feat(css/compat): Support color with hex alpha (#6643)

crates/swc_css_compat/src/compiler/color_hex_alpha.rs

@@ -0,0 +1,146 @@
+use swc_atoms::js_word;
+use swc_common::DUMMY_SP;
+use swc_css_ast::{
+    AbsoluteColorBase, AlphaValue, Color, ComponentValue, Delimiter, DelimiterValue, Function,
+    Ident, Number,
+};
+
+use crate::compiler::Compiler;
+
+#[inline]
+fn from_hex(c: u8) -> u8 {
+    match c {
+        b'0'..=b'9' => c - b'0',
+        b'a'..=b'f' => c - b'a' + 10,
+        b'A'..=b'F' => c - b'A' + 10,
+        _ => {
+            unreachable!();
+        }
+    }
+}
+
+#[inline]
+fn clamp_unit_f32(val: f64) -> u8 {
+    (val * 255.).round().max(0.).min(255.) as u8
+}
+
+fn shorten_hex_color(value: &str) -> Option<&str> {
+    let length = value.len();
+    let chars = value.as_bytes();
+
+    if length == 8
+        && (chars[6] == b'f' || chars[6] == b'F')
+        && (chars[7] == b'f' || chars[7] == b'F')
+    {
+        return Some(&value[0..6]);
+    } else if length == 4 && chars[3] == b'f' || chars[3] == b'F' {
+        return Some(&value[0..3]);
+    }
+
+    None
+}
+
+fn hex_to_rgba(hex: &str) -> (u8, u8, u8, f64) {
+    let hex = hex.as_bytes();
+
+    match hex.len() {
+        8 => {
+            let r = from_hex(hex[0]) * 16 + from_hex(hex[1]);
+            let g = from_hex(hex[2]) * 16 + from_hex(hex[3]);
+            let b = from_hex(hex[4]) * 16 + from_hex(hex[5]);
+            let a = (from_hex(hex[6]) * 16 + from_hex(hex[7])) as f64 / 255.0;
+
+            (r, g, b, a)
+        }
+        4 => {
+            let r = from_hex(hex[0]) * 17;
+            let g = from_hex(hex[1]) * 17;
+            let b = from_hex(hex[2]) * 17;
+            let a = (from_hex(hex[3]) * 17) as f64 / 255.0;
+
+            (r, g, b, a)
+        }
+
+        _ => {
+            unreachable!()
+        }
+    }
+}
+
+impl Compiler {
+    pub(crate) fn process_color_hex_alpha(&mut self, n: &mut ComponentValue) {
+        if let ComponentValue::Color(box Color::AbsoluteColorBase(AbsoluteColorBase::HexColor(
+            hex_color,
+        ))) = n
+        {
+            if hex_color.value.len() != 4 && hex_color.value.len() != 8 {
+                return;
+            }
+
+            if let Some(shortened) = shorten_hex_color(&hex_color.value) {
+                hex_color.value = shortened.into();
+                hex_color.raw = None;
+
+                return;
+            }
+
+            let rgba = hex_to_rgba(&hex_color.value);
+
+            let r = rgba.0 as f64;
+            let g = rgba.1 as f64;
+            let b = rgba.2 as f64;
+            let a = rgba.3;
+
+            let mut rounded_alpha = (a * 100.).round() / 100.;
+
+            if clamp_unit_f32(rounded_alpha) != clamp_unit_f32(a) {
+                rounded_alpha = (a * 1000.).round() / 1000.;
+            }
+
+            *n = ComponentValue::Color(Box::new(Color::AbsoluteColorBase(
+                AbsoluteColorBase::Function(Function {
+                    span: hex_color.span,
+                    name: Ident {
+                        span: DUMMY_SP,
+                        value: js_word!("rgba"),
+                        raw: None,
+                    },
+                    value: vec![
+                        ComponentValue::Number(Box::new(Number {
+                            span: DUMMY_SP,
+                            value: r,
+                            raw: None,
+                        })),
+                        ComponentValue::Delimiter(Box::new(Delimiter {
+                            span: DUMMY_SP,
+                            value: DelimiterValue::Comma,
+                        })),
+                        ComponentValue::Number(Box::new(Number {
+                            span: DUMMY_SP,
+                            value: g,
+                            raw: None,
+                        })),
+                        ComponentValue::Delimiter(Box::new(Delimiter {
+                            span: DUMMY_SP,
+                            value: DelimiterValue::Comma,
+                        })),
+                        ComponentValue::Number(Box::new(Number {
+                            span: DUMMY_SP,
+                            value: b,
+                            raw: None,
+                        })),
+                        ComponentValue::Delimiter(Box::new(Delimiter {
+                            span: DUMMY_SP,
+                            value: DelimiterValue::Comma,
+                        })),
+                        ComponentValue::AlphaValue(Box::new(AlphaValue::Number(Number {
+                            span: DUMMY_SP,
+                            value: rounded_alpha,
+                            raw: None,
+                        }))),
+                    ],
+                }),
+            )));
+        }
+    }
+}

crates/swc_css_compat/src/compiler/mod.rs

@@ -1,13 +1,14 @@
 use swc_common::{Spanned, DUMMY_SP};
 use swc_css_ast::{
-    AtRule, MediaAnd, MediaCondition, MediaConditionAllType, MediaConditionWithoutOr,
-    MediaInParens, MediaQuery, Rule,
+    AtRule, ComponentValue, MediaAnd, MediaCondition, MediaConditionAllType,
+    MediaConditionWithoutOr, MediaInParens, MediaQuery, Rule, SupportsCondition,
 };
 use swc_css_visit::{VisitMut, VisitMutWith};
 
 use self::custom_media::CustomMediaHandler;
 use crate::feature::Features;
 
