ClipArea.cpp revision 04d46eb69fb4f4c4c332c36c6ae845da3b2ae848 
1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16#include "ClipArea.h"
17
18#include "utils/LinearAllocator.h"
19
20#include <SkPath.h>
21#include <limits>
22#include <type_traits>
23
24namespace android {
25namespace uirenderer {
26
27static void handlePoint(Rect& transformedBounds, const Matrix4& transform, float x, float y) {
28    Vertex v = {x, y};
29    transform.mapPoint(v.x, v.y);
30    transformedBounds.expandToCover(v.x, v.y);
31}
32
33Rect transformAndCalculateBounds(const Rect& r, const Matrix4& transform) {
34    const float kMinFloat = std::numeric_limits<float>::lowest();
35    const float kMaxFloat = std::numeric_limits<float>::max();
36    Rect transformedBounds = { kMaxFloat, kMaxFloat, kMinFloat, kMinFloat };
37    handlePoint(transformedBounds, transform, r.left, r.top);
38    handlePoint(transformedBounds, transform, r.right, r.top);
39    handlePoint(transformedBounds, transform, r.left, r.bottom);
40    handlePoint(transformedBounds, transform, r.right, r.bottom);
41    return transformedBounds;
42}
43
44void ClipBase::dump() const {
45    ALOGD("mode %d" RECT_STRING, mode, RECT_ARGS(rect));
46}
47
48/*
49 * TransformedRectangle
50 */
51
52TransformedRectangle::TransformedRectangle() {
53}
54
55TransformedRectangle::TransformedRectangle(const Rect& bounds,
56        const Matrix4& transform)
57        : mBounds(bounds)
58        , mTransform(transform) {
59}
60
61bool TransformedRectangle::canSimplyIntersectWith(
62        const TransformedRectangle& other) const {
63
64    return mTransform == other.mTransform;
65}
66
67void TransformedRectangle::intersectWith(const TransformedRectangle& other) {
68    mBounds.doIntersect(other.mBounds);
69}
70
71bool TransformedRectangle::isEmpty() const {
72    return mBounds.isEmpty();
73}
74
75/*
76 * RectangleList
77 */
78
79RectangleList::RectangleList()
80        : mTransformedRectanglesCount(0) {
81}
82
83bool RectangleList::isEmpty() const {
84    if (mTransformedRectanglesCount < 1) {
85        return true;
86    }
87
88    for (int i = 0; i < mTransformedRectanglesCount; i++) {
89        if (mTransformedRectangles[i].isEmpty()) {
90            return true;
91        }
92    }
93    return false;
94}
95
96int RectangleList::getTransformedRectanglesCount() const {
97    return mTransformedRectanglesCount;
98}
99
100const TransformedRectangle& RectangleList::getTransformedRectangle(int i) const {
101    return mTransformedRectangles[i];
102}
103
104void RectangleList::setEmpty() {
105    mTransformedRectanglesCount = 0;
106}
107
108void RectangleList::set(const Rect& bounds, const Matrix4& transform) {
109    mTransformedRectanglesCount = 1;
110    mTransformedRectangles[0] = TransformedRectangle(bounds, transform);
111}
112
113bool RectangleList::intersectWith(const Rect& bounds,
114        const Matrix4& transform) {
115    TransformedRectangle newRectangle(bounds, transform);
116
117    // Try to find a rectangle with a compatible transformation
118    int index = 0;
119    for (; index < mTransformedRectanglesCount; index++) {
120        TransformedRectangle& tr(mTransformedRectangles[index]);
121        if (tr.canSimplyIntersectWith(newRectangle)) {
122            tr.intersectWith(newRectangle);
123            return true;
124        }
125    }
126
127    // Add it to the list if there is room
128    if (index < kMaxTransformedRectangles) {
129        mTransformedRectangles[index] = newRectangle;
130        mTransformedRectanglesCount += 1;
131        return true;
132    }
133
134    // This rectangle list is full
135    return false;
136}
137
138Rect RectangleList::calculateBounds() const {
139    Rect bounds;
140    for (int index = 0; index < mTransformedRectanglesCount; index++) {
141        const TransformedRectangle& tr(mTransformedRectangles[index]);
142        if (index == 0) {
143            bounds = tr.transformedBounds();
144        } else {
145            bounds.doIntersect(tr.transformedBounds());
