tests/TransferPixelsTest.cpp - platform/external/skia - Gitiles

 /*
  * Copyright 2017 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 // This is a GPU-backend specific test. It relies on static intializers to work

 #include "include/core/SkTypes.h"

 #include "include/core/SkSurface.h"
 #include "include/gpu/GrTexture.h"
 #include "src/gpu/GrContextPriv.h"
 #include "src/gpu/GrGpu.h"
 #include "src/gpu/GrImageInfo.h"
 #include "src/gpu/GrResourceProvider.h"
 #include "src/gpu/GrSurfaceProxy.h"
 #include "src/gpu/SkGr.h"
 #include "tests/Test.h"
 #include "tests/TestUtils.h"
 #include "tools/gpu/GrContextFactory.h"

 using sk_gpu_test::GrContextFactory;

 void fill_transfer_data(int left, int top, int width, int height, int bufferWidth,
                         GrColorType dstType, char* dst) {
     size_t dstBpp = GrColorTypeBytesPerPixel(dstType);
     auto dstLocation = [dst, dstBpp, bufferWidth](int x, int y) {
         return dst + y * dstBpp * bufferWidth + x * dstBpp;
     };
     // build red-green gradient
     for (int j = top; j < top + height; ++j) {
         for (int i = left; i < left + width; ++i) {
             auto r = (unsigned int)(256.f*((i - left) / (float)width));
             auto g = (unsigned int)(256.f*((j - top) / (float)height));
             r -= (r >> 8);
             g -= (g >> 8);
             // set b and a channels to be inverse of r and g just to have interesting values to
             // test.
             uint32_t srcPixel = GrColorPackRGBA(r, g, 0xff - r, 0xff - g);
             GrImageInfo srcInfo(GrColorType::kRGBA_8888, kUnpremul_SkAlphaType, nullptr, 1, 1);
             GrImageInfo dstInfo(dstType, kUnpremul_SkAlphaType, nullptr, 1, 1);
             GrConvertPixels(dstInfo, dstLocation(i, j), dstBpp, srcInfo, &srcPixel, 4);
         }
     }
 }

 void determine_tolerances(GrColorType a, GrColorType b, float tolerances[4]) {
     std::fill_n(tolerances, 4, 0);

     auto descA = GrGetColorTypeDesc(a);
     auto descB = GrGetColorTypeDesc(b);
     // For each channel x set the tolerance to 1 / (2^min(bits_in_a, bits_in_b) - 1) unless
     // one color type is missing the channel. In that case leave it at 0. If the other color
     // has the channel then it better be exactly 1 for alpha or 0 for rgb.
     for (int i = 0; i < 4; ++i) {
         if (descA[i] != descB[i]) {
             auto m = std::min(descA[i], descB[i]);
             if (m) {
                 tolerances[i] = 1.f / (m - 1);
             }
         }
     }
 }

 bool read_pixels_from_texture(GrTexture* texture, GrColorType colorType, char* dst,
                               float tolerances[4]) {
     auto* context = texture->getContext();
     auto* gpu = context->priv().getGpu();
     auto* caps = context->priv().caps();

     int w = texture->width();
     int h = texture->height();
     size_t rowBytes = GrColorTypeBytesPerPixel(colorType) * w;

     GrColorType srcCT = GrPixelConfigToColorType(texture->config());

     GrCaps::SupportedRead supportedRead =
             caps->supportedReadPixelsColorType(srcCT, texture->backendFormat(), colorType);
     std::fill_n(tolerances, 4, 0);
     if (supportedRead.fColorType != colorType) {
         size_t tmpRowBytes = GrColorTypeBytesPerPixel(supportedRead.fColorType) * w;
         std::unique_ptr<char[]> tmpPixels(new char[tmpRowBytes * h]);
         if (!gpu->readPixels(texture, 0, 0, w, h, colorType, supportedRead.fColorType,
                              tmpPixels.get(), tmpRowBytes)) {
             return false;
         }
         GrImageInfo tmpInfo(supportedRead.fColorType, kUnpremul_SkAlphaType, nullptr, w, h);
         GrImageInfo dstInfo(colorType,                kUnpremul_SkAlphaType, nullptr, w, h);
         determine_tolerances(tmpInfo.colorType(), dstInfo.colorType(), tolerances);
         return GrConvertPixels(dstInfo, dst, rowBytes, tmpInfo, tmpPixels.get(), tmpRowBytes,
                                false);
     }
     return gpu->readPixels(texture, 0, 0, w, h, colorType, supportedRead.fColorType, dst, rowBytes);
 }

 void basic_transfer_to_test(skiatest::Reporter* reporter, GrContext* context, GrColorType colorType,
                             GrRenderable renderable) {
     if (GrCaps::kNone_MapFlags == context->priv().caps()->mapBufferFlags()) {
         return;
     }

     auto* caps = context->priv().caps();

     auto backendFormat = caps->getDefaultBackendFormat(colorType, renderable);
     if (!backendFormat.isValid()) {
         return;
     }

     auto resourceProvider = context->priv().resourceProvider();
     GrGpu* gpu = context->priv().getGpu();

     const int kTextureWidth = 16;
     const int kTextureHeight = 16;
     int srcBufferWidth = caps->writePixelsRowBytesSupport() ? 20 : 16;
     const int kBufferHeight = 16;

