libs/hwui/TessellationCache.cpp - platform/frameworks/base - Gitiles

 /*
  * Copyright (C) 2014 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #define LOG_TAG "OpenGLRenderer"
 #define ATRACE_TAG ATRACE_TAG_VIEW

 #include <utils/JenkinsHash.h>
 #include <utils/Trace.h>

 #include "Caches.h"
 #include "OpenGLRenderer.h"
 #include "PathTessellator.h"
 #include "ShadowTessellator.h"
 #include "TessellationCache.h"

 #include "thread/Signal.h"
 #include "thread/Task.h"
 #include "thread/TaskProcessor.h"

 namespace android {
 namespace uirenderer {

 ///////////////////////////////////////////////////////////////////////////////
 // Cache entries
 ///////////////////////////////////////////////////////////////////////////////

 TessellationCache::Description::Description()
         : type(kNone)
         , scaleX(1.0f)
         , scaleY(1.0f)
         , aa(false)
         , cap(SkPaint::kDefault_Cap)
         , style(SkPaint::kFill_Style)
         , strokeWidth(1.0f) {
     memset(&shape, 0, sizeof(Shape));
 }

 TessellationCache::Description::Description(Type type, const Matrix4& transform, const SkPaint& paint)
         : type(type)
         , aa(paint.isAntiAlias())
         , cap(paint.getStrokeCap())
         , style(paint.getStyle())
         , strokeWidth(paint.getStrokeWidth()) {
     PathTessellator::extractTessellationScales(transform, &scaleX, &scaleY);
     memset(&shape, 0, sizeof(Shape));
 }

 hash_t TessellationCache::Description::hash() const {
     uint32_t hash = JenkinsHashMix(0, type);
     hash = JenkinsHashMix(hash, aa);
     hash = JenkinsHashMix(hash, cap);
     hash = JenkinsHashMix(hash, style);
     hash = JenkinsHashMix(hash, android::hash_type(strokeWidth));
     hash = JenkinsHashMix(hash, android::hash_type(scaleX));
     hash = JenkinsHashMix(hash, android::hash_type(scaleY));
     hash = JenkinsHashMixBytes(hash, (uint8_t*) &shape, sizeof(Shape));
     return JenkinsHashWhiten(hash);
 }

 void TessellationCache::Description::setupMatrixAndPaint(Matrix4* matrix, SkPaint* paint) const {
     matrix->loadScale(scaleX, scaleY, 1.0f);
     paint->setAntiAlias(aa);
     paint->setStrokeCap(cap);
     paint->setStyle(style);
     paint->setStrokeWidth(strokeWidth);
 }

 TessellationCache::ShadowDescription::ShadowDescription()
         : nodeKey(NULL) {
     memset(&matrixData, 0, 16 * sizeof(float));
 }

 TessellationCache::ShadowDescription::ShadowDescription(const void* nodeKey, const Matrix4* drawTransform)
         : nodeKey(nodeKey) {
     memcpy(&matrixData, drawTransform->data, 16 * sizeof(float));
 }

 hash_t TessellationCache::ShadowDescription::hash() const {
     uint32_t hash = JenkinsHashMixBytes(0, (uint8_t*) &nodeKey, sizeof(const void*));
     hash = JenkinsHashMixBytes(hash, (uint8_t*) &matrixData, 16 * sizeof(float));
     return JenkinsHashWhiten(hash);
 }

 ///////////////////////////////////////////////////////////////////////////////
 // General purpose tessellation task processing
 ///////////////////////////////////////////////////////////////////////////////

 class TessellationCache::TessellationTask : public Task<VertexBuffer*> {
 public:
     TessellationTask(Tessellator tessellator, const Description& description)
         : tessellator(tessellator)
         , description(description) {
     }

     ~TessellationTask() {}

     Tessellator tessellator;
     Description description;
 };

 class TessellationCache::TessellationProcessor : public TaskProcessor<VertexBuffer*> {
 public:
     TessellationProcessor(Caches& caches)
             : TaskProcessor<VertexBuffer*>(&caches.tasks) {}
     ~TessellationProcessor() {}

     virtual void onProcess(const sp<Task<VertexBuffer*> >& task) {
         TessellationTask* t = static_cast<TessellationTask*>(task.get());
         ATRACE_NAME("shape tessellation");
         VertexBuffer* buffer = t->tessellator(t->description);
         t->setResult(buffer);
     }
 };

 class TessellationCache::Buffer {
 public:
     Buffer(const sp<Task<VertexBuffer*> >& task)
             : mTask(task)
             , mBuffer(NULL) {
     }

