SkParsePath Class Reference

#include <SkParsePath.h>

Public Types
enum class	PathEncoding { Absolute , Relative }

Static Public Member Functions
static bool	FromSVGString (const char str[], SkPath *)
static SkString	ToSVGString (const SkPath &, PathEncoding=PathEncoding::Absolute)

Detailed Description

Definition at line 17 of file SkParsePath.h.

Member Enumeration Documentation

PathEncoding

enum class SkParsePath::PathEncoding

strong

Enumerator
Absolute
Relative

Definition at line 21 of file SkParsePath.h.

{ Absolute, Relative };

Member Function Documentation

FromSVGString()

bool SkParsePath::FromSVGString ( const char  str[], SkPath *  result  )

static

Definition at line 107 of file SkParsePath.cpp.

                                                                 {
    // We will write all data to this local path and only write it
    // to result if the whole parsing succeeds.
    SkPath path;
    SkPoint first = {0, 0};
    SkPoint c = {0, 0};
    SkPoint lastc = {0, 0};
    // We will use find_points and find_scalar to read into these.
    // There might not be enough data to fill them, so to avoid
    // MSAN warnings about using uninitialized bytes, we initialize
    // them there.
    SkPoint points[3] = {};
    SkScalar scratch = 0;
    char op = '\0';
    char previousOp = '\0';
    bool relative = false;
    for (;;) {
        if (!data) {
            // Truncated data
            return false;
        }
        data = skip_ws(data);
        if (data[0] == '\0') {
            break;
        }
        char ch = data[0];
        if (is_digit(ch) || ch == '-' || ch == '+' || ch == '.') {
            if (op == '\0' || op == 'Z') {
                return false;
            }
        } else if (is_sep(ch)) {
            data = skip_sep(data);
        } else {
            op = ch;
            relative = false;
            if (is_lower(op)) {
                op = (char) to_upper(op);
                relative = true;
            }
            data++;
            data = skip_sep(data);
        }
        switch (op) {
            case 'M':  // Move
                data = find_points(data, points, 1, relative, &c);
                // find_points might have failed, so this might be the
                // previous point. However, data will be set to nullptr
                // if it failed, so we will check this at the top of the loop.
                path.moveTo(points[0]);
                previousOp = '\0';
                op = 'L';
                c = points[0];
                break;
            case 'L':  // Line
                data = find_points(data, points, 1, relative, &c);
                path.lineTo(points[0]);
                c = points[0];
                break;
            case 'H':  // Horizontal Line
                data = find_scalar(data, &scratch, relative, c.fX);
                // Similarly, if there wasn't a scalar to read, data will
                // be set to nullptr and this lineTo is bogus but will
                // be ultimately ignored when the next time through the loop
                // detects that and bails out.
                path.lineTo(scratch, c.fY);
                c.fX = scratch;
                break;
            case 'V':  // Vertical Line
                data = find_scalar(data, &scratch, relative, c.fY);
                path.lineTo(c.fX, scratch);
                c.fY = scratch;
                break;
            case 'C':  // Cubic Bezier Curve
                data = find_points(data, points, 3, relative, &c);
                goto cubicCommon;
            case 'S':  // Continued "Smooth" Cubic Bezier Curve
                data = find_points(data, &points[1], 2, relative, &c);
                points[0] = c;
                if (previousOp == 'C' || previousOp == 'S') {
                    points[0].fX -= lastc.fX - c.fX;
                    points[0].fY -= lastc.fY - c.fY;
                }
            cubicCommon:
                path.cubicTo(points[0], points[1], points[2]);
                lastc = points[1];
                c = points[2];
                break;
            case 'Q':  // Quadratic Bezier Curve
                data = find_points(data, points, 2, relative, &c);
                goto quadraticCommon;
            case 'T':  // Continued Quadratic Bezier Curve
                data = find_points(data, &points[1], 1, relative, &c);
                points[0] = c;
                if (previousOp == 'Q' || previousOp == 'T') {
                    points[0].fX -= lastc.fX - c.fX;
                    points[0].fY -= lastc.fY - c.fY;
                }
            quadraticCommon:
                path.quadTo(points[0], points[1]);
                lastc = points[0];
                c = points[1];
                break;
            case 'A': {  // Arc (Elliptical)
                SkPoint radii;
                SkScalar angle;
                bool largeArc, sweep;
                if ((data = find_points(data, &radii, 1, false, nullptr))
                        && (data = skip_sep(data))
                        && (data = find_scalar(data, &angle, false, 0))
                        && (data = skip_sep(data))
                        && (data = find_flag(data, &largeArc))
                        && (data = skip_sep(data))
                        && (data = find_flag(data, &sweep))
                        && (data = skip_sep(data))
                        && (data = find_points(data, &points[0], 1, relative, &c))) {
                    path.arcTo(radii, angle, (SkPath::ArcSize) largeArc,
                            (SkPathDirection) !sweep, points[0]);
                    path.getLastPt(&c);
                }
                } break;
            case 'Z':  // Close Path
                path.close();
                c = first;
                break;
            default:
                return false;
        }
        if (previousOp == 0) {
            first = c;
        }
        previousOp = op;
    }
    // we're good, go ahead and swap in the result
    result->swap(path);
    return true;
}

ToSVGString()

SkString SkParsePath::ToSVGString ( const SkPath &  path, PathEncoding  encoding = PathEncoding::Absolute  )

static

Definition at line 246 of file SkParsePath.cpp.

                                                                           {
    SkDynamicMemoryWStream  stream;
 
    SkPoint current_point{0,0};
    const auto rel_selector = encoding == PathEncoding::Relative;
 
    const auto append_command = [&](char cmd, const SkPoint pts[], size_t count) {
        // Use lower case cmds for relative encoding.
        cmd += 32 * rel_selector;
        stream.write(&cmd, 1);
 
        for (size_t i = 0; i < count; ++i) {
            const auto pt = pts[i] - current_point;
            if (i > 0) {
                stream.write(" ", 1);
            }
            stream.writeScalarAsText(pt.fX);
            stream.write(" ", 1);
            stream.writeScalarAsText(pt.fY);
        }
 
        SkASSERT(count > 0);
        // For relative encoding, track the current point (otherwise == origin).
        current_point = pts[count - 1] * rel_selector;
    };
 
    SkPath::Iter    iter(path, false);
    SkPoint         pts[4];
 
    for (;;) {
        switch (iter.next(pts)) {
            case SkPath::kConic_Verb: {
                const SkScalar tol = SK_Scalar1 / 1024; // how close to a quad
                SkAutoConicToQuads quadder;
                const SkPoint* quadPts = quadder.computeQuads(pts, iter.conicWeight(), tol);
                for (int i = 0; i < quadder.countQuads(); ++i) {
                    append_command('Q', &quadPts[i*2 + 1], 2);
                }
            } break;
           case SkPath::kMove_Verb:
                append_command('M', &pts[0], 1);
                break;
            case SkPath::kLine_Verb:
                append_command('L', &pts[1], 1);
                break;
            case SkPath::kQuad_Verb:
                append_command('Q', &pts[1], 2);
                break;
            case SkPath::kCubic_Verb:
                append_command('C', &pts[1], 3);
                break;
            case SkPath::kClose_Verb:
                stream.write("Z", 1);
                break;
            case SkPath::kDone_Verb: {
                SkString str;
                str.resize(stream.bytesWritten());
                stream.copyTo(str.data());
                return str;
            }
        }
    }
}

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The documentation for this class was generated from the following files:

• third_party/skia/include/utils/SkParsePath.h
• third_party/skia/src/utils/SkParsePath.cpp