     GrSurfaceDesc desc;
     desc.fWidth = kTextureWidth;
     desc.fHeight = kTextureHeight;
     desc.fConfig = GrColorTypeToPixelConfig(colorType);

     sk_sp<GrTexture> tex =
             resourceProvider->createTexture(desc, backendFormat, renderable, 1, GrMipMapped::kNo,
                                             SkBudgeted::kNo, GrProtected::kNo);
     if (!tex) {
         ERRORF(reporter, "Could not create texture");
         return;
     }

     // We validate the results using GrGpu::readPixels, so exit if this is not supported.
     // TODO: Do this through GrSurfaceContext once it works for all color types or support
     // kCopyToTexture2D here.
     if (GrCaps::SurfaceReadPixelsSupport::kSupported !=
         caps->surfaceSupportsReadPixels(tex.get())) {
         return;
     }
     // GL requires a texture to be framebuffer bindable to call glReadPixels. However, we have not
     // incorporated that test into surfaceSupportsReadPixels(). TODO: Remove this once we handle
     // drawing to a bindable format.
     if (!caps->isFormatAsColorTypeRenderable(colorType, tex->backendFormat())) {
         return;
     }

     // The caps tell us what color type we are allowed to upload and read back from this texture,
     // either of which may differ from 'colorType'.
     GrCaps::SupportedWrite allowedSrc =
             caps->supportedWritePixelsColorType(colorType, tex->backendFormat(), colorType);
     size_t srcRowBytes = GrColorTypeBytesPerPixel(allowedSrc.fColorType) * srcBufferWidth;
     std::unique_ptr<char[]> srcData(new char[kTextureHeight * srcRowBytes]);

     fill_transfer_data(0, 0, kTextureWidth, kTextureHeight, srcBufferWidth, allowedSrc.fColorType,
                        srcData.get());

     // create and fill transfer buffer
     size_t size = srcRowBytes * kBufferHeight;
     sk_sp<GrGpuBuffer> buffer(resourceProvider->createBuffer(size, GrGpuBufferType::kXferCpuToGpu,
                                                              kDynamic_GrAccessPattern));
     if (!buffer) {
         return;
     }
     void* data = buffer->map();
     if (!buffer) {
         ERRORF(reporter, "Could not map buffer");
         return;
     }
     memcpy(data, srcData.get(), size);
     buffer->unmap();

     //////////////////////////
     // transfer full data

     bool result;
     result = gpu->transferPixelsTo(tex.get(), 0, 0, kTextureWidth, kTextureHeight, colorType,
                                    allowedSrc.fColorType, buffer.get(), 0, srcRowBytes);
     REPORTER_ASSERT(reporter, result);

     size_t dstRowBytes = GrColorTypeBytesPerPixel(colorType) * kTextureWidth;
     std::unique_ptr<char[]> dstBuffer(new char[dstRowBytes * kTextureHeight]());

     float compareTolerances[4] = {};
     result = read_pixels_from_texture(tex.get(), colorType, dstBuffer.get(), compareTolerances);
     if (!result) {
         ERRORF(reporter, "Could not read pixels from texture, color type: %d",
                static_cast<int>(colorType));
         return;
     }

     auto error = std::function<ComparePixmapsErrorReporter>(
             [reporter, colorType](int x, int y, const float diffs[4]) {
                 ERRORF(reporter,
                        "Error at (%d %d) in transfer, color type: %d, diffs: (%f, %f, %f, %f)", x,
                        y, colorType, diffs[0], diffs[1], diffs[2], diffs[3]);
             });
     GrImageInfo srcInfo(allowedSrc.fColorType, kUnpremul_SkAlphaType, nullptr, tex->width(),
                         tex->height());
     GrImageInfo dstInfo(colorType, kUnpremul_SkAlphaType, nullptr, tex->width(), tex->height());
     ComparePixels(srcInfo, srcData.get(), srcRowBytes, dstInfo, dstBuffer.get(), dstRowBytes,
                   compareTolerances, error);

     //////////////////////////
     // transfer partial data

     // We're relying on this cap to write partial texture data
     if (!caps->writePixelsRowBytesSupport()) {
         return;
     }
     // We keep a 1 to 1 correspondence between pixels in the buffer and the entire texture. We
     // update the contents of a sub-rect of the buffer and push that rect to the texture. We start
     // with a left sub-rect inset of 2 but may adjust that so we can fulfill the transfer buffer
     // offset alignment requirement.
     int left = 2;
     const int top = 10;
     const int width = 10;
     const int height = 2;
     size_t offset = top * srcRowBytes + left * GrColorTypeBytesPerPixel(allowedSrc.fColorType);
     while (offset % allowedSrc.fOffsetAlignmentForTransferBuffer) {
         offset += GrColorTypeBytesPerPixel(allowedSrc.fColorType);
         ++left;
         // We're assuming that the required alignment is 1 or a small multiple of the bpp, which
         // it is currently for all color types across all backends.
         SkASSERT(left + width <= tex->width());
     }

