When setting `font-family: monospace;` in CSS, we have to interpret
the keyword font sizes (small, medium, large, etc) as slightly smaller
for historical reasons. Normally the medium font size is 16px, but
for monospace it's 13px.
The way this needs to behave is extremely strange:
When encountering `font-family: monospace`, we have to go back and
replay the CSS cascade as if the medium font size had been 13px all
along. Otherwise relative values like 2em/200%/etc could have gotten
lost in the inheritance chain.
We implement this in a fairly naive way by explicitly checking for
`font-family: monospace` (note: it has to be *exactly* like that,
it can't be `font-family: monospace, Courier` or similar.)
When encountered, we simply walk the element ancestors and re-run the
cascade for the font-size property. This is clumsy and inefficient,
but it does work for the common cases.
Other browsers do more elaborate things that we should eventually care
about as well, such as user-configurable font settings, per-language
behavior, etc. For now, this is just something that allows us to handle
more WPT tests where things fall apart due to unexpected font sizes.
To learn more about the wonders of font-size, see this blog post:
https://manishearth.github.io/blog/2017/08/10/font-size-an-unexpectedly-complex-css-property/
By the time we're measuring the height of a BFC root, we've already
collapsed all relevant margins for the root and its descendants.
Given this, we should simply use 0 (relative to the BFC root) as the
lowest block axis coordinate (i.e Y value) for the margin edges.
This fixes a long-standing issue where BFC roots were sometimes not tall
enough to contain their children due to margins.
This was mainly a matter of deferring the wrapping of the button's
children until after its internal layout tree has been constructed.
That way we don't lose any pseudo elements spawned along the way.
Fixes#2397.
Fixes#2399.
When positioning floats against an edge, we are taking all current
relevant floats at that side into account to determine the Y offset at
which to place the new float. However, we were using the margin box
height instead of the absolute bottom position, which disregards the
current float's Y-position within the root, and we were setting the Y
offset to that height, instead of taking the new float's Y position
inside of the root into account.
The new code determines the lowest margin bottom value within the root
of the current floats, and adds the difference between that value and
the new float's Y position to the Y offset.
This improves the quality of our font rendering, especially when
animations are involved. Relevant changes:
* Skia fonts have their subpixel flag set, which means that individual
glyphs are rendered at subpixel offsets causing glyph runs as a
whole to look better.
* Fragment offsets are no longer rounded to whole device pixels, and
instead the floating point offset is kept. This allows us to pass
through the floating point baseline position all the way to the Skia
calls, which already expected that to be a float position.
The `scrollable-contains-table.html` ref test needed different table
headings since they would slightly inflate the column size in the test
file, but not the reference.
InlinePaintable was an ad-hoc paintable type required to support the
fragmentation of inline nodes across multiple lines. It existed because
there was no way to associate multiple paintables with a single layout
node. This resulted in a lot of duplicated code between PaintableBox and
InlinePaintable. For example, most of the CSS properties like
background, border, shadows, etc. and hit-testing are almost identical
for both of them. However, the code had to be duplicated to account for
the fact that InlinePaintable creates a box for each line. And we had
quite many places that operate on paintables with a code like:
```
if (box.is_paintable_box()) {
// do something
} else (box.is_inline_paintable()) {
// do exactly the same as for paintable box but using InlinePaintable
}
```
This change replaces the usage of `InlinePaintable` with
`PaintableWithLines` created for each line, which is now possible
because we support having multiple paintables per layout node. By doing
that, we remove lots of duplicated code and bring our implementation
closer to the spec.
It's possible to resolve box's height without doing inner layout, when
computed value is not auto. Doing that fixes height resolution, when box
with percentage height has containing block with percentage height.
