tools/DDLTileHelper.cpp - platform/external/skia - Gitiles

 /*
  * Copyright 2018 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include "tools/DDLTileHelper.h"

 #include "include/core/SkCanvas.h"
 #include "include/core/SkDeferredDisplayListRecorder.h"
 #include "include/core/SkPicture.h"
 #include "include/core/SkSurface.h"
 #include "include/core/SkSurfaceCharacterization.h"
 #include "src/core/SkDeferredDisplayListPriv.h"
 #include "src/core/SkTaskGroup.h"
 #include "src/gpu/GrContextPriv.h"
 #include "src/image/SkImage_Gpu.h"
 #include "tools/DDLPromiseImageHelper.h"

 void DDLTileHelper::TileData::init(int id,
                                    GrContext* context,
                                    const SkSurfaceCharacterization& dstSurfaceCharacterization,
                                    const SkIRect& clip) {
     fID = id;
     fClip = clip;

     fCharacterization = dstSurfaceCharacterization.createResized(clip.width(), clip.height());
     SkASSERT(fCharacterization.isValid());

     GrBackendFormat backendFormat = context->defaultBackendFormat(fCharacterization.colorType(),
                                                                   GrRenderable::kYes);
     SkDEBUGCODE(const GrCaps* caps = context->priv().caps());
     SkASSERT(caps->isFormatTexturable(backendFormat));

     fCallbackContext.reset(new PromiseImageCallbackContext(context, backendFormat));
 }

 DDLTileHelper::TileData::~TileData() {}

 void DDLTileHelper::TileData::createTileSpecificSKP(SkData* compressedPictureData,
                                                     const DDLPromiseImageHelper& helper) {
     SkASSERT(!fReconstitutedPicture);

     // This is bending the DDLRecorder contract! The promise images in the SKP should be
     // created by the same recorder used to create the matching DDL.
     SkDeferredDisplayListRecorder recorder(fCharacterization);

     fReconstitutedPicture = helper.reinflateSKP(&recorder, compressedPictureData, &fPromiseImages);

     auto ddl = recorder.detach();
     if (ddl->priv().numRenderTasks()) {
         // TODO: remove this once skbug.com/8424 is fixed. If the DDL resulting from the
         // reinflation of the SKPs contains opsTasks that means some image subset operation
         // created a draw.
         fReconstitutedPicture.reset();
     }
 }

 void DDLTileHelper::TileData::createDDL() {
     SkASSERT(!fDisplayList && fReconstitutedPicture);

     SkDeferredDisplayListRecorder recorder(fCharacterization);

     // DDL TODO: the DDLRecorder's GrContext isn't initialized until getCanvas is called.
     // Maybe set it up in the ctor?
     SkCanvas* recordingCanvas = recorder.getCanvas();

     // Because we cheated in createTileSpecificSKP and used the wrong DDLRecorder, the GrContext's
     // stored in fReconstitutedPicture's promise images are incorrect. Patch them with the correct
     // one now.
     for (int i = 0; i < fPromiseImages.count(); ++i) {
         GrContext* newContext = recordingCanvas->getGrContext();

         if (fPromiseImages[i]->isTextureBacked()) {
             SkImage_GpuBase* gpuImage = (SkImage_GpuBase*) fPromiseImages[i].get();
             gpuImage->resetContext(sk_ref_sp(newContext));
         }
     }

     recordingCanvas->clipRect(SkRect::MakeWH(fClip.width(), fClip.height()));
     recordingCanvas->translate(-fClip.fLeft, -fClip.fTop);

     // Note: in this use case we only render a picture to the deferred canvas
     // but, more generally, clients will use arbitrary draw calls.
     recordingCanvas->drawPicture(fReconstitutedPicture);

     fDisplayList = recorder.detach();
 }

 void DDLTileHelper::createComposeDDL() {
     SkASSERT(!fComposeDDL);

     SkDeferredDisplayListRecorder recorder(fDstCharacterization);

     SkCanvas* recordingCanvas = recorder.getCanvas();

     for (int i = 0; i < this->numTiles(); ++i) {
         TileData* tile = &fTiles[i];

         sk_sp<SkImage> promiseImage = tile->makePromiseImage(&recorder);

         SkIRect clipRect = tile->clipRect();

