gecko-dev/image/decoders/nsIconDecoder.cpp
Andrew Osmond fa360dba1b Bug 1901076 - Part 2. Expose frame count variant of metadata decoders. r=tnikkel
It is useful/necessary for WebCodecs image decoding support to be able
to calculate a frame count for the encoded image without actually
decoding every frame. It needs to be able to provide results without the
complete buffer as well.

Differential Revision: https://phabricator.services.mozilla.com/D212831
2024-06-24 22:44:30 +00:00

136 lines
4.3 KiB
C++

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 "nsIconDecoder.h"
#include "RasterImage.h"
#include "SurfacePipeFactory.h"
#include "gfxPlatform.h"
using namespace mozilla::gfx;
namespace mozilla {
namespace image {
static const uint32_t ICON_HEADER_SIZE = 4;
nsIconDecoder::nsIconDecoder(RasterImage* aImage)
: Decoder(aImage),
mLexer(Transition::To(State::HEADER, ICON_HEADER_SIZE),
Transition::TerminateSuccess()),
mBytesPerRow() // set by ReadHeader()
{
// Nothing to do
}
nsIconDecoder::~nsIconDecoder() {}
LexerResult nsIconDecoder::DoDecode(SourceBufferIterator& aIterator,
IResumable* aOnResume) {
MOZ_ASSERT(!HasError(), "Shouldn't call DoDecode after error!");
return mLexer.Lex(aIterator, aOnResume,
[=](State aState, const char* aData, size_t aLength) {
switch (aState) {
case State::HEADER:
return ReadHeader(aData);
case State::ROW_OF_PIXELS:
return ReadRowOfPixels(aData, aLength);
case State::FINISH:
return Finish();
default:
MOZ_CRASH("Unknown State");
}
});
}
LexerTransition<nsIconDecoder::State> nsIconDecoder::ReadHeader(
const char* aData) {
// Grab the width and height.
uint8_t width = uint8_t(aData[0]);
uint8_t height = uint8_t(aData[1]);
SurfaceFormat format = SurfaceFormat(aData[2]);
bool transform = bool(aData[3]);
if (format != SurfaceFormat::B8G8R8A8 && format != SurfaceFormat::B8G8R8X8 &&
format != SurfaceFormat::R8G8B8A8 && format != SurfaceFormat::R8G8B8X8 &&
format != SurfaceFormat::A8R8G8B8 && format != SurfaceFormat::X8R8G8B8) {
return Transition::TerminateFailure();
}
// FIXME(aosmond): On OSX we get the icon in device space and already
// premultiplied, so we can't support the surface flags with icons right now.
SurfacePipeFlags pipeFlags = SurfacePipeFlags();
if (transform) {
if (mCMSMode == CMSMode::All) {
mTransform = GetCMSsRGBTransform(format);
}
if (!(GetSurfaceFlags() & SurfaceFlags::NO_PREMULTIPLY_ALPHA)) {
pipeFlags |= SurfacePipeFlags::PREMULTIPLY_ALPHA;
}
}
// The input is 32bpp, so we expect 4 bytes of data per pixel.
mBytesPerRow = width * 4;
// Post our size to the superclass.
PostSize(width, height);
if (WantsFrameCount()) {
PostFrameCount(/* aFrameCount */ 1);
}
// Icons have alpha.
PostHasTransparency();
// If we're doing a metadata decode, we're done.
if (IsMetadataDecode()) {
return Transition::TerminateSuccess();
}
MOZ_ASSERT(!mImageData, "Already have a buffer allocated?");
Maybe<SurfacePipe> pipe = SurfacePipeFactory::CreateSurfacePipe(
this, Size(), OutputSize(), FullFrame(), format, SurfaceFormat::OS_RGBA,
/* aAnimParams */ Nothing(), mTransform, pipeFlags);
if (!pipe) {
return Transition::TerminateFailure();
}
mPipe = std::move(*pipe);
MOZ_ASSERT(mImageData, "Should have a buffer now");
return Transition::To(State::ROW_OF_PIXELS, mBytesPerRow);
}
LexerTransition<nsIconDecoder::State> nsIconDecoder::ReadRowOfPixels(
const char* aData, size_t aLength) {
MOZ_ASSERT(aLength % 4 == 0, "Rows should contain a multiple of four bytes");
auto result = mPipe.WriteBuffer(reinterpret_cast<const uint32_t*>(aData));
MOZ_ASSERT(result != WriteState::FAILURE);
Maybe<SurfaceInvalidRect> invalidRect = mPipe.TakeInvalidRect();
if (invalidRect) {
PostInvalidation(invalidRect->mInputSpaceRect,
Some(invalidRect->mOutputSpaceRect));
}
return result == WriteState::FINISHED
? Transition::To(State::FINISH, 0)
: Transition::To(State::ROW_OF_PIXELS, mBytesPerRow);
}
LexerTransition<nsIconDecoder::State> nsIconDecoder::Finish() {
PostFrameStop();
PostDecodeDone();
return Transition::TerminateSuccess();
}
} // namespace image
} // namespace mozilla