Before:
- resolve used width
- layout box's content
- resolve height
After:
- resolve used width
- resolve height if treated as not auto
- layout box's content
- resolve height if treated as auto
When a block container has `clear` set and some clearance is applied,
that clearance prevents margins from adjoining and therefore resets
the margin state. But when a floating box has `clear` set, that
clearance only goes between floating boxes so should not reset margin
state. BlockFormattingContexts already do that correctly, and this PR
changes InlineFormattingContext to do the same.
Fixes#1462; adds reduced input from that issue as test.
The `calculate_inner_width()` and `calculate_inner_height()` resolve
percentage paddings using the width returned by
`containing_block_width_for()`. However, this function does not account
for grids where the containing block is defined by the grid area to
which an item belongs.
This change fixes the issue by modifying `calculate_inner_width()` and
`calculate_inner_height()` to use the already resolved paddings from the
layout state. Corresponding changes ensure that paddings are resolved
and saved in the state before box-sizing is handled.
As a side effect, this change also improves abspos layout for BFC where
now paddings are resolved using padding box of containing block instead
of content box of containing block.
Append text chunks to either the start or end of the text fragment,
depending on the text direction. The direction is determined by what
script its code points are from.
We now follow the rules from the spec more closely, along with an
unspecified quirk for when the offsetParent is a non-positioned body
element. (Spec bug linked in a comment.)
This fixes a whole bunch of css-flexbox tests on WPT, which already had
correct layout, but the reported metrics from JS API were wrong.
When traversing the layout tree to find an appropriate box child to
derive the baseline from. Only the child's margin and offset was being
applied. Now we sum each offset on the recursive call.
Like 1132c858e9, out-of-flow elements such
as float elements would get inserted into block level `::before` and
`::after` pseudo-element nodes when they should instead be inserted as a
sibling to the pseudo element. This change fixes that.
This fixes a few layout issues on the swedish tax agency website
(skatteverket.se). :^)
Although the flex algorithm as specified does say to determine the cross
size of the flex container, this is not how our layout engine works.
The parent formatting context is responsible for sizing its children,
and since that's already happening, we can simply remove the cross
sizing step from FFC.
When iterating inline level chunks for a piece of text like " hello ",
we will get three separate items from InlineLevelIterator:
- Text " "
- Text "hello"
- Text " "
If the first item also had some leading margin (e.g margin-left: 10px)
we would lose that information when deciding that the whitespace is
collapsible.
This patch fixes the issue by accumulating the amount of leading margin
present in any collapsed whitespace items, and then adding them to the
next non-whitespace item in IFC.
It's a wee bit hackish, but so is the rest of the leading/trailing
margin mechanism.
This makes the header menu on https://www.gimp.org/ look proper. :^)
The paintable tree structure more closely matches the painting order
when fragments are owned by corresponding inline paintables. This
change does not affect the layout tree, as it is more convenient for
layout purposes to have all fragments owned by a block container in
one place.
Additionally, this improves performance significantly on pages with
many fragments, as we no longer have to walk the ancestor chain up
to the closest block container to determine if a fragment belongs
to an inline paintable.
This is a part of refactoring towards making the paintable tree
independent of the layout tree. Now, instead of transferring text
fragments from the layout tree to the paintable tree during the layout
commit phase, we allocate separate PaintableFragments that contain only
the information necessary for painting. Doing this also allows us to
get rid LineBoxes, as they are used only during layout.
This patch makes a few changes to the way we calculate line-height:
- `line-height: normal` is now resolved using metrics from the used
font (specifically, round(A + D + lineGap)).
- `line-height: calc(...)` is now resolved at style compute time.
- `line-height` values are now absolutized at style compute time.
As a consequence of the above, we no longer need to walk the DOM
ancestor chain looking for line-heights during style computation.
Instead, values are inherited, resolved and absolutized locally.
This is not only much faster, but also makes our line-height metrics
match those of other engines like Gecko and Blink.
Out-of-flow boxes (floating and absolutely-positioned elements) were
previously collected and put in the anonymous block wrapper as well, but
this actually made hit testing not able to find them, since they were
breaking expectations about tree structure that hit testing relies on.
