mirror of
https://github.com/LadybirdBrowser/ladybird.git
synced 2026-04-18 09:50:27 +00:00
80977b5fea
When an image has no intrinsic dimensions but has an intrinsic aspect ratio, the CSS default sizing algorithm should resolve its size as a contain constraint against the default object size. Previously, we returned the default size directly, which caused such images to stretch to fill the entire background positioning area. The SVG's default `preserveAspectRatio` would then center the content within that oversized viewport, making the image appear horizontally mispositioned.
65 lines
3.6 KiB
C++
65 lines
3.6 KiB
C++
/*
|
||
* Copyright (c) 2022, MacDue <macdue@dueutil.tech>
|
||
* Copyright (c) 2024, Sam Atkins <sam@ladybird.org>
|
||
*
|
||
* SPDX-License-Identifier: BSD-2-Clause
|
||
*/
|
||
|
||
#include "Sizing.h"
|
||
|
||
namespace Web::CSS {
|
||
|
||
// https://drafts.csswg.org/css-images/#default-sizing
|
||
CSSPixelSize run_default_sizing_algorithm(
|
||
Optional<CSSPixels> specified_width,
|
||
Optional<CSSPixels> specified_height,
|
||
SizeWithAspectRatio const& natural,
|
||
CSSPixelSize default_size)
|
||
{
|
||
// If the specified size is a definite width and height, the concrete object size is given that width and height.
|
||
if (specified_width.has_value() && specified_height.has_value())
|
||
return CSSPixelSize { specified_width.value(), specified_height.value() };
|
||
// If the specified size is only a width or height (but not both) then the concrete object size is given that specified width or height.
|
||
// The other dimension is calculated as follows:
|
||
if (specified_width.has_value() || specified_height.has_value()) {
|
||
// 1. If the object has a natural aspect ratio,
|
||
// the missing dimension of the concrete object size is calculated using that aspect ratio and the present dimension.
|
||
if (natural.has_aspect_ratio() && !natural.aspect_ratio->might_be_saturated()) {
|
||
if (specified_width.has_value())
|
||
return CSSPixelSize { specified_width.value(), (CSSPixels(1) / natural.aspect_ratio.value()) * specified_width.value() };
|
||
if (specified_height.has_value())
|
||
return CSSPixelSize { specified_height.value() * natural.aspect_ratio.value(), specified_height.value() };
|
||
}
|
||
// 2. Otherwise, if the missing dimension is present in the object’s natural dimensions,
|
||
// the missing dimension is taken from the object’s natural dimensions.
|
||
if (specified_height.has_value() && natural.has_width())
|
||
return CSSPixelSize { natural.width.value(), specified_height.value() };
|
||
if (specified_width.has_value() && natural.has_height())
|
||
return CSSPixelSize { specified_width.value(), natural.height.value() };
|
||
// 3. Otherwise, the missing dimension of the concrete object size is taken from the default object size.
|
||
if (specified_height.has_value())
|
||
return CSSPixelSize { default_size.width(), specified_height.value() };
|
||
if (specified_width.has_value())
|
||
return CSSPixelSize { specified_width.value(), default_size.height() };
|
||
VERIFY_NOT_REACHED();
|
||
}
|
||
// If the specified size has no constraints:
|
||
// 1. If the object has a natural height or width, its size is resolved as if its natural dimensions were given as the specified size.
|
||
if (natural.has_width() || natural.has_height())
|
||
return run_default_sizing_algorithm(natural.width, natural.height, natural, default_size);
|
||
|
||
// 2. Otherwise, its size is resolved as a contain constraint against the default object size.
|
||
if (natural.has_aspect_ratio() && !natural.aspect_ratio->might_be_saturated()) {
|
||
auto aspect_ratio = natural.aspect_ratio.value();
|
||
if (default_size.is_empty())
|
||
return default_size;
|
||
auto default_width = default_size.width().to_double();
|
||
auto default_height = default_size.height().to_double();
|
||
if (aspect_ratio.to_double() >= default_width / default_height)
|
||
return CSSPixelSize { default_size.width(), CSSPixels::nearest_value_for(default_width / aspect_ratio.to_double()) };
|
||
return CSSPixelSize { CSSPixels::nearest_value_for(default_height * aspect_ratio.to_double()), default_size.height() };
|
||
}
|
||
return default_size;
|
||
}
|
||
|
||
}
|