+mod color_hex_alpha;
 mod custom_media;
 mod media_query_ranges;
 
@@ -17,6 +18,7 @@ pub struct Compiler {
     #[allow(unused)]
     c: Config,
     custom_media: CustomMediaHandler,
+    in_supports_condition: bool,
 }
 
 #[derive(Debug)]
@@ -30,6 +32,7 @@ impl Compiler {
         Self {
             c: config,
             custom_media: Default::default(),
+            in_supports_condition: Default::default(),
         }
     }
 }
@@ -43,6 +46,16 @@ impl VisitMut for Compiler {
         }
     }
 
+    fn visit_mut_supports_condition(&mut self, n: &mut SupportsCondition) {
+        let old_in_support_condition = self.in_supports_condition;
+
+        self.in_supports_condition = true;
+
+        n.visit_mut_children_with(self);
+
+        self.in_supports_condition = old_in_support_condition;
+    }
+
     fn visit_mut_media_query(&mut self, n: &mut MediaQuery) {
         n.visit_mut_children_with(self);
 
@@ -105,4 +118,16 @@ impl VisitMut for Compiler {
             }
         }
     }
+
+    fn visit_mut_component_value(&mut self, n: &mut ComponentValue) {
+        n.visit_mut_children_with(self);
+
+        if self.in_supports_condition {
+            return;
+        }
+
+        if self.c.process.contains(Features::COLOR_HEX_ALPHA) {
+            self.process_color_hex_alpha(n);
+        }
+    }
 }

crates/swc_css_compat/src/feature.rs

@@ -5,5 +5,6 @@ bitflags! {
         const NESTING = 1 << 0;
         const CUSTOM_MEDIA = 1 << 1;
         const MEDIA_QUERY_RANGES = 1 << 2;
+        const COLOR_HEX_ALPHA = 1 << 3;
     }
 }

crates/swc_css_compat/tests/color-hex-alpha/input.css

@@ -0,0 +1,52 @@
+body {
+    background: #9d9 linear-gradient(#9823f8a9, #9823f834);
+    color: red;
+    color: #f00;
+    color: #f00f;
+    color: #FC0F;
+    color: #0000ff;
+    color: #0000ff00;
+    color: #FFFFFF;
+    content: "#f00";
+    content: "#0000ff00";
+}
+
+body {
+    background-color: #f3f3f3f3;
+    color: #0003;
+}
+
+#svg-element {
+    clip-path: url(#SVGID_1_);
+    clip-path: url(#aaaa);
+}
+
+.other {
+    background: #ff0099;
+    background: #ff0099ff;
+    background: #ff009900;
+}
+
+.short {
+    color: #ffff;
+    color: #ffffffff;
+    color: #abdabcff;
+    color: #000000FF;
+    color: #abcf;
+    color: #ff0f;
+    color: #000f;
+    color: #0000;
+    color: #001e;
+}
+
+@supports (color: #1111) {
+    .a {
+        color: #1111;
+    }
+}
+
+@supports (color: #11111111) {
+    .a {
+        color: #11111111;
+    }
+}

crates/swc_css_compat/tests/color-hex-alpha/input.expect.css

@@ -0,0 +1,46 @@
+body {
+  background: #9d9 linear-gradient(rgba(152, 35, 248, 0.663), rgba(152, 35, 248, 0.204));
+  color: red;
+  color: #f00;
+  color: #f00;
+  color: #FC0;
+  color: #0000ff;
+  color: rgba(0, 0, 255, 0);
+  color: #FFFFFF;
+  content: "#f00";
+  content: "#0000ff00";
+}
+body {
+  background-color: rgba(243, 243, 243, 0.953);
+  color: rgba(0, 0, 0, 0.2);
+}
+#svg-element {
+  clip-path: url(#SVGID_1_);
+  clip-path: url(#aaaa);
+}
+.other {
+  background: #ff0099;
+  background: #ff0099;
+  background: rgba(255, 0, 153, 0);
+}
+.short {
+  color: #fff;
+  color: #ffffff;
+  color: #abdabc;
+  color: #000000;
+  color: #abc;
+  color: #ff0;
+  color: #000;
+  color: rgba(0, 0, 0, 0);
+  color: rgba(0, 0, 17, 0.933);
+}
+@supports (color: #1111) {
+  .a {
+    color: rgba(17, 17, 17, 0.067);
+  }
+}
+@supports (color: #11111111) {
+  .a {
+    color: rgba(17, 17, 17, 0.067);
+  }
+}

crates/swc_css_compat/tests/fixture.rs

@@ -125,3 +125,25 @@ fn test_media_query_ranges(input: PathBuf) {
     })
     .unwrap();
 }
+
+#[testing::fixture("tests/color-hex-alpha/**/*.css", exclude("expect.css"))]
+fn test_color_hex_alpha(input: PathBuf) {
+    let output = input.with_extension("expect.css");
+
+    testing::run_test(false, |cm, _| {
+        //
+        let fm = cm.load_file(&input).unwrap();
+        let mut ss = parse_stylesheet(&fm);
+
+        ss.visit_mut_with(&mut Compiler::new(Config {
+            process: Features::COLOR_HEX_ALPHA,
+        }));
+
+        let s = print_stylesheet(&ss);
+
+        NormalizedOutput::from(s).compare_to_file(&output).unwrap();
+
+        Ok(())
+    })
+    .unwrap();
+}