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LibWeb: Apply 'min-width' and 'max-width' constraints to replaced boxes

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This is definitely not 100% correct but I tried implementing the basic
algorithms described in CSS 2.2. It's good enough to render the penguin
on @linusg's homepage at the right size. :^)
This commit is contained in:
Andreas Kling 2020-12-12 00:20:31 +01:00
parent 63067ada68
commit b60801a9ba
3 changed files with 120 additions and 37 deletions
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153
Libraries/LibWeb/Layout/FormattingContext.cpp
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@ -120,6 +120,78 @@ FormattingContext::ShrinkToFitResult FormattingContext::calculate_shrink_to_fit_
return { preferred_width, preferred_minimum_width };
}
static Gfx::FloatSize solve_replaced_size_constraint(float w, float h, const ReplacedBox& box)
{
// 10.4 Minimum and maximum widths: 'min-width' and 'max-width'
auto& containing_block = *box.containing_block();
auto specified_min_width = box.style().min_width().resolved_or_zero(box, containing_block.width()).to_px(box);
auto specified_max_width = box.style().max_width().resolved(CSS::Length::make_px(w), box, containing_block.width()).to_px(box);
auto specified_min_height = box.style().min_height().resolved_or_auto(box, containing_block.height()).to_px(box);
auto specified_max_height = box.style().max_height().resolved(CSS::Length::make_px(h), box, containing_block.height()).to_px(box);
auto min_width = min(specified_min_width, specified_max_width);
auto max_width = max(specified_min_width, specified_max_width);
auto min_height = min(specified_min_height, specified_max_height);
auto max_height = max(specified_min_height, specified_max_height);
if (w > max_width)
return { w, max(max_width * h / w, min_height) };
if (w < min_width)
return { max_width, min(min_width * h / w, max_height) };
if (h > max_height)
return { max(max_height * w / h, min_width), max_height };
if (h < min_height)
return { min(min_height * w / h, max_width), min_height };
if ((w > max_width && h > max_height) && (max_width / w < max_height / h))
return { max_width, max(min_height, max_width * h / w) };
if ((w > max_width && h > max_height) && (max_width / w > max_height / h))
return { max(min_width, max_height * w / h), max_height };
if ((w < min_width && h < min_height) && (min_width / w < min_height / h))
return { min(max_width, min_height * w / h), min_height };
if ((w < min_width && h < min_height) && (min_width / w > min_height / h))
return { min_width, min(max_height, min_width * h / w) };
if (w < min_width && h > max_height)
return { min_width, max_height };
if (w > max_width && h < min_height)
return { max_width, min_height };
return { w, h };
}
float FormattingContext::tentative_width_for_replaced_element(const ReplacedBox& box, const CSS::Length& width)
{
auto& containing_block = *box.containing_block();
auto specified_height = box.style().height().resolved_or_auto(box, containing_block.height());
float used_width = width.to_px(box);
// If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic width,
// then that intrinsic width is the used value of 'width'.
if (specified_height.is_auto() && width.is_auto() && box.has_intrinsic_width()) {
used_width = box.intrinsic_width();
}
// If 'height' and 'width' both have computed values of 'auto' and the element has no intrinsic width,
// but does have an intrinsic height and intrinsic ratio;
// or if 'width' has a computed value of 'auto',
// 'height' has some other computed value, and the element does have an intrinsic ratio; then the used value of 'width' is:
//
// (used height) * (intrinsic ratio)
else if ((specified_height.is_auto() && width.is_auto() && !box.has_intrinsic_width() && box.has_intrinsic_height() && box.has_intrinsic_ratio()) || (width.is_auto() && box.has_intrinsic_ratio())) {
used_width = compute_height_for_replaced_element(box) * box.intrinsic_ratio();
}
else if (width.is_auto() && box.has_intrinsic_width()) {
used_width = box.intrinsic_width();
}
else if (width.is_auto()) {
used_width = 300;
}
return used_width;
}
float FormattingContext::compute_width_for_replaced_element(const ReplacedBox& box)
{
// 10.3.4 Block-level, replaced elements in normal flow...
