ladybird/Userland/Libraries/LibWeb/CSS/Length.cpp
Aliaksandr Kalenik 147c3b3d97 LibWeb+WebContent: Forbid access to underlying type of CSSPixels
Although DistinctNumeric, which is supposed to abstract the underlying
type, was used to represent CSSPixels, we have a whole bunch of places
in the layout code that assume CSSPixels::value() returns a
floating-point type. This assumption makes it difficult to replace the
underlying type in CSSPixels with a non-floating type.

To make it easier to transition CSSPixels to fixed-point math, one step
we can take is to prevent access to the underlying type using value()
and instead use explicit conversions with the to_float(), to_double(),
and to_int() methods.
2023-06-13 06:08:27 +02:00

414 lines
13 KiB
C++

/*
* Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Tobias Christiansen <tobyase@serenityos.org>
* Copyright (c) 2022-2023, Sam Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/NonnullOwnPtr.h>
#include <AK/Variant.h>
#include <LibGfx/Font/Font.h>
#include <LibGfx/Rect.h>
#include <LibWeb/CSS/Length.h>
#include <LibWeb/CSS/Percentage.h>
#include <LibWeb/DOM/Document.h>
#include <LibWeb/HTML/BrowsingContext.h>
#include <LibWeb/HTML/HTMLHtmlElement.h>
#include <LibWeb/Layout/Node.h>
namespace Web::CSS {
Length::FontMetrics::FontMetrics(CSSPixels font_size, Gfx::FontPixelMetrics const& pixel_metrics, CSSPixels line_height)
: font_size(font_size)
, x_height(pixel_metrics.x_height)
// FIXME: This is only approximately the cap height. The spec suggests measuring the "O" glyph:
// https://www.w3.org/TR/css-values-4/#cap
, cap_height(pixel_metrics.ascent)
, zero_advance(pixel_metrics.advance_of_ascii_zero + pixel_metrics.glyph_spacing)
, line_height(line_height)
{
}
Length::Length(int value, Type type)
: m_type(type)
, m_value(value)
{
}
Length::Length(double value, Type type)
: m_type(type)
, m_value(value)
{
}
Length::~Length() = default;
Length Length::make_auto()
{
return Length(0, Type::Auto);
}
Length Length::make_px(CSSPixels value)
{
return Length(value.to_double(), Type::Px);
}
Length Length::percentage_of(Percentage const& percentage) const
{
if (is_auto()) {
dbgln("Attempting to get percentage of an auto length, this seems wrong? But for now we just return the original length.");
return *this;
}
// HACK: We round to 3 decimal places to emulate what happens in browsers that used fixed point math.
// FIXME: Remove this when converting CSSPixels to a fixed-point type.
// https://github.com/SerenityOS/serenity/issues/18566
auto value = percentage.as_fraction() * raw_value();
value *= 1000;
value = round(value);
value /= 1000;
return Length { value, m_type };
}
CSSPixels Length::font_relative_length_to_px(Length::FontMetrics const& font_metrics, Length::FontMetrics const& root_font_metrics) const
{
switch (m_type) {
case Type::Em:
return m_value * font_metrics.font_size.to_double();
case Type::Rem:
return m_value * root_font_metrics.font_size.to_double();
case Type::Ex:
return m_value * font_metrics.x_height.to_double();
case Type::Rex:
return m_value * root_font_metrics.x_height.to_double();
case Type::Cap:
return m_value * font_metrics.cap_height.to_double();
case Type::Rcap:
return m_value * root_font_metrics.cap_height.to_double();
case Type::Ch:
return m_value * font_metrics.zero_advance.to_double();
case Type::Rch:
return m_value * root_font_metrics.zero_advance.to_double();
case Type::Ic:
// FIXME: Use the "advance measure of the “水” (CJK water ideograph, U+6C34) glyph"
return m_value * font_metrics.font_size.to_double();
case Type::Ric:
// FIXME: Use the "advance measure of the “水” (CJK water ideograph, U+6C34) glyph"
return m_value * root_font_metrics.font_size.to_double();
case Type::Lh:
return m_value * font_metrics.line_height.to_double();
case Type::Rlh:
return m_value * root_font_metrics.line_height.to_double();
default:
VERIFY_NOT_REACHED();
}
}
CSSPixels Length::viewport_relative_length_to_px(CSSPixelRect const& viewport_rect) const
{
switch (m_type) {
case Type::Vw:
case Type::Svw:
case Type::Lvw:
case Type::Dvw:
return viewport_rect.width() * (m_value / 100);
case Type::Vh:
case Type::Svh:
case Type::Lvh:
case Type::Dvh:
return viewport_rect.height() * (m_value / 100);
case Type::Vi:
case Type::Svi:
case Type::Lvi:
case Type::Dvi:
// FIXME: Select the width or height based on which is the inline axis.