     ~Buffer() {
         mTask.clear();
         delete mBuffer;
     }

     unsigned int getSize() {
         blockOnPrecache();
         return mBuffer->getSize();
     }

     const VertexBuffer* getVertexBuffer() {
         blockOnPrecache();
         return mBuffer;
     }

 private:
     void blockOnPrecache() {
         if (mTask != NULL) {
             mBuffer = mTask->getResult();
             LOG_ALWAYS_FATAL_IF(mBuffer == NULL, "Failed to precache");
             mTask.clear();
         }
     }
     sp<Task<VertexBuffer*> > mTask;
     VertexBuffer* mBuffer;
 };

 ///////////////////////////////////////////////////////////////////////////////
 // Shadow tessellation task processing
 ///////////////////////////////////////////////////////////////////////////////

 class ShadowTask : public Task<TessellationCache::vertexBuffer_pair_t*> {
 public:
     ShadowTask(const Matrix4* drawTransform, const Rect& localClip, bool opaque,
             const SkPath* casterPerimeter, const Matrix4* transformXY, const Matrix4* transformZ,
             const Vector3& lightCenter, float lightRadius)
         : drawTransform(*drawTransform)
         , localClip(localClip)
         , opaque(opaque)
         , casterPerimeter(*casterPerimeter)
         , transformXY(*transformXY)
         , transformZ(*transformZ)
         , lightCenter(lightCenter)
         , lightRadius(lightRadius) {
     }

     ~ShadowTask() {
         TessellationCache::vertexBuffer_pair_t* bufferPair = getResult();
         delete bufferPair->getFirst();
         delete bufferPair->getSecond();
         delete bufferPair;
     }

     /* Note - we deep copy all task parameters, because *even though* pointers into Allocator
      * controlled objects (like the SkPath and Matrix4s) should be safe for the entire frame,
      * certain Allocators are destroyed before trim() is called to flush incomplete tasks.
      *
      * These deep copies could be avoided, long term, by cancelling or flushing outstanding tasks
      * before tearning down single-frame LinearAllocators.
      */
     const Matrix4 drawTransform;
     const Rect localClip;
     bool opaque;
     const SkPath casterPerimeter;
     const Matrix4 transformXY;
     const Matrix4 transformZ;
     const Vector3 lightCenter;
     const float lightRadius;
 };

 static void mapPointFakeZ(Vector3& point, const mat4* transformXY, const mat4* transformZ) {
     // map z coordinate with true 3d matrix
     point.z = transformZ->mapZ(point);

     // map x,y coordinates with draw/Skia matrix
     transformXY->mapPoint(point.x, point.y);
 }

 static void tessellateShadows(
         const Matrix4* drawTransform, const Rect* localClip,
         bool isCasterOpaque, const SkPath* casterPerimeter,
         const Matrix4* casterTransformXY, const Matrix4* casterTransformZ,
         const Vector3& lightCenter, float lightRadius,
         VertexBuffer& ambientBuffer, VertexBuffer& spotBuffer) {

     // tessellate caster outline into a 2d polygon
     Vector<Vertex> casterVertices2d;
     const float casterRefinementThresholdSquared = 20.0f; // TODO: experiment with this value
     PathTessellator::approximatePathOutlineVertices(*casterPerimeter,
             casterRefinementThresholdSquared, casterVertices2d);
     if (!ShadowTessellator::isClockwisePath(*casterPerimeter)) {
         ShadowTessellator::reverseVertexArray(casterVertices2d.editArray(),
                 casterVertices2d.size());
     }

     if (casterVertices2d.size() == 0) return;

     // map 2d caster poly into 3d
     const int casterVertexCount = casterVertices2d.size();
     Vector3 casterPolygon[casterVertexCount];
     float minZ = FLT_MAX;
     float maxZ = -FLT_MAX;
     for (int i = 0; i < casterVertexCount; i++) {
         const Vertex& point2d = casterVertices2d[i];
         casterPolygon[i] = (Vector3){point2d.x, point2d.y, 0};
         mapPointFakeZ(casterPolygon[i], casterTransformXY, casterTransformZ);
         minZ = fmin(minZ, casterPolygon[i].z);
         maxZ = fmax(maxZ, casterPolygon[i].z);
     }

     // map the centroid of the caster into 3d
     Vector2 centroid =  ShadowTessellator::centroid2d(
             reinterpret_cast<const Vector2*>(casterVertices2d.array()),
             casterVertexCount);
     Vector3 centroid3d = {centroid.x, centroid.y, 0};
     mapPointFakeZ(centroid3d, casterTransformXY, casterTransformZ);

