mirror of
				https://github.com/LadybirdBrowser/ladybird.git
				synced 2025-11-04 07:10:57 +00:00 
			
		
		
		
	I've also renamed the `m_type` and `type()` members to be `m_unit` and `unit()` instead, to match what they actually are.
		
			
				
	
	
		
			260 lines
		
	
	
	
		
			10 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
			
		
		
	
	
			260 lines
		
	
	
	
		
			10 KiB
		
	
	
	
		
			C++
		
	
	
	
	
	
/*
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 * Copyright (c) 2020-2024, Andreas Kling <andreas@ladybird.org>
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 * Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
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 * Copyright (c) 2022-2025, Sam Atkins <sam@ladybird.org>
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 *
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 * SPDX-License-Identifier: BSD-2-Clause
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 */
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#include <AK/NonnullOwnPtr.h>
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#include <AK/Variant.h>
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#include <LibGfx/Font/Font.h>
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#include <LibGfx/Rect.h>
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#include <LibWeb/CSS/Length.h>
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#include <LibWeb/CSS/Percentage.h>
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#include <LibWeb/CSS/StyleComputer.h>
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#include <LibWeb/DOM/Document.h>
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#include <LibWeb/HTML/BrowsingContext.h>
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#include <LibWeb/HTML/Window.h>
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#include <LibWeb/Layout/Node.h>
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namespace Web::CSS {
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Length::FontMetrics::FontMetrics(CSSPixels font_size, Gfx::FontPixelMetrics const& pixel_metrics)
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    : font_size(font_size)
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    , x_height(pixel_metrics.x_height)
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    // FIXME: This is only approximately the cap height. The spec suggests measuring the "O" glyph:
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    //        https://www.w3.org/TR/css-values-4/#cap
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    , cap_height(pixel_metrics.ascent)
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    , zero_advance(pixel_metrics.advance_of_ascii_zero)
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    , line_height(round(pixel_metrics.line_spacing()))
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{
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}
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Length::Length(double value, LengthUnit unit)
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    : m_unit(unit)
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    , m_value(value)
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{
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}
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Length::~Length() = default;
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Length Length::make_px(double value)
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{
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    return Length(value, LengthUnit::Px);
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}
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Length Length::make_px(CSSPixels value)
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{
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    return make_px(value.to_double());
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}
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Length Length::percentage_of(Percentage const& percentage) const
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{
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    return Length { percentage.as_fraction() * raw_value(), m_unit };
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}
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CSSPixels Length::font_relative_length_to_px(Length::FontMetrics const& font_metrics, Length::FontMetrics const& root_font_metrics) const
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{
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    switch (m_unit) {
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    case LengthUnit::Em:
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        return CSSPixels::nearest_value_for(m_value * font_metrics.font_size.to_double());
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    case LengthUnit::Rem:
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        return CSSPixels::nearest_value_for(m_value * root_font_metrics.font_size.to_double());
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    case LengthUnit::Ex:
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        return CSSPixels::nearest_value_for(m_value * font_metrics.x_height.to_double());
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    case LengthUnit::Rex:
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        return CSSPixels::nearest_value_for(m_value * root_font_metrics.x_height.to_double());
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    case LengthUnit::Cap:
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        return CSSPixels::nearest_value_for(m_value * font_metrics.cap_height.to_double());
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    case LengthUnit::Rcap:
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        return CSSPixels::nearest_value_for(m_value * root_font_metrics.cap_height.to_double());
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    case LengthUnit::Ch:
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        return CSSPixels::nearest_value_for(m_value * font_metrics.zero_advance.to_double());
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    case LengthUnit::Rch:
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        return CSSPixels::nearest_value_for(m_value * root_font_metrics.zero_advance.to_double());
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    case LengthUnit::Ic:
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        // FIXME: Use the "advance measure of the “水” (CJK water ideograph, U+6C34) glyph"
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        return CSSPixels::nearest_value_for(m_value * font_metrics.font_size.to_double());
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    case LengthUnit::Ric:
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        // FIXME: Use the "advance measure of the “水” (CJK water ideograph, U+6C34) glyph"
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        return CSSPixels::nearest_value_for(m_value * root_font_metrics.font_size.to_double());
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    case LengthUnit::Lh:
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        return CSSPixels::nearest_value_for(m_value * font_metrics.line_height.to_double());
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    case LengthUnit::Rlh:
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        return CSSPixels::nearest_value_for(m_value * root_font_metrics.line_height.to_double());
