ladybird/Libraries/LibGfx/ImageFormats/WebPLoader.cpp

/*
 * Copyright (c) 2023, Nico Weber <thakis@chromium.org>
 * Copyright (c) 2024, doctortheemh <doctortheemh@gmail.com>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Error.h>
#include <LibGfx/ImageFormats/WebPLoader.h>

#include <webp/decode.h>
#include <webp/demux.h>
#include <webp/mux.h>

namespace Gfx {

struct WebPLoadingContext {
    enum State {
        NotDecoded = 0,
        Error,
        HeaderDecoded,
        BitmapDecoded,
    };

    State state { State::NotDecoded };
    ReadonlyBytes data;

    // Image properties
    IntSize size;
    bool has_alpha;
    bool has_animation;
    size_t frame_count;
    size_t loop_count;
    ByteBuffer icc_data;
    Vector<int> frame_durations;

    Vector<ImageFrameDescriptor> frame_descriptors;

    // Incremental animation decoder state.
    WebPAnimDecoder* anim_decoder { nullptr };
    int anim_old_timestamp { 0 };
    size_t anim_frames_decoded { 0 };

    ~WebPLoadingContext()
    {
        if (anim_decoder)
            WebPAnimDecoderDelete(anim_decoder);
    }
};

WebPImageDecoderPlugin::WebPImageDecoderPlugin(ReadonlyBytes data, OwnPtr<WebPLoadingContext> context)
    : m_context(move(context))
{
    m_context->data = data;
}

WebPImageDecoderPlugin::~WebPImageDecoderPlugin() = default;

IntSize WebPImageDecoderPlugin::size()
{
    return m_context->size;
}

static ErrorOr<void> decode_webp_header(WebPLoadingContext& context)
{
    if (context.state >= WebPLoadingContext::HeaderDecoded)
        return {};

    int width = 0;
    int height = 0;
    int getinfo_result = WebPGetInfo(context.data.data(), context.data.size(), &width, &height);
    if (getinfo_result != 1)
        return Error::from_string_literal("Failed to decode webp image data");

    WebPBitstreamFeatures webp_bitstream_features {};
    VP8StatusCode vp8_result = WebPGetFeatures(context.data.data(), context.data.size(), &webp_bitstream_features);
    if (vp8_result != VP8_STATUS_OK)
        return Error::from_string_literal("Failed to get WebP bitstream features");

    // Image header now decoded, save some results for fast access in other parts of the plugin.
    context.size = IntSize { width, height };
    context.has_animation = webp_bitstream_features.has_animation;
    context.has_alpha = webp_bitstream_features.has_alpha;
    context.frame_count = 1;
    context.loop_count = 0;

    if (webp_bitstream_features.has_animation == 1) {
        WebPAnimDecoderOptions anim_decoder_options {};
        WebPAnimDecoderOptionsInit(&anim_decoder_options);
        anim_decoder_options.color_mode = MODE_BGRA;
        anim_decoder_options.use_threads = 1;

        WebPData webp_data { .bytes = context.data.data(), .size = context.data.size() };
        auto* anim_decoder = WebPAnimDecoderNew(&webp_data, &anim_decoder_options);
        if (anim_decoder == nullptr)
            return Error::from_string_literal("Failed to allocate WebPAnimDecoderNew failed");
        ScopeGuard guard { [=]() { WebPAnimDecoderDelete(anim_decoder); } };

        WebPAnimInfo anim_info {};
        int anim_getinfo_result = WebPAnimDecoderGetInfo(anim_decoder, &anim_info);
        if (anim_getinfo_result != 1)
            return Error::from_string_literal("Failed to get WebP animation info");

        context.frame_count = anim_info.frame_count;
        context.loop_count = anim_info.loop_count;

        // Extract frame durations from the demuxer without decoding pixels.
        auto* demux = WebPDemux(&webp_data);
        if (demux) {
            WebPIterator iter {};
            if (WebPDemuxGetFrame(demux, 1, &iter)) {
                do {
                    context.frame_durations.append(iter.duration);
                } while (WebPDemuxNextFrame(&iter));
                WebPDemuxReleaseIterator(&iter);
            }
            WebPDemuxDelete(demux);
        }
    }

    WebPData webp_data { .bytes = context.data.data(), .size = context.data.size() };
    if (WebPMux* mux = WebPMuxCreate(&webp_data, 0)) {
        ScopeGuard guard { [=]() { WebPMuxDelete(mux); } };

        uint32_t flag = 0;
        if (WebPMuxGetFeatures(mux, &flag) == WEBP_MUX_OK && (flag & ICCP_FLAG)) {
            WebPData icc_profile {};
            if (WebPMuxGetChunk(mux, "ICCP", &icc_profile) == WEBP_MUX_OK)
                context.icc_data = TRY(context.icc_data.copy(icc_profile.bytes, icc_profile.size));
        }
    }

    context.state = WebPLoadingContext::State::HeaderDecoded;
    return {};
}

static ErrorOr<void> ensure_anim_decoder(WebPLoadingContext& context)
{
    if (context.anim_decoder)
        return {};

    WebPAnimDecoderOptions options {};
    WebPAnimDecoderOptionsInit(&options);
    options.color_mode = MODE_BGRA;
    options.use_threads = 1;