@ -138,61 +210,68 @@ float FormattingContext::compute_width_for_replaced_element(const ReplacedBox& b
margin_right = zero_value;
auto specified_width = box.style().width().resolved_or_auto(box, containing_block.width());
auto specified_height = box.style().height().resolved_or_auto(box, containing_block.height());
// FIXME: Actually compute 'width'
auto computed_width = specified_width;
// 1. The tentative used width is calculated (without 'min-width' and 'max-width')
auto used_width = tentative_width_for_replaced_element(box, specified_width);
float used_width = specified_width.to_px(box);
// If 'height' and 'width' both have computed values of 'auto' and the element also has an intrinsic width,
// then that intrinsic width is the used value of 'width'.
if (specified_height.is_auto() && specified_width.is_auto() && box.has_intrinsic_width()) {
used_width = box.intrinsic_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 = box.style().max_width().resolved_or_auto(box, containing_block.width());
if (!specified_max_width.is_auto()) {
if (used_width > specified_max_width.to_px(box)) {
used_width = tentative_width_for_replaced_element(box, specified_max_width);
}
}
// If 'height' and 'width' both have computed values of 'auto' and the element has no intrinsic width,
// but does have an intrinsic height and intrinsic ratio;
// or if 'width' has a computed value of 'auto',
// 'height' has some other computed value, and the element does have an intrinsic ratio; then the used value of 'width' is:
//
// (used height) * (intrinsic ratio)
else if ((specified_height.is_auto() && specified_width.is_auto() && !box.has_intrinsic_width() && box.has_intrinsic_height() && box.has_intrinsic_ratio()) || (computed_width.is_auto() && box.has_intrinsic_ratio())) {
used_width = compute_height_for_replaced_element(box) * box.intrinsic_ratio();
}
else if (computed_width.is_auto() && box.has_intrinsic_width()) {
used_width = box.intrinsic_width();
}
else if (computed_width.is_auto()) {
used_width = 300;
// 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 = box.style().min_width().resolved_or_auto(box, containing_block.width());
if (!specified_min_width.is_auto()) {
if (used_width < specified_min_width.to_px(box)) {
used_width = tentative_width_for_replaced_element(box, specified_min_width);
}
}
return used_width;
}
float FormattingContext::tentative_height_for_replaced_element(const ReplacedBox& box, const CSS::Length& height)
{
auto& containing_block = *box.containing_block();
auto specified_width = box.style().width().resolved_or_auto(box, containing_block.width());
float used_height = height.to_px(box);
// If 'height' and 'width' both have computed values of 'auto' and the element also has
// an intrinsic height, then that intrinsic height is the used value of 'height'.
if (specified_width.is_auto() && height.is_auto() && box.has_intrinsic_height())
used_height = box.intrinsic_height();
else if (height.is_auto() && box.has_intrinsic_ratio())
used_height = compute_width_for_replaced_element(box) / box.intrinsic_ratio();
else if (height.is_auto() && box.has_intrinsic_height())
used_height = box.intrinsic_height();
else if (height.is_auto())
used_height = 150;
return used_height;
}
float FormattingContext::compute_height_for_replaced_element(const ReplacedBox& box)
{
// 10.6.2 Inline replaced elements, block-level replaced elements in normal flow,
// 'inline-block' replaced elements in normal flow and floating replaced elements
auto& containing_block = *box.containing_block();
auto& containing_block = *box.containing_block();
auto specified_width = box.style().width().resolved_or_auto(box, containing_block.width());
auto specified_height = box.style().height().resolved_or_auto(box, containing_block.height());
float used_height = specified_height.to_px(box);
float used_height = tentative_height_for_replaced_element(box, specified_height);
// If 'height' and 'width' both have computed values of 'auto' and the element also has
// an intrinsic height, then that intrinsic height is the used value of 'height'.
if (specified_width.is_auto() && specified_height.is_auto() && box.has_intrinsic_height())
used_height = box.intrinsic_height();
else if (specified_height.is_auto() && box.has_intrinsic_ratio())
used_height = compute_width_for_replaced_element(box) / box.intrinsic_ratio();
else if (specified_height.is_auto() && box.has_intrinsic_height())
used_height = box.intrinsic_height();
else if (specified_height.is_auto())
used_height = 150;
if (specified_width.is_auto() && specified_height.is_auto() && box.has_intrinsic_ratio()) {
float w = tentative_width_for_replaced_element(box, specified_width);
float h = used_height;
used_height = solve_replaced_size_constraint(w, h, box).height();
}
return used_height;
}