360c0eb509
In general it is not safe to convert any arbitrary floating-point value to CSSPixels. CSSPixels has a resolution of 0.015625, which for small values (e.g. scale factors between 0 and 1), can produce bad results if converted to CSSPixels then scaled back up. In the worst case values can underflow to zero and produce incorrect results.
106 lines
3.7 KiB
C++
106 lines
3.7 KiB
C++
/*
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* Copyright (c) 2022-2023, MacDue <macdue@dueutil.tech>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include "Position.h"
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#include <LibGfx/Point.h>
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#include <LibGfx/Rect.h>
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namespace Web::CSS {
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CSSPixelPoint PositionValue::resolved(Layout::Node const& node, CSSPixelRect const& rect) const
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{
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// Note: A preset + a none default x/y_relative_to is impossible in the syntax (and makes little sense)
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CSSPixels x = horizontal_position.visit(
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[&](HorizontalPreset preset) -> CSSPixels {
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return rect.width() * [&] {
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switch (preset) {
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case HorizontalPreset::Left:
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return CSSPixels(0.0);
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case HorizontalPreset::Center:
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return CSSPixels(0.5);
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case HorizontalPreset::Right:
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return CSSPixels(1.0);
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default:
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VERIFY_NOT_REACHED();
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}
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}();
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},
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[&](LengthPercentage length_percentage) -> CSSPixels {
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return length_percentage.to_px(node, rect.width());
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});
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CSSPixels y = vertical_position.visit(
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[&](VerticalPreset preset) -> CSSPixels {
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return rect.height() * [&] {
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switch (preset) {
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case VerticalPreset::Top:
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return CSSPixels(0.0);
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case VerticalPreset::Center:
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return CSSPixels(0.5);
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case VerticalPreset::Bottom:
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return CSSPixels(1.0);
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default:
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VERIFY_NOT_REACHED();
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}
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}();
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},
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[&](LengthPercentage length_percentage) -> CSSPixels {
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return length_percentage.to_px(node, rect.height());
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});
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if (x_relative_to == HorizontalEdge::Right)
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x = rect.width() - x;
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if (y_relative_to == VerticalEdge::Bottom)
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y = rect.height() - y;
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return CSSPixelPoint { rect.x() + x, rect.y() + y };
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}
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void PositionValue::serialize(StringBuilder& builder) const
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{
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// Note: This means our serialization with simplify any with explicit edges that are just `top left`.
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bool has_relative_edges = x_relative_to == HorizontalEdge::Right || y_relative_to == VerticalEdge::Bottom;
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if (has_relative_edges)
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builder.append(x_relative_to == HorizontalEdge::Left ? "left "sv : "right "sv);
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horizontal_position.visit(
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[&](HorizontalPreset preset) {
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builder.append([&] {
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switch (preset) {
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case HorizontalPreset::Left:
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return "left"sv;
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case HorizontalPreset::Center:
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return "center"sv;
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case HorizontalPreset::Right:
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return "right"sv;
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default:
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VERIFY_NOT_REACHED();
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}
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}());
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},
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[&](LengthPercentage length_percentage) {
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builder.append(length_percentage.to_string());
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});
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builder.append(' ');
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if (has_relative_edges)
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builder.append(y_relative_to == VerticalEdge::Top ? "top "sv : "bottom "sv);
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vertical_position.visit(
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[&](VerticalPreset preset) {
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builder.append([&] {
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switch (preset) {
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case VerticalPreset::Top:
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return "top"sv;
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case VerticalPreset::Center:
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return "center"sv;
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case VerticalPreset::Bottom:
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return "bottom"sv;
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default:
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VERIFY_NOT_REACHED();
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}
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}());
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},
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[&](LengthPercentage length_percentage) {
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builder.append(length_percentage.to_string());
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});
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}
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}
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