The name "initial containing block" was wrong for this, as it doesn't
correspond to the HTML element, and that's specifically what it's
supposed to do! :^)
This commit moves both the ImageStyleValue and LinearGradientStyleValue
to a common base class of AbstractImageStyleValue. This abstracts
getting the natural_width/height, loading/resolving, and painting
the image.
Now for 'free' you get:
- Linear gradients working with the various background sizing/repeat
properties.
- Linear gradients working as list-markers :^) -- best feature ever!
P.s. This commit is a little large as it's tricky to make this change
incrementally without breaking things.
This is just a quick test that everything is working. Currently
it paints the gradients with the existing
painter.fill_rect_with_gradient(). This can only handle two-color
orthogonal gradients.
Previously, this was slightly off and not doing what the spec comment
above asked for. This led to really small values for x_step and
y_step, making the `backgrounds.html' example use crazy amounts of
CPU whist painting.
This commit adds some much nicer border painting, which now supports:
- Elliptical corners
- Blending between different border thicknesses, with rounded corners
- Anti-aliasing
There are some little TODOs left to tackle:
- Painting the corners with line styles other than solid
- Blending between colors on the corners (see comments)
The painting requires allocating a small bitmap, that only fits the
corners (so in most cases this is very small).
This bitmap is then cached so for all paints but the first there will
be no further allocations.
Preserve floating point precision and delay rounding until the last
moment when figuring out where to paint background layers. This fixes an
issue on Acid3 where a thin sliver of red was visible because the
background X position was incorrectly rounded by 1px.
By using enclosing_int_rect(), borders and backgrounds of boxes were
sometimes 1 pixel off, making things slightly larger than they should
be. Fix this by using to_rounded() instead of enclosing_int_rect().
There's definitely more of these type of issues lurking in the code,
and we'll get to them in time.
This fixes the placement of several background images on Acid2, most
notably the background of the eyes and the red rectangle near the bottom
of the head.
Nobody makes undefined Lengths now, (although actually removing
Undefined will come in a later commit) so we can remove this parameter,
and `resolved_or_auto()`/`resolved_or_zero()`.
Most of the time, we cannot resolve a `calc()` expression until we go to
use it. Since any `<length-percentage>` can legally be a `calc
()`, let's store it in `LengthPercentage` rather than make every single
user care about this distinction.
Despite looking like it was still needed, it was only used for passing
to other calls to Length::resolved() recursively. This makes the
various `foo.resolved().resolved()` calls a lot less awkward.
(Though, still quite awkward.)
I think we'd need to separate calculated lengths out to properly tidy
these calls up, but one yak at a time. :^)
This reimplements image tiling instead of using `Painter::blit_tiled()`,
so that we will be able to handle CSS's more complicated repetition
rules. (Like `background-repeat: space`) Otherwise this does the same as
before. :^)
Previously, a `background-repeat` value of `no-repeat` in a direction
would cause the image to be drawn at exactly that size. This was fine if
the image was smaller than the element, but if it was larger, it would
draw outside its bounds. Now, it behaves itself. :^)