     // if the caster intersects the z=0 plane, lift it in Z so it doesn't
     if (minZ < SHADOW_MIN_CASTER_Z) {
         float casterLift = SHADOW_MIN_CASTER_Z - minZ;
         for (int i = 0; i < casterVertexCount; i++) {
             casterPolygon[i].z += casterLift;
         }
         centroid3d.z += casterLift;
     }

     // Check whether we want to draw the shadow at all by checking the caster's bounds against clip.
     // We only have ortho projection, so we can just ignore the Z in caster for
     // simple rejection calculation.
     Rect casterBounds(casterPerimeter->getBounds());
     casterTransformXY->mapRect(casterBounds);

     // actual tessellation of both shadows
     ShadowTessellator::tessellateAmbientShadow(
             isCasterOpaque, casterPolygon, casterVertexCount, centroid3d,
             casterBounds, *localClip, maxZ, ambientBuffer);

     ShadowTessellator::tessellateSpotShadow(
             isCasterOpaque, casterPolygon, casterVertexCount,
             *drawTransform, lightCenter, lightRadius, casterBounds, *localClip,
             spotBuffer);
 }

 class ShadowProcessor : public TaskProcessor<TessellationCache::vertexBuffer_pair_t*> {
 public:
     ShadowProcessor(Caches& caches)
             : TaskProcessor<TessellationCache::vertexBuffer_pair_t*>(&caches.tasks) {}
     ~ShadowProcessor() {}

     virtual void onProcess(const sp<Task<TessellationCache::vertexBuffer_pair_t*> >& task) {
         ShadowTask* t = static_cast<ShadowTask*>(task.get());
         ATRACE_NAME("shadow tessellation");

         VertexBuffer* ambientBuffer = new VertexBuffer;
         VertexBuffer* spotBuffer = new VertexBuffer;
         tessellateShadows(&t->drawTransform, &t->localClip, t->opaque, &t->casterPerimeter,
                 &t->transformXY, &t->transformZ, t->lightCenter, t->lightRadius,
                 *ambientBuffer, *spotBuffer);

         t->setResult(new TessellationCache::vertexBuffer_pair_t(ambientBuffer, spotBuffer));
     }
 };

 ///////////////////////////////////////////////////////////////////////////////
 // Cache constructor/destructor
 ///////////////////////////////////////////////////////////////////////////////

 TessellationCache::TessellationCache()
         : mSize(0)
         , mMaxSize(MB(DEFAULT_VERTEX_CACHE_SIZE))
         , mCache(LruCache<Description, Buffer*>::kUnlimitedCapacity)
         , mShadowCache(LruCache<ShadowDescription, Task<vertexBuffer_pair_t*>*>::kUnlimitedCapacity) {
     char property[PROPERTY_VALUE_MAX];
     if (property_get(PROPERTY_VERTEX_CACHE_SIZE, property, NULL) > 0) {
         INIT_LOGD("  Setting %s cache size to %sMB", name, property);
         setMaxSize(MB(atof(property)));
     } else {
         INIT_LOGD("  Using default %s cache size of %.2fMB", name, DEFAULT_VERTEX_CACHE_SIZE);
     }

     mCache.setOnEntryRemovedListener(&mBufferRemovedListener);
     mShadowCache.setOnEntryRemovedListener(&mBufferPairRemovedListener);
     mDebugEnabled = readDebugLevel() & kDebugCaches;
 }

 TessellationCache::~TessellationCache() {
     mCache.clear();
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Size management
 ///////////////////////////////////////////////////////////////////////////////

 uint32_t TessellationCache::getSize() {
     LruCache<Description, Buffer*>::Iterator iter(mCache);
     uint32_t size = 0;
     while (iter.next()) {
         size += iter.value()->getSize();
     }
     return size;
 }

 uint32_t TessellationCache::getMaxSize() {
     return mMaxSize;
 }

 void TessellationCache::setMaxSize(uint32_t maxSize) {
     mMaxSize = maxSize;
     while (mSize > mMaxSize) {
         mCache.removeOldest();
     }
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Caching
 ///////////////////////////////////////////////////////////////////////////////


 void TessellationCache::trim() {
     uint32_t size = getSize();
     while (size > mMaxSize) {
         size -= mCache.peekOldestValue()->getSize();
         mCache.removeOldest();
     }
     mShadowCache.clear();
 }

 void TessellationCache::clear() {
     mCache.clear();
     mShadowCache.clear();
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Callbacks
 ///////////////////////////////////////////////////////////////////////////////

