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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this file,
#include "WebGLContext.h"
#include "WebGLTexelConversions.h"
namespace mozilla {
using namespace WebGLTexelConversions;
namespace {
/** @class WebGLImageConverter
*
* This class is just a helper to implement WebGLContext::ConvertImage below.
*
* Design comments:
*
* WebGLContext::ConvertImage has to handle hundreds of format conversion paths.
* It is important to minimize executable code size here. Instead of passing
* around a large number of function parameters hundreds of times, we create a
* WebGLImageConverter object once, storing these parameters, and then we call
* the run() method on it.
*/
class WebGLImageConverter {
const size_t mWidth, mHeight;
const void* const mSrcStart;
void* const mDstStart;
const ptrdiff_t mSrcStride, mDstStride;
bool mAlreadyRun;
bool mSuccess;
/*
* Returns sizeof(texel)/sizeof(type). The point is that we will iterate over
* texels with typed pointers and this value will tell us by how much we need
* to increment these pointers to advance to the next texel.
*/
template <WebGLTexelFormat Format>
static size_t NumElementsPerTexelForFormat() {
switch (Format) {
case WebGLTexelFormat::A8:
case WebGLTexelFormat::A16F:
case WebGLTexelFormat::A32F:
case WebGLTexelFormat::R8:
case WebGLTexelFormat::R16F:
case WebGLTexelFormat::R32F:
case WebGLTexelFormat::RGB565:
case WebGLTexelFormat::RGB11F11F10F:
case WebGLTexelFormat::RGBA4444:
case WebGLTexelFormat::RGBA5551:
return 1;
case WebGLTexelFormat::RA8:
case WebGLTexelFormat::RA16F:
case WebGLTexelFormat::RA32F:
case WebGLTexelFormat::RG8:
case WebGLTexelFormat::RG16F:
case WebGLTexelFormat::RG32F:
return 2;
case WebGLTexelFormat::RGB8:
case WebGLTexelFormat::RGB16F:
case WebGLTexelFormat::RGB32F:
return 3;
case WebGLTexelFormat::RGBA8:
case WebGLTexelFormat::RGBA16F:
case WebGLTexelFormat::RGBA32F:
case WebGLTexelFormat::BGRX8:
case WebGLTexelFormat::BGRA8:
return 4;
default:
MOZ_ASSERT(false, "Unknown texel format. Coding mistake?");
return 0;
}
}
/*
* This is the completely format-specific templatized conversion function,
* that will be instantiated hundreds of times for all different combinations.
* It is important to avoid generating useless code here. In particular, many
* instantiations of this function template will never be called, so we try
* to return immediately in these cases to allow the compiler to avoid
* generating useless code.
*/
template <WebGLTexelFormat SrcFormat, WebGLTexelFormat DstFormat,
WebGLTexelPremultiplicationOp PremultiplicationOp>
void run() {
// check for never-called cases. We early-return to allow the compiler
// to avoid generating this code. It would be tempting to abort() instead,
// as returning early does leave the destination surface with uninitialized
// data, but that would not allow the compiler to avoid generating this
// code. So instead, we return early, so Success() will return false, and
// the caller must check that and abort in that case. See
// WebGLContext::ConvertImage.
if (SrcFormat == DstFormat &&
PremultiplicationOp == WebGLTexelPremultiplicationOp::None) {
// Should have used a fast exit path earlier, rather than entering this
// function. we explicitly return here to allow the compiler to avoid
// generating this code
return;
}
// Only textures uploaded from DOM elements or ImageData can allow DstFormat
// != SrcFormat. DOM elements can only give BGRA8, BGRX8, A8, RGB565
// formats. See DOMElementToImageSurface. ImageData is always RGBA8. So all
// other SrcFormat will always satisfy DstFormat==SrcFormat, so we can avoid
// compiling the code for all the unreachable paths.
const bool CanSrcFormatComeFromDOMElementOrImageData =
SrcFormat == WebGLTexelFormat::BGRA8 ||
SrcFormat == WebGLTexelFormat::BGRX8 ||
SrcFormat == WebGLTexelFormat::A8 ||
SrcFormat == WebGLTexelFormat::RGB565 ||
SrcFormat == WebGLTexelFormat::RGBA8;
if (!CanSrcFormatComeFromDOMElementOrImageData && SrcFormat != DstFormat) {
return;
}
// Likewise, only textures uploaded from DOM elements or ImageData can
// possibly have to be unpremultiplied.
if (!CanSrcFormatComeFromDOMElementOrImageData &&
PremultiplicationOp == WebGLTexelPremultiplicationOp::Unpremultiply) {
return;
}
// there is no point in premultiplication/unpremultiplication
// in the following cases:
// - the source format has no alpha
// - the source format has no color
// - the destination format has no color
if (!HasAlpha(SrcFormat) || !HasColor(SrcFormat) || !HasColor(DstFormat)) {
if (PremultiplicationOp != WebGLTexelPremultiplicationOp::None) {
return;
}
}
// end of early return cases.