     // change color of subrectangle
     fill_transfer_data(left, top, width, height, srcBufferWidth, allowedSrc.fColorType,
                        srcData.get());
     data = buffer->map();
     memcpy(data, srcData.get(), size);
     buffer->unmap();

     result = gpu->transferPixelsTo(tex.get(), left, top, width, height, colorType,
                                    allowedSrc.fColorType, buffer.get(), offset, srcRowBytes);
     if (!result) {
         gpu->transferPixelsTo(tex.get(), left, top, width, height, colorType, allowedSrc.fColorType,
                               buffer.get(), offset, srcRowBytes);
         ERRORF(reporter, "Could not transfer pixels to texture, color type: %d",
                static_cast<int>(colorType));
         return;
     }

     result = read_pixels_from_texture(tex.get(), colorType, dstBuffer.get(), compareTolerances);
     if (!result) {
         ERRORF(reporter, "Could not read pixels from texture, color type: %d",
                static_cast<int>(colorType));
         return;
     }
     ComparePixels(srcInfo, srcData.get(), srcRowBytes, dstInfo, dstBuffer.get(), dstRowBytes,
                   compareTolerances, error);
 }

 void basic_transfer_from_test(skiatest::Reporter* reporter, const sk_gpu_test::ContextInfo& ctxInfo,
                               GrColorType colorType, GrRenderable renderable) {
     auto context = ctxInfo.grContext();
     auto caps = context->priv().caps();
     if (GrCaps::kNone_MapFlags == caps->mapBufferFlags()) {
         return;
     }

     auto resourceProvider = context->priv().resourceProvider();
     GrGpu* gpu = context->priv().getGpu();

     const int kTextureWidth = 16;
     const int kTextureHeight = 16;

     // We'll do a full texture read into the buffer followed by a partial read. These values
     // describe the partial read subrect.
     const int kPartialLeft = 2;
     const int kPartialTop = 10;
     const int kPartialWidth = 10;
     const int kPartialHeight = 2;

     // create texture
     GrSurfaceDesc desc;
     desc.fWidth = kTextureWidth;
     desc.fHeight = kTextureHeight;
     desc.fConfig = GrColorTypeToPixelConfig(colorType);

     auto format = context->priv().caps()->getDefaultBackendFormat(colorType, renderable);
     if (!format.isValid()) {
         return;
     }

     size_t textureDataBpp = GrColorTypeBytesPerPixel(colorType);
     size_t textureDataRowBytes = kTextureWidth * textureDataBpp;
     std::unique_ptr<char[]> textureData(new char[kTextureHeight * textureDataRowBytes]);
     fill_transfer_data(0, 0, kTextureWidth, kTextureHeight, kTextureWidth, colorType,
                        textureData.get());
     GrMipLevel data;
     data.fPixels = textureData.get();
     data.fRowBytes = textureDataRowBytes;
     sk_sp<GrTexture> tex = resourceProvider->createTexture(
             desc, format, colorType, renderable, 1, SkBudgeted::kNo, GrProtected::kNo, &data, 1);
     if (!tex) {
         return;
     }

     if (GrCaps::SurfaceReadPixelsSupport::kSupported !=
         caps->surfaceSupportsReadPixels(tex.get())) {
         return;
     }
     // GL requires a texture to be framebuffer bindable to call glReadPixels. However, we have not
     // incorporated that test into surfaceSupportsReadPixels(). TODO: Remove this once we handle
     // drawing to a bindable format.
     if (!caps->isFormatAsColorTypeRenderable(colorType, tex->backendFormat())) {
         return;
     }

     // Create the transfer buffer.
     auto allowedRead =
             caps->supportedReadPixelsColorType(colorType, tex->backendFormat(), colorType);
     GrImageInfo readInfo(allowedRead.fColorType, kUnpremul_SkAlphaType, nullptr, kTextureWidth,
                          kTextureHeight);

     size_t bpp = GrColorTypeBytesPerPixel(allowedRead.fColorType);
     size_t fullBufferRowBytes = kTextureWidth * bpp;
     size_t partialBufferRowBytes = kPartialWidth * bpp;
     size_t offsetAlignment = allowedRead.fOffsetAlignmentForTransferBuffer;
     SkASSERT(offsetAlignment);

     size_t bufferSize = fullBufferRowBytes * kTextureHeight;
     // Arbitrary starting offset for the partial read.
     size_t partialReadOffset = GrSizeAlignUp(11, offsetAlignment);
     bufferSize = SkTMax(bufferSize, partialReadOffset + partialBufferRowBytes * kPartialHeight);

     sk_sp<GrGpuBuffer> buffer(resourceProvider->createBuffer(
             bufferSize, GrGpuBufferType::kXferGpuToCpu, kDynamic_GrAccessPattern));
     REPORTER_ASSERT(reporter, buffer);
     if (!buffer) {
         return;
     }

     int expectedTransferCnt = 0;
     gpu->stats()->reset();

     //////////////////////////
     // transfer full data
     bool result = gpu->transferPixelsFrom(tex.get(), 0, 0, kTextureWidth, kTextureHeight, colorType,
                                           allowedRead.fColorType, buffer.get(), 0);
     if (!result) {
         ERRORF(reporter, "transferPixelsFrom failed.");
         return;
     }
     ++expectedTransferCnt;

     GrFlushInfo flushInfo;
     flushInfo.fFlags = kSyncCpu_GrFlushFlag;
     if (context->priv().caps()->mapBufferFlags() & GrCaps::kAsyncRead_MapFlag) {
         gpu->finishFlush(nullptr, 0, SkSurface::BackendSurfaceAccess::kNoAccess, flushInfo,
                          GrPrepareForExternalIORequests());
     }

     // Copy the transfer buffer contents to a temporary so we can manipulate it.
     const auto* map = reinterpret_cast<const char*>(buffer->map());
     REPORTER_ASSERT(reporter, map);
     if (!map) {
         ERRORF(reporter, "Failed to map transfer buffer.");
         return;
     }
     std::unique_ptr<char[]> transferData(new char[kTextureHeight * fullBufferRowBytes]);
     memcpy(transferData.get(), map, fullBufferRowBytes * kTextureHeight);
     buffer->unmap();