 void TessellationCache::BufferRemovedListener::operator()(Description& description,
         Buffer*& buffer) {
     delete buffer;
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Shadows
 ///////////////////////////////////////////////////////////////////////////////

 void TessellationCache::precacheShadows(const Matrix4* drawTransform, const Rect& localClip,
         bool opaque, const SkPath* casterPerimeter,
         const Matrix4* transformXY, const Matrix4* transformZ,
         const Vector3& lightCenter, float lightRadius) {
     ShadowDescription key(casterPerimeter, drawTransform);

     sp<ShadowTask> task = new ShadowTask(drawTransform, localClip, opaque,
             casterPerimeter, transformXY, transformZ, lightCenter, lightRadius);
     if (mShadowProcessor == NULL) {
         mShadowProcessor = new ShadowProcessor(Caches::getInstance());
     }
     mShadowProcessor->add(task);

     task->incStrong(NULL); // not using sp<>s, so manually ref while in the cache
     mShadowCache.put(key, task.get());
 }

 void TessellationCache::getShadowBuffers(const Matrix4* drawTransform, const Rect& localClip,
         bool opaque, const SkPath* casterPerimeter,
         const Matrix4* transformXY, const Matrix4* transformZ,
         const Vector3& lightCenter, float lightRadius, vertexBuffer_pair_t& outBuffers) {
     ShadowDescription key(casterPerimeter, drawTransform);
     ShadowTask* task = static_cast<ShadowTask*>(mShadowCache.get(key));
     if (!task) {
         precacheShadows(drawTransform, localClip, opaque, casterPerimeter,
                 transformXY, transformZ, lightCenter, lightRadius);
         task = static_cast<ShadowTask*>(mShadowCache.get(key));
     }
     LOG_ALWAYS_FATAL_IF(task == NULL, "shadow not precached");
     outBuffers = *(task->getResult());
 }

 ///////////////////////////////////////////////////////////////////////////////
 // Tessellation precaching
 ///////////////////////////////////////////////////////////////////////////////

 TessellationCache::Buffer* TessellationCache::getOrCreateBuffer(
         const Description& entry, Tessellator tessellator) {
     Buffer* buffer = mCache.get(entry);
     if (!buffer) {
         // not cached, enqueue a task to fill the buffer
         sp<TessellationTask> task = new TessellationTask(tessellator, entry);
         buffer = new Buffer(task);

         if (mProcessor == NULL) {
             mProcessor = new TessellationProcessor(Caches::getInstance());
         }
         mProcessor->add(task);
         mCache.put(entry, buffer);
     }
     return buffer;
 }

 static VertexBuffer* tessellatePath(const TessellationCache::Description& description,
         const SkPath& path) {
     Matrix4 matrix;
     SkPaint paint;
     description.setupMatrixAndPaint(&matrix, &paint);
     VertexBuffer* buffer = new VertexBuffer();
     PathTessellator::tessellatePath(path, &paint, matrix, *buffer);
     return buffer;
 }

 ///////////////////////////////////////////////////////////////////////////////
 // RoundRect
 ///////////////////////////////////////////////////////////////////////////////

 static VertexBuffer* tessellateRoundRect(const TessellationCache::Description& description) {
     SkRect rect = SkRect::MakeWH(description.shape.roundRect.width,
             description.shape.roundRect.height);
     float rx = description.shape.roundRect.rx;
     float ry = description.shape.roundRect.ry;
     if (description.style == SkPaint::kStrokeAndFill_Style) {
         float outset = description.strokeWidth / 2;
         rect.outset(outset, outset);
         rx += outset;
         ry += outset;
     }
     SkPath path;
     path.addRoundRect(rect, rx, ry);
     return tessellatePath(description, path);
 }

 TessellationCache::Buffer* TessellationCache::getRoundRectBuffer(
         const Matrix4& transform, const SkPaint& paint,
         float width, float height, float rx, float ry) {
     Description entry(Description::kRoundRect, transform, paint);
     entry.shape.roundRect.width = width;
     entry.shape.roundRect.height = height;
     entry.shape.roundRect.rx = rx;
     entry.shape.roundRect.ry = ry;
     return getOrCreateBuffer(entry, &tessellateRoundRect);
 }
 const VertexBuffer* TessellationCache::getRoundRect(const Matrix4& transform, const SkPaint& paint,
         float width, float height, float rx, float ry) {
     return getRoundRectBuffer(transform, paint, width, height, rx, ry)->getVertexBuffer();
 }