         SkASSERT(clipRect.width() == promiseImage->width() &&
                  clipRect.height() == promiseImage->height());

         recordingCanvas->drawImage(promiseImage, clipRect.fLeft, clipRect.fTop);
     }

     fComposeDDL = recorder.detach();
     SkASSERT(fComposeDDL);
 }

 void DDLTileHelper::TileData::precompile(GrContext* context) {
     SkASSERT(fDisplayList);

     SkDeferredDisplayList::ProgramIterator iter(context, fDisplayList.get());
     for (; !iter.done(); iter.next()) {
         iter.compile();
     }
 }

 sk_sp<SkSurface> DDLTileHelper::TileData::makeWrappedTileDest(GrContext* context) {
     SkASSERT(fCallbackContext && fCallbackContext->promiseImageTexture());

     auto promiseImageTexture = fCallbackContext->promiseImageTexture();
     if (!promiseImageTexture->backendTexture().isValid()) {
         return nullptr;
     }

     // Here we are, unfortunately, aliasing the backend texture held by the SkPromiseImageTexture.
     // Both the tile's destination surface and the promise image used to draw the tile will be
     // backed by the same backendTexture - unbeknownst to Ganesh.
     return SkSurface::MakeFromBackendTexture(context,
                                              promiseImageTexture->backendTexture(),
                                              fCharacterization.origin(),
                                              fCharacterization.sampleCount(),
                                              fCharacterization.colorType(),
                                              fCharacterization.refColorSpace(),
                                              &fCharacterization.surfaceProps());
 }

 void DDLTileHelper::TileData::drawSKPDirectly(GrContext* context) {
     SkASSERT(!fDisplayList && !fTileSurface && fReconstitutedPicture);

     fTileSurface = this->makeWrappedTileDest(context);
     if (fTileSurface) {
         SkCanvas* tileCanvas = fTileSurface->getCanvas();

         tileCanvas->clipRect(SkRect::MakeWH(fClip.width(), fClip.height()));
         tileCanvas->translate(-fClip.fLeft, -fClip.fTop);

         tileCanvas->drawPicture(fReconstitutedPicture);

         // We can't snap an image here bc, since we're using wrapped backend textures for the
         // surfaces, that would incur a copy.
     }
 }

 void DDLTileHelper::TileData::draw(GrContext* context) {
     SkASSERT(fDisplayList && !fTileSurface);

     // The tile's surface needs to be held until after the DDL is flushed bc the DDL doesn't take
     // a ref on its destination proxy.
     // TODO: make the DDL (or probably the drawing manager) take a ref on the destination proxy
     // (maybe in GrDrawingManager::addDDLTarget).
     fTileSurface = this->makeWrappedTileDest(context);
     if (fTileSurface) {
         fTileSurface->draw(fDisplayList);

         // We can't snap an image here bc, since we're using wrapped backend textures for the
         // surfaces, that would incur a copy.
     }
 }

 void DDLTileHelper::TileData::reset() {
     // TODO: when DDLs are re-renderable we don't need to do this
     fDisplayList = nullptr;

     fTileSurface = nullptr;
 }

 sk_sp<SkImage> DDLTileHelper::TileData::makePromiseImage(SkDeferredDisplayListRecorder* recorder) {
     SkASSERT(fCallbackContext);

     // The promise image gets a ref on the promise callback context
     sk_sp<SkImage> promiseImage = recorder->makePromiseTexture(
                                     fCallbackContext->backendFormat(),
                                     fClip.width(),
                                     fClip.height(),
                                     GrMipMapped::kNo,
                                     GrSurfaceOrigin::kBottomLeft_GrSurfaceOrigin,
                                     fCharacterization.colorType(),
                                     kPremul_SkAlphaType,
                                     fCharacterization.refColorSpace(),
                                     PromiseImageCallbackContext::PromiseImageFulfillProc,
                                     PromiseImageCallbackContext::PromiseImageReleaseProc,
                                     PromiseImageCallbackContext::PromiseImageDoneProc,
                                     (void*)this->refCallbackContext().release(),
                                     SkDeferredDisplayListRecorder::PromiseImageApiVersion::kNew);
     fCallbackContext->wasAddedToImage();

     return promiseImage;
 }

 void DDLTileHelper::TileData::CreateBackendTexture(GrContext* context, TileData* tile) {
     SkASSERT(context->asDirectContext());
     SkASSERT(tile->fCallbackContext && !tile->fCallbackContext->promiseImageTexture());

