ClipArea.cpp revision 02806288d1c56475413888a934c796e6e4eb11c5 
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 (!mPostViewportClipObserved && op == SkRegion::kIntersect_Op) op = SkRegion::kReplace_Op;
221    onClipUpdated();
222    switch (mMode) {
223    case ClipMode::Rectangle:
224        rectangleModeClipRectWithTransform(r, transform, op);
225        break;
226    case ClipMode::RectangleList:
227        rectangleListModeClipRectWithTransform(r, transform, op);
228        break;
229    case ClipMode::Region:
230        regionModeClipRectWithTransform(r, transform, op);
231        break;
232    }
233}
234
235void ClipArea::clipRegion(const SkRegion& region, SkRegion::Op op) {
236    if (!mPostViewportClipObserved && op == SkRegion::kIntersect_Op) op = SkRegion::kReplace_Op;
237    onClipUpdated();
238    enterRegionMode();
239    mClipRegion.op(region, op);
240    onClipRegionUpdated();
241}
242
243void ClipArea::clipPathWithTransform(const SkPath& path, const mat4* transform,
244        SkRegion::Op op) {
245    if (!mPostViewportClipObserved && op == SkRegion::kIntersect_Op) op = SkRegion::kReplace_Op;
246    onClipUpdated();
247    SkMatrix skTransform;
248    transform->copyTo(skTransform);
249    SkPath transformed;
250    path.transform(skTransform, &transformed);
251    SkRegion region;
252    regionFromPath(transformed, region);
253    clipRegion(region, op);
254}
255
256/*
257 * Rectangle mode
258 */
259
260void ClipArea::enterRectangleMode() {
261    // Entering rectangle mode discards any
262    // existing clipping information from the other modes.
263    // The only way this occurs is by a clip setting operation.
264    mMode = ClipMode::Rectangle;
265}
266
267void ClipArea::rectangleModeClipRectWithTransform(const Rect& r,
268        const mat4* transform, SkRegion::Op op) {
269
270    if (op == SkRegion::kReplace_Op && transform->rectToRect()) {
271        mClipRect = r;
272        transform->mapRect(mClipRect);
273        return;
274    } else if (op != SkRegion::kIntersect_Op) {
275        enterRegionMode();
276        regionModeClipRectWithTransform(r, transform, op);
277        return;
278    }
279
280    if (transform->rectToRect()) {
281        Rect transformed(r);
282        transform->mapRect(transformed);
283        mClipRect.doIntersect(transformed);
284        return;
285    }
286
287    enterRectangleListMode();
288    rectangleListModeClipRectWithTransform(r, transform, op);
289}
290
291/*
292 * RectangleList mode implementation
293 */
294
295void ClipArea::enterRectangleListMode() {
296    // Is is only legal to enter rectangle list mode from
297    // rectangle mode, since rectangle list mode cannot represent
298    // all clip areas that can be represented by a region.
299    ALOG_ASSERT(mMode == ClipMode::Rectangle);
300    mMode = ClipMode::RectangleList;
301    mRectangleList.set(mClipRect, Matrix4::identity());
302}
303
304void ClipArea::rectangleListModeClipRectWithTransform(const Rect& r,
305        const mat4* transform, SkRegion::Op op) {
306    if (op != SkRegion::kIntersect_Op
307            || !mRectangleList.intersectWith(r, *transform)) {
308        enterRegionMode();
309        regionModeClipRectWithTransform(r, transform, op);
310    }
311}
312
313/*
314 * Region mode implementation
315 */
316
317void ClipArea::enterRegionMode() {
318    ClipMode oldMode = mMode;
319    mMode = ClipMode::Region;
320    if (oldMode != ClipMode::Region) {
321        if (oldMode == ClipMode::Rectangle) {
322            mClipRegion.setRect(mClipRect.toSkIRect());
323        } else {
324            mClipRegion = mRectangleList.convertToRegion(createViewportRegion());
325            onClipRegionUpdated();
326        }
327    }
328}
329
330void ClipArea::regionModeClipRectWithTransform(const Rect& r,
331        const mat4* transform, SkRegion::Op op) {
332    SkPath transformedRect = pathFromTransformedRectangle(r, *transform);
333    SkRegion transformedRectRegion;
334    regionFromPath(transformedRect, transformedRectRegion);
335    mClipRegion.op(transformedRectRegion, op);
336    onClipRegionUpdated();
337}
338
339void ClipArea::onClipRegionUpdated() {
340    if (!mClipRegion.isEmpty()) {
341        mClipRect.set(mClipRegion.getBounds());
342
343        if (mClipRegion.isRect()) {
344            mClipRegion.setEmpty();
345            enterRectangleMode();
346        }
347    } else {
348        mClipRect.setEmpty();
349    }
350}
351
352/**
353 * Clip serialization
354 */
355
356const ClipBase* ClipArea::serializeClip(LinearAllocator& allocator) {
357    if (!mPostViewportClipObserved) {
358        // Only initial clip-to-viewport observed, so no serialization of clip necessary
359        return nullptr;
360    }
361
362    static_assert(std::is_trivially_destructible<Rect>::value,
