servo: Merge #5980 - layout: Implement `<table width>` and `<center>` (from pcwalton:table-width-and-center); r=mbrubeck

Improves Hacker News. r? @mbrubeck Source-Repo: https://github.com/servo/servo Source-Revision: c1e15e827edeef264afbbf1eae4be46de19fa0ef
2015-05-11 15:25:42 -05:00 · 2015-05-11 15:25:42 -05:00 · dc52df6960
--- a/servo/components/layout/block.rs
+++ b/servo/components/layout/block.rs
@ -55,7 +55,7 @@ use std::cmp::{max, min};
 use std::fmt;
 use std::sync::Arc;
 use style::computed_values::{border_collapse, box_sizing, display, float, overflow_x, overflow_y};
-use style::computed_values::{position};
+use style::computed_values::{position, text_align};
 use style::properties::ComputedValues;
 use style::values::computed::{LengthOrPercentage, LengthOrPercentageOrAuto};
 use style::values::computed::{LengthOrPercentageOrNone};
@ -1954,6 +1954,7 @@ pub struct ISizeConstraintInput {
    pub inline_end_margin: MaybeAuto,
    pub inline_start: MaybeAuto,
    pub inline_end: MaybeAuto,
+    pub text_align: text_align::T,
    pub available_inline_size: Au,
 }

@ -1963,6 +1964,7 @@ impl ISizeConstraintInput {
               inline_end_margin: MaybeAuto,
               inline_start: MaybeAuto,
               inline_end: MaybeAuto,
+               text_align: text_align::T,
               available_inline_size: Au)
           -> ISizeConstraintInput {
        ISizeConstraintInput {
@ -1971,6 +1973,7 @@ impl ISizeConstraintInput {
            inline_end_margin: inline_end_margin,
            inline_start: inline_start,
            inline_end: inline_end,
+            text_align: text_align,
            available_inline_size: available_inline_size,
        }
    }
@ -2066,6 +2069,7 @@ pub trait ISizeAndMarginsComputer {
                                                        containing_block_inline_size),
                                  MaybeAuto::from_style(position.inline_end,
                                                        containing_block_inline_size),
+                                  style.get_inheritedtext().text_align,
                                  available_inline_size)
    }

@ -2241,18 +2245,28 @@ pub trait ISizeAndMarginsComputer {
        // available_inline-size
        let (inline_start_margin, mut inline_size, inline_end_margin) =
            match (inline_start_margin, computed_inline_size, inline_end_margin) {
-                // If all have a computed value other than 'auto', the system is
-                // over-constrained so we discard the end margin.
+                // If all have a computed value other than 'auto', the system is over-constrained.
                (MaybeAuto::Specified(margin_start),
                 MaybeAuto::Specified(inline_size),
                 MaybeAuto::Specified(margin_end)) => {
-                    if parent_has_same_direction {
-                        (margin_start, inline_size, available_inline_size -
-                         (margin_start + inline_size))
-                    } else {
-                        (available_inline_size - (margin_end + inline_size),
-                         inline_size,
-                         margin_end)
+                    match (input.text_align, parent_has_same_direction) {
+                        (text_align::T::servo_center, _) => {
+                            // This is used for `<center>` and friends per HTML5 § 14.3.3. Make the
+                            // inline-start and inline-end margins equal per HTML5 § 14.2.
+                            let margin = (available_inline_size - inline_size).scale_by(0.5);
+                            (margin, inline_size, margin)
+                        }
+                        (_, true) => {
+                            // Ignore the end margin.
+                            (margin_start, inline_size, available_inline_size -
+                             (margin_start + inline_size))
+                        }
+                        (_, false) => {
+                            // Ignore the start margin.
+                            (available_inline_size - (margin_end + inline_size),
+                             inline_size,
+                             margin_end)
+                        }
                    }
                }
                // If exactly one value is 'auto', solve for it
--- a/servo/components/layout/inline.rs
+++ b/servo/components/layout/inline.rs
@ -917,7 +917,7 @@ impl InlineFlow {
                InlineFlow::justify_inline_fragments(fragments, line, slack_inline_size)
            }
            text_align::T::justify | text_align::T::start => {}
-            text_align::T::center => {
+            text_align::T::center | text_align::T::servo_center => {
                inline_start_position_for_fragment = inline_start_position_for_fragment +
                    slack_inline_size.scale_by(0.5)
            }
--- a/servo/components/style/legacy.rs
+++ b/servo/components/style/legacy.rs
@ -75,6 +75,14 @@ pub trait PresentationalHintSynthesis {
                                                                    E: TElement<'a> +
                                                                       TElementAttributes<'a>,
                                                                    V: VecLike<DeclarationBlock<Vec<PropertyDeclaration>>>;
+    /// Synthesizes rules for the legacy `width` attribute.
+    fn synthesize_presentational_hint_for_legacy_width_attribute<'a,E,V>(
+            &self,
+            element: E,
+            matching_rules_list: &mut V,
+            shareable: &mut bool)
+            where E: TElement<'a> + TElementAttributes<'a>,
+                  V: VecLike<DeclarationBlock<Vec<PropertyDeclaration>>>;
 }

 impl PresentationalHintSynthesis for Stylist {
@ -97,27 +105,20 @@ impl PresentationalHintSynthesis for Stylist {