     GrImageInfo transferInfo(allowedRead.fColorType, kUnpremul_SkAlphaType, nullptr, kTextureWidth,
                              kTextureHeight);

     float tol[4];
     determine_tolerances(allowedRead.fColorType, colorType, tol);
     auto error = std::function<ComparePixmapsErrorReporter>(
             [reporter, colorType](int x, int y, const float diffs[4]) {
                 ERRORF(reporter,
                        "Error at (%d %d) in transfer, color type: %d, diffs: (%f, %f, %f, %f)", x,
                        y, colorType, diffs[0], diffs[1], diffs[2], diffs[3]);
             });
     GrImageInfo textureDataInfo(colorType, kUnpremul_SkAlphaType, nullptr, kTextureWidth,
                                 kTextureHeight);
     ComparePixels(textureDataInfo, textureData.get(), textureDataRowBytes, transferInfo,
                   transferData.get(), fullBufferRowBytes, tol, error);

     ///////////////////////
     // Now test a partial read at an offset into the buffer.
     result = gpu->transferPixelsFrom(tex.get(), kPartialLeft, kPartialTop, kPartialWidth,
                                      kPartialHeight, colorType, allowedRead.fColorType,
                                      buffer.get(), partialReadOffset);
     if (!result) {
         ERRORF(reporter, "transferPixelsFrom failed.");
         return;
     }
     ++expectedTransferCnt;

     if (context->priv().caps()->mapBufferFlags() & GrCaps::kAsyncRead_MapFlag) {
         gpu->finishFlush(nullptr, 0, SkSurface::BackendSurfaceAccess::kNoAccess, flushInfo,
                          GrPrepareForExternalIORequests());
     }

     map = reinterpret_cast<const char*>(buffer->map());
     REPORTER_ASSERT(reporter, map);
     if (!map) {
         ERRORF(reporter, "Failed to map transfer buffer.");
         return;
     }
     const char* bufferStart = reinterpret_cast<const char*>(map) + partialReadOffset;
     memcpy(transferData.get(), bufferStart, partialBufferRowBytes * kTextureHeight);
     buffer->unmap();

     transferInfo = transferInfo.makeWH(kPartialWidth, kPartialHeight);
     const char* textureDataStart =
             textureData.get() + textureDataRowBytes * kPartialTop + textureDataBpp * kPartialLeft;
     textureDataInfo = textureDataInfo.makeWH(kPartialWidth, kPartialHeight);
     ComparePixels(textureDataInfo, textureDataStart, textureDataRowBytes, transferInfo,
                   transferData.get(), partialBufferRowBytes, tol, error);
 #if GR_GPU_STATS
     REPORTER_ASSERT(reporter, gpu->stats()->transfersFromSurface() == expectedTransferCnt);
 #else
     (void)expectedTransferCnt;
 #endif
 }

 DEF_GPUTEST_FOR_RENDERING_CONTEXTS(TransferPixelsToTest, reporter, ctxInfo) {
     if (!ctxInfo.grContext()->priv().caps()->transferBufferSupport()) {
         return;
     }
     for (auto renderable : {GrRenderable::kNo, GrRenderable::kYes}) {
         for (auto colorType : {
                      GrColorType::kAlpha_8,
                      GrColorType::kBGR_565,
                      GrColorType::kABGR_4444,
                      GrColorType::kRGBA_8888,
                      GrColorType::kRGBA_8888_SRGB,
                      //  GrColorType::kRGB_888x, Broken in GL until we have kRGB_888
                      GrColorType::kRG_88,
                      GrColorType::kBGRA_8888,
                      GrColorType::kRGBA_1010102,
                      GrColorType::kGray_8,
                      GrColorType::kAlpha_F16,
                      GrColorType::kRGBA_F16,
                      GrColorType::kRGBA_F16_Clamped,
                      GrColorType::kRGBA_F32,
                      GrColorType::kAlpha_16,
                      GrColorType::kRG_1616,
                      GrColorType::kRGBA_16161616,
                      GrColorType::kRG_F16,
              }) {
             basic_transfer_to_test(reporter, ctxInfo.grContext(), colorType, renderable);
         }
     }
 }

 // TODO(bsalomon): Metal
 DEF_GPUTEST_FOR_RENDERING_CONTEXTS(TransferPixelsFromTest, reporter, ctxInfo) {
     if (!ctxInfo.grContext()->priv().caps()->transferBufferSupport()) {
         return;
     }
     for (auto renderable : {GrRenderable::kNo, GrRenderable::kYes}) {
         for (auto colorType : {
                      GrColorType::kAlpha_8,
                      GrColorType::kAlpha_16,
                      GrColorType::kBGR_565,
                      GrColorType::kABGR_4444,
                      GrColorType::kRGBA_8888,
                      GrColorType::kRGBA_8888_SRGB,
                      //  GrColorType::kRGB_888x, Broken in GL until we have kRGB_888
                      GrColorType::kRG_88,
                      GrColorType::kBGRA_8888,
                      GrColorType::kRGBA_1010102,
                      GrColorType::kGray_8,
                      GrColorType::kAlpha_F16,
                      GrColorType::kRGBA_F16,
                      GrColorType::kRGBA_F16_Clamped,
                      GrColorType::kRGBA_F32,
                      GrColorType::kRG_1616,
                      GrColorType::kRGBA_16161616,
                      GrColorType::kRG_F16,
              }) {
             basic_transfer_from_test(reporter, ctxInfo, colorType, renderable);
         }
     }
 }
	/*
	* Copyright 2017 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	// This is a GPU-backend specific test. It relies on static intializers to work

