ladybird/Libraries/LibWeb/CSS/StyleValues/ImageStyleValue.cpp

/*
 * Copyright (c) 2018-2023, Andreas Kling <andreas@ladybird.org>
 * Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
 * Copyright (c) 2021-2025, Sam Atkins <sam@ladybird.org>
 * Copyright (c) 2022-2023, MacDue <macdue@dueutil.tech>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/AnyOf.h>
#include <AK/NeverDestroyed.h>
#include <LibGfx/DecodedImageFrame.h>
#include <LibWeb/CSS/CSSStyleSheet.h>
#include <LibWeb/CSS/ComputedValues.h>
#include <LibWeb/CSS/Fetch.h>
#include <LibWeb/CSS/StyleValues/ImageStyleValue.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/DOMURL/DOMURL.h>
#include <LibWeb/HTML/DecodedImageData.h>
#include <LibWeb/HTML/PotentialCORSRequest.h>
#include <LibWeb/HTML/Scripting/Environments.h>
#include <LibWeb/HTML/SharedResourceRequest.h>
#include <LibWeb/Painting/DisplayListRecorder.h>
#include <LibWeb/Painting/DisplayListRecordingContext.h>
#include <LibWeb/Platform/Timer.h>

namespace Web::CSS {

static HashTable<ImageStyleValue const*>& active_animation_timers()
{
    static NeverDestroyed<HashTable<ImageStyleValue const*>> timers;
    return *timers;
}

ValueComparingNonnullRefPtr<ImageStyleValue const> ImageStyleValue::create(URL const& url)
{
    return adopt_ref(*new (nothrow) ImageStyleValue(url));
}

ValueComparingNonnullRefPtr<ImageStyleValue const> ImageStyleValue::create(::URL::URL const& url)
{
    return adopt_ref(*new (nothrow) ImageStyleValue(URL { url.to_string() }));
}

ImageStyleValue::ImageStyleValue(URL const& url)
    : AbstractImageStyleValue(Type::Image)
    , m_url(url)
{
}

ImageStyleValue::~ImageStyleValue() = default;

u64 ImageStyleValue::active_animation_timer_count(DOM::Document const& document)
{
    u64 count = 0;
    for (auto const* image_style_value : active_animation_timers()) {
        if (any_of(image_style_value->m_clients, [&](auto const* client) {
                return client->document() == &document;
            }))
            ++count;
    }
    return count;
}

void ImageStyleValue::visit_edges(JS::Cell::Visitor& visitor) const
{
    Base::visit_edges(visitor);
    // FIXME: visit_edges in non-GC allocated classes is confusing pattern.
    //        Consider making StyleValue to be GC allocated instead.
    visitor.visit(m_resource_request);
    visitor.visit(m_style_sheet);
    visitor.visit(m_timer);
}

void ImageStyleValue::load_any_resources(DOM::Document& document)
{
    if (m_resource_request)
        return;
    m_document = &document;

    RuleOrDeclaration rule_or_declaration {
        .environment_settings_object = document.relevant_settings_object(),
        .value = RuleOrDeclaration::Rule {
            .parent_style_sheet = m_style_sheet.ptr(),
        }
    };

    m_resource_request = fetch_an_external_image_for_a_stylesheet(m_url, rule_or_declaration, m_style_sheet ? *m_style_sheet->owning_document() : document);

    if (m_resource_request) {
        m_resource_request->add_callbacks(
            weak_callback(*this, [](auto& self) {
                if (!self.m_document)
                    return;

                for (auto* client : self.m_clients)
                    client->image_style_value_did_update(self);

                auto image_data = self.m_resource_request->image_data();
                if (image_data->is_animated() && image_data->frame_count() > 1) {
                    for (auto* client : self.m_clients) {
                        if (auto document = client->document()) {
                            self.start_animation_timer_if_needed(*document);
                            break;
                        }
                    }
                }
            }),
            nullptr);
    }
}

void ImageStyleValue::start_animation_timer_if_needed(DOM::Document& document) const
{
    if (m_clients.is_empty() || !is_animatable())
        return;

    if (m_timer && m_timer->is_active())
        return;

    if (!m_timer) {
        auto timer = Platform::Timer::create(document.heap());
        m_timer = timer;
        auto weak_self = make_weak_ptr<ImageStyleValue>();
        timer->on_timeout = GC::create_function(document.heap(), [weak_self] {
            if (weak_self)
                weak_self->animate();
        });
    }

    m_timer->set_interval(current_frame_duration());
    m_timer->start();
    active_animation_timers().set(this);
}

void ImageStyleValue::stop_animation_timer() const
{
    if (m_timer && m_timer->is_active()) {
        m_timer->stop();
        active_animation_timers().remove(this);
    }
}

bool ImageStyleValue::is_animatable() const
{
    auto image_data = this->image_data();
    if (!image_data || !image_data->is_animated() || image_data->frame_count() <= 1)
        return false;

    return !animation_has_completed();
}

bool ImageStyleValue::animation_has_completed() const
{
    auto image_data = this->image_data();
    return image_data && image_data->loop_count() > 0 && m_loops_completed == image_data->loop_count();
}

int ImageStyleValue::current_frame_duration() const
{
    auto image_data = this->image_data();
    if (!image_data)
        return 0;

    return image_data->frame_duration(m_current_frame_index);
}

void ImageStyleValue::animate()
{
    if (!m_resource_request)
        return;
    auto image_data = m_resource_request->image_data();
    if (!image_data)
        return;