146        }
147    }
148    return bounds;
149}
150
151static SkPath pathFromTransformedRectangle(const Rect& bounds,
152        const Matrix4& transform) {
153    SkPath rectPath;
154    SkPath rectPathTransformed;
155    rectPath.addRect(bounds.left, bounds.top, bounds.right, bounds.bottom);
156    SkMatrix skTransform;
157    transform.copyTo(skTransform);
158    rectPath.transform(skTransform, &rectPathTransformed);
159    return rectPathTransformed;
160}
161
162SkRegion RectangleList::convertToRegion(const SkRegion& clip) const {
163    SkRegion rectangleListAsRegion;
164    for (int index = 0; index < mTransformedRectanglesCount; index++) {
165        const TransformedRectangle& tr(mTransformedRectangles[index]);
166        SkPath rectPathTransformed = pathFromTransformedRectangle(
167                tr.getBounds(), tr.getTransform());
168        if (index == 0) {
169            rectangleListAsRegion.setPath(rectPathTransformed, clip);
170        } else {
171            SkRegion rectRegion;
172            rectRegion.setPath(rectPathTransformed, clip);
173            rectangleListAsRegion.op(rectRegion, SkRegion::kIntersect_Op);
174        }
175    }
176    return rectangleListAsRegion;
177}
178
179void RectangleList::transform(const Matrix4& transform) {
180    for (int index = 0; index < mTransformedRectanglesCount; index++) {
181        mTransformedRectangles[index].transform(transform);
182    }
183}
184
185/*
186 * ClipArea
187 */
188
189ClipArea::ClipArea()
190        : mMode(ClipMode::Rectangle) {
191}
192
193/*
194 * Interface
195 */
196
197void ClipArea::setViewportDimensions(int width, int height) {
198    mPostViewportClipObserved = false;
199    mViewportBounds.set(0, 0, width, height);
200    mClipRect = mViewportBounds;
201}
202
203void ClipArea::setEmpty() {
204    onClipUpdated();
205    mMode = ClipMode::Rectangle;
206    mClipRect.setEmpty();
207    mClipRegion.setEmpty();
208    mRectangleList.setEmpty();
209}
210
211void ClipArea::setClip(float left, float top, float right, float bottom) {
212    onClipUpdated();
213    mMode = ClipMode::Rectangle;
214    mClipRect.set(left, top, right, bottom);
215    mClipRegion.setEmpty();
216}
217
218void ClipArea::clipRectWithTransform(const Rect& r, const mat4* transform,
219        SkRegion::Op op) {
220    if (op == SkRegion::kReplace_Op) mReplaceOpObserved = true;
221    if (!mPostViewportClipObserved && op == SkRegion::kIntersect_Op) op = SkRegion::kReplace_Op;
222    onClipUpdated();
223    switch (mMode) {
224    case ClipMode::Rectangle:
225        rectangleModeClipRectWithTransform(r, transform, op);
226        break;
227    case ClipMode::RectangleList:
228        rectangleListModeClipRectWithTransform(r, transform, op);
229        break;
230    case ClipMode::Region:
231        regionModeClipRectWithTransform(r, transform, op);
232        break;
233    }
234}
235
236void ClipArea::clipRegion(const SkRegion& region, SkRegion::Op op) {
237    if (op == SkRegion::kReplace_Op) mReplaceOpObserved = true;
238    if (!mPostViewportClipObserved && op == SkRegion::kIntersect_Op) op = SkRegion::kReplace_Op;
239    onClipUpdated();
240    enterRegionMode();
241    mClipRegion.op(region, op);
242    onClipRegionUpdated();
243}
244
245void ClipArea::clipPathWithTransform(const SkPath& path, const mat4* transform,
246        SkRegion::Op op) {
247    if (op == SkRegion::kReplace_Op) mReplaceOpObserved = true;
248    if (!mPostViewportClipObserved && op == SkRegion::kIntersect_Op) op = SkRegion::kReplace_Op;
249    onClipUpdated();
250    SkMatrix skTransform;
251    transform->copyTo(skTransform);
252    SkPath transformed;
253    path.transform(skTransform, &transformed);
254    SkRegion region;
255    regionFromPath(transformed, region);
256    clipRegion(region, op);
257}
258
259/*
260 * Rectangle mode
261 */
262
263void ClipArea::enterRectangleMode() {
264    // Entering rectangle mode discards any
265    // existing clipping information from the other modes.
