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style: Simplify computed::LengthOrPercentage and friends.

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This is a first step to share LengthOrPercentage representation between Rust and
Gecko.

We need to preserve whether the value came from a calc() expression, for now at
least, since we do different things depending on whether we're calc or not right
now. See https://github.com/w3c/csswg-drafts/issues/3482 and dependent bugs for
example.

That means that the gecko conversion code needs to handle calc() in a bit of an
awkward way until I change it to not be needed (patches for that incoming in the
next few weeks I hope).

I need to add a hack to exclude other things from the PartialEq implementation
because the new conversion code is less lossy than the old one, and we relied on
the lousiness in AnimationValue comparison (in order to start transitions and
such, in [1] for example).

I expect to remove that manual PartialEq implementation as soon as I'm done with
the conversion.

The less lossy conversion does fix a few serialization bugs for animation values
though, like not loosing 0% values in calc() when interpolating lengths and
percentages, see the two modified tests:

 * property-types.js
 * test_animation_properties.html

Differential Revision: https://phabricator.services.mozilla.com/D15793
This commit is contained in:
Emilio Cobos Álvarez 2019-01-06 23:01:00 +01:00
parent bffe2a699e
commit ca503b4908
22 changed files with 338 additions and 644 deletions
Download patch file Download diff file Expand all files Collapse all files

25
components/style/values/animated/transform.rs
View file

@ -1167,17 +1167,6 @@ impl Animate for ComputedTransformOperation {
// See https://bugzilla.mozilla.org/show_bug.cgi?id=1318591#c0.
impl ComputeSquaredDistance for ComputedTransformOperation {
fn compute_squared_distance(&self, other: &Self) -> Result<SquaredDistance, ()> {
// For translate, We don't want to require doing layout in order to calculate the result, so
// drop the percentage part. However, dropping percentage makes us impossible to
// compute the distance for the percentage-percentage case, but Gecko uses the
// same formula, so it's fine for now.
// Note: We use pixel value to compute the distance for translate, so we have to
// convert Au into px.
let extract_pixel_length = |lop: &LengthOrPercentage| match *lop {
LengthOrPercentage::Length(px) => px.px(),
LengthOrPercentage::Percentage(_) => 0.,
LengthOrPercentage::Calc(calc) => calc.length().px(),
};
match (self, other) {
(&TransformOperation::Matrix3D(ref this), &TransformOperation::Matrix3D(ref other)) => {
this.compute_squared_distance(other)
@ -1199,10 +1188,16 @@ impl ComputeSquaredDistance for ComputedTransformOperation {
&TransformOperation::Translate3D(ref fx, ref fy, ref fz),
&TransformOperation::Translate3D(ref tx, ref ty, ref tz),
) => {
let fx = extract_pixel_length(&fx);
let fy = extract_pixel_length(&fy);
let tx = extract_pixel_length(&tx);
let ty = extract_pixel_length(&ty);
// For translate, We don't want to require doing layout in order
// to calculate the result, so drop the percentage part.
//
// However, dropping percentage makes us impossible to compute
// the distance for the percentage-percentage case, but Gecko
// uses the same formula, so it's fine for now.
let fx = fx.length_component().px();
let fy = fy.length_component().px();
let tx = tx.length_component().px();
let ty = ty.length_component().px();
Ok(fx.compute_squared_distance(&tx)? +
fy.compute_squared_distance(&ty)? +