    m_current_frame_index = (m_current_frame_index + 1) % image_data->frame_count();
    m_current_frame_index = image_data->notify_frame_advanced(m_current_frame_index);
    auto current_frame_duration = image_data->frame_duration(m_current_frame_index);

    if (m_timer && current_frame_duration != m_timer->interval())
        m_timer->restart(current_frame_duration);

    if (m_current_frame_index == image_data->frame_count() - 1) {
        ++m_loops_completed;
        if (animation_has_completed())
            stop_animation_timer();
    }

    if (on_animate)
        on_animate();
}

bool ImageStyleValue::is_paintable() const
{
    return image_data();
}

Optional<Gfx::DecodedImageFrame> ImageStyleValue::frame(size_t frame_index, Gfx::IntSize size) const
{
    if (auto image_data = this->image_data())
        return image_data->frame(frame_index, size);
    return {};
}

void ImageStyleValue::serialize(StringBuilder& builder, SerializationMode) const
{
    builder.append(m_url.to_string());
}

bool ImageStyleValue::equals(StyleValue const& other) const
{
    if (type() != other.type())
        return false;
    return m_url == other.as_image().m_url;
}

Optional<CSSPixels> ImageStyleValue::natural_width() const
{
    if (auto image_data = this->image_data())
        return image_data->intrinsic_width();
    return {};
}

Optional<CSSPixels> ImageStyleValue::natural_height() const
{
    if (auto image_data = this->image_data())
        return image_data->intrinsic_height();
    return {};
}

Optional<CSSPixelFraction> ImageStyleValue::natural_aspect_ratio() const
{
    if (auto image_data = this->image_data())
        return image_data->intrinsic_aspect_ratio();
    return {};
}

void ImageStyleValue::paint(DisplayListRecordingContext& context, DevicePixelRect const& dest_rect, CSS::ImageRendering image_rendering) const
{
    auto image_data = this->image_data();
    if (!image_data)
        return;

    auto dest_int_rect = dest_rect.to_type<int>();
    auto rect = image_data->frame_rect(m_current_frame_index).value_or(dest_int_rect);
    auto scaling_mode = to_gfx_scaling_mode(image_rendering, rect.size(), dest_int_rect.size());
    image_data->paint(context, m_current_frame_index, dest_int_rect, dest_int_rect, scaling_mode);
}

Optional<Gfx::DecodedImageFrame> ImageStyleValue::current_frame(DevicePixelRect const& dest_rect) const
{
    return frame(m_current_frame_index, dest_rect.size().to_type<int>());
}

GC::Ptr<HTML::DecodedImageData> ImageStyleValue::image_data() const
{
    if (!m_resource_request)
        return nullptr;
    return m_resource_request->image_data();
}

Optional<Gfx::Color> ImageStyleValue::color_if_single_pixel_bitmap() const
{
    if (auto decoded_frame = frame(m_current_frame_index); decoded_frame.has_value()) {
        auto const& bitmap = decoded_frame->bitmap();
        if (bitmap.width() == 1 && bitmap.height() == 1)
            return bitmap.get_pixel(0, 0);
    }
    return {};
}

void ImageStyleValue::set_style_sheet(GC::Ptr<CSSStyleSheet> style_sheet)
{
    Base::set_style_sheet(style_sheet);
    m_style_sheet = style_sheet;

    if (m_style_sheet)
        m_style_sheet->register_pending_image_value(*this);
}

ValueComparingNonnullRefPtr<StyleValue const> ImageStyleValue::absolutized(ComputationContext const&) const
{
    if (m_url.url().is_empty())
        return *this;

    // FIXME: The spec has been updated to handle this better. The computation of the base URL here is roughly based on:
    //        https://drafts.csswg.org/css-values-4/#style-resource-base-url
    //        https://github.com/w3c/csswg-drafts/pull/12261
    auto base_url = [&]() -> Optional<::URL::URL> {
        if (m_style_sheet) {
            return m_style_sheet->base_url()
                .value_or_lazy_evaluated_optional([&]() { return m_style_sheet->location(); })
                .value_or_lazy_evaluated_optional([&]() { return HTML::relevant_settings_object(*m_style_sheet).api_base_url(); });
        }

        if (m_document)
            return m_document->base_url();

        return {};
    }();

    if (base_url.has_value()) {
        if (auto resolved_url = DOMURL::parse(m_url.url(), *base_url); resolved_url.has_value())
            return ImageStyleValue::create(*resolved_url);
    }

    return *this;
}

void ImageStyleValue::register_client(Client& client) const
{
    auto result = m_clients.set(&client);
    VERIFY(result == AK::HashSetResult::InsertedNewEntry);
    if (auto document = client.document())
        start_animation_timer_if_needed(*document);
}

void ImageStyleValue::unregister_client(Client& client) const
{
    auto did_remove = m_clients.remove(&client);
    VERIFY(did_remove);

    if (m_clients.is_empty())
        stop_animation_timer();
}

ImageStyleValue::Client::Client(DOM::Document& document, ImageStyleValue const& image_style_value)
    : m_image_style_value(image_style_value)
    , m_document(document)
{
    m_image_style_value.register_client(*this);
}

ImageStyleValue::Client::~Client()
{
}

void ImageStyleValue::Client::image_style_value_finalize()
{
    m_image_style_value.unregister_client(*this);
}

}