	#include "include/core/SkTypes.h"

	#include "include/core/SkSurface.h"
	#include "include/gpu/GrTexture.h"
	#include "src/gpu/GrContextPriv.h"
	#include "src/gpu/GrGpu.h"
	#include "src/gpu/GrImageInfo.h"
	#include "src/gpu/GrResourceProvider.h"
	#include "src/gpu/GrSurfaceProxy.h"
	#include "src/gpu/SkGr.h"
	#include "tests/Test.h"
	#include "tests/TestUtils.h"
	#include "tools/gpu/GrContextFactory.h"

	using sk_gpu_test::GrContextFactory;

	void fill_transfer_data(int left, int top, int width, int height, int bufferWidth,
	GrColorType dstType, char* dst) {
	size_t dstBpp = GrColorTypeBytesPerPixel(dstType);
	auto dstLocation = [dst, dstBpp, bufferWidth](int x, int y) {
	return dst + y * dstBpp * bufferWidth + x * dstBpp;
	};
	// build red-green gradient
	for (int j = top; j < top + height; ++j) {
	for (int i = left; i < left + width; ++i) {
	auto r = (unsigned int)(256.f*((i - left) / (float)width));
	auto g = (unsigned int)(256.f*((j - top) / (float)height));
	r -= (r >> 8);
	g -= (g >> 8);
	// set b and a channels to be inverse of r and g just to have interesting values to
	// test.
	uint32_t srcPixel = GrColorPackRGBA(r, g, 0xff - r, 0xff - g);
	GrImageInfo srcInfo(GrColorType::kRGBA_8888, kUnpremul_SkAlphaType, nullptr, 1, 1);
	GrImageInfo dstInfo(dstType, kUnpremul_SkAlphaType, nullptr, 1, 1);
	GrConvertPixels(dstInfo, dstLocation(i, j), dstBpp, srcInfo, &srcPixel, 4);
	}
	}
	}

	void determine_tolerances(GrColorType a, GrColorType b, float tolerances[4]) {
	std::fill_n(tolerances, 4, 0);

	auto descA = GrGetColorTypeDesc(a);
	auto descB = GrGetColorTypeDesc(b);
	// For each channel x set the tolerance to 1 / (2^min(bits_in_a, bits_in_b) - 1) unless
	// one color type is missing the channel. In that case leave it at 0. If the other color
	// has the channel then it better be exactly 1 for alpha or 0 for rgb.
	for (int i = 0; i < 4; ++i) {
	if (descA[i] != descB[i]) {
	auto m = std::min(descA[i], descB[i]);
	if (m) {
	tolerances[i] = 1.f / (m - 1);
	}
	}
	}
	}

	bool read_pixels_from_texture(GrTexture* texture, GrColorType colorType, char* dst,
	float tolerances[4]) {
	auto* context = texture->getContext();
	auto* gpu = context->priv().getGpu();
	auto* caps = context->priv().caps();

	int w = texture->width();
	int h = texture->height();
	size_t rowBytes = GrColorTypeBytesPerPixel(colorType) * w;

	GrColorType srcCT = GrPixelConfigToColorType(texture->config());

	GrCaps::SupportedRead supportedRead =
	caps->supportedReadPixelsColorType(srcCT, texture->backendFormat(), colorType);
	std::fill_n(tolerances, 4, 0);
	if (supportedRead.fColorType != colorType) {
	size_t tmpRowBytes = GrColorTypeBytesPerPixel(supportedRead.fColorType) * w;
	std::unique_ptr<char[]> tmpPixels(new char[tmpRowBytes * h]);
	if (!gpu->readPixels(texture, 0, 0, w, h, colorType, supportedRead.fColorType,
	tmpPixels.get(), tmpRowBytes)) {
	return false;
	}
	GrImageInfo tmpInfo(supportedRead.fColorType, kUnpremul_SkAlphaType, nullptr, w, h);
	GrImageInfo dstInfo(colorType, kUnpremul_SkAlphaType, nullptr, w, h);
	determine_tolerances(tmpInfo.colorType(), dstInfo.colorType(), tolerances);
	return GrConvertPixels(dstInfo, dst, rowBytes, tmpInfo, tmpPixels.get(), tmpRowBytes,
	false);
	}
	return gpu->readPixels(texture, 0, 0, w, h, colorType, supportedRead.fColorType, dst, rowBytes);
	}

	void basic_transfer_to_test(skiatest::Reporter* reporter, GrContext* context, GrColorType colorType,
	GrRenderable renderable) {
	if (GrCaps::kNone_MapFlags == context->priv().caps()->mapBufferFlags()) {
	return;
	}

	auto* caps = context->priv().caps();

	auto backendFormat = caps->getDefaultBackendFormat(colorType, renderable);
	if (!backendFormat.isValid()) {
	return;
	}

	auto resourceProvider = context->priv().resourceProvider();
	GrGpu* gpu = context->priv().getGpu();

	const int kTextureWidth = 16;
	const int kTextureHeight = 16;
	int srcBufferWidth = caps->writePixelsRowBytesSupport() ? 20 : 16;
	const int kBufferHeight = 16;