266    // The only way this occurs is by a clip setting operation.
267    mMode = ClipMode::Rectangle;
268}
269
270void ClipArea::rectangleModeClipRectWithTransform(const Rect& r,
271        const mat4* transform, SkRegion::Op op) {
272
273    if (op == SkRegion::kReplace_Op && transform->rectToRect()) {
274        mClipRect = r;
275        transform->mapRect(mClipRect);
276        return;
277    } else if (op != SkRegion::kIntersect_Op) {
278        enterRegionMode();
279        regionModeClipRectWithTransform(r, transform, op);
280        return;
281    }
282
283    if (transform->rectToRect()) {
284        Rect transformed(r);
285        transform->mapRect(transformed);
286        mClipRect.doIntersect(transformed);
287        return;
288    }
289
290    enterRectangleListMode();
291    rectangleListModeClipRectWithTransform(r, transform, op);
292}
293
294/*
295 * RectangleList mode implementation
296 */
297
298void ClipArea::enterRectangleListMode() {
299    // Is is only legal to enter rectangle list mode from
300    // rectangle mode, since rectangle list mode cannot represent
301    // all clip areas that can be represented by a region.
302    ALOG_ASSERT(mMode == ClipMode::Rectangle);
303    mMode = ClipMode::RectangleList;
304    mRectangleList.set(mClipRect, Matrix4::identity());
305}
306
307void ClipArea::rectangleListModeClipRectWithTransform(const Rect& r,
308        const mat4* transform, SkRegion::Op op) {
309    if (op != SkRegion::kIntersect_Op
310            || !mRectangleList.intersectWith(r, *transform)) {
311        enterRegionMode();
312        regionModeClipRectWithTransform(r, transform, op);
313    }
314}
315
316/*
317 * Region mode implementation
318 */
319
320void ClipArea::enterRegionMode() {
321    ClipMode oldMode = mMode;
322    mMode = ClipMode::Region;
323    if (oldMode != ClipMode::Region) {
324        if (oldMode == ClipMode::Rectangle) {
325            mClipRegion.setRect(mClipRect.toSkIRect());
326        } else {
327            mClipRegion = mRectangleList.convertToRegion(createViewportRegion());
328            onClipRegionUpdated();
329        }
330    }
331}
332
333void ClipArea::regionModeClipRectWithTransform(const Rect& r,
334        const mat4* transform, SkRegion::Op op) {
335    SkPath transformedRect = pathFromTransformedRectangle(r, *transform);
336    SkRegion transformedRectRegion;
337    regionFromPath(transformedRect, transformedRectRegion);
338    mClipRegion.op(transformedRectRegion, op);
339    onClipRegionUpdated();
340}
341
342void ClipArea::onClipRegionUpdated() {
343    if (!mClipRegion.isEmpty()) {
344        mClipRect.set(mClipRegion.getBounds());
345
346        if (mClipRegion.isRect()) {
347            mClipRegion.setEmpty();
348            enterRectangleMode();
349        }
350    } else {
351        mClipRect.setEmpty();
352    }
353}
354
355/**
356 * Clip serialization
357 */
358
359const ClipBase* ClipArea::serializeClip(LinearAllocator& allocator) {
360    if (!mPostViewportClipObserved) {
361        // Only initial clip-to-viewport observed, so no serialization of clip necessary
362        return nullptr;
363    }
364
365    static_assert(std::is_trivially_destructible<Rect>::value,
366            "expect Rect to be trivially destructible");
367    static_assert(std::is_trivially_destructible<RectangleList>::value,
368            "expect RectangleList to be trivially destructible");
369
370    if (mLastSerialization == nullptr) {
371        ClipBase* serialization = nullptr;
372        switch (mMode) {
373        case ClipMode::Rectangle:
374            serialization = allocator.create<ClipRect>(mClipRect);
375            break;
376        case ClipMode::RectangleList:
377            serialization = allocator.create<ClipRectList>(mRectangleList);
378            serialization->rect = mRectangleList.calculateBounds();
379            break;
380        case ClipMode::Region:
381            serialization = allocator.create<ClipRegion>(mClipRegion);
382            serialization->rect.set(mClipRegion.getBounds());