    WebPData webp_data { .bytes = context.data.data(), .size = context.data.size() };
    context.anim_decoder = WebPAnimDecoderNew(&webp_data, &options);
    if (!context.anim_decoder)
        return Error::from_string_literal("Failed to create WebPAnimDecoder");

    context.anim_old_timestamp = 0;
    context.anim_frames_decoded = 0;

    return {};
}

static ErrorOr<ImageFrameDescriptor> decode_next_webp_animation_frame(WebPLoadingContext& context)
{
    TRY(ensure_anim_decoder(context));

    if (!WebPAnimDecoderHasMoreFrames(context.anim_decoder))
        return Error::from_string_literal("No more frames to decode");

    uint8_t* frame_data = nullptr;
    int timestamp = 0;
    if (!WebPAnimDecoderGetNext(context.anim_decoder, &frame_data, &timestamp))
        return Error::from_string_literal("Failed to decode animated frame");

    auto bitmap_format = context.has_alpha ? BitmapFormat::BGRA8888 : BitmapFormat::BGRx8888;
    auto bitmap = TRY(Bitmap::create(bitmap_format, Gfx::AlphaType::Unpremultiplied, context.size));
    memcpy(bitmap->scanline_u8(0), frame_data, context.size.width() * context.size.height() * 4);

    auto duration = timestamp - context.anim_old_timestamp;
    context.anim_old_timestamp = timestamp;
    ++context.anim_frames_decoded;

    return ImageFrameDescriptor { bitmap, duration };
}

static ErrorOr<void> decode_webp_image(WebPLoadingContext& context)
{
    VERIFY(context.state >= WebPLoadingContext::State::HeaderDecoded);
    VERIFY(!context.has_animation);

    auto bitmap_format = context.has_alpha ? BitmapFormat::BGRA8888 : BitmapFormat::BGRx8888;
    auto bitmap = TRY(Bitmap::create(bitmap_format, Gfx::AlphaType::Unpremultiplied, context.size));

    auto image_data = WebPDecodeBGRAInto(context.data.data(), context.data.size(), bitmap->scanline_u8(0), bitmap->data_size(), bitmap->pitch());
    if (image_data == nullptr)
        return Error::from_string_literal("Failed to decode webp image into bitmap");

    context.frame_descriptors.append(ImageFrameDescriptor { bitmap, 0 });

    return {};
}

bool WebPImageDecoderPlugin::sniff(ReadonlyBytes data)
{
    WebPLoadingContext context;
    context.data = data;
    return !decode_webp_header(context).is_error();
}

ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> WebPImageDecoderPlugin::create(ReadonlyBytes data)
{
    auto context = TRY(try_make<WebPLoadingContext>());
    auto plugin = TRY(adopt_nonnull_own_or_enomem(new (nothrow) WebPImageDecoderPlugin(data, move(context))));
    TRY(decode_webp_header(*plugin->m_context));
    return plugin;
}

bool WebPImageDecoderPlugin::is_animated()
{
    return m_context->has_animation;
}

size_t WebPImageDecoderPlugin::loop_count()
{
    if (!is_animated())
        return 0;

    return m_context->loop_count;
}

size_t WebPImageDecoderPlugin::frame_count()
{
    if (!is_animated())
        return 1;

    return m_context->frame_count;
}

size_t WebPImageDecoderPlugin::first_animated_frame_index()
{
    return 0;
}

ErrorOr<ImageFrameDescriptor> WebPImageDecoderPlugin::frame(size_t index, Optional<IntSize>)
{
    if (index >= frame_count())
        return Error::from_string_literal("WebPImageDecoderPlugin: Invalid frame index");

    if (m_context->state == WebPLoadingContext::State::Error)
        return Error::from_string_literal("WebPImageDecoderPlugin: Decoding failed");

    if (m_context->has_animation) {
        // Reset the decoder if requesting a frame we've already passed.
        if (index < m_context->anim_frames_decoded) {
            if (m_context->anim_decoder) {
                WebPAnimDecoderReset(m_context->anim_decoder);
                m_context->anim_frames_decoded = 0;
                m_context->anim_old_timestamp = 0;
            }
        }

        // Skip frames before the requested index.
        while (m_context->anim_frames_decoded < index)
            (void)TRY(decode_next_webp_animation_frame(*m_context));

        // Decode and return the requested frame without caching it.
        return TRY(decode_next_webp_animation_frame(*m_context));
    }

    if (m_context->state < WebPLoadingContext::State::BitmapDecoded) {
        TRY(decode_webp_image(*m_context));
        m_context->state = WebPLoadingContext::State::BitmapDecoded;
    }

    if (index >= m_context->frame_descriptors.size())
        return Error::from_string_literal("WebPImageDecoderPlugin: Invalid frame index");
    return m_context->frame_descriptors[index];
}

int WebPImageDecoderPlugin::frame_duration(size_t index)
{
    if (index < m_context->frame_durations.size())
        return m_context->frame_durations[index];
    if (index < m_context->frame_descriptors.size())
        return m_context->frame_descriptors[index].duration;
    return 0;
}

ErrorOr<Optional<ReadonlyBytes>> WebPImageDecoderPlugin::icc_data()
{
    if (m_context->state < WebPLoadingContext::State::HeaderDecoded)
        (void)frame(0);

    if (!m_context->icc_data.is_empty())
        return m_context->icc_data;
    return OptionalNone {};
}

}