     GrBackendTexture beTex = context->createBackendTexture(tile->fCharacterization);
     tile->fCallbackContext->setBackendTexture(beTex);
 }

 void DDLTileHelper::TileData::DeleteBackendTexture(GrContext* context, TileData* tile) {
     SkASSERT(context->asDirectContext());
     SkASSERT(tile->fCallbackContext);

     // TODO: it seems that, on the Linux bots, backend texture creation is failing
     // a lot (skbug.com/10142)
     SkASSERT(!tile->fCallbackContext->promiseImageTexture() ||
              tile->fCallbackContext->promiseImageTexture()->backendTexture().isValid());

     tile->fTileSurface = nullptr;

     SkASSERT(tile->fCallbackContext->unique());
     tile->fCallbackContext.reset();
 }

 ///////////////////////////////////////////////////////////////////////////////////////////////////

 DDLTileHelper::DDLTileHelper(GrContext* context,
                              const SkSurfaceCharacterization& dstChar,
                              const SkIRect& viewport,
                              int numDivisions)
         : fNumDivisions(numDivisions)
         , fTiles(numDivisions * numDivisions)
         , fDstCharacterization(dstChar) {
     SkASSERT(fNumDivisions > 0);

     int xTileSize = viewport.width()/fNumDivisions;
     int yTileSize = viewport.height()/fNumDivisions;

     // Create the destination tiles
     for (int y = 0, yOff = 0; y < fNumDivisions; ++y, yOff += yTileSize) {
         int ySize = (y < fNumDivisions-1) ? yTileSize : viewport.height()-yOff;

         for (int x = 0, xOff = 0; x < fNumDivisions; ++x, xOff += xTileSize) {
             int xSize = (x < fNumDivisions-1) ? xTileSize : viewport.width()-xOff;

             SkIRect clip = SkIRect::MakeXYWH(xOff, yOff, xSize, ySize);

             SkASSERT(viewport.contains(clip));

             fTiles[y*fNumDivisions+x].init(y*fNumDivisions+x, context, dstChar, clip);
         }
     }
 }

 void DDLTileHelper::createSKPPerTile(SkData* compressedPictureData,
                                      const DDLPromiseImageHelper& helper) {
     for (int i = 0; i < this->numTiles(); ++i) {
         fTiles[i].createTileSpecificSKP(compressedPictureData, helper);
     }
 }

 void DDLTileHelper::createDDLsInParallel() {
 #if 1
     SkTaskGroup().batch(this->numTiles(), [&](int i) { fTiles[i].createDDL(); });
     SkTaskGroup().add([this]{ this->createComposeDDL(); });
     SkTaskGroup().wait();
 #else
     // Use this code path to debug w/o threads
     for (int i = 0; i < this->numTiles(); ++i) {
         fTiles[i].createDDL();
     }
     this->createComposeDDL();
 #endif
 }

 // On the gpu thread:
 //    precompile any programs
 //    replay the DDL into a surface to make the tile image
 //    compose the tile image into the main canvas
 static void do_gpu_stuff(GrContext* context, DDLTileHelper::TileData* tile) {

     // TODO: schedule program compilation as their own tasks
     tile->precompile(context);

     tile->draw(context);

     tile->dropDDL();
 }

 // We expect to have more than one recording thread but just one gpu thread
 void DDLTileHelper::kickOffThreadedWork(SkTaskGroup* recordingTaskGroup,
                                         SkTaskGroup* gpuTaskGroup,
                                         GrContext* gpuThreadContext) {
     SkASSERT(recordingTaskGroup && gpuTaskGroup && gpuThreadContext);

     for (int i = 0; i < this->numTiles(); ++i) {
         TileData* tile = &fTiles[i];

         // On a recording thread:
         //    generate the tile's DDL
         //    schedule gpu-thread processing of the DDL
         // Note: a finer grained approach would be add a scheduling task which would evaluate
         //       which DDLs were ready to be rendered based on their prerequisites
         recordingTaskGroup->add([tile, gpuTaskGroup, gpuThreadContext]() {
                                     tile->createDDL();