383            break;
384        }
385        serialization->intersectWithRoot = mReplaceOpObserved;
386        // TODO: this is only done for draw time, should eventually avoid for record time
387        serialization->rect.snapToPixelBoundaries();
388        mLastSerialization = serialization;
389    }
390    return mLastSerialization;
391}
392
393inline static const RectangleList& getRectList(const ClipBase* scb) {
394    return reinterpret_cast<const ClipRectList*>(scb)->rectList;
395}
396
397inline static const SkRegion& getRegion(const ClipBase* scb) {
398    return reinterpret_cast<const ClipRegion*>(scb)->region;
399}
400
401// Conservative check for too many rectangles to fit in rectangle list.
402// For simplicity, doesn't account for rect merging
403static bool cannotFitInRectangleList(const ClipArea& clipArea, const ClipBase* scb) {
404    int currentRectCount = clipArea.isRectangleList()
405            ? clipArea.getRectangleList().getTransformedRectanglesCount()
406            : 1;
407    int recordedRectCount = (scb->mode == ClipMode::RectangleList)
408            ? getRectList(scb).getTransformedRectanglesCount()
409            : 1;
410    return currentRectCount + recordedRectCount > RectangleList::kMaxTransformedRectangles;
411}
412
413static const ClipRect sEmptyClipRect(Rect(0, 0));
414
415const ClipBase* ClipArea::serializeIntersectedClip(LinearAllocator& allocator,
416        const ClipBase* recordedClip, const Matrix4& recordedClipTransform) {
417
418    // if no recordedClip passed, just serialize current state
419    if (!recordedClip) return serializeClip(allocator);
420
421    // if either is empty, clip is empty
422    if (CC_UNLIKELY(recordedClip->rect.isEmpty())|| mClipRect.isEmpty()) return &sEmptyClipRect;
423
424    if (!mLastResolutionResult
425            || recordedClip != mLastResolutionClip
426            || recordedClipTransform != mLastResolutionTransform) {
427        mLastResolutionClip = recordedClip;
428        mLastResolutionTransform = recordedClipTransform;
429
430        if (CC_LIKELY(mMode == ClipMode::Rectangle
431                && recordedClip->mode == ClipMode::Rectangle
432                && recordedClipTransform.rectToRect())) {
433            // common case - result is a single rectangle
434            auto rectClip = allocator.create<ClipRect>(recordedClip->rect);
435            recordedClipTransform.mapRect(rectClip->rect);
436            rectClip->rect.doIntersect(mClipRect);
437            rectClip->rect.snapToPixelBoundaries();
438            mLastResolutionResult = rectClip;
439        } else if (CC_UNLIKELY(mMode == ClipMode::Region
440                || recordedClip->mode == ClipMode::Region
441                || cannotFitInRectangleList(*this, recordedClip))) {
442            // region case
443            SkRegion other;
444            switch (recordedClip->mode) {
445            case ClipMode::Rectangle:
446                if (CC_LIKELY(recordedClipTransform.rectToRect())) {
447                    // simple transform, skip creating SkPath
448                    Rect resultClip(recordedClip->rect);
449                    recordedClipTransform.mapRect(resultClip);
450                    other.setRect(resultClip.toSkIRect());
451                } else {
452                    SkPath transformedRect = pathFromTransformedRectangle(recordedClip->rect,
453                            recordedClipTransform);
454                    other.setPath(transformedRect, createViewportRegion());
455                }
456                break;
457            case ClipMode::RectangleList: {
458                RectangleList transformedList(getRectList(recordedClip));
459                transformedList.transform(recordedClipTransform);
460                other = transformedList.convertToRegion(createViewportRegion());
461                break;
462            }
463            case ClipMode::Region:
464                other = getRegion(recordedClip);
465
466                // TODO: handle non-translate transforms properly!
