Implemented paint worklets invoking worklet scripts.

components/layout/display_list_builder.rs

@@ -1172,6 +1172,7 @@ impl FragmentDisplayListBuilding for Fragment {
         };
 
         // TODO: add a one-place cache to avoid drawing the paint image every time.
+        // https://github.com/servo/servo/issues/17369
         debug!("Drawing a paint image {}({},{}).", name, size.width.to_px(), size.height.to_px());
         let mut image = match executor.draw_a_paint_image(name, size) {
             Ok(image) => image,

components/script/dom/bindings/conversions.rs

@@ -32,6 +32,7 @@
 //! | sequences               | `Vec<T>`                         |
 //! | union types             | `T`                              |
 
+use dom::bindings::error::{Error, Fallible};
 use dom::bindings::inheritance::Castable;
 use dom::bindings::js::Root;
 use dom::bindings::num::Finite;
@@ -48,15 +49,15 @@ use js::glue::{GetProxyPrivate, IsWrapper};
 use js::glue::{RUST_JSID_IS_INT, RUST_JSID_TO_INT};
 use js::glue::{RUST_JSID_IS_STRING, RUST_JSID_TO_STRING, UnwrapObject};
 use js::jsapi::{HandleId, HandleObject, HandleValue, JSContext, JSObject, JSString};
-use js::jsapi::{JS_GetLatin1StringCharsAndLength, JS_GetReservedSlot};
-use js::jsapi::{JS_GetTwoByteStringCharsAndLength, JS_IsArrayObject};
+use js::jsapi::{JS_GetLatin1StringCharsAndLength, JS_GetProperty, JS_GetReservedSlot};
+use js::jsapi::{JS_GetTwoByteStringCharsAndLength, JS_IsArrayObject, JS_IsExceptionPending};
 use js::jsapi::{JS_NewStringCopyN, JS_StringHasLatin1Chars, MutableHandleValue};
-use js::jsval::{ObjectValue, StringValue};
+use js::jsval::{ObjectValue, StringValue, UndefinedValue};
 use js::rust::{ToString, get_object_class, is_dom_class, is_dom_object, maybe_wrap_value};
 use libc;
 use num_traits::Float;
 use servo_config::opts;
-use std::{char, ptr, slice};
+use std::{char, ffi, ptr, slice};
 
 /// A trait to check whether a given `JSObject` implements an IDL interface.
 pub trait IDLInterface {
@@ -481,3 +482,45 @@ pub unsafe fn is_array_like(cx: *mut JSContext, value: HandleValue) -> bool {
     assert!(JS_IsArrayObject(cx, value, &mut result));
     result
 }
+
+/// Get a property from a JS object.
+pub unsafe fn get_property_jsval(cx: *mut JSContext,
+                                 object: HandleObject,
+                                 name: &str,
+                                 rval: MutableHandleValue)
+                                 -> Fallible<()>
+{
+    rval.set(UndefinedValue());
+    let cname = match ffi::CString::new(name) {
+        Ok(cname) => cname,
+        Err(_) => return Ok(()),
+    };
+    JS_GetProperty(cx, object, cname.as_ptr(), rval);
+    if JS_IsExceptionPending(cx) {
+        return Err(Error::JSFailed);
+    }
+    Ok(())
+}
+
+/// Get a property from a JS object, and convert it to a Rust value.
+pub unsafe fn get_property<T>(cx: *mut JSContext,
+                              object: HandleObject,
+                              name: &str,
+                              option: T::Config)
+                              -> Fallible<Option<T>> where
+    T: FromJSValConvertible
+{
+    debug!("Getting property {}.", name);
+    rooted!(in(cx) let mut result = UndefinedValue());
+    get_property_jsval(cx, object, name, result.handle_mut())?;
+    if result.is_undefined() {
+        debug!("No property {}.", name);
+        return Ok(None);
+    }
+    debug!("Converting property {}.", name);
+    match T::from_jsval(cx, result.handle(), option) {
+        Ok(ConversionResult::Success(value)) => Ok(Some(value)),
+        Ok(ConversionResult::Failure(_)) => Ok(None),
+        Err(()) => Err(Error::JSFailed),
+    }
+}

components/script/dom/mod.rs

@@ -391,6 +391,8 @@ pub mod node;
 pub mod nodeiterator;
 pub mod nodelist;
 pub mod pagetransitionevent;
+pub mod paintrenderingcontext2d;
+pub mod paintsize;
 pub mod paintworkletglobalscope;
 pub mod performance;
 pub mod performancetiming;

components/script/dom/paintrenderingcontext2d.rs

@@ -0,0 +1,29 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use dom::bindings::codegen::Bindings::PaintRenderingContext2DBinding;
+use dom::bindings::js::Root;
+use dom::bindings::reflector::Reflector;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::paintworkletglobalscope::PaintWorkletGlobalScope;
+use dom_struct::dom_struct;
+
+#[dom_struct]
+pub struct PaintRenderingContext2D {
+    reflector: Reflector,
+}
+
+impl PaintRenderingContext2D {
+    fn new_inherited() -> PaintRenderingContext2D {
+        PaintRenderingContext2D {
+            reflector: Reflector::new(),
+        }
+    }
+
+    pub fn new(global: &PaintWorkletGlobalScope) -> Root<PaintRenderingContext2D> {
+        reflect_dom_object(box PaintRenderingContext2D::new_inherited(),
+                           global,
+                           PaintRenderingContext2DBinding::Wrap)
+    }
+}

components/script/dom/paintsize.rs

@@ -0,0 +1,47 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use app_units::Au;
+use dom::bindings::codegen::Bindings::PaintSizeBinding;
+use dom::bindings::codegen::Bindings::PaintSizeBinding::PaintSizeMethods;
+use dom::bindings::js::Root;
+use dom::bindings::num::Finite;
+use dom::bindings::reflector::Reflector;
+use dom::bindings::reflector::reflect_dom_object;
+use dom::paintworkletglobalscope::PaintWorkletGlobalScope;
+use dom_struct::dom_struct;
+use euclid::Size2D;
+
+#[dom_struct]
+pub struct PaintSize {
+    reflector: Reflector,
+    width: Finite<f64>,
+    height: Finite<f64>,
+}
+
+impl PaintSize {
+    fn new_inherited(size: Size2D<Au>) -> PaintSize {
+        PaintSize {
+            reflector: Reflector::new(),
+            width: Finite::wrap(size.width.to_px().abs() as f64),
+            height: Finite::wrap(size.height.to_px().abs() as f64),
+        }
+    }
+
+    pub fn new(global: &PaintWorkletGlobalScope, size: Size2D<Au>) -> Root<PaintSize> {
+        reflect_dom_object(box PaintSize::new_inherited(size), global, PaintSizeBinding::Wrap)
+    }
+}
+
+impl PaintSizeMethods for PaintSize {
+    /// https://drafts.css-houdini.org/css-paint-api/#paintsize
+    fn Width(&self) -> Finite<f64> {
+        self.width
+    }
+
+    /// https://drafts.css-houdini.org/css-paint-api/#paintsize
+    fn Height(&self) -> Finite<f64> {
+        self.height
+    }
+}