MOZ_ASSERT(!mAlreadyRun, "converter should be run only once!");
mAlreadyRun = true;
// gather some compile-time meta-data about the formats at hand.
using SrcType = typename DataTypeForFormat<SrcFormat>::Type;
using DstType = typename DataTypeForFormat<DstFormat>::Type;
const WebGLTexelFormat IntermediateSrcFormat =
IntermediateFormat<SrcFormat>::Value;
const WebGLTexelFormat IntermediateDstFormat =
IntermediateFormat<DstFormat>::Value;
using IntermediateSrcType =
typename DataTypeForFormat<IntermediateSrcFormat>::Type;
using IntermediateDstType =
typename DataTypeForFormat<IntermediateDstFormat>::Type;
const size_t NumElementsPerSrcTexel =
NumElementsPerTexelForFormat<SrcFormat>();
const size_t NumElementsPerDstTexel =
NumElementsPerTexelForFormat<DstFormat>();
const size_t MaxElementsPerTexel = 4;
MOZ_ASSERT(NumElementsPerSrcTexel <= MaxElementsPerTexel,
"unhandled format");
MOZ_ASSERT(NumElementsPerDstTexel <= MaxElementsPerTexel,
"unhandled format");
// we assume that the strides are multiples of the sizeof of respective
// types. this assumption will allow us to iterate over src and dst images
// using typed pointers, e.g. uint8_t* or uint16_t* or float*, instead of
// untyped pointers. So this assumption allows us to write cleaner and safer
// code, but it might not be true forever and if it eventually becomes
// wrong, we'll have to revert to always iterating using uint8_t* pointers
// regardless of the types at hand.
MOZ_ASSERT(
mSrcStride % sizeof(SrcType) == 0 && mDstStride % sizeof(DstType) == 0,
"Unsupported: texture stride is not a multiple of sizeof(type)");
const ptrdiff_t srcStrideInElements =
mSrcStride / static_cast<ptrdiff_t>(sizeof(SrcType));
const ptrdiff_t dstStrideInElements =
mDstStride / static_cast<ptrdiff_t>(sizeof(DstType));
// Pop quiz: What's `ptrdiff_t(-16) / sizeof(int32_t)`?
// Did you guess +4611686018427387900?
MOZ_ASSERT(bool(srcStrideInElements < 0) == bool(mSrcStride < 0));
MOZ_ASSERT(bool(dstStrideInElements < 0) == bool(mDstStride < 0));
const SrcType* srcRowStart = static_cast<const SrcType*>(mSrcStart);
DstType* dstRowStart = static_cast<DstType*>(mDstStart);
// the loop performing the texture format conversion
for (size_t i = 0; i < mHeight; ++i) {
const SrcType* srcRowEnd = srcRowStart + mWidth * NumElementsPerSrcTexel;
const SrcType* srcPtr = srcRowStart;
DstType* dstPtr = dstRowStart;
while (srcPtr != srcRowEnd) {
// convert a single texel. We proceed in 3 steps: unpack the source
// texel so the corresponding interchange format (e.g. unpack RGB565 to
// RGBA8), convert the resulting data type to the destination type (e.g.
// convert from RGBA8 to RGBA32F), and finally pack the destination
// texel (e.g. pack RGBA32F to RGB32F).
IntermediateSrcType unpackedSrc[MaxElementsPerTexel];
IntermediateDstType unpackedDst[MaxElementsPerTexel];
// unpack a src texel to corresponding intermediate src format.
// for example, unpack RGB565 to RGBA8
unpack<SrcFormat>(srcPtr, unpackedSrc);
// convert the data type to the destination type, if needed.
// for example, convert RGBA8 to RGBA32F
convertType(unpackedSrc, unpackedDst);
// pack the destination texel.