467                other.translate(recordedClipTransform.getTranslateX(),
468                        recordedClipTransform.getTranslateY());
469            }
470
471            ClipRegion* regionClip = allocator.create<ClipRegion>();
472            switch (mMode) {
473            case ClipMode::Rectangle:
474                regionClip->region.op(mClipRect.toSkIRect(), other, SkRegion::kIntersect_Op);
475                break;
476            case ClipMode::RectangleList:
477                regionClip->region.op(mRectangleList.convertToRegion(createViewportRegion()),
478                        other, SkRegion::kIntersect_Op);
479                break;
480            case ClipMode::Region:
481                regionClip->region.op(mClipRegion, other, SkRegion::kIntersect_Op);
482                break;
483            }
484            // Don't need to snap, since region's in int bounds
485            regionClip->rect.set(regionClip->region.getBounds());
486            mLastResolutionResult = regionClip;
487        } else {
488            auto rectListClip = allocator.create<ClipRectList>(mRectangleList);
489            auto&& rectList = rectListClip->rectList;
490            if (mMode == ClipMode::Rectangle) {
491                rectList.set(mClipRect, Matrix4::identity());
492            }
493
494            if (recordedClip->mode == ClipMode::Rectangle) {
495                rectList.intersectWith(recordedClip->rect, recordedClipTransform);
496            } else {
497                const RectangleList& other = getRectList(recordedClip);
498                for (int i = 0; i < other.getTransformedRectanglesCount(); i++) {
499                    auto&& tr = other.getTransformedRectangle(i);
500                    Matrix4 totalTransform(recordedClipTransform);
501                    totalTransform.multiply(tr.getTransform());
502                    rectList.intersectWith(tr.getBounds(), totalTransform);
503                }
504            }
505            rectListClip->rect = rectList.calculateBounds();
506            rectListClip->rect.snapToPixelBoundaries();
507            mLastResolutionResult = rectListClip;
508        }
509    }
510    return mLastResolutionResult;
511}
512
513void ClipArea::applyClip(const ClipBase* clip, const Matrix4& transform) {
514    if (!clip) return; // nothing to do
515
516    if (CC_LIKELY(clip->mode == ClipMode::Rectangle)) {
517        clipRectWithTransform(clip->rect, &transform, SkRegion::kIntersect_Op);
518    } else if (CC_LIKELY(clip->mode == ClipMode::RectangleList)) {
519        auto&& rectList = getRectList(clip);
520        for (int i = 0; i < rectList.getTransformedRectanglesCount(); i++) {
521            auto&& tr = rectList.getTransformedRectangle(i);
522            Matrix4 totalTransform(transform);
523            totalTransform.multiply(tr.getTransform());
524            clipRectWithTransform(tr.getBounds(), &totalTransform, SkRegion::kIntersect_Op);
525        }
526    } else {
527        SkRegion region(getRegion(clip));
528        // TODO: handle non-translate transforms properly!
529        region.translate(transform.getTranslateX(), transform.getTranslateY());
530        clipRegion(region, SkRegion::kIntersect_Op);
531    }
532}
533
534} /* namespace uirenderer */
535} /* namespace android */
536