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LibWeb: Wrap font metrics into a struct

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Rather than passing an increasingly-unwieldy number of font parameters
individually to every function that resolves lengths, let's wrap them
up.

This is frustratingly close to being `Gfx::FontPixelMetrics`, but bitmap
fonts cause issues: We choose the closest font to what the CSS
requests, but that might have a wildly different size than what the
page expects, so we have to fudge the numbers.

No behaviour changes.
This commit is contained in:
Sam Atkins 2023-04-28 16:29:12 +01:00 • committed by Andreas Kling
parent 4a191875a9
commit 0679b4e0b9
14 changed files with 107 additions and 62 deletions
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43
Userland/Libraries/LibWeb/CSS/Length.cpp
View file

@ -18,6 +18,14 @@
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)
, 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)
@ -59,22 +67,21 @@ Length Length::resolved(Layout::Node const& layout_node) const
return *this;
}
CSSPixels Length::relative_length_to_px(CSSPixelRect const& viewport_rect, Gfx::FontPixelMetrics const& font_metrics, CSSPixels font_size, CSSPixels root_font_size, CSSPixels line_height, CSSPixels root_line_height) const
CSSPixels Length::relative_length_to_px(CSSPixelRect const& viewport_rect, FontMetrics const& font_metrics, FontMetrics const& root_font_metrics) const
{
switch (m_type) {
case Type::Em:
return m_value * font_size;
return m_value * font_metrics.font_size;
case Type::Rem:
return m_value * root_font_size;
return m_value * root_font_metrics.font_size;
case Type::Ex:
return m_value * font_metrics.x_height;
case Type::Ch:
// FIXME: Use layout_node.font().pixel_size() when writing-mode is not horizontal-tb (it has to be implemented first)
return m_value * (font_metrics.advance_of_ascii_zero + font_metrics.glyph_spacing);
return m_value * font_metrics.zero_advance;
case Type::Lh:
return m_value * line_height;
return m_value * font_metrics.line_height;
case Type::Rlh:
return m_value * root_line_height;
return m_value * root_font_metrics.line_height;
case Type::Vw:
return viewport_rect.width() * (m_value / 100);
case Type::Vh:
@ -99,7 +106,19 @@ CSSPixels Length::to_px(Layout::Node const& layout_node) const
auto* root_element = layout_node.document().document_element();
if (!root_element || !root_element->layout_node())
return 0;
return to_px(viewport_rect, layout_node.font().pixel_metrics(), layout_node.computed_values().font_size(), root_element->layout_node()->computed_values().font_size(), layout_node.line_height(), root_element->layout_node()->line_height());
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 to_px(viewport_rect, font_metrics, root_font_metrics);
}
ErrorOr<String> Length::to_string() const
@ -193,20 +212,20 @@ Optional<Length::Type> Length::unit_from_name(StringView name)
return {};
}
Optional<Length> Length::absolutize(CSSPixelRect const& viewport_rect, Gfx::FontPixelMetrics const& font_metrics, CSSPixels font_size, CSSPixels root_font_size, CSSPixels line_height, CSSPixels root_line_height) const
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, font_size, root_font_size, line_height, root_line_height);
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, Gfx::FontPixelMetrics const& font_metrics, CSSPixels font_size, CSSPixels root_font_size, CSSPixels line_height, CSSPixels root_line_height) const
Length Length::absolutized(CSSPixelRect const& viewport_rect, FontMetrics const& font_metrics, FontMetrics const& root_font_metrics) const
{
return absolutize(viewport_rect, font_metrics, font_size, root_font_size, line_height, root_line_height).value_or(*this);
return absolutize(viewport_rect, font_metrics, root_font_metrics).value_or(*this);
}
}