363            "expect Rect to be trivially destructible");
364    static_assert(std::is_trivially_destructible<RectangleList>::value,
365            "expect RectangleList to be trivially destructible");
366
367    if (mLastSerialization == nullptr) {
368        ClipBase* serialization = nullptr;
369        switch (mMode) {
370        case ClipMode::Rectangle:
371            serialization = allocator.create<ClipRect>(mClipRect);
372            break;
373        case ClipMode::RectangleList:
374            serialization = allocator.create<ClipRectList>(mRectangleList);
375            serialization->rect = mRectangleList.calculateBounds();
376            break;
377        case ClipMode::Region:
378            serialization = allocator.create<ClipRegion>(mClipRegion);
379            serialization->rect.set(mClipRegion.getBounds());
380            break;
381        }
382        // TODO: this is only done for draw time, should eventually avoid for record time
383        serialization->rect.snapToPixelBoundaries();
384        mLastSerialization = serialization;
385    }
386    return mLastSerialization;
387}
388
389inline static const RectangleList& getRectList(const ClipBase* scb) {
390    return reinterpret_cast<const ClipRectList*>(scb)->rectList;
391}
392
393inline static const SkRegion& getRegion(const ClipBase* scb) {
394    return reinterpret_cast<const ClipRegion*>(scb)->region;
395}
396
397// Conservative check for too many rectangles to fit in rectangle list.
398// For simplicity, doesn't account for rect merging
399static bool cannotFitInRectangleList(const ClipArea& clipArea, const ClipBase* scb) {
400    int currentRectCount = clipArea.isRectangleList()
401            ? clipArea.getRectangleList().getTransformedRectanglesCount()
402            : 1;
403    int recordedRectCount = (scb->mode == ClipMode::RectangleList)
404            ? getRectList(scb).getTransformedRectanglesCount()
405            : 1;
406    return currentRectCount + recordedRectCount > RectangleList::kMaxTransformedRectangles;
407}
408
409static const ClipRect sEmptyClipRect(Rect(0, 0));
410
411const ClipBase* ClipArea::serializeIntersectedClip(LinearAllocator& allocator,
412        const ClipBase* recordedClip, const Matrix4& recordedClipTransform) {
413
414    // if no recordedClip passed, just serialize current state
415    if (!recordedClip) return serializeClip(allocator);
416
417    // if either is empty, clip is empty
418    if (CC_UNLIKELY(recordedClip->rect.isEmpty())|| mClipRect.isEmpty()) return &sEmptyClipRect;
419
420    if (!mLastResolutionResult
421            || recordedClip != mLastResolutionClip
422            || recordedClipTransform != mLastResolutionTransform) {
423        mLastResolutionClip = recordedClip;
424        mLastResolutionTransform = recordedClipTransform;
425
426        if (CC_LIKELY(mMode == ClipMode::Rectangle
427                && recordedClip->mode == ClipMode::Rectangle
428                && recordedClipTransform.rectToRect())) {
429            // common case - result is a single rectangle
430            auto rectClip = allocator.create<ClipRect>(recordedClip->rect);
431            recordedClipTransform.mapRect(rectClip->rect);
432            rectClip->rect.doIntersect(mClipRect);
433            rectClip->rect.snapToPixelBoundaries();
434            mLastResolutionResult = rectClip;
435        } else if (CC_UNLIKELY(mMode == ClipMode::Region
436                || recordedClip->mode == ClipMode::Region
437                || cannotFitInRectangleList(*this, recordedClip))) {
438            // region case
439            SkRegion other;
440            switch (recordedClip->mode) {
441            case ClipMode::Rectangle:
442                if (CC_LIKELY(recordedClipTransform.rectToRect())) {
443                    // simple transform, skip creating SkPath
444                    Rect resultClip(recordedClip->rect);
445                    recordedClipTransform.mapRect(resultClip);
446                    other.setRect(resultClip.toSkIRect());
447                } else {
448                    SkPath transformedRect = pathFromTransformedRectangle(recordedClip->rect,
449                            recordedClipTransform);
450                    other.setPath(transformedRect, createViewportRegion());
451                }
452                break;
453            case ClipMode::RectangleList: {
454                RectangleList transformedList(getRectList(recordedClip));
455                transformedList.transform(recordedClipTransform);
456                other = transformedList.convertToRegion(createViewportRegion());
457                break;
458            }
459            case ClipMode::Region:
460                other = getRegion(recordedClip);
461
462                // TODO: handle non-translate transforms properly!