return viewport_rect.width() * (m_value / 100);
case Type::Vb:
case Type::Svb:
case Type::Lvb:
case Type::Dvb:
// FIXME: Select the width or height based on which is the block axis.
return viewport_rect.height() * (m_value / 100);
case Type::Vmin:
case Type::Svmin:
case Type::Lvmin:
case Type::Dvmin:
return min(viewport_rect.width(), viewport_rect.height()) * (m_value / 100);
case Type::Vmax:
case Type::Svmax:
case Type::Lvmax:
case Type::Dvmax:
return max(viewport_rect.width(), viewport_rect.height()) * (m_value / 100);
default:
VERIFY_NOT_REACHED();
}
}
Length::ResolutionContext Length::ResolutionContext::for_layout_node(Layout::Node const& node)
{
auto const* root_element = node.document().document_element();
VERIFY(root_element);
VERIFY(root_element->layout_node());
return Length::ResolutionContext {
.viewport_rect = node.browsing_context().viewport_rect(),
.font_metrics = { node.computed_values().font_size(), node.font().pixel_metrics(), node.line_height() },
.root_font_metrics = { root_element->layout_node()->computed_values().font_size(), root_element->layout_node()->font().pixel_metrics(), root_element->layout_node()->line_height() },
};
}
CSSPixels Length::to_px(ResolutionContext const& context) const
{
return to_px(context.viewport_rect, context.font_metrics, context.root_font_metrics);
}
CSSPixels Length::to_px(Layout::Node const& layout_node) const
{
if (is_auto()) {
// FIXME: We really, really shouldn't end up here, but we do, and so frequently that
// adding a dbgln() here outputs a couple hundred lines loading `welcome.html`.
return 0;
}
if (is_absolute())
return absolute_length_to_px();
if (!layout_node.document().browsing_context())
return 0;
if (is_font_relative()) {
auto* root_element = layout_node.document().document_element();
if (!root_element || !root_element->layout_node())
return 0;
FontMetrics font_metrics {
layout_node.computed_values().font_size(),
layout_node.font().pixel_metrics(),
layout_node.line_height()
};
FontMetrics root_font_metrics {
root_element->layout_node()->computed_values().font_size(),
root_element->layout_node()->font().pixel_metrics(),
root_element->layout_node()->line_height()
};
return font_relative_length_to_px(font_metrics, root_font_metrics);
}
VERIFY(is_viewport_relative());
auto const& viewport_rect = layout_node.document().browsing_context()->viewport_rect();
return viewport_relative_length_to_px(viewport_rect);
}
ErrorOr<String> Length::to_string() const
{
if (is_auto())
return "auto"_string;
return String::formatted("{}{}", m_value, unit_name());
}
char const* Length::unit_name() const
{
switch (m_type) {
case Type::Em:
return "em";
case Type::Rem:
return "rem";
case Type::Ex:
return "ex";
case Type::Rex:
return "rex";
case Type::Cap:
return "cap";
case Type::Rcap:
return "rcap";
case Type::Ch:
return "ch";
case Type::Rch:
return "rch";
case Type::Ic:
return "ic";
case Type::Ric:
return "ric";
case Type::Lh:
return "lh";
case Type::Rlh:
return "rlh";
case Type::Vw:
return "vw";
case Type::Svw:
return "svw";
case Type::Lvw:
return "lvw";
case Type::Dvw:
return "dvw";
case Type::Vh:
return "vh";
case Type::Svh:
return "svh";
case Type::Lvh:
return "lvh";
case Type::Dvh:
return "dvh";
case Type::Vi:
return "vi";
case Type::Svi:
return "svi";
case Type::Lvi:
return "lvi";
case Type::Dvi:
return "dvi";
case Type::Vb:
return "vb";
case Type::Svb:
return "svb";
case Type::Lvb:
return "lvb";
case Type::Dvb:
return "dvb";
case Type::Vmin:
return "vmin";
case Type::Svmin:
return "svmin";
case Type::Lvmin:
return "lvmin";
case Type::Dvmin:
return "dvmin";
case Type::Vmax:
return "vmax";
case Type::Svmax:
return "svmax";
case Type::Lvmax:
return "lvmax";
case Type::Dvmax:
return "dvmax";
case Type::Cm:
return "cm";
case Type::Mm:
return "mm";
case Type::Q:
return "Q";
case Type::In:
return "in";
case Type::Pt:
return "pt";
case Type::Pc:
return "pc";
case Type::Px:
return "px";
case Type::Auto:
return "auto";
}
VERIFY_NOT_REACHED();
}
Optional<Length::Type> Length::unit_from_name(StringView name)
{