        match element.get_local_name() {
            name if *name == atom!("td") => {
-                match element.get_length_attribute(LengthAttribute::Width) {
-                    LengthOrPercentageOrAuto::Auto => {}
-                    LengthOrPercentageOrAuto::Percentage(percentage) => {
-                        let width_value = specified::LengthOrPercentageOrAuto::Percentage(percentage);
-                        matching_rules_list.push(from_declaration(
-                                PropertyDeclaration::Width(SpecifiedValue(width_value))));
-                        *shareable = false
-                    }
-                    LengthOrPercentageOrAuto::Length(length) => {
-                        let width_value = specified::LengthOrPercentageOrAuto::Length(specified::Length::Absolute(length));
-                        matching_rules_list.push(from_declaration(
-                                PropertyDeclaration::Width(SpecifiedValue(width_value))));
-                        *shareable = false
-                    }
-                }
+                self.synthesize_presentational_hint_for_legacy_width_attribute(
+                    element,
+                    matching_rules_list,
+                    shareable);
                self.synthesize_presentational_hint_for_legacy_border_attribute(
                    element,
                    matching_rules_list,
                    shareable);
            }
            name if *name == atom!("table") => {
+                self.synthesize_presentational_hint_for_legacy_width_attribute(
+                    element,
+                    matching_rules_list,
+                    shareable);
                self.synthesize_presentational_hint_for_legacy_border_attribute(
                    element,
                    matching_rules_list,
@ -221,6 +222,31 @@ impl PresentationalHintSynthesis for Stylist {
            }
        }
    }
+
+    fn synthesize_presentational_hint_for_legacy_width_attribute<'a,E,V>(
+            &self,
+            element: E,
+            matching_rules_list: &mut V,
+            shareable: &mut bool)
+            where E: TElement<'a> + TElementAttributes<'a>,
+                  V: VecLike<DeclarationBlock<Vec<PropertyDeclaration>>> {
+        match element.get_length_attribute(LengthAttribute::Width) {
+            LengthOrPercentageOrAuto::Auto => {}
+            LengthOrPercentageOrAuto::Percentage(percentage) => {
+                let width_value = specified::LengthOrPercentageOrAuto::Percentage(percentage);
+                matching_rules_list.push(from_declaration(
+                        PropertyDeclaration::Width(SpecifiedValue(width_value))));
+                *shareable = false
+            }
+            LengthOrPercentageOrAuto::Length(length) => {
+                let width_value = specified::LengthOrPercentageOrAuto::Length(
+                    specified::Length::Absolute(length));
+                matching_rules_list.push(from_declaration(
+                        PropertyDeclaration::Width(SpecifiedValue(width_value))));
+                *shareable = false
+            }
+        }
+    }
 }


--- a/servo/components/style/properties.mako.rs
+++ b/servo/components/style/properties.mako.rs
@ -1735,10 +1735,10 @@ pub mod longhands {
        impl ComputedValueAsSpecified for SpecifiedValue {}
        pub mod computed_value {
            macro_rules! define_text_align {
-                ( $( $name: ident => $discriminant: expr, )+ ) => {
+                ( $( $name: ident ( $string: expr ) => $discriminant: expr, )+ ) => {
                    define_css_keyword_enum! { T:
                        $(
-                            stringify!($name) => $name,
+                            $string => $name,
                        )+
                    }
                    impl T {
@ -1761,12 +1761,13 @@ pub mod longhands {
                }
            }
            define_text_align! {
-                start => 0,
-                end => 1,
-                left => 2,
-                right => 3,
-                center => 4,
-                justify => 5,
+                start("start") => 0,
+                end("end") => 1,
+                left("left") => 2,
+                right("right") => 3,
+                center("center") => 4,
+                justify("justify") => 5,
+                servo_center("-servo-center") => 6,
            }
        }
        #[inline] pub fn get_initial_value() -> computed_value::T {
--- a/servo/resources/presentational-hints.css
+++ b/servo/resources/presentational-hints.css
@ -11,7 +11,6 @@ pre[wrap] { white-space: pre-wrap; }
 FIXME: also "align descendants"
 https://html.spec.whatwg.org/multipage/#align-descendants
 */
-center, div[align=center i], div[align=middle i] { text-align: center; }
 div[align=left i] { text-align: left; }
 div[align=right i] { text-align: right; }
 div[align=justify i] { text-align: justify; }
--- a/servo/resources/quirks-mode.css
+++ b/servo/resources/quirks-mode.css
@ -19,6 +19,17 @@ table {
  font-size: initial;
  line-height: initial;
  white-space: initial;
+  /* text-align: initial; -- see FIXME below */
+}
+
+/*
+ * FIXME(pcwalton): Actually saying `text-align: initial` above breaks `<table>` inside `<center>`
+ * in quirks mode. This is because we (following Gecko, WebKit, and Blink) implement the  HTML5
+ * align-descendants rules with a special `text-align: -servo-center`. `text-align: initial`, if
+ * placed on the `<table>` element per the spec, would break this behavior. So we place it on
+ * `<tbody>` instead.
+ */
+tbody {
  text-align: initial;
 }

--- a/servo/resources/servo.css
+++ b/servo/resources/servo.css
@ -19,3 +19,5 @@ td[align="left"]    { text-align: left; }
 td[align="center"]  { text-align: center; }
 td[align="right"]   { text-align: right; }

+center, div[align=center i], div[align=middle i] { text-align: -servo-center; }
+