 }; // namespace uirenderer
 }; // namespace android
	/*
	* Copyright (C) 2014 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#define LOG_TAG "OpenGLRenderer"
	#define ATRACE_TAG ATRACE_TAG_VIEW

	#include <utils/JenkinsHash.h>
	#include <utils/Trace.h>

	#include "Caches.h"
	#include "OpenGLRenderer.h"
	#include "PathTessellator.h"
	#include "ShadowTessellator.h"
	#include "TessellationCache.h"

	#include "thread/Signal.h"
	#include "thread/Task.h"
	#include "thread/TaskProcessor.h"

	namespace android {
	namespace uirenderer {

	///////////////////////////////////////////////////////////////////////////////
	// Cache entries
	///////////////////////////////////////////////////////////////////////////////

	TessellationCache::Description::Description()
	: type(kNone)
	, scaleX(1.0f)
	, scaleY(1.0f)
	, aa(false)
	, cap(SkPaint::kDefault_Cap)
	, style(SkPaint::kFill_Style)
	, strokeWidth(1.0f) {
	memset(&shape, 0, sizeof(Shape));
	}

	TessellationCache::Description::Description(Type type, const Matrix4& transform, const SkPaint& paint)
	: type(type)
	, aa(paint.isAntiAlias())
	, cap(paint.getStrokeCap())
	, style(paint.getStyle())
	, strokeWidth(paint.getStrokeWidth()) {
	PathTessellator::extractTessellationScales(transform, &scaleX, &scaleY);
	memset(&shape, 0, sizeof(Shape));
	}

	hash_t TessellationCache::Description::hash() const {
	uint32_t hash = JenkinsHashMix(0, type);
	hash = JenkinsHashMix(hash, aa);
	hash = JenkinsHashMix(hash, cap);
	hash = JenkinsHashMix(hash, style);
	hash = JenkinsHashMix(hash, android::hash_type(strokeWidth));
	hash = JenkinsHashMix(hash, android::hash_type(scaleX));
	hash = JenkinsHashMix(hash, android::hash_type(scaleY));
	hash = JenkinsHashMixBytes(hash, (uint8_t*) &shape, sizeof(Shape));
	return JenkinsHashWhiten(hash);
	}

	void TessellationCache::Description::setupMatrixAndPaint(Matrix4* matrix, SkPaint* paint) const {
	matrix->loadScale(scaleX, scaleY, 1.0f);
	paint->setAntiAlias(aa);
	paint->setStrokeCap(cap);
	paint->setStyle(style);
	paint->setStrokeWidth(strokeWidth);
	}

	TessellationCache::ShadowDescription::ShadowDescription()
	: nodeKey(NULL) {
	memset(&matrixData, 0, 16 * sizeof(float));
	}

	TessellationCache::ShadowDescription::ShadowDescription(const void* nodeKey, const Matrix4* drawTransform)
	: nodeKey(nodeKey) {
	memcpy(&matrixData, drawTransform->data, 16 * sizeof(float));
	}

	hash_t TessellationCache::ShadowDescription::hash() const {
	uint32_t hash = JenkinsHashMixBytes(0, (uint8_t) &nodeKey, sizeof(const void));
	hash = JenkinsHashMixBytes(hash, (uint8_t) &matrixData, 16 sizeof(float));
	return JenkinsHashWhiten(hash);
	}

	///////////////////////////////////////////////////////////////////////////////
	// General purpose tessellation task processing
	///////////////////////////////////////////////////////////////////////////////

	class TessellationCache::TessellationTask : public Task<VertexBuffer*> {
	public:
	TessellationTask(Tessellator tessellator, const Description& description)
	: tessellator(tessellator)
	, description(description) {
	}

	~TessellationTask() {}

	Tessellator tessellator;
	Description description;
	};

	class TessellationCache::TessellationProcessor : public TaskProcessor<VertexBuffer*> {
	public:
	TessellationProcessor(Caches& caches)
	: TaskProcessor<VertexBuffer*>(&caches.tasks) {}
	~TessellationProcessor() {}

	virtual void onProcess(const sp<Task<VertexBuffer*> >& task) {
	TessellationTask* t = static_cast<TessellationTask*>(task.get());
	ATRACE_NAME("shape tessellation");
	VertexBuffer* buffer = t->tessellator(t->description);
	t->setResult(buffer);
	}
	};

	class TessellationCache::Buffer {
	public:
	Buffer(const sp<Task<VertexBuffer*> >& task)
	: mTask(task)
	, mBuffer(NULL) {
	}