if (name.equals_ignoring_ascii_case("em"sv)) {
return Length::Type::Em;
} else if (name.equals_ignoring_ascii_case("rem"sv)) {
return Length::Type::Rem;
} else if (name.equals_ignoring_ascii_case("ex"sv)) {
return Length::Type::Ex;
} else if (name.equals_ignoring_ascii_case("rex"sv)) {
return Length::Type::Rex;
} else if (name.equals_ignoring_ascii_case("cap"sv)) {
return Length::Type::Cap;
} else if (name.equals_ignoring_ascii_case("rcap"sv)) {
return Length::Type::Rcap;
} else if (name.equals_ignoring_ascii_case("ch"sv)) {
return Length::Type::Ch;
} else if (name.equals_ignoring_ascii_case("rch"sv)) {
return Length::Type::Rch;
} else if (name.equals_ignoring_ascii_case("ic"sv)) {
return Length::Type::Ic;
} else if (name.equals_ignoring_ascii_case("ric"sv)) {
return Length::Type::Ric;
} else if (name.equals_ignoring_ascii_case("lh"sv)) {
return Length::Type::Lh;
} else if (name.equals_ignoring_ascii_case("rlh"sv)) {
return Length::Type::Rlh;
} else if (name.equals_ignoring_ascii_case("vw"sv)) {
return Length::Type::Vw;
} else if (name.equals_ignoring_ascii_case("svw"sv)) {
return Length::Type::Svw;
} else if (name.equals_ignoring_ascii_case("lvw"sv)) {
return Length::Type::Lvw;
} else if (name.equals_ignoring_ascii_case("dvw"sv)) {
return Length::Type::Dvw;
} else if (name.equals_ignoring_ascii_case("vh"sv)) {
return Length::Type::Vh;
} else if (name.equals_ignoring_ascii_case("svh"sv)) {
return Length::Type::Svh;
} else if (name.equals_ignoring_ascii_case("lvh"sv)) {
return Length::Type::Lvh;
} else if (name.equals_ignoring_ascii_case("dvh"sv)) {
return Length::Type::Dvh;
} else if (name.equals_ignoring_ascii_case("vi"sv)) {
return Length::Type::Vi;
} else if (name.equals_ignoring_ascii_case("svi"sv)) {
return Length::Type::Svi;
} else if (name.equals_ignoring_ascii_case("lvi"sv)) {
return Length::Type::Lvi;
} else if (name.equals_ignoring_ascii_case("dvi"sv)) {
return Length::Type::Dvi;
} else if (name.equals_ignoring_ascii_case("vb"sv)) {
return Length::Type::Vb;
} else if (name.equals_ignoring_ascii_case("svb"sv)) {
return Length::Type::Svb;
} else if (name.equals_ignoring_ascii_case("lvb"sv)) {
return Length::Type::Lvb;
} else if (name.equals_ignoring_ascii_case("dvb"sv)) {
return Length::Type::Dvb;
} else if (name.equals_ignoring_ascii_case("vmin"sv)) {
return Length::Type::Vmin;
} else if (name.equals_ignoring_ascii_case("svmin"sv)) {
return Length::Type::Svmin;
} else if (name.equals_ignoring_ascii_case("lvmin"sv)) {
return Length::Type::Lvmin;
} else if (name.equals_ignoring_ascii_case("dvmin"sv)) {
return Length::Type::Dvmin;
} else if (name.equals_ignoring_ascii_case("vmax"sv)) {
return Length::Type::Vmax;
} else if (name.equals_ignoring_ascii_case("svmax"sv)) {
return Length::Type::Svmax;
} else if (name.equals_ignoring_ascii_case("lvmax"sv)) {
return Length::Type::Lvmax;
} else if (name.equals_ignoring_ascii_case("dvmax"sv)) {
return Length::Type::Dvmax;
} else if (name.equals_ignoring_ascii_case("cm"sv)) {
return Length::Type::Cm;
} else if (name.equals_ignoring_ascii_case("mm"sv)) {
return Length::Type::Mm;
} else if (name.equals_ignoring_ascii_case("Q"sv)) {
return Length::Type::Q;
} else if (name.equals_ignoring_ascii_case("in"sv)) {
return Length::Type::In;
} else if (name.equals_ignoring_ascii_case("pt"sv)) {
return Length::Type::Pt;
} else if (name.equals_ignoring_ascii_case("pc"sv)) {
return Length::Type::Pc;
} else if (name.equals_ignoring_ascii_case("px"sv)) {
return Length::Type::Px;
}
return {};
}
Optional<Length> Length::absolutize(CSSPixelRect const& viewport_rect, FontMetrics const& font_metrics, FontMetrics const& root_font_metrics) const
{
if (is_px())
return {};
if (is_absolute() || is_relative()) {
auto px = to_px(viewport_rect, font_metrics, root_font_metrics);
return CSS::Length::make_px(px);
}
return {};
}
Length Length::absolutized(CSSPixelRect const& viewport_rect, FontMetrics const& font_metrics, FontMetrics const& root_font_metrics) const
{
return absolutize(viewport_rect, font_metrics, root_font_metrics).value_or(*this);
}
}