1/*
2 * Copyright 2006 The Android Open Source Project
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8#include "SkDashPathEffect.h"
9#include "SkDashImpl.h"
10#include "SkDashPathPriv.h"
11#include "SkReadBuffer.h"
12#include "SkWriteBuffer.h"
13#include "SkStrokeRec.h"
14
15SkDashImpl::SkDashImpl(const SkScalar intervals[], int count, SkScalar phase)
16        : fPhase(0)
17        , fInitialDashLength(-1)
18        , fInitialDashIndex(0)
19        , fIntervalLength(0) {
20    SkASSERT(intervals);
21    SkASSERT(count > 1 && SkIsAlign2(count));
22
23    fIntervals = (SkScalar*)sk_malloc_throw(sizeof(SkScalar) * count);
24    fCount = count;
25    for (int i = 0; i < count; i++) {
26        fIntervals[i] = intervals[i];
27    }
28
29    // set the internal data members
30    SkDashPath::CalcDashParameters(phase, fIntervals, fCount,
31            &fInitialDashLength, &fInitialDashIndex, &fIntervalLength, &fPhase);
32}
33
34SkDashImpl::~SkDashImpl() {
35    sk_free(fIntervals);
36}
37
38bool SkDashImpl::filterPath(SkPath* dst, const SkPath& src, SkStrokeRec* rec,
39                            const SkRect* cullRect) const {
40    return SkDashPath::InternalFilter(dst, src, rec, cullRect, fIntervals, fCount,
41                                      fInitialDashLength, fInitialDashIndex, fIntervalLength);
42}
43
44static void outset_for_stroke(SkRect* rect, const SkStrokeRec& rec) {
45    SkScalar radius = SkScalarHalf(rec.getWidth());
46    if (0 == radius) {
47        radius = SK_Scalar1;    // hairlines
48    }
49    if (SkPaint::kMiter_Join == rec.getJoin()) {
50        radius *= rec.getMiter();
51    }
52    rect->outset(radius, radius);
53}
54
55// Attempt to trim the line to minimally cover the cull rect (currently
56// only works for horizontal and vertical lines).
57// Return true if processing should continue; false otherwise.
58static bool cull_line(SkPoint* pts, const SkStrokeRec& rec,
59                      const SkMatrix& ctm, const SkRect* cullRect,
60                      const SkScalar intervalLength) {
61    if (nullptr == cullRect) {
62        SkASSERT(false); // Shouldn't ever occur in practice
63        return false;
64    }
65
66    SkScalar dx = pts[1].x() - pts[0].x();
67    SkScalar dy = pts[1].y() - pts[0].y();
68
69    if ((dx && dy) || (!dx && !dy)) {
70        return false;
71    }
72
73    SkRect bounds = *cullRect;
74    outset_for_stroke(&bounds, rec);
75
76    // cullRect is in device space while pts are in the local coordinate system
77    // defined by the ctm. We want our answer in the local coordinate system.
78
79    SkASSERT(ctm.rectStaysRect());
80    SkMatrix inv;
81    if (!ctm.invert(&inv)) {
82        return false;
83    }
84
85    inv.mapRect(&bounds);
86
87    if (dx) {
88        SkASSERT(dx && !dy);
89        SkScalar minX = pts[0].fX;
90        SkScalar maxX = pts[1].fX;
91
92        if (dx < 0) {
93            SkTSwap(minX, maxX);
94        }
95
96        SkASSERT(minX < maxX);
97        if (maxX <= bounds.fLeft || minX >= bounds.fRight) {
98            return false;
99        }
100
101        // Now we actually perform the chop, removing the excess to the left and
102        // right of the bounds (keeping our new line "in phase" with the dash,
103        // hence the (mod intervalLength).
104
105        if (minX < bounds.fLeft) {
106            minX = bounds.fLeft - SkScalarMod(bounds.fLeft - minX, intervalLength);
107        }
108        if (maxX > bounds.fRight) {
109            maxX = bounds.fRight + SkScalarMod(maxX - bounds.fRight, intervalLength);
110        }
111
112        SkASSERT(maxX > minX);
113        if (dx < 0) {
114            SkTSwap(minX, maxX);
115        }
116        pts[0].fX = minX;
117        pts[1].fX = maxX;
118    } else {
119        SkASSERT(dy && !dx);
120        SkScalar minY = pts[0].fY;
121        SkScalar maxY = pts[1].fY;
122
123        if (dy < 0) {
124            SkTSwap(minY, maxY);
125        }
126
127        SkASSERT(minY < maxY);
128        if (maxY <= bounds.fTop || minY >= bounds.fBottom) {
129            return false;
130        }
131
132        // Now we actually perform the chop, removing the excess to the top and
133        // bottom of the bounds (keeping our new line "in phase" with the dash,
134        // hence the (mod intervalLength).
