gecko-dev/dom/canvas/WebGLTexelConversions.cpp

408 lines
18 KiB
C++

/* 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,
* You can obtain one at http://mozilla.org/MPL/2.0/. */
#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<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) Format>
static size_t NumElementsPerTexelForFormat() {
switch (Format) {
case WebGLTexelFormat::R8:
case WebGLTexelFormat::A8:
case WebGLTexelFormat::R16F:
case WebGLTexelFormat::A16F:
case WebGLTexelFormat::R32F:
case WebGLTexelFormat::A32F:
case WebGLTexelFormat::RGBA5551:
case WebGLTexelFormat::RGBA4444:
case WebGLTexelFormat::RGB565:
return 1;
case WebGLTexelFormat::RA8:
case WebGLTexelFormat::RA16F:
case WebGLTexelFormat::RA32F:
return 2;
case WebGLTexelFormat::RGB8:
case WebGLTexelFormat::RGB16F:
case WebGLTexelFormat::RGB32F:
return 3;
case WebGLTexelFormat::RGBA8:
case WebGLTexelFormat::BGRA8:
case WebGLTexelFormat::BGRX8:
case WebGLTexelFormat::RGBA16F:
case WebGLTexelFormat::RGBA32F:
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<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) SrcFormat,
MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) DstFormat,
MOZ_ENUM_CLASS_ENUM_TYPE(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.
typedef
typename DataTypeForFormat<SrcFormat>::Type
SrcType;
typedef
typename DataTypeForFormat<DstFormat>::Type
DstType;
const MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) IntermediateSrcFormat
= IntermediateFormat<SrcFormat>::Value;
const MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) IntermediateDstFormat
= IntermediateFormat<DstFormat>::Value;
typedef
typename DataTypeForFormat<IntermediateSrcFormat>::Type
IntermediateSrcType;
typedef
typename DataTypeForFormat<IntermediateDstFormat>::Type
IntermediateDstType;
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 / sizeof(SrcType);
const ptrdiff_t dstStrideInElements = mDstStride / sizeof(DstType);
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;
return;
}
template<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) SrcFormat,
MOZ_ENUM_CLASS_ENUM_TYPE(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<MOZ_ENUM_CLASS_ENUM_TYPE(WebGLTexelFormat) SrcFormat>
void run(WebGLTexelFormat dstFormat,
WebGLTexelPremultiplicationOp premultiplicationOp)
{
#define WEBGLIMAGECONVERTER_CASE_DSTFORMAT(DstFormat) \
case DstFormat: \
return run<SrcFormat, DstFormat>(premultiplicationOp);
switch (dstFormat) {
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::R32F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::A32F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RA32F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB565)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGB32F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA8)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA5551)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA4444)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA16F)
WEBGLIMAGECONVERTER_CASE_DSTFORMAT(WebGLTexelFormat::RGBA32F)
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) {
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::R32F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::A32F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RA32F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::BGRX8) // source format only
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB565)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGB32F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::BGRA8)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA5551)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA4444)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA16F)
WEBGLIMAGECONVERTER_CASE_SRCFORMAT(WebGLTexelFormat::RGBA32F)
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
WebGLContext::ConvertImage(size_t width, size_t height, size_t srcStride, size_t dstStride,
const uint8_t* src, uint8_t *dst,
WebGLTexelFormat srcFormat, bool srcPremultiplied,
WebGLTexelFormat dstFormat, bool dstPremultiplied,
size_t dstTexelSize)
{
if (width <= 0 || height <= 0)
return true;
const bool FormatsRequireNoPremultiplicationOp =
!HasAlpha(srcFormat) ||
!HasColor(srcFormat) ||
!HasColor(dstFormat);
if (srcFormat == dstFormat &&
(FormatsRequireNoPremultiplicationOp || srcPremultiplied == dstPremultiplied))
{
// fast exit path: we just have to memcpy all the rows.
//
// The case where absolutely nothing needs to be done is supposed to have
// been handled earlier (in TexImage2D_base, etc).
//
// So the case we're handling here is when even though no format conversion is needed,
// we still might have to flip vertically and/or to adjust to a different stride.
MOZ_ASSERT(mPixelStoreFlipY || srcStride != dstStride, "Performance trap -- should handle this case earlier, to avoid memcpy");
size_t row_size = width * dstTexelSize; // doesn't matter, src and dst formats agree
const uint8_t* ptr = src;
const uint8_t* src_end = src + height * srcStride;
uint8_t* dst_row = mPixelStoreFlipY
? dst + (height-1) * dstStride
: dst;
ptrdiff_t dstStrideSigned(dstStride);
ptrdiff_t dst_delta = mPixelStoreFlipY ? -dstStrideSigned : dstStrideSigned;
while(ptr != src_end) {
memcpy(dst_row, ptr, row_size);
ptr += srcStride;
dst_row += dst_delta;
}
return true;
}
if (srcFormat == WebGLTexelFormat::FormatNotSupportingAnyConversion ||
dstFormat == WebGLTexelFormat::FormatNotSupportingAnyConversion)
{
return false;
}
uint8_t* dstStart = dst;
ptrdiff_t signedDstStride = dstStride;
if (mPixelStoreFlipY) {
dstStart = dst + (height - 1) * dstStride;
signedDstStride = -signedDstStride;
}
WebGLImageConverter converter(width, height, src, dstStart, srcStride, signedDstStride);
const WebGLTexelPremultiplicationOp premultiplicationOp
= FormatsRequireNoPremultiplicationOp ? WebGLTexelPremultiplicationOp::None
: (!srcPremultiplied && dstPremultiplied) ? WebGLTexelPremultiplicationOp::Premultiply
: (srcPremultiplied && !dstPremultiplied) ? WebGLTexelPremultiplicationOp::Unpremultiply
: WebGLTexelPremultiplicationOp::None;
converter.run(srcFormat, dstFormat, premultiplicationOp);
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.
NS_RUNTIMEABORT("programming mistake in WebGL texture conversions");
}
return true;
}
} // end namespace mozilla