Auto merge of #15821 - montrivo:ImDataConstructors, r=Ms2ger

Implement ImageData constructors #15671 -- 1

<!-- Please describe your changes on the following line: -->
Implement ImageData constructors
* new constructors in the imagedata.rs file
* modification of the ImageData::new method
* new method ImageData::from_vec
* new wpt test file imagedata.html

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes affect #15671  (github issue number if applicable).

<!-- Either: -->
- [X] There are tests for these changes OR
- [ ] These changes do not require tests because _____

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

<!-- Reviewable:start -->
---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/15821)
<!-- Reviewable:end -->

components/script/dom/imagedata.rs

@@ -5,6 +5,7 @@
 use core::nonzero::NonZero;
 use dom::bindings::codegen::Bindings::ImageDataBinding;
 use dom::bindings::codegen::Bindings::ImageDataBinding::ImageDataMethods;
+use dom::bindings::error::{Fallible, Error};
 use dom::bindings::js::Root;
 use dom::bindings::reflector::{Reflector, reflect_dom_object};
 use dom::globalscope::GlobalScope;
@@ -28,14 +29,7 @@ pub struct ImageData {
 impl ImageData {
     #[allow(unsafe_code)]
     pub fn new(global: &GlobalScope, width: u32, height: u32, mut data: Option<Vec<u8>>) -> Root<ImageData> {
-        let imagedata = box ImageData {
-            reflector_: Reflector::new(),
-            width: width,
-            height: height,
-            data: Heap::default(),
-        };
         let len = width * height * 4;
-
         unsafe {
             let cx = global.get_cx();
             rooted!(in (cx) let mut js_object = ptr::null_mut());
@@ -47,11 +41,88 @@ impl ImageData {
                 None => CreateWith::Length(len),
             };
             Uint8ClampedArray::create(cx, data, js_object.handle_mut()).unwrap();
-            (*imagedata).data.set(js_object.get());
+            Self::new_with_jsobject(global, width, Some(height), Some(js_object.get())).unwrap()
+        }
+    }
+
+    #[allow(unsafe_code)]
+    unsafe fn new_with_jsobject(global: &GlobalScope,
+                                width: u32,
+                                mut opt_height: Option<u32>,
+                                opt_jsobject: Option<*mut JSObject>)
+                                -> Fallible<Root<ImageData>> {
+        assert!(opt_jsobject.is_some() || opt_height.is_some());
+
+        if width == 0 {
+            return Err(Error::IndexSize);
         }
 
-        reflect_dom_object(imagedata,
-                           global, ImageDataBinding::Wrap)
+        // 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 mut array = try!(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 {
+                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 {
+            return Err(Error::IndexSize);
+        }
+
+        let imagedata = box ImageData {
+            reflector_: Reflector::new(),
+            width: width,
+            height: height,
+            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());
+            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<Root<Self>> {
+        unsafe { Self::new_with_jsobject(global, width, Some(height), None) }
+    }
+
+    // https://html.spec.whatwg.org/multipage/#pixel-manipulation:dom-imagedata-4
+    #[allow(unsafe_code)]
+    #[allow(unused_variables)]
+    pub unsafe fn Constructor_(cx: *mut JSContext,
+                               global: &GlobalScope,
+                               jsobject: *mut JSObject,
+                               width: u32,
+                               opt_height: Option<u32>)
+                               -> Fallible<Root<Self>> {
+        Self::new_with_jsobject(global, width, opt_height, Some(jsobject))
     }
 
     #[allow(unsafe_code)]

components/script/dom/webidls/ImageData.webidl

@@ -9,9 +9,9 @@
  * You are granted a license to use, reproduce and create derivative works of this document.
  */
 
-//[Constructor(unsigned long sw, unsigned long sh),
-//Constructor(Uint8ClampedArray data, unsigned long sw, optional unsigned long sh),
-[Exposed=(Window,Worker)]
+[Constructor(unsigned long sw, unsigned long sh),
+ Constructor(/* Uint8ClampedArray */ object data, unsigned long sw, optional unsigned long sh),
+ Exposed=(Window,Worker)]
 interface ImageData {
   //[Constant]
   readonly attribute unsigned long width;

tests/wpt/metadata/2dcontext/pixel-manipulation/2d.imageData.object.ctor.html.ini

