathDataNode(PathDataNode nodeFrom,
PathDataNode nodeTo, float fraction) {
for (int i = 0; i < nodeFrom.mParams.length; i++) {
mParams[i] = nodeFrom.mParams[i] * (1 - fraction)
+ nodeTo.mParams[i] * fraction;
}
}
private static void addCommand(Path path, float[] current,
char previousCmd, char cmd, float[] val) {
int incr = 2;
float currentX = current[0];
float currentY = current[1];
float ctrlPointX = current[2];
float ctrlPointY = current[3];
float currentSegmentStartX = current[4];
float currentSegmentStartY = current[5];
float reflectiveCtrlPointX;
float reflectiveCtrlPointY;
switch (cmd) {
case 'z':
case 'Z':
path.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;
path.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 (int k = 0; k < val.length; k += incr) {
switch (cmd) {
case 'm': // moveto - Start a new sub-path (relative)
path.rMoveTo(val[k + 0], val[k + 1]);
currentX += val[k + 0];
currentY += val[k + 1];
currentSegmentStartX = currentX;
currentSegmentStartY = currentY;
break;
case 'M': // moveto - Start a new sub-path
path.moveTo(val[k + 0], val[k + 1]);
currentX = val[k + 0];
currentY = val[k + 1];
currentSegmentStartX = currentX;
currentSegmentStartY = currentY;
break;
case 'l': // lineto - Draw a line from the current point (relative)
path.rLineTo(val[k + 0], val[k + 1]);
currentX += val[k + 0];
currentY += val[k + 1];
break;
case 'L': // lineto - Draw a line from the current point
path.lineTo(val[k + 0], val[k + 1]);
currentX = val[k + 0];
currentY = val[k + 1];
break;
case 'h': // horizontal lineto - Draws a horizontal line (relative)
path.rLineTo(val[k + 0], 0);
currentX += val[k + 0];
break;
case 'H': // horizontal lineto - Draws a horizontal line
path.lineTo(val[k + 0], currentY);
currentX = val[k + 0];
break;
case 'v': // vertical lineto - Draws a vertical line from the current point (r)
path.rLineTo(0, val[k + 0]);
currentY += val[k + 0];
break;
case 'V': // vertical lineto - Draws a vertical line from the current point
path.lineTo(currentX, val[k + 0]);
currentY = val[k + 0];
break;
case 'c': // curveto - Draws a cubic Bézier curve (relative)
path.rCubicTo(val[k + 0], val[k + 1], val[k + 2], val[k + 3],
val[k + 4], val[k + 5]);
ctrlPointX = currentX + val[k + 2];
ctrlPointY = currentY + val[k + 3];
currentX += val[k + 4];
currentY += val[k + 5];
break;
case 'C': // curveto - Draws a cubic Bézier curve
path.cubicTo(val[k + 0], val[k + 1], val[k + 2], val[k + 3],
val[k + 4], val[k + 5]);
currentX = val[k + 4];
currentY = val[k + 5];
ctrlPointX = val[k + 2];
ctrlPointY = val[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;
}
path.rCubicTo(reflectiveCtrlPointX, reflectiveCtrlPointY,
val[k + 0], val[k + 1],
val[k + 2], val[k + 3]);
ctrlPointX = currentX + val[k + 0];
ctrlPointY = currentY + val[k + 1];
currentX += val[k + 2];
currentY += val[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;
}
path.cubicTo(reflectiveCtrlPointX, reflectiveCtrlPointY,
val[k + 0], val[k + 1], val[k + 2], val[k + 3]);
ctrlPointX = val[k + 0];
ctrlPointY = val[k + 1];
currentX = val[k + 2];
currentY = val[k + 3];
break;
case 'q': // Draws a quadratic Bézier (relative)
path.rQuadTo(val[k + 0], val[k + 1], val[k + 2], val[k + 3]);
ctrlPointX = currentX + val[k + 0];
ctrlPointY = currentY + val[k + 1];
currentX += val[k + 2];
currentY += val[k + 3];
break;
case 'Q': // Draws a quadratic Bézier
path.quadTo(val[k + 0], val[k + 1], val[k + 2], val[k + 3]);
ctrlPointX = val[k + 0];
ctrlPointY = val[k + 1];
currentX = val[k + 2];
currentY = val[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;
}
path.rQuadTo(reflectiveCtrlPointX, reflectiveCtrlPointY,
val[k + 0], val[k + 1]);
ctrlPointX = currentX + reflectiveCtrlPointX;
ctrlPointY = currentY + reflectiveCtrlPointY;
currentX += val[k + 0];
currentY += val[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;
}
path.quadTo(reflectiveCtrlPointX, reflectiveCtrlPointY,
val[k + 0], val[k + 1]);
ctrlPointX = reflectiveCtrlPointX;
ctrlPointY = reflectiveCtrlPointY;
currentX = val[k + 0];
currentY = val[k + 1];
break;
case 'a': // Draws an elliptical arc
// (rx ry x-axis-rotation large-arc-flag sweep-flag x y)
drawArc(path,
currentX,
currentY,
val[k + 5] + currentX,
val[k + 6] + currentY,
val[k + 0],
val[k + 1],
val[k + 2],
val[k + 3] != 0,
val[k + 4] != 0);
currentX += val[k + 5];
currentY += val[k + 6];
ctrlPointX = currentX;
ctrlPointY = currentY;
break;
case 'A': // Draws an elliptical arc
drawArc(path,
currentX,
currentY,
val[k + 5],
val[k + 6],
val[k + 0],
val[k + 1],
val[k + 2],
val[k + 3] != 0,
val[k + 4] != 0);
currentX = val[k + 5];
currentY = val[k + 6];
ctrlPointX = currentX;
ctrlPointY = currentY;
break;
}
previousCmd = cmd;
}
current[0] = currentX;
current[1] = currentY;
current[2] = ctrlPointX;
current[3] = ctrlPointY;
current[4] = currentSegmentStartX;
current[5] = currentSegmentStartY;
}
private static void drawArc(Path p,
float x0,
float y0,
float x1,
float y1,
float a,
float b,
float theta,
boolean isMoreThanHalf,
boolean isPositiveArc) {
/* Convert rotation angle from degrees to radians */
double thetaD = Math.toRadians(theta);
/* Pre-compute rotation matrix entries */
double cosTheta = Math.cos(thetaD);
double sinTheta = Math.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) {
Log.w(LOGTAG, " Points are coincident");
return; /* Points are coincident */
}
double disc = 1.0 / dsq - 1.0 / 4.0;
if (disc < 0.0) {
Log.w(LOGTAG, "Points are too far apart " + dsq);
float adjust = (float) (Math.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 = Math.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 = Math.atan2((y0p - cy), (x0p - cx));
double eta1 = Math.atan2((y1p - cy), (x1p - cx));
double sweep = (eta1 - eta0);
if (isPositiveArc != (sweep >= 0)) {
if (sweep > 0) {
sweep -= 2 * Math.PI;
} else {
sweep += 2 * Math.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);
}
/**
* 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
*/
private static void arcToBezier(Path 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 = Math.abs((int) Math.ceil(sweep * 4 / Math.PI));
double eta1 = start;
double cosTheta = Math.cos(theta);
double sinTheta = Math.sin(theta);
double cosEta1 = Math.cos(eta1);
double sinEta1 = Math.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 = Math.sin(eta2);
double cosEta2 = Math.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 = Math.tan((eta2 - eta1) / 2);
double alpha =
Math.sin(eta2 - eta1) * (Math.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;
}
}
}
}