135
136        if (minY < bounds.fTop) {
137            minY = bounds.fTop - SkScalarMod(bounds.fTop - minY, intervalLength);
138        }
139        if (maxY > bounds.fBottom) {
140            maxY = bounds.fBottom + SkScalarMod(maxY - bounds.fBottom, intervalLength);
141        }
142
143        SkASSERT(maxY > minY);
144        if (dy < 0) {
145            SkTSwap(minY, maxY);
146        }
147        pts[0].fY = minY;
148        pts[1].fY = maxY;
149    }
150
151    return true;
152}
153
154// Currently asPoints is more restrictive then it needs to be. In the future
155// we need to:
156//      allow kRound_Cap capping (could allow rotations in the matrix with this)
157//      allow paths to be returned
158bool SkDashImpl::asPoints(PointData* results, const SkPath& src, const SkStrokeRec& rec,
159                          const SkMatrix& matrix, const SkRect* cullRect) const {
160    // width < 0 -> fill && width == 0 -> hairline so requiring width > 0 rules both out
161    if (0 >= rec.getWidth()) {
162        return false;
163    }
164
165    // TODO: this next test could be eased up. We could allow any number of
166    // intervals as long as all the ons match and all the offs match.
167    // Additionally, they do not necessarily need to be integers.
168    // We cannot allow arbitrary intervals since we want the returned points
169    // to be uniformly sized.
170    if (fCount != 2 ||
171        !SkScalarNearlyEqual(fIntervals[0], fIntervals[1]) ||
172        !SkScalarIsInt(fIntervals[0]) ||
173        !SkScalarIsInt(fIntervals[1])) {
174        return false;
175    }
176
177    SkPoint pts[2];
178
179    if (!src.isLine(pts)) {
180        return false;
181    }
182
183    // TODO: this test could be eased up to allow circles
184    if (SkPaint::kButt_Cap != rec.getCap()) {
185        return false;
186    }
187
188    // TODO: this test could be eased up for circles. Rotations could be allowed.
189    if (!matrix.rectStaysRect()) {
190        return false;
191    }
192
193    // See if the line can be limited to something plausible.
194    if (!cull_line(pts, rec, matrix, cullRect, fIntervalLength)) {
195        return false;
196    }
197
198    SkScalar length = SkPoint::Distance(pts[1], pts[0]);
199
200    SkVector tangent = pts[1] - pts[0];
201    if (tangent.isZero()) {
202        return false;
203    }
204
205    tangent.scale(SkScalarInvert(length));
206
207    // TODO: make this test for horizontal & vertical lines more robust
208    bool isXAxis = true;
209    if (SkScalarNearlyEqual(SK_Scalar1, tangent.fX) ||
210        SkScalarNearlyEqual(-SK_Scalar1, tangent.fX)) {
211        results->fSize.set(SkScalarHalf(fIntervals[0]), SkScalarHalf(rec.getWidth()));
212    } else if (SkScalarNearlyEqual(SK_Scalar1, tangent.fY) ||
213               SkScalarNearlyEqual(-SK_Scalar1, tangent.fY)) {
214        results->fSize.set(SkScalarHalf(rec.getWidth()), SkScalarHalf(fIntervals[0]));
215        isXAxis = false;
216    } else if (SkPaint::kRound_Cap != rec.getCap()) {
217        // Angled lines don't have axis-aligned boxes.
218        return false;
219    }
220
221    if (results) {
222        results->fFlags = 0;
223        SkScalar clampedInitialDashLength = SkMinScalar(length, fInitialDashLength);
224
225        if (SkPaint::kRound_Cap == rec.getCap()) {
226            results->fFlags |= PointData::kCircles_PointFlag;
227        }
228
229        results->fNumPoints = 0;
230        SkScalar len2 = length;
231        if (clampedInitialDashLength > 0 || 0 == fInitialDashIndex) {
232            SkASSERT(len2 >= clampedInitialDashLength);
233            if (0 == fInitialDashIndex) {
234                if (clampedInitialDashLength > 0) {
235                    if (clampedInitialDashLength >= fIntervals[0]) {
236                        ++results->fNumPoints;  // partial first dash
237                    }
238                    len2 -= clampedInitialDashLength;
239                }
240                len2 -= fIntervals[1];  // also skip first space
241                if (len2 < 0) {
242                    len2 = 0;
243                }
244            } else {
245                len2 -= clampedInitialDashLength; // skip initial partial empty
246            }
247        }
248        // Too many midpoints can cause results->fNumPoints to overflow or
249        // otherwise cause the results->fPoints allocation below to OOM.
250        // Cap it to a sane value.