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    default:
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        VERIFY_NOT_REACHED();
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    }
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}
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CSSPixels Length::viewport_relative_length_to_px(CSSPixelRect const& viewport_rect) const
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{
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    switch (m_unit) {
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    case LengthUnit::Vw:
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    case LengthUnit::Svw:
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    case LengthUnit::Lvw:
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    case LengthUnit::Dvw:
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        return viewport_rect.width() * (CSSPixels::nearest_value_for(m_value) / 100);
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    case LengthUnit::Vh:
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    case LengthUnit::Svh:
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    case LengthUnit::Lvh:
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    case LengthUnit::Dvh:
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        return viewport_rect.height() * (CSSPixels::nearest_value_for(m_value) / 100);
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    case LengthUnit::Vi:
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    case LengthUnit::Svi:
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    case LengthUnit::Lvi:
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    case LengthUnit::Dvi:
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        // FIXME: Select the width or height based on which is the inline axis.
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        return viewport_rect.width() * (CSSPixels::nearest_value_for(m_value) / 100);
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    case LengthUnit::Vb:
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    case LengthUnit::Svb:
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    case LengthUnit::Lvb:
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    case LengthUnit::Dvb:
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        // FIXME: Select the width or height based on which is the block axis.
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        return viewport_rect.height() * (CSSPixels::nearest_value_for(m_value) / 100);
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    case LengthUnit::Vmin:
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    case LengthUnit::Svmin:
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    case LengthUnit::Lvmin:
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    case LengthUnit::Dvmin:
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        return min(viewport_rect.width(), viewport_rect.height()) * (CSSPixels::nearest_value_for(m_value) / 100);
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    case LengthUnit::Vmax:
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    case LengthUnit::Svmax:
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    case LengthUnit::Lvmax:
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    case LengthUnit::Dvmax:
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        return max(viewport_rect.width(), viewport_rect.height()) * (CSSPixels::nearest_value_for(m_value) / 100);
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    default:
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        VERIFY_NOT_REACHED();
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    }
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}
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Length::ResolutionContext Length::ResolutionContext::for_element(DOM::AbstractElement const& element)
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{
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    auto const* root_element = element.element().document().document_element();
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    VERIFY(element.computed_properties());
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    VERIFY(root_element);
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    VERIFY(root_element->computed_properties());
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    return Length::ResolutionContext {
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        .viewport_rect = element.element().navigable()->viewport_rect(),
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        .font_metrics = { element.computed_properties()->font_size(), element.computed_properties()->first_available_computed_font().pixel_metrics() },
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        .root_font_metrics = { root_element->computed_properties()->font_size(), root_element->computed_properties()->first_available_computed_font().pixel_metrics() }
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    };
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}
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Length::ResolutionContext Length::ResolutionContext::for_window(HTML::Window const& window)
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{
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    auto const& initial_font = window.associated_document().style_computer().initial_font();
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    Gfx::FontPixelMetrics const& initial_font_metrics = initial_font.pixel_metrics();
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    Length::FontMetrics font_metrics { CSSPixels { initial_font.pixel_size() }, initial_font_metrics };
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    return Length::ResolutionContext {
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        .viewport_rect = window.page().web_exposed_screen_area(),
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        .font_metrics = font_metrics,
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        .root_font_metrics = font_metrics,
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    };
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}
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Length::ResolutionContext Length::ResolutionContext::for_layout_node(Layout::Node const& node)
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{
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    Layout::Node const* root_layout_node;
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    if (is<DOM::Document>(node.dom_node())) {
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        root_layout_node = &node;
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    } else {
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        auto const* root_element = node.document().document_element();
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        VERIFY(root_element);
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        VERIFY(root_element->layout_node());
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        root_layout_node = root_element->layout_node();
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    }
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    return Length::ResolutionContext {
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        .viewport_rect = node.navigable()->viewport_rect(),
