Once we've performed the cascade on a set of values for an element,
we should have enough information to resolve/absolutize some lengths.
Basically, any CSS length that isn't "auto" or a percentage can be
turned into an absolute length (in pixels) as long as we have the
following information:
- The viewport rect
- The parent element's font
- The document element's font
- The element's own font
To ensure that we can absolutize lengths relative to the element's own
font, we now do a separate first pass where font-related properties are
defaulted (in the cascade spec sense of the word) and become usable.
There's a lot more work to do here, but this should open up a lot of
simplification in layout code, since it will no longer need to care
about relative lengths. Layout still needs to resolve percentages, since
we can't do that for some properties until the containing block
dimensions are known.
The original name was based on the window.getComputedStyle() API.
However, "Computed" in "getComputedStyle" is actually a misnomer that
the platform is stuck with due to backwards compatibility.
What getComputedStyle() returns is actually a mix of computed and used
values. The spec calls it the "resolved" values. So let's call this
declaration subclass "ResolvedCSSStyleDeclaration" to match.
This replaces a bunch of casts with `.as_foo()` calls, and adjusts calls
to the old `is_foo()` methods that now are better as `has_foo()`.
Also tidied up some whitespace to be more consistent.
This does a few things, that are hard to separate. For a while now, it's
been confuzing what `StyleValue::is_foo()` actually means. It sometimes
was used to check the type, and sometimes to see if it could return a
certain value type. The new naming scheme is:
- `is_length()` - is it a LengthStyleValue?
- `as_length()` - casts it to LengthStyleValue
- `has_length()` - can it return a Length?
- `to_length()` - gets the internal value out (eg, Length)
This also means, no more `static_cast<LengthStyleValue const&>(*this)`
stuff when dealing with StyleValues. :^)
Hopefully this will be a bit clearer going forward. There are lots of
places using the original methods, so I'll be going through them to
hopefully catch any issues.
FontPickerWeightModel is no longer necessary as variants contain
weight as part of a complete typeface description. This fixes fonts
not inventorying correctly in picker when they contained more than
bold and regular typefaces. Weight mapping has been moved into
LibGfx/FontStyleMapping.h
Previously the algorithm was being performed from the start of the
string to the end, which was a little more convenient when writing
the code, but made it more annoying to be able to properly talk
about the "start" of where the changes were happening, since we
can only re-construct the changes in reverse order of the initial
traversal.
Basically, doing the initial pass in reverse lets us reconstruct
the hunks in the correct order to begin with, and not have to worry
about reversing the hunks / lines within the hunks
This behaves very much like the regular diff command, showing the
start lines and ranges of additions/changes/deletions in both the
source and target files.
Previously any children would be layout using a BlockFormattingContext.
Now we at least differentiate between IFC and BFC if the sizes in
question are not constrained by other things.
Calling `is_identifier()` here was wrong, since it just means you can
get an Identifier from it. This meant that an `auto` LengthStyleValue
would return true, then it would get `static_cast` to the wrong class,
and return a garbage value.
Basically, I really need to tidy up the API for StyleValue, so it's
clear whether `is_foo()` means the object is a `FooStyleValue`, or it
can just return a `foo` value.
For `number` and `integer` types, you can add a range afterwards to add
a range check, using similar syntax to that used in the CSS specs. For
example:
```json
"font-weight": {
...
"valid-types": [
"number [1,1000]"
],
...
}
```
This limits any numbers to the range `1 <= n <= 1000`.