	GrSurfaceDesc desc;
	desc.fWidth = kTextureWidth;
	desc.fHeight = kTextureHeight;
	desc.fConfig = GrColorTypeToPixelConfig(colorType);

	sk_sp<GrTexture> tex =
	resourceProvider->createTexture(desc, backendFormat, renderable, 1, GrMipMapped::kNo,
	SkBudgeted::kNo, GrProtected::kNo);
	if (!tex) {
	ERRORF(reporter, "Could not create texture");
	return;
	}

	// We validate the results using GrGpu::readPixels, so exit if this is not supported.
	// TODO: Do this through GrSurfaceContext once it works for all color types or support
	// kCopyToTexture2D here.
	if (GrCaps::SurfaceReadPixelsSupport::kSupported !=
	caps->surfaceSupportsReadPixels(tex.get())) {
	return;
	}
	// GL requires a texture to be framebuffer bindable to call glReadPixels. However, we have not
	// incorporated that test into surfaceSupportsReadPixels(). TODO: Remove this once we handle
	// drawing to a bindable format.
	if (!caps->isFormatAsColorTypeRenderable(colorType, tex->backendFormat())) {
	return;
	}

	// The caps tell us what color type we are allowed to upload and read back from this texture,
	// either of which may differ from 'colorType'.
	GrCaps::SupportedWrite allowedSrc =
	caps->supportedWritePixelsColorType(colorType, tex->backendFormat(), colorType);
	size_t srcRowBytes = GrColorTypeBytesPerPixel(allowedSrc.fColorType) * srcBufferWidth;
	std::unique_ptr<char[]> srcData(new char[kTextureHeight * srcRowBytes]);

	fill_transfer_data(0, 0, kTextureWidth, kTextureHeight, srcBufferWidth, allowedSrc.fColorType,
	srcData.get());

	// create and fill transfer buffer
	size_t size = srcRowBytes * kBufferHeight;
	sk_sp<GrGpuBuffer> buffer(resourceProvider->createBuffer(size, GrGpuBufferType::kXferCpuToGpu,
	kDynamic_GrAccessPattern));
	if (!buffer) {
	return;
	}
	void* data = buffer->map();
	if (!buffer) {
	ERRORF(reporter, "Could not map buffer");
	return;
	}
	memcpy(data, srcData.get(), size);
	buffer->unmap();

	//////////////////////////
	// transfer full data

	bool result;
	result = gpu->transferPixelsTo(tex.get(), 0, 0, kTextureWidth, kTextureHeight, colorType,
	allowedSrc.fColorType, buffer.get(), 0, srcRowBytes);
	REPORTER_ASSERT(reporter, result);

	size_t dstRowBytes = GrColorTypeBytesPerPixel(colorType) * kTextureWidth;
	std::unique_ptr<char[]> dstBuffer(new char[dstRowBytes * kTextureHeight]());

	float compareTolerances[4] = {};
	result = read_pixels_from_texture(tex.get(), colorType, dstBuffer.get(), compareTolerances);
	if (!result) {
	ERRORF(reporter, "Could not read pixels from texture, color type: %d",
	static_cast<int>(colorType));
	return;
	}

	auto error = std::function<ComparePixmapsErrorReporter>(
	[reporter, colorType](int x, int y, const float diffs[4]) {
	ERRORF(reporter,
	"Error at (%d %d) in transfer, color type: %d, diffs: (%f, %f, %f, %f)", x,
	y, colorType, diffs[0], diffs[1], diffs[2], diffs[3]);
	});
	GrImageInfo srcInfo(allowedSrc.fColorType, kUnpremul_SkAlphaType, nullptr, tex->width(),
	tex->height());
	GrImageInfo dstInfo(colorType, kUnpremul_SkAlphaType, nullptr, tex->width(), tex->height());
	ComparePixels(srcInfo, srcData.get(), srcRowBytes, dstInfo, dstBuffer.get(), dstRowBytes,
	compareTolerances, error);

	//////////////////////////
	// transfer partial data

	// We're relying on this cap to write partial texture data
	if (!caps->writePixelsRowBytesSupport()) {
	return;
	}
	// We keep a 1 to 1 correspondence between pixels in the buffer and the entire texture. We
	// update the contents of a sub-rect of the buffer and push that rect to the texture. We start
	// with a left sub-rect inset of 2 but may adjust that so we can fulfill the transfer buffer
	// offset alignment requirement.
	int left = 2;
	const int top = 10;
	const int width = 10;
	const int height = 2;
	size_t offset = top * srcRowBytes + left * GrColorTypeBytesPerPixel(allowedSrc.fColorType);
	while (offset % allowedSrc.fOffsetAlignmentForTransferBuffer) {
	offset += GrColorTypeBytesPerPixel(allowedSrc.fColorType);
	++left;
	// We're assuming that the required alignment is 1 or a small multiple of the bpp, which
	// it is currently for all color types across all backends.
	SkASSERT(left + width <= tex->width());
	}

