We were introducing a line break and applying vertical clearance to the
inline formatting context, but that vertical clearance only applied to
new floating boxes. We should move the current block offset to the
vertical clearance to make sure the next line box starts beyond the
cleared floats.
There was a layout test for `<br>` with `clear: ..` set, but that test
did not actually do anything - removing the `clear` property would
result in the same layout. Replace that test with something that
actually tests float clearing.
Relates to #4058.
When generating line boxes, we place floats simultaneously with the
other items on the same line. The CSS text spec requires us to trim the
whitespace at the end of each line, but we only did so after laying out
all the line boxes.
This changes the way we calculate the current line box width for floats
by subtracting the amount of pixels that the current trailing whitespace
is using.
Fixes#4050.
We were only pruning trailing whitespace on lines. This patch makes it
so we also don't add whitespace as the leading line box fragment on new
lines.
This logic is pretty crufty and I think we can do better, but for now
I've just made it handle this extra case so we can stop having lines
that start with a space character. :^)
In order for inline elements (e.g <span>) to contribute padding etc.
to line boxes, we now create special "leading" and "trailing" fragments
for Layout::InlineNode and size them according to the horizontal
padding values.
The height of these fragments is taken from the tallest fragment on the
line. (Perhaps we should stop having per-fragment heights and just keep
a single height per line box, but that's a separate issue.)
In order to make things look nice, we now also adjust the height of all
fragments on a line so that nobody is shorter than the CSS line-height.
Bring the names of various boxes closer to spec language. This should
hopefully make things easier to understand and hack on. :^)
Some notable changes:
- LayoutNode -> Layout::Node
- LayoutBox -> Layout::Box
- LayoutBlock -> Layout::BlockBox
- LayoutReplaced -> Layout::ReplacedBox
- LayoutDocument -> Layout::InitialContainingBlockBox
- LayoutText -> Layout::TextNode
- LayoutInline -> Layout::InlineNode
Note that this is not strictly a "box tree" as we also hang inline/text
nodes in the same tree, and they don't generate boxes. (Instead, they
contribute line box fragments to their containing block!)
This kind of HTML now produces a single piece of whitespace:
<span> </span> <span> </span> <span> </span>
We achieve this by checking if the last fragment on the last line ends
in whitespace. If so, we either don't add a fragment at all (for the
current chunk) or we simply skip over all whitespace at the head of
the current chunk (instead of collapsing it to a single ' '.)
The box tree and line boxes now all store a relative offset from their
containing block, instead of an absolute (document-relative) position.
This removes a huge pain point from the layout system which was having
to adjust offsets recursively when something moved. It also makes some
layout logic significantly simpler.
Every box can still find its absolute position by walking its chain
of containing blocks and accumulating the translation from the root.
This is currently what we do both for rendering and hit testing.