                                     gpuTaskGroup->add([gpuThreadContext, tile]() {
                                         do_gpu_stuff(gpuThreadContext, tile);
                                     });
                                 });
     }

     recordingTaskGroup->add([this] { this->createComposeDDL(); });
 }

 // Only called from ViaDDL
 void DDLTileHelper::precompileAndDrawAllTiles(GrContext* context) {
     for (int i = 0; i < this->numTiles(); ++i) {
         fTiles[i].precompile(context);
         fTiles[i].draw(context);
     }
 }

 // Only called from skpbench
 void DDLTileHelper::interleaveDDLCreationAndDraw(GrContext* context) {
     for (int i = 0; i < this->numTiles(); ++i) {
         fTiles[i].createDDL();
         fTiles[i].draw(context);
     }
 }

 // Only called from skpbench
 void DDLTileHelper::drawAllTilesDirectly(GrContext* context) {
     for (int i = 0; i < this->numTiles(); ++i) {
         fTiles[i].drawSKPDirectly(context);
     }
 }

 void DDLTileHelper::dropCallbackContexts() {
     for (int i = 0; i < this->numTiles(); ++i) {
         fTiles[i].dropCallbackContext();
     }
 }

 void DDLTileHelper::resetAllTiles() {
     for (int i = 0; i < this->numTiles(); ++i) {
         fTiles[i].reset();
     }
     fComposeDDL.reset();
 }

 void DDLTileHelper::createBackendTextures(SkTaskGroup* taskGroup, GrContext* context) {
     SkASSERT(context->asDirectContext());

     if (taskGroup) {
         for (int i = 0; i < this->numTiles(); ++i) {
             TileData* tile = &fTiles[i];

             taskGroup->add([context, tile]() { TileData::CreateBackendTexture(context, tile); });
         }
     } else {
         for (int i = 0; i < this->numTiles(); ++i) {
             TileData::CreateBackendTexture(context, &fTiles[i]);
         }
     }
 }

 void DDLTileHelper::deleteBackendTextures(SkTaskGroup* taskGroup, GrContext* context) {
     SkASSERT(context->asDirectContext());

     if (taskGroup) {
         for (int i = 0; i < this->numTiles(); ++i) {
             TileData* tile = &fTiles[i];

             taskGroup->add([context, tile]() { TileData::DeleteBackendTexture(context, tile); });
         }
     } else {
         for (int i = 0; i < this->numTiles(); ++i) {
             TileData::DeleteBackendTexture(context, &fTiles[i]);
         }
     }
 }
	/*
	* Copyright 2018 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include "tools/DDLTileHelper.h"

	#include "include/core/SkCanvas.h"
	#include "include/core/SkDeferredDisplayListRecorder.h"
	#include "include/core/SkPicture.h"
	#include "include/core/SkSurface.h"
	#include "include/core/SkSurfaceCharacterization.h"
	#include "src/core/SkDeferredDisplayListPriv.h"
	#include "src/core/SkTaskGroup.h"
	#include "src/gpu/GrContextPriv.h"
	#include "src/image/SkImage_Gpu.h"
	#include "tools/DDLPromiseImageHelper.h"

	void DDLTileHelper::TileData::init(int id,
	GrContext* context,
	const SkSurfaceCharacterization& dstSurfaceCharacterization,
	const SkIRect& clip) {
	fID = id;
	fClip = clip;

	fCharacterization = dstSurfaceCharacterization.createResized(clip.width(), clip.height());
	SkASSERT(fCharacterization.isValid());

	GrBackendFormat backendFormat = context->defaultBackendFormat(fCharacterization.colorType(),
	GrRenderable::kYes);
	SkDEBUGCODE(const GrCaps* caps = context->priv().caps());
	SkASSERT(caps->isFormatTexturable(backendFormat));

	fCallbackContext.reset(new PromiseImageCallbackContext(context, backendFormat));
	}

	DDLTileHelper::TileData::~TileData() {}

	void DDLTileHelper::TileData::createTileSpecificSKP(SkData* compressedPictureData,
	const DDLPromiseImageHelper& helper) {
	SkASSERT(!fReconstitutedPicture);

	// This is bending the DDLRecorder contract! The promise images in the SKP should be
	// created by the same recorder used to create the matching DDL.
	SkDeferredDisplayListRecorder recorder(fCharacterization);

	fReconstitutedPicture = helper.reinflateSKP(&recorder, compressedPictureData, &fPromiseImages);

	auto ddl = recorder.detach();
	if (ddl->priv().numRenderTasks()) {
	// TODO: remove this once skbug.com/8424 is fixed. If the DDL resulting from the
	// reinflation of the SKPs contains opsTasks that means some image subset operation
	// created a draw.
	fReconstitutedPicture.reset();
	}
	}

	void DDLTileHelper::TileData::createDDL() {
	SkASSERT(!fDisplayList && fReconstitutedPicture);