	~Buffer() {
	mTask.clear();
	delete mBuffer;
	}

	unsigned int getSize() {
	blockOnPrecache();
	return mBuffer->getSize();
	}

	const VertexBuffer* getVertexBuffer() {
	blockOnPrecache();
	return mBuffer;
	}

	private:
	void blockOnPrecache() {
	if (mTask != NULL) {
	mBuffer = mTask->getResult();
	LOG_ALWAYS_FATAL_IF(mBuffer == NULL, "Failed to precache");
	mTask.clear();
	}
	}
	sp<Task<VertexBuffer*> > mTask;
	VertexBuffer* mBuffer;
	};

	///////////////////////////////////////////////////////////////////////////////
	// Shadow tessellation task processing
	///////////////////////////////////////////////////////////////////////////////

	class ShadowTask : public Task<TessellationCache::vertexBuffer_pair_t*> {
	public:
	ShadowTask(const Matrix4* drawTransform, const Rect& localClip, bool opaque,
	const SkPath* casterPerimeter, const Matrix4* transformXY, const Matrix4* transformZ,
	const Vector3& lightCenter, float lightRadius)
	: drawTransform(*drawTransform)
	, localClip(localClip)
	, opaque(opaque)
	, casterPerimeter(*casterPerimeter)
	, transformXY(*transformXY)
	, transformZ(*transformZ)
	, lightCenter(lightCenter)
	, lightRadius(lightRadius) {
	}

	~ShadowTask() {
	TessellationCache::vertexBuffer_pair_t* bufferPair = getResult();
	delete bufferPair->getFirst();
	delete bufferPair->getSecond();
	delete bufferPair;
	}

	/* Note - we deep copy all task parameters, because even though pointers into Allocator
	* controlled objects (like the SkPath and Matrix4s) should be safe for the entire frame,
	* certain Allocators are destroyed before trim() is called to flush incomplete tasks.
	*
	* These deep copies could be avoided, long term, by cancelling or flushing outstanding tasks
	* before tearning down single-frame LinearAllocators.
	*/
	const Matrix4 drawTransform;
	const Rect localClip;
	bool opaque;
	const SkPath casterPerimeter;
	const Matrix4 transformXY;
	const Matrix4 transformZ;
	const Vector3 lightCenter;
	const float lightRadius;
	};

	static void mapPointFakeZ(Vector3& point, const mat4* transformXY, const mat4* transformZ) {
	// map z coordinate with true 3d matrix
	point.z = transformZ->mapZ(point);

	// map x,y coordinates with draw/Skia matrix
	transformXY->mapPoint(point.x, point.y);
	}

	static void tessellateShadows(
	const Matrix4* drawTransform, const Rect* localClip,
	bool isCasterOpaque, const SkPath* casterPerimeter,
	const Matrix4* casterTransformXY, const Matrix4* casterTransformZ,
	const Vector3& lightCenter, float lightRadius,
	VertexBuffer& ambientBuffer, VertexBuffer& spotBuffer) {

	// tessellate caster outline into a 2d polygon
	Vector<Vertex> casterVertices2d;
	const float casterRefinementThresholdSquared = 20.0f; // TODO: experiment with this value
	PathTessellator::approximatePathOutlineVertices(*casterPerimeter,
	casterRefinementThresholdSquared, casterVertices2d);
	if (!ShadowTessellator::isClockwisePath(*casterPerimeter)) {
	ShadowTessellator::reverseVertexArray(casterVertices2d.editArray(),
	casterVertices2d.size());
	}

	if (casterVertices2d.size() == 0) return;

	// map 2d caster poly into 3d
	const int casterVertexCount = casterVertices2d.size();
	Vector3 casterPolygon[casterVertexCount];
	float minZ = FLT_MAX;
	float maxZ = -FLT_MAX;
	for (int i = 0; i < casterVertexCount; i++) {
	const Vertex& point2d = casterVertices2d[i];
	casterPolygon[i] = (Vector3){point2d.x, point2d.y, 0};
	mapPointFakeZ(casterPolygon[i], casterTransformXY, casterTransformZ);
	minZ = fmin(minZ, casterPolygon[i].z);
	maxZ = fmax(maxZ, casterPolygon[i].z);
	}

	// map the centroid of the caster into 3d
	Vector2 centroid = ShadowTessellator::centroid2d(
	reinterpret_cast<const Vector2*>(casterVertices2d.array()),
	casterVertexCount);
	Vector3 centroid3d = {centroid.x, centroid.y, 0};
	mapPointFakeZ(centroid3d, casterTransformXY, casterTransformZ);

