1
2/*
3 * Copyright 2011 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8#include "SkParse.h"
9#include "SkParsePath.h"
10
11static inline bool is_between(int c, int min, int max) {
12    return (unsigned)(c - min) <= (unsigned)(max - min);
13}
14
15static inline bool is_ws(int c) {
16    return is_between(c, 1, 32);
17}
18
19static inline bool is_digit(int c) {
20    return is_between(c, '0', '9');
21}
22
23static inline bool is_sep(int c) {
24    return is_ws(c) || c == ',';
25}
26
27static inline bool is_lower(int c) {
28    return is_between(c, 'a', 'z');
29}
30
31static inline int to_upper(int c) {
32    return c - 'a' + 'A';
33}
34
35static const char* skip_ws(const char str[]) {
36    SkASSERT(str);
37    while (is_ws(*str))
38        str++;
39    return str;
40}
41
42static const char* skip_sep(const char str[]) {
43    SkASSERT(str);
44    while (is_sep(*str))
45        str++;
46    return str;
47}
48
49static const char* find_points(const char str[], SkPoint value[], int count,
50                               bool isRelative, SkPoint* relative) {
51    str = SkParse::FindScalars(str, &value[0].fX, count * 2);
52    if (isRelative) {
53        for (int index = 0; index < count; index++) {
54            value[index].fX += relative->fX;
55            value[index].fY += relative->fY;
56        }
57    }
58    return str;
59}
60
61static const char* find_scalar(const char str[], SkScalar* value,
62                               bool isRelative, SkScalar relative) {
63    str = SkParse::FindScalar(str, value);
64    if (isRelative) {
65        *value += relative;
66    }
67    return str;
68}
69
70bool SkParsePath::FromSVGString(const char data[], SkPath* result) {
71    SkPath path;
72    SkPoint f = {0, 0};
73    SkPoint c = {0, 0};
74    SkPoint lastc = {0, 0};
75    SkPoint points[3];
76    char op = '\0';
77    char previousOp = '\0';
78    bool relative = false;
79    for (;;) {
80        data = skip_ws(data);
81        if (data[0] == '\0') {
82            break;
83        }
84        char ch = data[0];
85        if (is_digit(ch) || ch == '-' || ch == '+') {
86            if (op == '\0') {
87                return false;
88            }
89        } else {
90            op = ch;
91            relative = false;
92            if (is_lower(op)) {
93                op = (char) to_upper(op);
94                relative = true;
95            }
96            data++;
97            data = skip_sep(data);
98        }
99        switch (op) {
100            case 'M':
101                data = find_points(data, points, 1, relative, &c);
102                path.moveTo(points[0]);
103                op = 'L';
104                c = points[0];
105                break;
106            case 'L':
107                data = find_points(data, points, 1, relative, &c);
108                path.lineTo(points[0]);
109                c = points[0];
110                break;
111            case 'H': {
112                SkScalar x;
113                data = find_scalar(data, &x, relative, c.fX);
114                path.lineTo(x, c.fY);
115                c.fX = x;
116            } break;
117            case 'V': {
118                SkScalar y;
119                data = find_scalar(data, &y, relative, c.fY);
120                path.lineTo(c.fX, y);
121                c.fY = y;
122            } break;
123            case 'C':
124                data = find_points(data, points, 3, relative, &c);
125                goto cubicCommon;
126            case 'S':
127                data = find_points(data, &points[1], 2, relative, &c);
128                points[0] = c;
129                if (previousOp == 'C' || previousOp == 'S') {
130                    points[0].fX -= lastc.fX - c.fX;
131                    points[0].fY -= lastc.fY - c.fY;
132                }
133            cubicCommon:
134                path.cubicTo(points[0], points[1], points[2]);
135                lastc = points[1];
136                c = points[2];
137                break;
138            case 'Q':  // Quadratic Bezier Curve
139                data = find_points(data, points, 2, relative, &c);
140                goto quadraticCommon;
141            case 'T':
142                data = find_points(data, &points[1], 1, relative, &c);
143                points[0] = points[1];
144                if (previousOp == 'Q' || previousOp == 'T') {
145                    points[0].fX = c.fX * 2 - lastc.fX;
146                    points[0].fY = c.fY * 2 - lastc.fY;
147                }
148            quadraticCommon:
149                path.quadTo(points[0], points[1]);
150                lastc = points[0];
151                c = points[1];
152                break;
153            case 'Z':
154                path.close();
155#if 0   // !!! still a bug?
156                if (fPath.isEmpty() && (f.fX != 0 || f.fY != 0)) {
157                    c.fX -= SkScalar.Epsilon;   // !!! enough?
158                    fPath.moveTo(c);
159                    fPath.lineTo(f);
160                    fPath.close();
161                }
162#endif
163                c = f;
164                op = '\0';
165                break;
166            case '~': {
167                SkPoint args[2];
168                data = find_points(data, args, 2, false, NULL);
169                path.moveTo(args[0].fX, args[0].fY);
170                path.lineTo(args[1].fX, args[1].fY);
171            } break;
172            default:
173                return false;
174        }
175        if (previousOp == 0) {
176            f = c;
177        }
178        previousOp = op;
179    }
180    // we're good, go ahead and swap in the result
181    result->swap(path);
182    return true;
183}
184
185///////////////////////////////////////////////////////////////////////////////
186
187#include "SkString.h"
188#include "SkStream.h"
189
190static void write_scalar(SkWStream* stream, SkScalar value) {
191    char buffer[64];
192#ifdef SK_BUILD_FOR_WIN32
193    int len = _snprintf(buffer, sizeof(buffer), "%g", value);
194#else
195    int len = snprintf(buffer, sizeof(buffer), "%g", value);
196#endif
197    char* stop = buffer + len;
198    stream->write(buffer, stop - buffer);
199}
200
201static void append_scalars(SkWStream* stream, char verb, const SkScalar data[],
202                           int count) {
203    stream->write(&verb, 1);
204    write_scalar(stream, data[0]);
205    for (int i = 1; i < count; i++) {
206        stream->write(" ", 1);
207        write_scalar(stream, data[i]);
208    }
209}
210
211void SkParsePath::ToSVGString(const SkPath& path, SkString* str) {
212    SkDynamicMemoryWStream  stream;
213
214    SkPath::Iter    iter(path, false);
215    SkPoint         pts[4];
216
217    for (;;) {
218        switch (iter.next(pts, false)) {
219             case SkPath::kConic_Verb:
220                SkASSERT(0);
221                break;
222           case SkPath::kMove_Verb:
223                append_scalars(&stream, 'M', &pts[0].fX, 2);
224                break;
225            case SkPath::kLine_Verb:
226                append_scalars(&stream, 'L', &pts[1].fX, 2);
227                break;
228            case SkPath::kQuad_Verb:
229                append_scalars(&stream, 'Q', &pts[1].fX, 4);
230                break;
231            case SkPath::kCubic_Verb:
232                append_scalars(&stream, 'C', &pts[1].fX, 6);
233                break;
234            case SkPath::kClose_Verb:
235                stream.write("Z", 1);
236                break;
237            case SkPath::kDone_Verb:
238                str->resize(stream.getOffset());
239                stream.copyTo(str->writable_str());
240            return;
241        }
242    }
243}
244