	SkDeferredDisplayListRecorder recorder(fCharacterization);

	// DDL TODO: the DDLRecorder's GrContext isn't initialized until getCanvas is called.
	// Maybe set it up in the ctor?
	SkCanvas* recordingCanvas = recorder.getCanvas();

	// Because we cheated in createTileSpecificSKP and used the wrong DDLRecorder, the GrContext's
	// stored in fReconstitutedPicture's promise images are incorrect. Patch them with the correct
	// one now.
	for (int i = 0; i < fPromiseImages.count(); ++i) {
	GrContext* newContext = recordingCanvas->getGrContext();

	if (fPromiseImages[i]->isTextureBacked()) {
	SkImage_GpuBase* gpuImage = (SkImage_GpuBase*) fPromiseImages[i].get();
	gpuImage->resetContext(sk_ref_sp(newContext));
	}
	}

	recordingCanvas->clipRect(SkRect::MakeWH(fClip.width(), fClip.height()));
	recordingCanvas->translate(-fClip.fLeft, -fClip.fTop);

	// Note: in this use case we only render a picture to the deferred canvas
	// but, more generally, clients will use arbitrary draw calls.
	recordingCanvas->drawPicture(fReconstitutedPicture);

	fDisplayList = recorder.detach();
	}

	void DDLTileHelper::createComposeDDL() {
	SkASSERT(!fComposeDDL);

	SkDeferredDisplayListRecorder recorder(fDstCharacterization);

	SkCanvas* recordingCanvas = recorder.getCanvas();

	for (int i = 0; i < this->numTiles(); ++i) {
	TileData* tile = &fTiles[i];

	sk_sp<SkImage> promiseImage = tile->makePromiseImage(&recorder);

	SkIRect clipRect = tile->clipRect();

	SkASSERT(clipRect.width() == promiseImage->width() &&
	clipRect.height() == promiseImage->height());

	recordingCanvas->drawImage(promiseImage, clipRect.fLeft, clipRect.fTop);
	}

	fComposeDDL = recorder.detach();
	SkASSERT(fComposeDDL);
	}

	void DDLTileHelper::TileData::precompile(GrContext* context) {
	SkASSERT(fDisplayList);

	SkDeferredDisplayList::ProgramIterator iter(context, fDisplayList.get());
	for (; !iter.done(); iter.next()) {
	iter.compile();
	}
	}

	sk_sp<SkSurface> DDLTileHelper::TileData::makeWrappedTileDest(GrContext* context) {
	SkASSERT(fCallbackContext && fCallbackContext->promiseImageTexture());

	auto promiseImageTexture = fCallbackContext->promiseImageTexture();
	if (!promiseImageTexture->backendTexture().isValid()) {
	return nullptr;
	}

	// Here we are, unfortunately, aliasing the backend texture held by the SkPromiseImageTexture.
	// Both the tile's destination surface and the promise image used to draw the tile will be
	// backed by the same backendTexture - unbeknownst to Ganesh.
	return SkSurface::MakeFromBackendTexture(context,
	promiseImageTexture->backendTexture(),
	fCharacterization.origin(),
	fCharacterization.sampleCount(),
	fCharacterization.colorType(),
	fCharacterization.refColorSpace(),
	&fCharacterization.surfaceProps());
	}

	void DDLTileHelper::TileData::drawSKPDirectly(GrContext* context) {
	SkASSERT(!fDisplayList && !fTileSurface && fReconstitutedPicture);

	fTileSurface = this->makeWrappedTileDest(context);
	if (fTileSurface) {
	SkCanvas* tileCanvas = fTileSurface->getCanvas();

	tileCanvas->clipRect(SkRect::MakeWH(fClip.width(), fClip.height()));
	tileCanvas->translate(-fClip.fLeft, -fClip.fTop);

	tileCanvas->drawPicture(fReconstitutedPicture);

	// We can't snap an image here bc, since we're using wrapped backend textures for the
	// surfaces, that would incur a copy.
	}
	}

	void DDLTileHelper::TileData::draw(GrContext* context) {
	SkASSERT(fDisplayList && !fTileSurface);