251        SkScalar numIntervals = len2 / fIntervalLength;
252        if (!SkScalarIsFinite(numIntervals) || numIntervals > SkDashPath::kMaxDashCount) {
253            return false;
254        }
255        int numMidPoints = SkScalarFloorToInt(numIntervals);
256        results->fNumPoints += numMidPoints;
257        len2 -= numMidPoints * fIntervalLength;
258        bool partialLast = false;
259        if (len2 > 0) {
260            if (len2 < fIntervals[0]) {
261                partialLast = true;
262            } else {
263                ++numMidPoints;
264                ++results->fNumPoints;
265            }
266        }
267
268        results->fPoints = new SkPoint[results->fNumPoints];
269
270        SkScalar    distance = 0;
271        int         curPt = 0;
272
273        if (clampedInitialDashLength > 0 || 0 == fInitialDashIndex) {
274            SkASSERT(clampedInitialDashLength <= length);
275
276            if (0 == fInitialDashIndex) {
277                if (clampedInitialDashLength > 0) {
278                    // partial first block
279                    SkASSERT(SkPaint::kRound_Cap != rec.getCap()); // can't handle partial circles
280                    SkScalar x = pts[0].fX + tangent.fX * SkScalarHalf(clampedInitialDashLength);
281                    SkScalar y = pts[0].fY + tangent.fY * SkScalarHalf(clampedInitialDashLength);
282                    SkScalar halfWidth, halfHeight;
283                    if (isXAxis) {
284                        halfWidth = SkScalarHalf(clampedInitialDashLength);
285                        halfHeight = SkScalarHalf(rec.getWidth());
286                    } else {
287                        halfWidth = SkScalarHalf(rec.getWidth());
288                        halfHeight = SkScalarHalf(clampedInitialDashLength);
289                    }
290                    if (clampedInitialDashLength < fIntervals[0]) {
291                        // This one will not be like the others
292                        results->fFirst.addRect(x - halfWidth, y - halfHeight,
293                                                x + halfWidth, y + halfHeight);
294                    } else {
295                        SkASSERT(curPt < results->fNumPoints);
296                        results->fPoints[curPt].set(x, y);
297                        ++curPt;
298                    }
299
300                    distance += clampedInitialDashLength;
301                }
302
303                distance += fIntervals[1];  // skip over the next blank block too
304            } else {
305                distance += clampedInitialDashLength;
306            }
307        }
308
309        if (0 != numMidPoints) {
310            distance += SkScalarHalf(fIntervals[0]);
311
312            for (int i = 0; i < numMidPoints; ++i) {
313                SkScalar x = pts[0].fX + tangent.fX * distance;
314                SkScalar y = pts[0].fY + tangent.fY * distance;
315
316                SkASSERT(curPt < results->fNumPoints);
317                results->fPoints[curPt].set(x, y);
318                ++curPt;
319
320                distance += fIntervalLength;
321            }
322
323            distance -= SkScalarHalf(fIntervals[0]);
324        }
325
326        if (partialLast) {
327            // partial final block
328            SkASSERT(SkPaint::kRound_Cap != rec.getCap()); // can't handle partial circles
329            SkScalar temp = length - distance;
330            SkASSERT(temp < fIntervals[0]);
331            SkScalar x = pts[0].fX + tangent.fX * (distance + SkScalarHalf(temp));
332            SkScalar y = pts[0].fY + tangent.fY * (distance + SkScalarHalf(temp));
333            SkScalar halfWidth, halfHeight;
334            if (isXAxis) {
335                halfWidth = SkScalarHalf(temp);
336                halfHeight = SkScalarHalf(rec.getWidth());
337            } else {
338                halfWidth = SkScalarHalf(rec.getWidth());
339                halfHeight = SkScalarHalf(temp);
340            }
341            results->fLast.addRect(x - halfWidth, y - halfHeight,
342                                   x + halfWidth, y + halfHeight);
343        }
344
345        SkASSERT(curPt == results->fNumPoints);
346    }
347
348    return true;
349}
350
351SkPathEffect::DashType SkDashImpl::asADash(DashInfo* info) const {
352    if (info) {
353        if (info->fCount >= fCount && info->fIntervals) {
354            memcpy(info->fIntervals, fIntervals, fCount * sizeof(SkScalar));
355        }
356        info->fCount = fCount;
357        info->fPhase = fPhase;
358    }
359    return kDash_DashType;
360}
361
362void SkDashImpl::flatten(SkWriteBuffer& buffer) const {
363    buffer.writeScalar(fPhase);
364    buffer.writeScalarArray(fIntervals, fCount);
365}
366
367sk_sp<SkFlattenable> SkDashImpl::CreateProc(SkReadBuffer& buffer) {
368    const SkScalar phase = buffer.readScalar();
369    uint32_t count = buffer.getArrayCount();
370    SkAutoSTArray<32, SkScalar> intervals(count);
371    if (buffer.readScalarArray(intervals.get(), count)) {
372        return SkDashPathEffect::Make(intervals.get(), SkToInt(count), phase);
373    }
374    return nullptr;
375}
376
377#ifndef SK_IGNORE_TO_STRING
378void SkDashImpl::toString(SkString* str) const {
379    str->appendf("SkDashPathEffect: (");
380    str->appendf("count: %d phase %.2f intervals: (", fCount, fPhase);
381    for (int i = 0; i < fCount; ++i) {
382        str->appendf("%.2f", fIntervals[i]);
383        if (i < fCount-1) {
384            str->appendf(", ");
385        }
386    }
387    str->appendf("))");
388}
389#endif
390
391//////////////////////////////////////////////////////////////////////////////////////////////////
392
393sk_sp<SkPathEffect> SkDashPathEffect::Make(const SkScalar intervals[], int count, SkScalar phase) {
394    if (!SkDashPath::ValidDashPath(phase, intervals, count)) {
395        return nullptr;
396    }
397    return sk_sp<SkPathEffect>(new SkDashImpl(intervals, count, phase));
398}
399