463                other.translate(recordedClipTransform.getTranslateX(),
464                        recordedClipTransform.getTranslateY());
465            }
466
467            ClipRegion* regionClip = allocator.create<ClipRegion>();
468            switch (mMode) {
469            case ClipMode::Rectangle:
470                regionClip->region.op(mClipRect.toSkIRect(), other, SkRegion::kIntersect_Op);
471                break;
472            case ClipMode::RectangleList:
473                regionClip->region.op(mRectangleList.convertToRegion(createViewportRegion()),
474                        other, SkRegion::kIntersect_Op);
475                break;
476            case ClipMode::Region:
477                regionClip->region.op(mClipRegion, other, SkRegion::kIntersect_Op);
478                break;
479            }
480            // Don't need to snap, since region's in int bounds
481            regionClip->rect.set(regionClip->region.getBounds());
482            mLastResolutionResult = regionClip;
483        } else {
484            auto rectListClip = allocator.create<ClipRectList>(mRectangleList);
485            auto&& rectList = rectListClip->rectList;
486            if (mMode == ClipMode::Rectangle) {
487                rectList.set(mClipRect, Matrix4::identity());
488            }
489
490            if (recordedClip->mode == ClipMode::Rectangle) {
491                rectList.intersectWith(recordedClip->rect, recordedClipTransform);
492            } else {
493                const RectangleList& other = getRectList(recordedClip);
494                for (int i = 0; i < other.getTransformedRectanglesCount(); i++) {
495                    auto&& tr = other.getTransformedRectangle(i);
496                    Matrix4 totalTransform(recordedClipTransform);
497                    totalTransform.multiply(tr.getTransform());
498                    rectList.intersectWith(tr.getBounds(), totalTransform);
499                }
500            }
501            rectListClip->rect = rectList.calculateBounds();
502            rectListClip->rect.snapToPixelBoundaries();
503            mLastResolutionResult = rectListClip;
504        }
505    }
506    return mLastResolutionResult;
507}
508
509void ClipArea::applyClip(const ClipBase* clip, const Matrix4& transform) {
510    if (!clip) return; // nothing to do
511
512    if (CC_LIKELY(clip->mode == ClipMode::Rectangle)) {
513        clipRectWithTransform(clip->rect, &transform, SkRegion::kIntersect_Op);
514    } else if (CC_LIKELY(clip->mode == ClipMode::RectangleList)) {
515        auto&& rectList = getRectList(clip);
516        for (int i = 0; i < rectList.getTransformedRectanglesCount(); i++) {
517            auto&& tr = rectList.getTransformedRectangle(i);
518            Matrix4 totalTransform(transform);
519            totalTransform.multiply(tr.getTransform());
520            clipRectWithTransform(tr.getBounds(), &totalTransform, SkRegion::kIntersect_Op);
521        }
522    } else {
523        SkRegion region(getRegion(clip));
524        // TODO: handle non-translate transforms properly!
525        region.translate(transform.getTranslateX(), transform.getTranslateY());
526        clipRegion(region, SkRegion::kIntersect_Op);
527    }
528}
529
530} /* namespace uirenderer */
531} /* namespace android */
532