	// The tile's surface needs to be held until after the DDL is flushed bc the DDL doesn't take
	// a ref on its destination proxy.
	// TODO: make the DDL (or probably the drawing manager) take a ref on the destination proxy
	// (maybe in GrDrawingManager::addDDLTarget).
	fTileSurface = this->makeWrappedTileDest(context);
	if (fTileSurface) {
	fTileSurface->draw(fDisplayList);

	// We can't snap an image here bc, since we're using wrapped backend textures for the
	// surfaces, that would incur a copy.
	}
	}

	void DDLTileHelper::TileData::reset() {
	// TODO: when DDLs are re-renderable we don't need to do this
	fDisplayList = nullptr;

	fTileSurface = nullptr;
	}

	sk_sp<SkImage> DDLTileHelper::TileData::makePromiseImage(SkDeferredDisplayListRecorder* recorder) {
	SkASSERT(fCallbackContext);

	// The promise image gets a ref on the promise callback context
	sk_sp<SkImage> promiseImage = recorder->makePromiseTexture(
	fCallbackContext->backendFormat(),
	fClip.width(),
	fClip.height(),
	GrMipMapped::kNo,
	GrSurfaceOrigin::kBottomLeft_GrSurfaceOrigin,
	fCharacterization.colorType(),
	kPremul_SkAlphaType,
	fCharacterization.refColorSpace(),
	PromiseImageCallbackContext::PromiseImageFulfillProc,
	PromiseImageCallbackContext::PromiseImageReleaseProc,
	PromiseImageCallbackContext::PromiseImageDoneProc,
	(void*)this->refCallbackContext().release(),
	SkDeferredDisplayListRecorder::PromiseImageApiVersion::kNew);
	fCallbackContext->wasAddedToImage();

	return promiseImage;
	}

	void DDLTileHelper::TileData::CreateBackendTexture(GrContext* context, TileData* tile) {
	SkASSERT(context->asDirectContext());
	SkASSERT(tile->fCallbackContext && !tile->fCallbackContext->promiseImageTexture());

	GrBackendTexture beTex = context->createBackendTexture(tile->fCharacterization);
	tile->fCallbackContext->setBackendTexture(beTex);
	}

	void DDLTileHelper::TileData::DeleteBackendTexture(GrContext* context, TileData* tile) {
	SkASSERT(context->asDirectContext());
	SkASSERT(tile->fCallbackContext);

	// TODO: it seems that, on the Linux bots, backend texture creation is failing
	// a lot (skbug.com/10142)
	SkASSERT(!tile->fCallbackContext->promiseImageTexture() \|\|
	tile->fCallbackContext->promiseImageTexture()->backendTexture().isValid());

	tile->fTileSurface = nullptr;

	SkASSERT(tile->fCallbackContext->unique());
	tile->fCallbackContext.reset();
	}

	///////////////////////////////////////////////////////////////////////////////////////////////////

	DDLTileHelper::DDLTileHelper(GrContext* context,
	const SkSurfaceCharacterization& dstChar,
	const SkIRect& viewport,
	int numDivisions)
	: fNumDivisions(numDivisions)
	, fTiles(numDivisions * numDivisions)
	, fDstCharacterization(dstChar) {
	SkASSERT(fNumDivisions > 0);

	int xTileSize = viewport.width()/fNumDivisions;
	int yTileSize = viewport.height()/fNumDivisions;

	// Create the destination tiles
	for (int y = 0, yOff = 0; y < fNumDivisions; ++y, yOff += yTileSize) {
	int ySize = (y < fNumDivisions-1) ? yTileSize : viewport.height()-yOff;

	for (int x = 0, xOff = 0; x < fNumDivisions; ++x, xOff += xTileSize) {
	int xSize = (x < fNumDivisions-1) ? xTileSize : viewport.width()-xOff;

	SkIRect clip = SkIRect::MakeXYWH(xOff, yOff, xSize, ySize);