After this change, we simply let out-of-flow boxes stay in their
original parent, preserving the author's intended box tree structure.
Sizing already worked correctly, but before this change, we were too
aggressive with inserting line breaks when negative margins would
still an atomic inline to fit on the line.
When a box does not have a top, left, bottom, or right, there is no
need to adjust the offset for positioning relative to the padding edge,
because the box remains in the normal flow.
By using available_inner_space_or_constraints_from(available_space), we
ensure that the available space used to calculate the min/max content
height is constrained by the width specified for the box itself
(I know that at least GFC always expects available width to be
constrained by specified width if there is any).
This change improves layout in "Recent news" block on
https://telegram.org/
493dd5d93c caused the `::before`
pseudo-element node to be inserted before the element's content, which
caused issues with how we determine where to insert inline nodes into
the layout tree. At the time, I noticed the issue with contents of flex
containers, and prevented them from merging into a `::before` box.
However, a similar situation happens when we're not in a flex container,
but the pseudo-element has `display: block`. This commit fixes that
situation by using the same logic in both places, so a similar mistake
can't be made again.
This fixes the tab text being invisible on GitHub project pages. :^)
Before, we only ensured that boxes establishing BFC did not overlap
with floats because that is what CSS 2.2 specification says. However,
we should also apply the same for boxes establishing FFC or GFC as this
aligns with the behavior of other browsers.
Fixes https://github.com/SerenityOS/serenity/issues/21095
When calculating the edge offset of the next floating item based on the
offset of the preceding floating item, we need to ensure that the
preceding offset is always > 0. This isn't explicitly written in the
spec, but all other popular engines do that.
Fixes https://github.com/SerenityOS/serenity/issues/21023
Before, we completely ignored clearance for block-level boxes if they
were floated. This was incorrect because it is valid for a block-level
box to be floated and still have clearance. However, unlike clearance
on normal flow boxes, clearance on floating boxes does not affect the
y-position of subsequent normal flow boxes. Instead, it pushes the
box's position to the very beginning of an edge.
Work towards https://github.com/SerenityOS/serenity/issues/21023
When a button should use flex for alignment and also has ::before
and/or ::after, we previously did the following:
1. Prepended/appended the button's children with boxes for
pseudo-elements.
2. Replaced the button's direct children with a flex container that
contains its children.
As a result, the generated boxes for ::before/::after ended up as
children of the generated flex item, instead of being direct children
of the button layout box as they were supposed to be.
This change reverses these steps, ensuring that boxes for
pseudo-elements are generated only after modifications inside the
button layout are completed.
When modifying the button layout during tree building to use flex for
vertical alignment, let's explicitly set the button box's children to
be non-inline. It doesn't make sense to layout the button as an IFC
when its only child is a flex container.
Before, we were using the line height from NodeWithStyle::line_height()
to calculate the y offset for floats inside the IFC. However, this
value doesn't always correspond to the actual height of a line box. For
instance, adding a fragment for an inline-block might change the height
of the line box. With this change, we recalculate the height of the
line box after adding a new fragment and use this recalculated height
value to determine the y position for floats.
Fixes https://github.com/SerenityOS/serenity/issues/20982
Using flex layout inside button solves the issue with wrongly calculated
height when it has: pseudo element and whitespaces inside.
Also using flex instead of a table layout allows for the same vertical
alignment but with fewer layout nodes: a flex container and anonymous
wrapper for content instead of a table wrapper, table, row, and cell.
Previously we always set the height of the HTML element equal to the
viewport height but now this will only happen in quirks mode as it is
intended. Otherwise the html element height will be computed as auto.
Since we always pass the px value as an argument to resolved(), we can
pass it directly as CSSPixels instead of wrapping it in Length. This
approach allows us to avoid converting to a double, resulting in fewer
precision issues.
