Add shell.background-color.rgba to prefs (#30488)

* Add shell.transparent-background.enabled to prefs

* Rename config to background_color

* Rename to background-color and.rgba add PrefValue::Array variant

8 files changed, 108 insertions, 37 deletions

diff --git a/Cargo.lock b/Cargo.lock
index cb5fbc98430..417992bdc68 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -915,6 +915,7 @@ dependencies = [
  "profile_traits",
  "script_traits",
  "servo-media",
+ "servo_config",
  "servo_geometry",
  "servo_url",
  "style_traits",
diff --git a/components/compositing/Cargo.toml b/components/compositing/Cargo.toml
index ff02ad2e93f..b2fa4608669 100644
--- a/components/compositing/Cargo.toml
+++ b/components/compositing/Cargo.toml
@@ -35,6 +35,7 @@ num-traits = { workspace = true }
 pixels = { path = "../pixels", optional = true }
 profile_traits = { path = "../profile_traits" }
 script_traits = { path = "../script_traits" }
+servo_config = { path = "../config" }
 servo-media = { git = "https://github.com/servo/media" }
 servo_geometry = { path = "../geometry" }
 servo_url = { path = "../url" }
diff --git a/components/compositing/compositor.rs b/components/compositing/compositor.rs
index 4798970a8be..59845759ca0 100644
--- a/components/compositing/compositor.rs
+++ b/components/compositing/compositor.rs
@@ -1873,7 +1873,7 @@ impl<Window: WindowMethods + ?Sized> IOCompositor<Window> {
             self.assert_gl_framebuffer_complete();
         }
 
-        // Make the viewport white.
+        // Set the viewport background based on prefs.
         let viewport = self.embedder_coordinates.get_flipped_viewport();
         gl.scissor(
             viewport.origin.x,
@@ -1881,7 +1881,14 @@ impl<Window: WindowMethods + ?Sized> IOCompositor<Window> {
             viewport.size.width,
             viewport.size.height,
         );
-        gl.clear_color(1.0, 1.0, 1.0, 1.0);
+
+        let color = servo_config::pref!(shell.background_color.rgba);
+        gl.clear_color(
+            color[0] as f32,
+            color[1] as f32,
+            color[2] as f32,
+            color[3] as f32,
+        );
         gl.enable(gleam::gl::SCISSOR_TEST);
         gl.clear(gleam::gl::COLOR_BUFFER_BIT);
         gl.disable(gleam::gl::SCISSOR_TEST);
diff --git a/components/config/pref_util.rs b/components/config/pref_util.rs
index 08de25cb399..11e2f7f94a8 100644
--- a/components/config/pref_util.rs
+++ b/components/config/pref_util.rs
@@ -3,6 +3,7 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use std::collections::HashMap;
+use std::convert::TryInto;
 use std::fmt;
 use std::str::FromStr;
 use std::sync::RwLock;
@@ -16,6 +17,7 @@ pub enum PrefValue {
     Int(i64),
     Str(String),
     Bool(bool),
+    Array(Vec<PrefValue>),
     Missing,
 }
 