@@ -0,0 +1,4 @@
+[2d.imageData.object.ctor.html]
+  type: testharness
+  [ImageData does not have a usable constructor]
+    expected: FAIL

tests/wpt/metadata/MANIFEST.json

@@ -92591,6 +92591,12 @@
      {}
     ]
    ],
+   "html/semantics/embedded-content/the-canvas-element/imagedata.html": [
+    [
+     "/html/semantics/embedded-content/the-canvas-element/imagedata.html",
+     {}
+    ]
+   ],
    "html/semantics/embedded-content/the-canvas-element/initial.colour.html": [
     [
      "/html/semantics/embedded-content/the-canvas-element/initial.colour.html",
@@ -175580,6 +175586,10 @@
    "38b6f3c5707b360427854b82054d86f5364dc0b8",
    "testharness"
   ],
+  "html/semantics/embedded-content/the-canvas-element/imagedata.html": [
+   "e685ab0d76bdd1b60a5d6f1e2126ea1a89db97d1",
+   "testharness"
+  ],
   "html/semantics/embedded-content/the-canvas-element/initial.colour.html": [
    "22ddb77f5a18a19edc409d36532120f852bfbc57",
    "testharness"

tests/wpt/metadata/html/dom/interfaces.html.ini

@@ -4116,9 +4116,6 @@
   [TextMetrics interface: attribute ideographicBaseline]
     expected: FAIL
 
-  [ImageData interface object length]
-    expected: FAIL
-
   [DrawingStyle interface: existence and properties of interface object]
     expected: FAIL
 

tests/wpt/metadata/html/dom/interfaces.worker.js.ini

@@ -1,8 +1,5 @@
 [interfaces.worker.html]
   type: testharness
-  [ImageData interface object length]
-    expected: FAIL
-
   [Path2D interface: existence and properties of interface object]
     expected: FAIL
 

tests/wpt/web-platform-tests/html/semantics/embedded-content/the-canvas-element/imagedata.html

@@ -0,0 +1,58 @@
+<!doctype html>
+<meta charset="utf-8">
+<title>ImageData Tests</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+test(function() {
+    assert_throws("IndexSizeError", function() {
+        new ImageData(0, 1);
+    });
+}, "ImageData(w, h), width cannot be 0");
+
+test(function() {
+    assert_throws("IndexSizeError", function() {
+        new ImageData(1, 0);
+    });
+}, "ImageData(w, h), height cannot be 0");
+
+test(function() {
+    var imageData = new ImageData(2, 3);
+    assert_equals(imageData.width, 2);
+    assert_equals(imageData.height, 3);
+    assert_equals(imageData.data.length, 24);
+    assert_true(imageData.data instanceof Uint8ClampedArray);
+}, "ImageData(w, h), exposed attributes check");
+
+test(function() {
+    assert_throws("InvalidStateError", function() {
+        new ImageData(new Uint8ClampedArray(3), 1);
+    });
+}, "ImageData(buffer, w), the buffer size must be a multiple of 4");
+
+test(function() {
+    assert_throws("IndexSizeError", function() {
+        new ImageData(new Uint8ClampedArray(16), 3);
+    });
+}, "ImageData(buffer, w), buffer size must be a multiple of the image width");
+
+test(function() {
+    assert_throws("IndexSizeError", function() {
+        new ImageData(new Uint8ClampedArray(16), 4, 3);
+    });
+}, "ImageData(buffer, w, h), buffer.lenght == 4 * w * h must be true");
+
+test(function() {
+    assert_throws(new TypeError(), function() {
+        new ImageData(new Int8Array(1), 1);
+    });
+}, "ImageData(buffer, w, opt h), Uint8ClampedArray argument type check");
+
+test(function() {
+    var imageData = new ImageData(new Uint8ClampedArray(24), 2);
+    assert_equals(imageData.width, 2);
+    assert_equals(imageData.height, 3);
+    assert_equals(imageData.data.length, 24);
+    assert_true(imageData.data instanceof Uint8ClampedArray);
+}, "ImageData(buffer, w, opt h), exposed attributes check");
+</script>