// for example, pack RGBA32F to RGB32F
pack<DstFormat, PremultiplicationOp>(unpackedDst, dstPtr);
srcPtr += NumElementsPerSrcTexel;
dstPtr += NumElementsPerDstTexel;
}
srcRowStart += srcStrideInElements;
dstRowStart += dstStrideInElements;
}
mSuccess = true;
}
template <WebGLTexelFormat SrcFormat, WebGLTexelFormat DstFormat>
void run(WebGLTexelPremultiplicationOp premultiplicationOp) {
#define WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP(PremultiplicationOp) \
case PremultiplicationOp: \
return run<SrcFormat, DstFormat, PremultiplicationOp>();
switch (premultiplicationOp) {
WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP(
WebGLTexelPremultiplicationOp::None)
WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP(
WebGLTexelPremultiplicationOp::Premultiply)
WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP(
WebGLTexelPremultiplicationOp::Unpremultiply)
default:
MOZ_ASSERT(false, "unhandled case. Coding mistake?");
}
#undef WEBGLIMAGECONVERTER_CASE_PREMULTIPLICATIONOP
}
template <WebGLTexelFormat SrcFormat>
void run(WebGLTexelFormat dstFormat,
WebGLTexelPremultiplicationOp premultiplicationOp) {
#define WEBGLIMAGECONVERTER_CASE_DSTFORMAT(DstFormat) \
case DstFormat: \
return run<SrcFormat, DstFormat>(premultiplicationOp);
switch (dstFormat) {
// 1-channel formats
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A32F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R32F)
// 2-channel formats
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA32F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RG8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RG16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RG32F)
// 3-channel formats
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB565)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB11F11F10F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB32F)
// 4-channel formats
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA4444)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA5551)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA32F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::BGRA8)
default:
MOZ_ASSERT(false, "unhandled case. Coding mistake?");
}
#undef WEBGLIMAGECONVERTER_CASE_DSTFORMAT
}
public:
void run(WebGLTexelFormat srcFormat, WebGLTexelFormat dstFormat,
WebGLTexelPremultiplicationOp premultiplicationOp) {
#define WEBGLIMAGECONVERTER_CASE_SRCFORMAT(SrcFormat) \
case SrcFormat: \
return run<SrcFormat>(dstFormat, premultiplicationOp);
switch (srcFormat) {
// 1-channel formats
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A32F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R32F)
// 2-channel formats
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA32F)
// 3-channel formats
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB565)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB32F)
// 4-channel formats
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA4444)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA5551)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA32F)
// DOM element source formats
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::BGRX8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::BGRA8)
default:
MOZ_ASSERT(false, "unhandled case. Coding mistake?");
}
#undef WEBGLIMAGECONVERTER_CASE_SRCFORMAT
}
WebGLImageConverter(size_t width, size_t height, const void* srcStart,
void* dstStart, ptrdiff_t srcStride, ptrdiff_t dstStride)
: mWidth(width),
mHeight(height),
mSrcStart(srcStart),
mDstStart(dstStart),
mSrcStride(srcStride),
mDstStride(dstStride),
mAlreadyRun(false),
mSuccess(false) {}
bool Success() const { return mSuccess; }
};
} // end anonymous namespace
bool ConvertImage(size_t width, size_t height, const void* srcBegin,
size_t srcStride, gl::OriginPos srcOrigin,
WebGLTexelFormat srcFormat, bool srcPremultiplied,
void* dstBegin, size_t dstStride, gl::OriginPos dstOrigin,
WebGLTexelFormat dstFormat, bool dstPremultiplied,
bool* const out_wasTrivial) {
*out_wasTrivial = true;
if (srcFormat == WebGLTexelFormat::FormatNotSupportingAnyConversion ||
dstFormat == WebGLTexelFormat::FormatNotSupportingAnyConversion) {
return false;
}
if (!width || !height) return true;
const bool shouldYFlip = (srcOrigin != dstOrigin);
const bool canSkipPremult =
(!HasAlpha(srcFormat) || !HasColor(srcFormat) || !HasColor(dstFormat));
WebGLTexelPremultiplicationOp premultOp;
if (canSkipPremult) {
premultOp = WebGLTexelPremultiplicationOp::None;
} else if (!srcPremultiplied && dstPremultiplied) {
premultOp = WebGLTexelPremultiplicationOp::Premultiply;
} else if (srcPremultiplied && !dstPremultiplied) {
premultOp = WebGLTexelPremultiplicationOp::Unpremultiply;
} else {
premultOp = WebGLTexelPremultiplicationOp::None;
}
const uint8_t* srcItr = (const uint8_t*)srcBegin;
const uint8_t* const srcEnd = srcItr + srcStride * height;
uint8_t* dstItr = (uint8_t*)dstBegin;
ptrdiff_t dstItrStride = dstStride;
if (shouldYFlip) {
dstItr = dstItr + dstStride * (height - 1);
dstItrStride = -dstItrStride;
}
if (srcFormat == dstFormat &&
premultOp == WebGLTexelPremultiplicationOp::None) {
// Fast exit path: we just have to memcpy all the rows.
const auto bytesPerPixel = TexelBytesForFormat(srcFormat);
const size_t bytesPerRow = bytesPerPixel * width;
while (srcItr != srcEnd) {
memcpy(dstItr, srcItr, bytesPerRow);
srcItr += srcStride;
dstItr += dstItrStride;
}
return true;
}
*out_wasTrivial = false;
WebGLImageConverter converter(width, height, srcItr, dstItr, srcStride,
dstItrStride);
converter.run(srcFormat, dstFormat, premultOp);
if (!converter.Success()) {
// the dst image may be left uninitialized, so we better not try to
// continue even in release builds. This should never happen anyway,
// and would be a bug in our code.
MOZ_CRASH("programming mistake in WebGL texture conversions");
}
return true;
}
} // end namespace mozilla