serenity/Userland/Libraries/LibWeb/Painting/MarkerPaintable.cpp

/*
 * Copyright (c) 2018-2022, Andreas Kling <kling@serenityos.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <LibGfx/AntiAliasingPainter.h>
#include <LibGfx/StylePainter.h>
#include <LibJS/Heap/Heap.h>
#include <LibWeb/Layout/ListItemMarkerBox.h>
#include <LibWeb/Painting/MarkerPaintable.h>

namespace Web::Painting {

JS::NonnullGCPtr<MarkerPaintable> MarkerPaintable::create(Layout::ListItemMarkerBox const& layout_box)
{
    return layout_box.heap().allocate_without_realm<MarkerPaintable>(layout_box);
}

MarkerPaintable::MarkerPaintable(Layout::ListItemMarkerBox const& layout_box)
    : PaintableBox(layout_box)
{
}

Layout::ListItemMarkerBox const& MarkerPaintable::layout_box() const
{
    return static_cast<Layout::ListItemMarkerBox const&>(layout_node());
}

constexpr float sin_60_deg = 0.866025403f;

void MarkerPaintable::paint(PaintContext& context, PaintPhase phase) const
{
    if (phase == PaintPhase::Overlay)
        PaintableBox::paint(context, phase);
    if (phase != PaintPhase::Foreground)
        return;

    CSSPixelRect enclosing = absolute_rect().to_rounded<CSSPixels>();
    auto device_enclosing = context.enclosing_device_rect(enclosing);

    CSSPixels marker_width = enclosing.height() / 2.0;

    if (auto const* list_style_image = layout_box().list_style_image()) {
        CSSPixelRect image_rect {
            0, 0,
            list_style_image->natural_width().value_or(marker_width),
            list_style_image->natural_height().value_or(marker_width)
        };
        image_rect.center_within(enclosing);

        auto device_image_rect = context.enclosing_device_rect(image_rect);
        list_style_image->resolve_for_size(layout_box(), image_rect.size());
        list_style_image->paint(context, device_image_rect, computed_values().image_rendering());
        return;
    }

    CSSPixelRect marker_rect { 0, 0, marker_width, marker_width };
    marker_rect.center_within(enclosing);
    auto device_marker_rect = context.enclosing_device_rect(marker_rect);

    float left = device_marker_rect.x().value();
    float right = left + device_marker_rect.width().value();
    float top = device_marker_rect.y().value();
    float bottom = top + device_marker_rect.height().value();

    auto color = computed_values().color();

    Gfx::AntiAliasingPainter aa_painter { context.painter() };

    switch (layout_box().list_style_type()) {
    case CSS::ListStyleType::Square:
        context.painter().fill_rect(device_marker_rect.to_type<int>(), color);
        break;
    case CSS::ListStyleType::Circle:
        aa_painter.draw_ellipse(device_marker_rect.to_type<int>(), color, 1);
        break;
    case CSS::ListStyleType::Disc:
        aa_painter.fill_ellipse(device_marker_rect.to_type<int>(), color);
        break;
    case CSS::ListStyleType::DisclosureClosed: {
        // https://drafts.csswg.org/css-counter-styles-3/#disclosure-closed
        // For the disclosure-open and disclosure-closed counter styles, the marker must be an image or character suitable for indicating the open and closed states of a disclosure widget, such as HTML’s details element.
        // FIXME: If the image is directional, it must respond to the writing mode of the element, similar to the bidi-sensitive images feature of the Images 4 module.

        // Draw an equilateral triangle pointing right.
        auto path = Gfx::Path();
        path.move_to({ left, top });
        path.line_to({ left + sin_60_deg * (right - left), (top + bottom) / 2 });
        path.line_to({ left, bottom });
        path.close();
        aa_painter.fill_path(path, color);
        break;
    }
    case CSS::ListStyleType::DisclosureOpen: {
        // https://drafts.csswg.org/css-counter-styles-3/#disclosure-open
        // For the disclosure-open and disclosure-closed counter styles, the marker must be an image or character suitable for indicating the open and closed states of a disclosure widget, such as HTML’s details element.
        // FIXME: If the image is directional, it must respond to the writing mode of the element, similar to the bidi-sensitive images feature of the Images 4 module.

        // Draw an equilateral triangle pointing down.
        auto path = Gfx::Path();
        path.move_to({ left, top });
        path.line_to({ right, top });
        path.line_to({ (left + right) / 2, top + sin_60_deg * (bottom - top) });
        path.close();
        aa_painter.fill_path(path, color);
        break;
    }
    case CSS::ListStyleType::Decimal:
    case CSS::ListStyleType::DecimalLeadingZero:
    case CSS::ListStyleType::LowerAlpha:
    case CSS::ListStyleType::LowerLatin:
    case CSS::ListStyleType::LowerRoman:
    case CSS::ListStyleType::UpperAlpha:
    case CSS::ListStyleType::UpperLatin:
    case CSS::ListStyleType::UpperRoman:
        if (layout_box().text().is_null())
            break;
        // FIXME: This should use proper text layout logic!
        // This does not line up with the text in the <li> element which looks very sad :(
        context.painter().draw_text(device_enclosing.to_type<int>(), layout_box().text(), layout_box().scaled_font(context), Gfx::TextAlignment::Center, color);
        break;
    case CSS::ListStyleType::None:
        return;

    default:
        VERIFY_NOT_REACHED();
    }
}

}