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115e5f42af
While 788d5368a7 took care of better text
marker positioning, this improves graphical marker positioning instead.
By looking at how Firefox and Chrome render markers, it's clear that
there are three parts to positioning a graphical marker:
* The containing space that the marker resides in;
* The marker dimensions;
* The distance between the marker and the start of the list item.
The space that the marker can be contained in, is the area to the left
of the list item with a height of the marker's line-height. The marker
dimensions are relative to the marker's font's pixel size: most of them
are a square at 35% of the font size, but the disclosure markers are
sized at 50% instead. Finally, the marker distance is always gauged at
50% of the font size.
So for example, a list item with `list-style-type: disc` and `font-size:
20px`, has 10px between its start and the right side of the marker, and
the marker's dimensions are 7x7.
The percentages I've chosen closely resemble how Firefox lays out its
list item markers.
123 lines
5.3 KiB
C++
123 lines
5.3 KiB
C++
/*
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* Copyright (c) 2018-2022, Andreas Kling <andreas@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <LibGC/Heap.h>
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#include <LibWeb/Layout/ListItemMarkerBox.h>
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#include <LibWeb/Painting/DisplayListRecorder.h>
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#include <LibWeb/Painting/MarkerPaintable.h>
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namespace Web::Painting {
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GC_DEFINE_ALLOCATOR(MarkerPaintable);
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GC::Ref<MarkerPaintable> MarkerPaintable::create(Layout::ListItemMarkerBox const& layout_box)
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{
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return layout_box.heap().allocate<MarkerPaintable>(layout_box);
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}
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MarkerPaintable::MarkerPaintable(Layout::ListItemMarkerBox const& layout_box)
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: PaintableBox(layout_box)
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{
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}
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Layout::ListItemMarkerBox const& MarkerPaintable::layout_box() const
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{
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return static_cast<Layout::ListItemMarkerBox const&>(layout_node());
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}
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constexpr float sin_60_deg = 0.866025403f;
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void MarkerPaintable::paint(PaintContext& context, PaintPhase phase) const
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{
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if (!is_visible())
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return;
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if (phase == PaintPhase::Overlay)
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PaintableBox::paint(context, phase);
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if (phase != PaintPhase::Foreground)
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return;
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auto marker_rect = absolute_rect().to_rounded<CSSPixels>();
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auto device_rect = context.enclosing_device_rect(marker_rect);
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if (auto const* list_style_image = layout_box().list_style_image()) {
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list_style_image->resolve_for_size(layout_box(), marker_rect.size());
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list_style_image->paint(context, device_rect, computed_values().image_rendering());
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return;
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}
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float left = device_rect.x().value();
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float right = left + device_rect.width().value();
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float top = device_rect.y().value();
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float bottom = top + device_rect.height().value();
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auto color = computed_values().color();
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if (auto text = layout_box().text(); text.has_value()) {
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// FIXME: This should use proper text layout logic!
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// This does not line up with the text in the <li> element which looks very sad :(
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context.display_list_recorder().draw_text(device_rect.to_type<int>(), *text, layout_box().font(context), Gfx::TextAlignment::Center, color);
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} else if (auto const* counter_style = layout_box().list_style_type().get_pointer<CSS::CounterStyleNameKeyword>()) {
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switch (*counter_style) {
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case CSS::CounterStyleNameKeyword::Square:
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context.display_list_recorder().fill_rect(device_rect.to_type<int>(), color);
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break;
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case CSS::CounterStyleNameKeyword::Circle:
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context.display_list_recorder().draw_ellipse(device_rect.to_type<int>(), color, 1);
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break;
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case CSS::CounterStyleNameKeyword::Disc:
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context.display_list_recorder().fill_ellipse(device_rect.to_type<int>(), color);
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break;
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case CSS::CounterStyleNameKeyword::DisclosureClosed: {
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// https://drafts.csswg.org/css-counter-styles-3/#disclosure-closed
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// For the disclosure-open and disclosure-closed counter styles, the marker must be an image or character
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// suitable for indicating the open and closed states of a disclosure widget, such as HTML’s details element.
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// FIXME: If the image is directional, it must respond to the writing mode of the element, similar to the
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// bidi-sensitive images feature of the Images 4 module.
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// Draw an equilateral triangle pointing right.
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auto path = Gfx::Path();
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path.move_to({ left, top });
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path.line_to({ left + sin_60_deg * (right - left), (top + bottom) / 2 });
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path.line_to({ left, bottom });
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path.close();
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context.display_list_recorder().fill_path({ .path = path, .color = color, .winding_rule = Gfx::WindingRule::EvenOdd });
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break;
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}
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case CSS::CounterStyleNameKeyword::DisclosureOpen: {
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// https://drafts.csswg.org/css-counter-styles-3/#disclosure-open
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// For the disclosure-open and disclosure-closed counter styles, the marker must be an image or character
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// suitable for indicating the open and closed states of a disclosure widget, such as HTML’s details element.
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// FIXME: If the image is directional, it must respond to the writing mode of the element, similar to the
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// bidi-sensitive images feature of the Images 4 module.
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// Draw an equilateral triangle pointing down.
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auto path = Gfx::Path();
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path.move_to({ left, top });
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path.line_to({ right, top });
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path.line_to({ (left + right) / 2, top + sin_60_deg * (bottom - top) });
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path.close();
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context.display_list_recorder().fill_path({ .path = path, .color = color, .winding_rule = Gfx::WindingRule::EvenOdd });
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break;
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}
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case CSS::CounterStyleNameKeyword::None:
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return;
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case CSS::CounterStyleNameKeyword::Decimal:
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case CSS::CounterStyleNameKeyword::DecimalLeadingZero:
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case CSS::CounterStyleNameKeyword::LowerAlpha:
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case CSS::CounterStyleNameKeyword::LowerLatin:
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case CSS::CounterStyleNameKeyword::LowerRoman:
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case CSS::CounterStyleNameKeyword::UpperAlpha:
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case CSS::CounterStyleNameKeyword::UpperLatin:
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case CSS::CounterStyleNameKeyword::UpperRoman:
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// These are handled by text() already.
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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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}
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