	// if the caster intersects the z=0 plane, lift it in Z so it doesn't
	if (minZ < SHADOW_MIN_CASTER_Z) {
	float casterLift = SHADOW_MIN_CASTER_Z - minZ;
	for (int i = 0; i < casterVertexCount; i++) {
	casterPolygon[i].z += casterLift;
	}
	centroid3d.z += casterLift;
	}

	// Check whether we want to draw the shadow at all by checking the caster's bounds against clip.
	// We only have ortho projection, so we can just ignore the Z in caster for
	// simple rejection calculation.
	Rect casterBounds(casterPerimeter->getBounds());
	casterTransformXY->mapRect(casterBounds);

	// actual tessellation of both shadows
	ShadowTessellator::tessellateAmbientShadow(
	isCasterOpaque, casterPolygon, casterVertexCount, centroid3d,
	casterBounds, *localClip, maxZ, ambientBuffer);

	ShadowTessellator::tessellateSpotShadow(
	isCasterOpaque, casterPolygon, casterVertexCount,
	drawTransform, lightCenter, lightRadius, casterBounds, localClip,
	spotBuffer);
	}

	class ShadowProcessor : public TaskProcessor<TessellationCache::vertexBuffer_pair_t*> {
	public:
	ShadowProcessor(Caches& caches)
	: TaskProcessor<TessellationCache::vertexBuffer_pair_t*>(&caches.tasks) {}
	~ShadowProcessor() {}

	virtual void onProcess(const sp<Task<TessellationCache::vertexBuffer_pair_t*> >& task) {
	ShadowTask* t = static_cast<ShadowTask*>(task.get());
	ATRACE_NAME("shadow tessellation");

	VertexBuffer* ambientBuffer = new VertexBuffer;
	VertexBuffer* spotBuffer = new VertexBuffer;
	tessellateShadows(&t->drawTransform, &t->localClip, t->opaque, &t->casterPerimeter,
	&t->transformXY, &t->transformZ, t->lightCenter, t->lightRadius,
	ambientBuffer, spotBuffer);

	t->setResult(new TessellationCache::vertexBuffer_pair_t(ambientBuffer, spotBuffer));
	}
	};

	///////////////////////////////////////////////////////////////////////////////
	// Cache constructor/destructor
	///////////////////////////////////////////////////////////////////////////////

	TessellationCache::TessellationCache()
	: mSize(0)
	, mMaxSize(MB(DEFAULT_VERTEX_CACHE_SIZE))
	, mCache(LruCache<Description, Buffer*>::kUnlimitedCapacity)
	, mShadowCache(LruCache<ShadowDescription, Task<vertexBuffer_pair_t>>::kUnlimitedCapacity) {
	char property[PROPERTY_VALUE_MAX];
	if (property_get(PROPERTY_VERTEX_CACHE_SIZE, property, NULL) > 0) {
	INIT_LOGD(" Setting %s cache size to %sMB", name, property);
	setMaxSize(MB(atof(property)));
	} else {
	INIT_LOGD(" Using default %s cache size of %.2fMB", name, DEFAULT_VERTEX_CACHE_SIZE);
	}

	mCache.setOnEntryRemovedListener(&mBufferRemovedListener);
	mShadowCache.setOnEntryRemovedListener(&mBufferPairRemovedListener);
	mDebugEnabled = readDebugLevel() & kDebugCaches;
	}

	TessellationCache::~TessellationCache() {
	mCache.clear();
	}

	///////////////////////////////////////////////////////////////////////////////
	// Size management
	///////////////////////////////////////////////////////////////////////////////

	uint32_t TessellationCache::getSize() {
	LruCache<Description, Buffer*>::Iterator iter(mCache);
	uint32_t size = 0;
	while (iter.next()) {
	size += iter.value()->getSize();
	}
	return size;
	}

	uint32_t TessellationCache::getMaxSize() {
	return mMaxSize;
	}

	void TessellationCache::setMaxSize(uint32_t maxSize) {
	mMaxSize = maxSize;
	while (mSize > mMaxSize) {
	mCache.removeOldest();
	}
	}

	///////////////////////////////////////////////////////////////////////////////
	// Caching
	///////////////////////////////////////////////////////////////////////////////


	void TessellationCache::trim() {
	uint32_t size = getSize();
	while (size > mMaxSize) {
	size -= mCache.peekOldestValue()->getSize();
	mCache.removeOldest();
	}
	mShadowCache.clear();
	}

	void TessellationCache::clear() {
	mCache.clear();
	mShadowCache.clear();
	}

	///////////////////////////////////////////////////////////////////////////////
	// Callbacks
	///////////////////////////////////////////////////////////////////////////////

	void TessellationCache::BufferRemovedListener::operator()(Description& description,
	Buffer*& buffer) {
	delete buffer;
	}

