Refactor constructor code to align with spec.

components/script/dom/imagedata.rs

@@ -42,15 +42,14 @@ impl ImageData {
         unsafe {
             let cx = global.get_cx();
             rooted!(in (*cx) let mut js_object = ptr::null_mut::<JSObject>());
-            let data = match data {
-                Some(ref mut d) => {
-                    d.resize(len as usize, 0);
-                    CreateWith::Slice(&d[..])
-                },
-                None => CreateWith::Length(len),
-            };
-            Uint8ClampedArray::create(*cx, data, js_object.handle_mut()).unwrap();
-            Self::new_with_jsobject(global, width, Some(height), Some(js_object.get()))
+            if let Some(ref mut d) = data {
+                d.resize(len as usize, 0);
+                let data = CreateWith::Slice(&d[..]);
+                Uint8ClampedArray::create(*cx, data, js_object.handle_mut()).unwrap();
+                Self::new_with_jsobject(global, width, Some(height), js_object.get())
+            } else {
+                Self::new_without_jsobject(global, width, height)
+            }
         }
     }
 
@@ -58,43 +57,28 @@ impl ImageData {
     unsafe fn new_with_jsobject(
         global: &GlobalScope,
         width: u32,
-        mut opt_height: Option<u32>,
-        opt_jsobject: Option<*mut JSObject>,
+        opt_height: Option<u32>,
+        jsobject: *mut JSObject,
     ) -> Fallible<DomRoot<ImageData>> {
-        assert!(opt_jsobject.is_some() || opt_height.is_some());
+        // checking jsobject type
+        let cx = global.get_cx();
+        typedarray!(in(*cx) let array_res: Uint8ClampedArray = jsobject);
+        let array = array_res.map_err(|_| {
+            Error::Type("Argument to Image data is not an Uint8ClampedArray".to_owned())
+        })?;
 
-        if width == 0 {
+        let byte_len = array.as_slice().len() as u32;
+        if byte_len == 0 || byte_len % 4 != 0 {
+            return Err(Error::InvalidState);
+        }
+
+        let len = byte_len / 4;
+        if width == 0 || len % width != 0 {
             return Err(Error::IndexSize);
         }
 
-        // checking jsobject type and verifying (height * width * 4 == jsobject.byte_len())
-        if let Some(jsobject) = opt_jsobject {
-            let cx = global.get_cx();
-            typedarray!(in(*cx) let array_res: Uint8ClampedArray = jsobject);
-            let array = array_res.map_err(|_| {
-                Error::Type("Argument to Image data is not an Uint8ClampedArray".to_owned())
-            })?;
-
-            let byte_len = array.as_slice().len() as u32;
-            if byte_len % 4 != 0 || byte_len == 0 {
-                return Err(Error::InvalidState);
-            }
-
-            let len = byte_len / 4;
-            if width == 0 || len % width != 0 {
-                return Err(Error::IndexSize);
-            }
-
-            let height = len / width;
-            if opt_height.map_or(false, |x| height != x) {
-                return Err(Error::IndexSize);
-            } else {
-                opt_height = Some(height);
-            }
-        }
-
-        let height = opt_height.unwrap();
-        if height == 0 {
+        let height = len / width;
+        if opt_height.map_or(false, |x| height != x) {
             return Err(Error::IndexSize);
         }
 
@@ -105,15 +89,7 @@ impl ImageData {
             data: Heap::default(),
         });
 
-        if let Some(jsobject) = opt_jsobject {
-            (*imagedata).data.set(jsobject);
-        } else {
-            let len = width * height * 4;
-            let cx = global.get_cx();
-            rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
-            Uint8ClampedArray::create(*cx, CreateWith::Length(len), array.handle_mut()).unwrap();
-            (*imagedata).data.set(array.get());
-        }
+        (*imagedata).data.set(jsobject);
 
         Ok(reflect_dom_object(
             imagedata,
@@ -122,10 +98,39 @@ impl ImageData {
         ))
     }
 
+    #[allow(unsafe_code)]
+    unsafe fn new_without_jsobject(
+        global: &GlobalScope,
+        width: u32,
+        height: u32,
+    ) -> Fallible<DomRoot<ImageData>> {
+        if width == 0 || height == 0 {
+            return Err(Error::IndexSize);
+        }
+
+        let imagedata = Box::new(ImageData {
+            reflector_: Reflector::new(),
+            width: width,
+            height: height,
+            data: Heap::default(),
+        });
+
+        let len = width * height * 4;
+        let cx = global.get_cx();
+        rooted!(in (*cx) let mut array = ptr::null_mut::<JSObject>());
+        Uint8ClampedArray::create(*cx, CreateWith::Length(len), array.handle_mut()).unwrap();
+        (*imagedata).data.set(array.get());
+
+        Ok(reflect_dom_object(
+            imagedata,
+            global,
+            ImageDataBinding::Wrap,
+        ))
+    }
     // https://html.spec.whatwg.org/multipage/#pixel-manipulation:dom-imagedata-3
     #[allow(unsafe_code)]
     pub fn Constructor(global: &GlobalScope, width: u32, height: u32) -> Fallible<DomRoot<Self>> {
-        unsafe { Self::new_with_jsobject(global, width, Some(height), None) }
+        unsafe { Self::new_without_jsobject(global, width, height) }
     }
 
     // https://html.spec.whatwg.org/multipage/#pixel-manipulation:dom-imagedata-4
@@ -138,7 +143,7 @@ impl ImageData {
         width: u32,
         opt_height: Option<u32>,
     ) -> Fallible<DomRoot<Self>> {
-        Self::new_with_jsobject(global, width, opt_height, Some(jsobject))
+        Self::new_with_jsobject(global, width, opt_height, jsobject)
     }
 
     /// Nothing must change the array on the JS side while the slice is live.