ladybird/Userland/Libraries/LibWeb/CSS/Position.cpp
Andreas Kling 655d9d1462 LibWeb: Make CSSPixels and Length use 64-bit (double) floating point
This fixes a plethora of rounding problems on many websites.
In the future, we may want to replace this with fixed-point arithmetic
(bug #18566) for performance (and consistency with other engines),
but in the meantime this makes the web look a bit better. :^)

There's a lot more things that could be converted to doubles, which
would reduce the amount of casting necessary in this patch.
We can do that incrementally, however.
2023-05-24 14:40:35 +02:00

108 lines
3.8 KiB
C++

/*
* Copyright (c) 2022-2023, MacDue <macdue@dueutil.tech>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "Position.h"
#include <LibGfx/Point.h>
#include <LibGfx/Rect.h>
namespace Web::CSS {
CSSPixelPoint PositionValue::resolved(Layout::Node const& node, CSSPixelRect const& rect) const
{
// Note: A preset + a none default x/y_relative_to is impossible in the syntax (and makes little sense)
CSSPixels x = horizontal_position.visit(
[&](HorizontalPreset preset) -> CSSPixels {
return rect.width() * [&] {
switch (preset) {
case HorizontalPreset::Left:
return 0.;
case HorizontalPreset::Center:
return 0.5;
case HorizontalPreset::Right:
return 1.;
default:
VERIFY_NOT_REACHED();
}
}();
},
[&](LengthPercentage length_percentage) -> CSSPixels {
return length_percentage.to_px(node, rect.width());
});
CSSPixels y = vertical_position.visit(
[&](VerticalPreset preset) -> CSSPixels {
return rect.height() * [&] {
switch (preset) {
case VerticalPreset::Top:
return 0.;
case VerticalPreset::Center:
return 0.5;
case VerticalPreset::Bottom:
return 1.;
default:
VERIFY_NOT_REACHED();
}
}();
},
[&](LengthPercentage length_percentage) -> CSSPixels {
return length_percentage.to_px(node, rect.height());
});
if (x_relative_to == HorizontalEdge::Right)
x = rect.width() - x;
if (y_relative_to == VerticalEdge::Bottom)
y = rect.height() - y;
return CSSPixelPoint { rect.x() + x, rect.y() + y };
}
ErrorOr<void> PositionValue::serialize(StringBuilder& builder) const
{
// Note: This means our serialization with simplify any with explicit edges that are just `top left`.
bool has_relative_edges = x_relative_to == HorizontalEdge::Right || y_relative_to == VerticalEdge::Bottom;
if (has_relative_edges)
TRY(builder.try_append(x_relative_to == HorizontalEdge::Left ? "left "sv : "right "sv));
TRY(horizontal_position.visit(
[&](HorizontalPreset preset) -> ErrorOr<void> {
return builder.try_append([&] {
switch (preset) {
case HorizontalPreset::Left:
return "left"sv;
case HorizontalPreset::Center:
return "center"sv;
case HorizontalPreset::Right:
return "right"sv;
default:
VERIFY_NOT_REACHED();
}
}());
},
[&](LengthPercentage length_percentage) -> ErrorOr<void> {
return builder.try_appendff(TRY(length_percentage.to_string()));
}));
TRY(builder.try_append(' '));
if (has_relative_edges)
TRY(builder.try_append(y_relative_to == VerticalEdge::Top ? "top "sv : "bottom "sv));
TRY(vertical_position.visit(
[&](VerticalPreset preset) -> ErrorOr<void> {
return builder.try_append([&] {
switch (preset) {
case VerticalPreset::Top:
return "top"sv;
case VerticalPreset::Center:
return "center"sv;
case VerticalPreset::Bottom:
return "bottom"sv;
default:
VERIFY_NOT_REACHED();
}
}());
},
[&](LengthPercentage length_percentage) -> ErrorOr<void> {
return builder.try_append(TRY(length_percentage.to_string()));
}));
return {};
}
}