	///////////////////////////////////////////////////////////////////////////////
	// Shadows
	///////////////////////////////////////////////////////////////////////////////

	void TessellationCache::precacheShadows(const Matrix4* drawTransform, const Rect& localClip,
	bool opaque, const SkPath* casterPerimeter,
	const Matrix4* transformXY, const Matrix4* transformZ,
	const Vector3& lightCenter, float lightRadius) {
	ShadowDescription key(casterPerimeter, drawTransform);

	sp<ShadowTask> task = new ShadowTask(drawTransform, localClip, opaque,
	casterPerimeter, transformXY, transformZ, lightCenter, lightRadius);
	if (mShadowProcessor == NULL) {
	mShadowProcessor = new ShadowProcessor(Caches::getInstance());
	}
	mShadowProcessor->add(task);

	task->incStrong(NULL); // not using sp<>s, so manually ref while in the cache
	mShadowCache.put(key, task.get());
	}

	void TessellationCache::getShadowBuffers(const Matrix4* drawTransform, const Rect& localClip,
	bool opaque, const SkPath* casterPerimeter,
	const Matrix4* transformXY, const Matrix4* transformZ,
	const Vector3& lightCenter, float lightRadius, vertexBuffer_pair_t& outBuffers) {
	ShadowDescription key(casterPerimeter, drawTransform);
	ShadowTask* task = static_cast<ShadowTask*>(mShadowCache.get(key));
	if (!task) {
	precacheShadows(drawTransform, localClip, opaque, casterPerimeter,
	transformXY, transformZ, lightCenter, lightRadius);
	task = static_cast<ShadowTask*>(mShadowCache.get(key));
	}
	LOG_ALWAYS_FATAL_IF(task == NULL, "shadow not precached");
	outBuffers = *(task->getResult());
	}

	///////////////////////////////////////////////////////////////////////////////
	// Tessellation precaching
	///////////////////////////////////////////////////////////////////////////////

	TessellationCache::Buffer* TessellationCache::getOrCreateBuffer(
	const Description& entry, Tessellator tessellator) {
	Buffer* buffer = mCache.get(entry);
	if (!buffer) {
	// not cached, enqueue a task to fill the buffer
	sp<TessellationTask> task = new TessellationTask(tessellator, entry);
	buffer = new Buffer(task);

	if (mProcessor == NULL) {
	mProcessor = new TessellationProcessor(Caches::getInstance());
	}
	mProcessor->add(task);
	mCache.put(entry, buffer);
	}
	return buffer;
	}

	static VertexBuffer* tessellatePath(const TessellationCache::Description& description,
	const SkPath& path) {
	Matrix4 matrix;
	SkPaint paint;
	description.setupMatrixAndPaint(&matrix, &paint);
	VertexBuffer* buffer = new VertexBuffer();
	PathTessellator::tessellatePath(path, &paint, matrix, *buffer);
	return buffer;
	}

	///////////////////////////////////////////////////////////////////////////////
	// RoundRect
	///////////////////////////////////////////////////////////////////////////////

	static VertexBuffer* tessellateRoundRect(const TessellationCache::Description& description) {
	SkRect rect = SkRect::MakeWH(description.shape.roundRect.width,
	description.shape.roundRect.height);
	float rx = description.shape.roundRect.rx;
	float ry = description.shape.roundRect.ry;
	if (description.style == SkPaint::kStrokeAndFill_Style) {
	float outset = description.strokeWidth / 2;
	rect.outset(outset, outset);
	rx += outset;
	ry += outset;
	}
	SkPath path;
	path.addRoundRect(rect, rx, ry);
	return tessellatePath(description, path);
	}

	TessellationCache::Buffer* TessellationCache::getRoundRectBuffer(
	const Matrix4& transform, const SkPaint& paint,
	float width, float height, float rx, float ry) {
	Description entry(Description::kRoundRect, transform, paint);
	entry.shape.roundRect.width = width;
	entry.shape.roundRect.height = height;
	entry.shape.roundRect.rx = rx;
	entry.shape.roundRect.ry = ry;
	return getOrCreateBuffer(entry, &tessellateRoundRect);
	}
	const VertexBuffer* TessellationCache::getRoundRect(const Matrix4& transform, const SkPaint& paint,
	float width, float height, float rx, float ry) {
	return getRoundRectBuffer(transform, paint, width, height, rx, ry)->getVertexBuffer();
	}

	}; // namespace uirenderer
	}; // namespace android