	// change color of subrectangle
	fill_transfer_data(left, top, width, height, srcBufferWidth, allowedSrc.fColorType,
	srcData.get());
	data = buffer->map();
	memcpy(data, srcData.get(), size);
	buffer->unmap();

	result = gpu->transferPixelsTo(tex.get(), left, top, width, height, colorType,
	allowedSrc.fColorType, buffer.get(), offset, srcRowBytes);
	if (!result) {
	gpu->transferPixelsTo(tex.get(), left, top, width, height, colorType, allowedSrc.fColorType,
	buffer.get(), offset, srcRowBytes);
	ERRORF(reporter, "Could not transfer pixels to texture, color type: %d",
	static_cast<int>(colorType));
	return;
	}

	result = read_pixels_from_texture(tex.get(), colorType, dstBuffer.get(), compareTolerances);
	if (!result) {
	ERRORF(reporter, "Could not read pixels from texture, color type: %d",
	static_cast<int>(colorType));
	return;
	}
	ComparePixels(srcInfo, srcData.get(), srcRowBytes, dstInfo, dstBuffer.get(), dstRowBytes,
	compareTolerances, error);
	}

	void basic_transfer_from_test(skiatest::Reporter* reporter, const sk_gpu_test::ContextInfo& ctxInfo,
	GrColorType colorType, GrRenderable renderable) {
	auto context = ctxInfo.grContext();
	auto caps = context->priv().caps();
	if (GrCaps::kNone_MapFlags == caps->mapBufferFlags()) {
	return;
	}

	auto resourceProvider = context->priv().resourceProvider();
	GrGpu* gpu = context->priv().getGpu();

	const int kTextureWidth = 16;
	const int kTextureHeight = 16;

	// We'll do a full texture read into the buffer followed by a partial read. These values
	// describe the partial read subrect.
	const int kPartialLeft = 2;
	const int kPartialTop = 10;
	const int kPartialWidth = 10;
	const int kPartialHeight = 2;

	// create texture
	GrSurfaceDesc desc;
	desc.fWidth = kTextureWidth;
	desc.fHeight = kTextureHeight;
	desc.fConfig = GrColorTypeToPixelConfig(colorType);

	auto format = context->priv().caps()->getDefaultBackendFormat(colorType, renderable);
	if (!format.isValid()) {
	return;
	}

	size_t textureDataBpp = GrColorTypeBytesPerPixel(colorType);
	size_t textureDataRowBytes = kTextureWidth * textureDataBpp;
	std::unique_ptr<char[]> textureData(new char[kTextureHeight * textureDataRowBytes]);
	fill_transfer_data(0, 0, kTextureWidth, kTextureHeight, kTextureWidth, colorType,
	textureData.get());
	GrMipLevel data;
	data.fPixels = textureData.get();
	data.fRowBytes = textureDataRowBytes;
	sk_sp<GrTexture> tex = resourceProvider->createTexture(
	desc, format, colorType, renderable, 1, SkBudgeted::kNo, GrProtected::kNo, &data, 1);
	if (!tex) {
	return;
	}

	if (GrCaps::SurfaceReadPixelsSupport::kSupported !=
	caps->surfaceSupportsReadPixels(tex.get())) {
	return;
	}
	// GL requires a texture to be framebuffer bindable to call glReadPixels. However, we have not
	// incorporated that test into surfaceSupportsReadPixels(). TODO: Remove this once we handle
	// drawing to a bindable format.
	if (!caps->isFormatAsColorTypeRenderable(colorType, tex->backendFormat())) {
	return;
	}

	// Create the transfer buffer.
	auto allowedRead =
	caps->supportedReadPixelsColorType(colorType, tex->backendFormat(), colorType);
	GrImageInfo readInfo(allowedRead.fColorType, kUnpremul_SkAlphaType, nullptr, kTextureWidth,
	kTextureHeight);

	size_t bpp = GrColorTypeBytesPerPixel(allowedRead.fColorType);
	size_t fullBufferRowBytes = kTextureWidth * bpp;
	size_t partialBufferRowBytes = kPartialWidth * bpp;
	size_t offsetAlignment = allowedRead.fOffsetAlignmentForTransferBuffer;
	SkASSERT(offsetAlignment);

	size_t bufferSize = fullBufferRowBytes * kTextureHeight;
	// Arbitrary starting offset for the partial read.
	size_t partialReadOffset = GrSizeAlignUp(11, offsetAlignment);
	bufferSize = SkTMax(bufferSize, partialReadOffset + partialBufferRowBytes * kPartialHeight);

	sk_sp<GrGpuBuffer> buffer(resourceProvider->createBuffer(
	bufferSize, GrGpuBufferType::kXferGpuToCpu, kDynamic_GrAccessPattern));
	REPORTER_ASSERT(reporter, buffer);
	if (!buffer) {
	return;
	}

	int expectedTransferCnt = 0;
	gpu->stats()->reset();

	//////////////////////////
	// transfer full data
	bool result = gpu->transferPixelsFrom(tex.get(), 0, 0, kTextureWidth, kTextureHeight, colorType,
	allowedRead.fColorType, buffer.get(), 0);
	if (!result) {
	ERRORF(reporter, "transferPixelsFrom failed.");
	return;
	}
	++expectedTransferCnt;

	GrFlushInfo flushInfo;
	flushInfo.fFlags = kSyncCpu_GrFlushFlag;
	if (context->priv().caps()->mapBufferFlags() & GrCaps::kAsyncRead_MapFlag) {
	gpu->finishFlush(nullptr, 0, SkSurface::BackendSurfaceAccess::kNoAccess, flushInfo,
	GrPrepareForExternalIORequests());
	}

	// Copy the transfer buffer contents to a temporary so we can manipulate it.
	const auto* map = reinterpret_cast<const char*>(buffer->map());
	REPORTER_ASSERT(reporter, map);
	if (!map) {
	ERRORF(reporter, "Failed to map transfer buffer.");
	return;
	}
	std::unique_ptr<char[]> transferData(new char[kTextureHeight * fullBufferRowBytes]);
	memcpy(transferData.get(), map, fullBufferRowBytes * kTextureHeight);
	buffer->unmap();

