537f289c0c
Prep for moving display-list rasterization out of LibWeb by moving the device-pixel corner radius, corner clip, and anti-aliasing types to LibGfx. Keep BorderRadiiData in LibWeb as the CSS-pixel representation and convert it to Gfx corner radii when recording display-list commands.
46 lines
2.2 KiB
C++
46 lines
2.2 KiB
C++
/*
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* Copyright (c) 2020, Andreas Kling <andreas@ladybird.org>
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* Copyright (c) 2021-2023, Sam Atkins <atkinssj@serenityos.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/Math.h>
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#include <LibGfx/CornerRadii.h>
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namespace Gfx {
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// https://drafts.csswg.org/css-backgrounds/#shadow-shape
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static void add_spread_distance_to_border_radius(int& border_radius, int spread_distance)
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{
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if (border_radius == 0 || spread_distance == 0)
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return;
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// To preserve the box's shape when spread is applied, the corner radii of the shadow are also increased (decreased,
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// for inner shadows) from the border-box (padding-box) radii by adding (subtracting) the spread distance (and flooring
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// at zero). However, in order to create a sharper corner when the border radius is small (and thus ensure continuity
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// between round and sharp corners), when the border radius is less than the spread distance (or in the case of an inner
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// shadow, less than the absolute value of a negative spread distance), the spread distance is first multiplied by the
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// proportion 1 + (r-1)^3, where r is the ratio of the border radius to the spread distance, in calculating the corner
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// radii of the spread shadow shape.
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if (border_radius > AK::abs(spread_distance)) {
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border_radius += spread_distance;
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} else {
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auto r = static_cast<float>(border_radius) / AK::abs(spread_distance);
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border_radius += spread_distance * (1 + AK::pow(r - 1, 3.0f));
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}
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}
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void CornerRadii::adjust_corners_for_spread_distance(int spread_distance)
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{
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add_spread_distance_to_border_radius(top_left.horizontal_radius, spread_distance);
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add_spread_distance_to_border_radius(top_left.vertical_radius, spread_distance);
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add_spread_distance_to_border_radius(top_right.horizontal_radius, spread_distance);
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add_spread_distance_to_border_radius(top_right.vertical_radius, spread_distance);
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add_spread_distance_to_border_radius(bottom_right.horizontal_radius, spread_distance);
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add_spread_distance_to_border_radius(bottom_right.vertical_radius, spread_distance);
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add_spread_distance_to_border_radius(bottom_left.horizontal_radius, spread_distance);
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add_spread_distance_to_border_radius(bottom_left.vertical_radius, spread_distance);
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}
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}
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