@@ -149,6 +151,36 @@ impl_from_pref! {
     PrefValue::Bool => bool,
 }
 
+impl From<[f64; 4]> for PrefValue {
+    fn from(other: [f64; 4]) -> PrefValue {
+        PrefValue::Array(IntoIterator::into_iter(other).map(|v| v.into()).collect())
+    }
+}
+
+impl From<PrefValue> for [f64; 4] {
+    fn from(other: PrefValue) -> [f64; 4] {
+        match other {
+            PrefValue::Array(values) if values.len() == 4 => {
+                let mut f = values.into_iter().map(|v| v.try_into());
+                if f.all(|v| v.is_ok()) {
+                    let f = f.flatten().collect::<Vec<f64>>();
+                    return [f[0], f[1], f[2], f[3]];
+                } else {
+                    panic!(
+                        "Cannot convert PrefValue to {:?}",
+                        std::any::type_name::<[f64; 4]>()
+                    )
+                }
+            },
+            _ => panic!(
+                "Cannot convert {:?} to {:?}",
+                other,
+                std::any::type_name::<[f64; 4]>()
+            ),
+        }
+    }
+}
+
 #[derive(Debug)]
 pub enum PrefError {
     NoSuchPref(String),
diff --git a/components/config/prefs.rs b/components/config/prefs.rs
index fd6de4dd2fd..0974ed19a9b 100644
--- a/components/config/prefs.rs
+++ b/components/config/prefs.rs
@@ -73,6 +73,17 @@ pub fn read_prefs_map(txt: &str) -> Result<HashMap<String, PrefValue>, PrefError
                     Value::Number(n) if n.is_i64() => PrefValue::Int(n.as_i64().unwrap()),
                     Value::Number(n) if n.is_f64() => PrefValue::Float(n.as_f64().unwrap()),
                     Value::String(s) => PrefValue::Str(s.to_owned()),
+                    Value::Array(v) => {
+                        let mut array = v.iter().map(|v| PrefValue::from_json_value(v));
+                        if array.all(|v| v.is_some()) {
+                            PrefValue::Array(array.flatten().collect())
+                        } else {
+                            return Err(PrefError::InvalidValue(format!(
+                                "Invalid value: {}",
+                                pref_value
+                            )));
+                        }
+                    },
                     _ => {
                         return Err(PrefError::InvalidValue(format!(
                             "Invalid value: {}",
@@ -478,6 +489,10 @@ mod gen {
                 max_length: i64,
             },
             shell: {
+                background_color: {
+                    #[serde(rename = "shell.background-color.rgba")]
+                    rgba: [f64; 4],
+                },
                 crash_reporter: {
                     enabled: bool,
                 },
diff --git a/components/devtools/actors/preference.rs b/components/devtools/actors/preference.rs
index 860b476d250..75ce7e0364e 100644
--- a/components/devtools/actors/preference.rs
+++ b/components/devtools/actors/preference.rs
@@ -37,41 +37,50 @@ impl Actor for PreferenceActor {
         _id: StreamId,
     ) -> Result<ActorMessageStatus, ()> {
         let pref_value = pref_map().get(msg_type);
-        Ok(match pref_value {
-            PrefValue::Float(value) => {
-                let reply = FloatReply {
-                    from: self.name(),
-                    value: value,
-                };
-                let _ = stream.write_json_packet(&reply);
-                ActorMessageStatus::Processed
-            },
-            PrefValue::Int(value) => {
-                let reply = IntReply {
-                    from: self.name(),
-                    value: value,
-                };
-                let _ = stream.write_json_packet(&reply);
-                ActorMessageStatus::Processed
-            },
-            PrefValue::Str(value) => {
-                let reply = CharReply {
-                    from: self.name(),
-                    value: value,
-                };
-                let _ = stream.write_json_packet(&reply);
-                ActorMessageStatus::Processed
-            },
-            PrefValue::Bool(value) => {
-                let reply = BoolReply {
-                    from: self.name(),
-                    value: value,
-                };
-                let _ = stream.write_json_packet(&reply);
-                ActorMessageStatus::Processed
-            },
-            PrefValue::Missing => handle_missing_preference(self.name(), msg_type, stream),
-        })
+        Ok(handle_preference_value(
+            pref_value,
+            self.name(),
+            msg_type,
+            stream,
+        ))
+    }
+}
+
+fn handle_preference_value(
+    pref_value: PrefValue,
+    name: String,
+    msg_type: &str,
+    stream: &mut TcpStream,
+) -> ActorMessageStatus {
+    match pref_value {
+        PrefValue::Float(value) => {
+            let reply = FloatReply { from: name, value };
+            let _ = stream.write_json_packet(&reply);
+            ActorMessageStatus::Processed
+        },
+        PrefValue::Int(value) => {
+            let reply = IntReply { from: name, value };
+            let _ = stream.write_json_packet(&reply);
+            ActorMessageStatus::Processed
+        },
+        PrefValue::Str(value) => {
+            let reply = CharReply { from: name, value };
+            let _ = stream.write_json_packet(&reply);
+            ActorMessageStatus::Processed
+        },
+        PrefValue::Bool(value) => {
+            let reply = BoolReply { from: name, value };
+            let _ = stream.write_json_packet(&reply);
+            ActorMessageStatus::Processed
+        },
+        PrefValue::Array(values) => {
+            let mut result = ActorMessageStatus::Processed;
+            for value in values {
+                result = handle_preference_value(value, name.clone(), msg_type, stream);
+            }
+            result
+        },
+        PrefValue::Missing => handle_missing_preference(name, msg_type, stream),
     }
 }
 
diff --git a/components/webdriver_server/lib.rs b/components/webdriver_server/lib.rs
index 1c2682ded5f..50337ecaa0a 100644
--- a/components/webdriver_server/lib.rs
+++ b/components/webdriver_server/lib.rs
@@ -283,6 +283,11 @@ impl Serialize for WebDriverPrefValue {
             PrefValue::Float(f) => serializer.serialize_f64(f),
             PrefValue::Int(i) => serializer.serialize_i64(i),
             PrefValue::Missing => serializer.serialize_unit(),
+            PrefValue::Array(ref v) => v
+                .iter()
+                .map(|value| WebDriverPrefValue(value.clone()))
+                .collect::<Vec<WebDriverPrefValue>>()
+                .serialize(serializer),
         }
     }
 }
diff --git a/resources/prefs.json b/resources/prefs.json
index 1881a525087..ebd7d6824b0 100644
--- a/resources/prefs.json
+++ b/resources/prefs.json
@@ -110,6 +110,7 @@
   "network.http-cache.disabled": false,
   "network.mime.sniff": false,
   "session-history.max-length": 20,
+  "shell.background-color.rgba": [1.0, 1.0, 1.0, 1.0],
   "shell.crash_reporter.enabled": false,
   "shell.homepage": "https://servo.org",
   "shell.keep_screen_on.enabled": false,