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Code Issues Projects Releases Packages Wiki Activity Actions 10

LibHTML: Implement basic 'max-width' and 'min-width' support

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These CSS properties constrain the computed width of a block-level box
to a maximum, followed by a minimum value.

This makes the "better mother fricken website" look more like it's
intended to (which helps makes the author's point, I suppose.)
This commit is contained in:
Andreas Kling 2019-11-18 12:21:37 +01:00
parent df16c9676b
commit b08de46480
Notes: sideshowbarker 2024-07-19 11:09:49 +09:00
1 changed files with 82 additions and 49 deletions
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131
Libraries/LibHTML/Layout/LayoutBlock.cpp
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@ -157,66 +157,99 @@ void LayoutBlock::compute_width()
auto auto_value = Length();
auto zero_value = Length(0, Length::Type::Absolute);
auto width = style.length_or_fallback(CSS::PropertyID::Width, auto_value);
auto margin_left = style.length_or_fallback(CSS::PropertyID::MarginLeft, zero_value);
auto margin_right = style.length_or_fallback(CSS::PropertyID::MarginRight, zero_value);
auto border_left = style.length_or_fallback(CSS::PropertyID::BorderLeftWidth, zero_value);
auto border_right = style.length_or_fallback(CSS::PropertyID::BorderRightWidth, zero_value);
auto padding_left = style.length_or_fallback(CSS::PropertyID::PaddingLeft, zero_value);
auto padding_right = style.length_or_fallback(CSS::PropertyID::PaddingRight, zero_value);
Length margin_left;
Length margin_right;
Length border_left;
Length border_right;
Length padding_left;
Length padding_right;
auto try_compute_width = [&](const auto& a_width) {
Length width = a_width;
#ifdef HTML_DEBUG
dbg() << " Left: " << margin_left << "+" << border_left << "+" << padding_left;
dbg() << "Right: " << margin_right << "+" << border_right << "+" << padding_right;
#endif
margin_left = style.length_or_fallback(CSS::PropertyID::MarginLeft, zero_value);
margin_right = style.length_or_fallback(CSS::PropertyID::MarginRight, zero_value);
border_left = style.length_or_fallback(CSS::PropertyID::BorderLeftWidth, zero_value);
border_right = style.length_or_fallback(CSS::PropertyID::BorderRightWidth, zero_value);
padding_left = style.length_or_fallback(CSS::PropertyID::PaddingLeft, zero_value);
padding_right = style.length_or_fallback(CSS::PropertyID::PaddingRight, zero_value);
int total_px = 0;
for (auto& value : { margin_left, border_left, padding_left, width, padding_right, border_right, margin_right }) {
total_px += value.to_px();
}
#ifdef HTML_DEBUG
dbg() << " Left: " << margin_left << "+" << border_left << "+" << padding_left;
dbg() << "Right: " << margin_right << "+" << border_right << "+" << padding_right;
dbg() << "Total: " << total_px;
#endif
int total_px = 0;
for (auto& value : { margin_left, border_left, padding_left, width, padding_right, border_right, margin_right }) {
total_px += value.to_px();
}
// 10.3.3 Block-level, non-replaced elements in normal flow
// If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
if (width.is_auto() && total_px > containing_block()->width()) {
if (margin_left.is_auto())
margin_left = zero_value;
if (margin_right.is_auto())
margin_right = zero_value;
}
#ifdef HTML_DEBUG
dbg() << "Total: " << total_px;
#endif
// 10.3.3 cont'd.
auto underflow_px = containing_block()->width() - total_px;
// 10.3.3 Block-level, non-replaced elements in normal flow
// If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width' (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then any 'auto' values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
if (width.is_auto() && total_px > containing_block()->width()) {
if (margin_left.is_auto())
margin_left = zero_value;
if (margin_right.is_auto())
margin_right = zero_value;
}
// 10.3.3 cont'd.
auto underflow_px = containing_block()->width() - total_px;
if (width.is_auto()) {
if (margin_left.is_auto())
margin_left = zero_value;
if (margin_right.is_auto())
margin_right = zero_value;
if (underflow_px >= 0) {
width = Length(underflow_px, Length::Type::Absolute);
if (width.is_auto()) {
if (margin_left.is_auto())
margin_left = zero_value;
if (margin_right.is_auto())
margin_right = zero_value;
if (underflow_px >= 0) {
width = Length(underflow_px, Length::Type::Absolute);
} else {
width = zero_value;
margin_right = Length(margin_right.to_px() + underflow_px, Length::Type::Absolute);
}
} else {
width = zero_value;
margin_right = Length(margin_right.to_px() + underflow_px, Length::Type::Absolute);
if (!margin_left.is_auto() && !margin_right.is_auto()) {
margin_right = Length(margin_right.to_px() + underflow_px, Length::Type::Absolute);
} else if (!margin_left.is_auto() && margin_right.is_auto()) {
margin_right = Length(underflow_px, Length::Type::Absolute);
} else if (margin_left.is_auto() && !margin_right.is_auto()) {
margin_left = Length(underflow_px, Length::Type::Absolute);
} else { // margin_left.is_auto() && margin_right.is_auto()
auto half_of_the_underflow = Length(underflow_px / 2, Length::Type::Absolute);
margin_left = half_of_the_underflow;
margin_right = half_of_the_underflow;
}
}
} else {
if (!margin_left.is_auto() && !margin_right.is_auto()) {
margin_right = Length(margin_right.to_px() + underflow_px, Length::Type::Absolute);
} else if (!margin_left.is_auto() && margin_right.is_auto()) {
margin_right = Length(underflow_px, Length::Type::Absolute);
} else if (margin_left.is_auto() && !margin_right.is_auto()) {
margin_left = Length(underflow_px, Length::Type::Absolute);
} else { // margin_left.is_auto() && margin_right.is_auto()
auto half_of_the_underflow = Length(underflow_px / 2, Length::Type::Absolute);
margin_left = half_of_the_underflow;
margin_right = half_of_the_underflow;
return width;
};
auto specified_width = style.length_or_fallback(CSS::PropertyID::Width, auto_value);
// 1. The tentative used width is calculated (without 'min-width' and 'max-width')
auto used_width = try_compute_width(specified_width);
// 2. The tentative used width is greater than 'max-width', the rules above are applied again,
// but this time using the computed value of 'max-width' as the computed value for 'width'.
auto specified_max_width = style.length_or_fallback(CSS::PropertyID::MaxWidth, auto_value);
if (!specified_max_width.is_auto()) {
if (used_width.to_px() > specified_max_width.to_px()) {
used_width = try_compute_width(specified_max_width);
}
}
rect().set_width(width.to_px());
// 3. If the resulting width is smaller than 'min-width', the rules above are applied again,
// but this time using the value of 'min-width' as the computed value for 'width'.
auto specified_min_width = style.length_or_fallback(CSS::PropertyID::MinWidth, auto_value);
if (!specified_min_width.is_auto()) {
if (used_width.to_px() < specified_min_width.to_px()) {
used_width = try_compute_width(specified_min_width);
}
}
rect().set_width(used_width.to_px());
box_model().margin().left = margin_left;
box_model().margin().right = margin_right;
box_model().border().left = border_left;