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        .font_metrics = { node.computed_values().font_size(), node.first_available_font().pixel_metrics() },
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        .root_font_metrics = { root_layout_node->computed_values().font_size(), root_layout_node->first_available_font().pixel_metrics() },
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    };
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}
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CSSPixels Length::to_px(ResolutionContext const& context) const
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{
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    return to_px(context.viewport_rect, context.font_metrics, context.root_font_metrics);
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}
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CSSPixels Length::to_px_slow_case(Layout::Node const& layout_node) const
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{
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    if (!layout_node.document().browsing_context())
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        return 0;
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    if (is_font_relative()) {
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        auto* root_element = layout_node.document().document_element();
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        if (!root_element || !root_element->layout_node())
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            return 0;
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        FontMetrics font_metrics {
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            layout_node.computed_values().font_size(),
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            layout_node.first_available_font().pixel_metrics(),
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        };
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        FontMetrics root_font_metrics {
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            root_element->layout_node()->computed_values().font_size(),
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            root_element->layout_node()->first_available_font().pixel_metrics(),
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        };
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        return font_relative_length_to_px(font_metrics, root_font_metrics);
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    }
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    VERIFY(is_viewport_relative());
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    auto const& viewport_rect = layout_node.document().viewport_rect();
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    return viewport_relative_length_to_px(viewport_rect);
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}
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String Length::to_string(SerializationMode serialization_mode) const
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{
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    // https://drafts.csswg.org/cssom/#serialize-a-css-value
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    // -> <length>
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    // The <number> component serialized as per <number> followed by the unit in its canonical form as defined in its
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    // respective specification.
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    // FIXME: Manually skip this for px so we avoid rounding errors in absolute_length_to_px.
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    //        Maybe provide alternative functions that don't produce CSSPixels?
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    if (serialization_mode == SerializationMode::ResolvedValue && is_absolute() && m_unit != LengthUnit::Px) {
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        StringBuilder builder;
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        serialize_a_number(builder, absolute_length_to_px().to_double());
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        builder.append("px"sv);
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        return builder.to_string_without_validation();
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    }
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    StringBuilder builder;
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    serialize_a_number(builder, m_value);
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    builder.append(unit_name());
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    return builder.to_string_without_validation();
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}
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Optional<Length> Length::absolutize(CSSPixelRect const& viewport_rect, FontMetrics const& font_metrics, FontMetrics const& root_font_metrics) const
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{
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    if (is_px())
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        return {};
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    if (is_absolute() || is_relative()) {
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        auto px = to_px(viewport_rect, font_metrics, root_font_metrics);
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        return CSS::Length::make_px(px);
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    }
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    return {};
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}
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Length Length::absolutized(CSSPixelRect const& viewport_rect, FontMetrics const& font_metrics, FontMetrics const& root_font_metrics) const
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{
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    return absolutize(viewport_rect, font_metrics, root_font_metrics).value_or(*this);
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}
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Length Length::resolve_calculated(NonnullRefPtr<CalculatedStyleValue const> const& calculated, Layout::Node const& layout_node, Length const& reference_value)
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{
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    CalculationResolutionContext context {
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        .percentage_basis = reference_value,
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        .length_resolution_context = ResolutionContext::for_layout_node(layout_node),
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    };
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    return calculated->resolve_length(context).value();
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}
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Length Length::resolve_calculated(NonnullRefPtr<CalculatedStyleValue const> const& calculated, Layout::Node const& layout_node, CSSPixels reference_value)
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{
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    return resolve_calculated(calculated, layout_node, make_px(reference_value));
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}
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}
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