	SkASSERT(viewport.contains(clip));

	fTiles[yfNumDivisions+x].init(yfNumDivisions+x, context, dstChar, clip);
	}
	}
	}

	void DDLTileHelper::createSKPPerTile(SkData* compressedPictureData,
	const DDLPromiseImageHelper& helper) {
	for (int i = 0; i < this->numTiles(); ++i) {
	fTiles[i].createTileSpecificSKP(compressedPictureData, helper);
	}
	}

	void DDLTileHelper::createDDLsInParallel() {
	#if 1
	SkTaskGroup().batch(this->numTiles(), [&](int i) { fTiles[i].createDDL(); });
	SkTaskGroup().add([this]{ this->createComposeDDL(); });
	SkTaskGroup().wait();
	#else
	// Use this code path to debug w/o threads
	for (int i = 0; i < this->numTiles(); ++i) {
	fTiles[i].createDDL();
	}
	this->createComposeDDL();
	#endif
	}

	// On the gpu thread:
	// precompile any programs
	// replay the DDL into a surface to make the tile image
	// compose the tile image into the main canvas
	static void do_gpu_stuff(GrContext* context, DDLTileHelper::TileData* tile) {

	// TODO: schedule program compilation as their own tasks
	tile->precompile(context);

	tile->draw(context);

	tile->dropDDL();
	}

	// We expect to have more than one recording thread but just one gpu thread
	void DDLTileHelper::kickOffThreadedWork(SkTaskGroup* recordingTaskGroup,
	SkTaskGroup* gpuTaskGroup,
	GrContext* gpuThreadContext) {
	SkASSERT(recordingTaskGroup && gpuTaskGroup && gpuThreadContext);

	for (int i = 0; i < this->numTiles(); ++i) {
	TileData* tile = &fTiles[i];

	// On a recording thread:
	// generate the tile's DDL
	// schedule gpu-thread processing of the DDL
	// Note: a finer grained approach would be add a scheduling task which would evaluate
	// which DDLs were ready to be rendered based on their prerequisites
	recordingTaskGroup->add([tile, gpuTaskGroup, gpuThreadContext]() {
	tile->createDDL();

	gpuTaskGroup->add([gpuThreadContext, tile]() {
	do_gpu_stuff(gpuThreadContext, tile);
	});
	});
	}

	recordingTaskGroup->add([this] { this->createComposeDDL(); });
	}

	// Only called from ViaDDL
	void DDLTileHelper::precompileAndDrawAllTiles(GrContext* context) {
	for (int i = 0; i < this->numTiles(); ++i) {
	fTiles[i].precompile(context);
	fTiles[i].draw(context);
	}
	}

	// Only called from skpbench
	void DDLTileHelper::interleaveDDLCreationAndDraw(GrContext* context) {
	for (int i = 0; i < this->numTiles(); ++i) {
	fTiles[i].createDDL();
	fTiles[i].draw(context);
	}
	}

	// Only called from skpbench
	void DDLTileHelper::drawAllTilesDirectly(GrContext* context) {
	for (int i = 0; i < this->numTiles(); ++i) {
	fTiles[i].drawSKPDirectly(context);
	}
	}

	void DDLTileHelper::dropCallbackContexts() {
	for (int i = 0; i < this->numTiles(); ++i) {
	fTiles[i].dropCallbackContext();
	}
	}

	void DDLTileHelper::resetAllTiles() {
	for (int i = 0; i < this->numTiles(); ++i) {
	fTiles[i].reset();
	}
	fComposeDDL.reset();
	}

	void DDLTileHelper::createBackendTextures(SkTaskGroup* taskGroup, GrContext* context) {
	SkASSERT(context->asDirectContext());

	if (taskGroup) {
	for (int i = 0; i < this->numTiles(); ++i) {
	TileData* tile = &fTiles[i];

	taskGroup->add([context, tile]() { TileData::CreateBackendTexture(context, tile); });
	}
	} else {
	for (int i = 0; i < this->numTiles(); ++i) {
	TileData::CreateBackendTexture(context, &fTiles[i]);
	}
	}
	}

	void DDLTileHelper::deleteBackendTextures(SkTaskGroup* taskGroup, GrContext* context) {
	SkASSERT(context->asDirectContext());

	if (taskGroup) {
	for (int i = 0; i < this->numTiles(); ++i) {
	TileData* tile = &fTiles[i];

	taskGroup->add([context, tile]() { TileData::DeleteBackendTexture(context, tile); });
	}
	} else {
	for (int i = 0; i < this->numTiles(); ++i) {
	TileData::DeleteBackendTexture(context, &fTiles[i]);
	}
	}
	}