	GrImageInfo transferInfo(allowedRead.fColorType, kUnpremul_SkAlphaType, nullptr, kTextureWidth,
	kTextureHeight);

	float tol[4];
	determine_tolerances(allowedRead.fColorType, colorType, tol);
	auto error = std::function<ComparePixmapsErrorReporter>(
	[reporter, colorType](int x, int y, const float diffs[4]) {
	ERRORF(reporter,
	"Error at (%d %d) in transfer, color type: %d, diffs: (%f, %f, %f, %f)", x,
	y, colorType, diffs[0], diffs[1], diffs[2], diffs[3]);
	});
	GrImageInfo textureDataInfo(colorType, kUnpremul_SkAlphaType, nullptr, kTextureWidth,
	kTextureHeight);
	ComparePixels(textureDataInfo, textureData.get(), textureDataRowBytes, transferInfo,
	transferData.get(), fullBufferRowBytes, tol, error);

	///////////////////////
	// Now test a partial read at an offset into the buffer.
	result = gpu->transferPixelsFrom(tex.get(), kPartialLeft, kPartialTop, kPartialWidth,
	kPartialHeight, colorType, allowedRead.fColorType,
	buffer.get(), partialReadOffset);
	if (!result) {
	ERRORF(reporter, "transferPixelsFrom failed.");
	return;
	}
	++expectedTransferCnt;

	if (context->priv().caps()->mapBufferFlags() & GrCaps::kAsyncRead_MapFlag) {
	gpu->finishFlush(nullptr, 0, SkSurface::BackendSurfaceAccess::kNoAccess, flushInfo,
	GrPrepareForExternalIORequests());
	}

	map = reinterpret_cast<const char*>(buffer->map());
	REPORTER_ASSERT(reporter, map);
	if (!map) {
	ERRORF(reporter, "Failed to map transfer buffer.");
	return;
	}
	const char* bufferStart = reinterpret_cast<const char*>(map) + partialReadOffset;
	memcpy(transferData.get(), bufferStart, partialBufferRowBytes * kTextureHeight);
	buffer->unmap();

	transferInfo = transferInfo.makeWH(kPartialWidth, kPartialHeight);
	const char* textureDataStart =
	textureData.get() + textureDataRowBytes * kPartialTop + textureDataBpp * kPartialLeft;
	textureDataInfo = textureDataInfo.makeWH(kPartialWidth, kPartialHeight);
	ComparePixels(textureDataInfo, textureDataStart, textureDataRowBytes, transferInfo,
	transferData.get(), partialBufferRowBytes, tol, error);
	#if GR_GPU_STATS
	REPORTER_ASSERT(reporter, gpu->stats()->transfersFromSurface() == expectedTransferCnt);
	#else
	(void)expectedTransferCnt;
	#endif
	}

	DEF_GPUTEST_FOR_RENDERING_CONTEXTS(TransferPixelsToTest, reporter, ctxInfo) {
	if (!ctxInfo.grContext()->priv().caps()->transferBufferSupport()) {
	return;
	}
	for (auto renderable : {GrRenderable::kNo, GrRenderable::kYes}) {
	for (auto colorType : {
	GrColorType::kAlpha_8,
	GrColorType::kBGR_565,
	GrColorType::kABGR_4444,
	GrColorType::kRGBA_8888,
	GrColorType::kRGBA_8888_SRGB,
	// GrColorType::kRGB_888x, Broken in GL until we have kRGB_888
	GrColorType::kRG_88,
	GrColorType::kBGRA_8888,
	GrColorType::kRGBA_1010102,
	GrColorType::kGray_8,
	GrColorType::kAlpha_F16,
	GrColorType::kRGBA_F16,
	GrColorType::kRGBA_F16_Clamped,
	GrColorType::kRGBA_F32,
	GrColorType::kAlpha_16,
	GrColorType::kRG_1616,
	GrColorType::kRGBA_16161616,
	GrColorType::kRG_F16,
	}) {
	basic_transfer_to_test(reporter, ctxInfo.grContext(), colorType, renderable);
	}
	}
	}

	// TODO(bsalomon): Metal
	DEF_GPUTEST_FOR_RENDERING_CONTEXTS(TransferPixelsFromTest, reporter, ctxInfo) {
	if (!ctxInfo.grContext()->priv().caps()->transferBufferSupport()) {
	return;
	}
	for (auto renderable : {GrRenderable::kNo, GrRenderable::kYes}) {
	for (auto colorType : {
	GrColorType::kAlpha_8,
	GrColorType::kAlpha_16,
	GrColorType::kBGR_565,
	GrColorType::kABGR_4444,
	GrColorType::kRGBA_8888,
	GrColorType::kRGBA_8888_SRGB,
	// GrColorType::kRGB_888x, Broken in GL until we have kRGB_888
	GrColorType::kRG_88,
	GrColorType::kBGRA_8888,
	GrColorType::kRGBA_1010102,
	GrColorType::kGray_8,
	GrColorType::kAlpha_F16,
	GrColorType::kRGBA_F16,
	GrColorType::kRGBA_F16_Clamped,
	GrColorType::kRGBA_F32,
	GrColorType::kRG_1616,
	GrColorType::kRGBA_16161616,
	GrColorType::kRG_F16,
	}) {
	basic_transfer_from_test(reporter, ctxInfo, colorType, renderable);
	}
	}
	}