Increase accuracy of various Web APIs (#2946)

src/platform_impl/web/web_sys/canvas.rs

@@ -28,6 +28,7 @@ pub struct Canvas {
     common: Common,
     id: WindowId,
     pub has_focus: Arc<AtomicBool>,
+    pub is_intersecting: Option<bool>,
     on_touch_start: Option<EventListenerHandle<dyn FnMut(Event)>>,
     on_touch_end: Option<EventListenerHandle<dyn FnMut(Event)>>,
     on_focus: Option<EventListenerHandle<dyn FnMut(FocusEvent)>>,
@@ -97,6 +98,7 @@ impl Canvas {
             },
             id,
             has_focus: Arc::new(AtomicBool::new(false)),
+            is_intersecting: None,
             on_touch_start: None,
             on_touch_end: None,
             on_blur: None,
@@ -134,11 +136,29 @@ impl Canvas {
 
     pub fn position(&self) -> LogicalPosition<f64> {
         let bounds = self.common.raw.get_bounding_client_rect();
-
-        LogicalPosition {
+        let mut position = LogicalPosition {
             x: bounds.x(),
             y: bounds.y(),
+        };
+
+        let document = self.window().document().expect("Failed to obtain document");
+
+        if document.contains(Some(self.raw())) {
+            let style = self
+                .window()
+                .get_computed_style(self.raw())
+                .expect("Failed to obtain computed style")
+                // this can't fail: we aren't using a pseudo-element
+                .expect("Invalid pseudo-element");
+            if style.get_property_value("display").unwrap() != "none" {
+                position.x += super::style_size_property(&style, "border-left-width")
+                    + super::style_size_property(&style, "padding-left");
+                position.y += super::style_size_property(&style, "border-top-width")
+                    + super::style_size_property(&style, "padding-top");
+            }
         }
+
+        position
     }
 
     pub fn old_size(&self) -> PhysicalSize<u32> {

src/platform_impl/web/web_sys/intersection_handle.rs

@@ -12,19 +12,9 @@ impl IntersectionObserverHandle {
     where
         F: 'static + FnMut(bool),
     {
-        let mut skip = true;
         let closure = Closure::new(move |entries: Array| {
             let entry: IntersectionObserverEntry = entries.get(0).unchecked_into();
-
-            let is_intersecting = entry.is_intersecting();
-
-            // skip first intersection
-            if skip && is_intersecting {
-                skip = false;
-                return;
-            }
-
-            callback(is_intersecting);
+            callback(entry.is_intersecting());
         });
         let observer = IntersectionObserver::new(closure.as_ref().unchecked_ref())
             // we don't provide any `options`

src/platform_impl/web/web_sys/mod.rs

@@ -75,13 +75,17 @@ pub fn set_canvas_size(
 ) {
     let document = window.document().expect("Failed to obtain document");
 
+    if !document.contains(Some(raw)) {
+        return;
+    }
+
     let style = window
         .get_computed_style(raw)
         .expect("Failed to obtain computed style")
         // this can't fail: we aren't using a pseudo-element
         .expect("Invalid pseudo-element");
 
-    if !document.contains(Some(raw)) || style.get_property_value("display").unwrap() == "none" {
+    if style.get_property_value("display").unwrap() == "none" {
         return;
     }
 
@@ -144,20 +148,4 @@ pub fn is_visible(window: &web_sys::Window) -> bool {
     document.visibility_state() == VisibilityState::Visible
 }
 
-pub fn is_intersecting(window: &web_sys::Window, canvas: &HtmlCanvasElement) -> bool {
-    let rect = canvas.get_bounding_client_rect();
-    // This should never panic.
-    let window_width = window.inner_width().unwrap().as_f64().unwrap() as i32;
-    let window_height = window.inner_height().unwrap().as_f64().unwrap() as i32;
-    let left = rect.left() as i32;
-    let width = rect.width() as i32;
-    let top = rect.top() as i32;
-    let height = rect.height() as i32;
-
-    let horizontal = left <= window_width && left + width >= 0;
-    let vertical = top <= window_height && top + height >= 0;
-
-    horizontal && vertical
-}
-
 pub type RawCanvasType = HtmlCanvasElement;