VectorDrawable native rendering - Step 1 of MANY
Implement path parsing from string to skia path in native. The parsing
contains two main stages:
1) Parse string into a list of nodes that contains one operation (such
as move) and a vector of floats as params for that operation.
2) Interpret the operations defined in the nodes into SkPath operations,
and create a skia path
Also provided unit test for parsing a string path into a list of nodes,
and then to a skia path.
Change-Id: I0ce13df5e3bb90987dcdc80fe8b039af175ad2e2
diff --git a/libs/hwui/VectorDrawablePath.cpp b/libs/hwui/VectorDrawablePath.cpp
new file mode 100644
index 0000000..115435c
--- /dev/null
+++ b/libs/hwui/VectorDrawablePath.cpp
@@ -0,0 +1,496 @@
+/*
+ * 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 "VectorDrawablePath.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);
+};
+
+VectorDrawablePath::VectorDrawablePath(const char* pathStr, size_t strLength) {
+ PathParser::getPathDataFromString(&mData, pathStr, strLength);
+ verbsToPath(&mSkPath, &mData);
+}
+
+VectorDrawablePath::VectorDrawablePath(const PathData& data) {
+ mData = data;
+ // Now we need to construct a path
+ verbsToPath(&mSkPath, &data);
+}
+
+VectorDrawablePath::VectorDrawablePath(const VectorDrawablePath& path) {
+ mData = path.mData;
+ verbsToPath(&mSkPath, &mData);
+}
+
+bool VectorDrawablePath::canMorph(const PathData& morphTo) {
+ if (mData.verbs.size() != morphTo.verbs.size()) {
+ return false;
+ }
+
+ for (unsigned int i = 0; i < mData.verbs.size(); i++) {
+ if (mData.verbs[i] != morphTo.verbs[i]
+ || mData.verbSizes[i] != morphTo.verbSizes[i]) {
+ return false;
+ }
+ }
+ return true;
+}
+
+bool VectorDrawablePath::canMorph(const VectorDrawablePath& path) {
+ return canMorph(path.mData);
+}
+ /**
+ * Convert an array of PathVerb to Path.
+ */
+void VectorDrawablePath::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 - 1u);
+ 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 VectorDrawablePath::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);
+}
+
+
+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;
+ }
+ previousCmd = cmd;
+ }
+}
+
+}; // namespace uirenderer
+}; // namespace android