api: overhaul pointer API

- Rename `CursorMoved` to `PointerMoved`.
- Rename `CursorEntered` to `PointerEntered`.
- Rename `CursorLeft` to `PointerLeft`.
- Rename `MouseInput` to `PointerButton`.
- Add `position` to every `PointerEvent`.
- Remove `Touch`, which is folded into the `Pointer*` events.
- New `PointerType` added to `PointerEntered` and `PointerLeft`,
  signifying which pointer type is the source of this event.
- New `PointerSource` added to `PointerMoved`, similar to `PointerType`
  but holding additional data.
- New `ButtonSource` added to `PointerButton`, similar to `PointerType`
  but holding pointer type specific buttons. Use
  `ButtonSource::mouse_button()` to easily normalize any pointer button
  type to a generic mouse button.
- In the same spirit rename `DeviceEvent::MouseMotion` to `PointerMotion`.
- Remove `Force::Calibrated::altitude_angle`.

Fixes #3833.
Fixes #883.
Fixes #336.

Co-authored-by: Kirill Chibisov <contact@kchibisov.com>

src/platform_impl/web/web_sys/event.rs

@@ -6,8 +6,9 @@ use wasm_bindgen::prelude::wasm_bindgen;
 use wasm_bindgen::{JsCast, JsValue};
 use web_sys::{KeyboardEvent, MouseEvent, Navigator, PointerEvent, WheelEvent};
 
+use super::super::FingerId;
 use super::Engine;
-use crate::event::{MouseButton, MouseScrollDelta};
+use crate::event::{MouseButton, MouseScrollDelta, PointerKind};
 use crate::keyboard::{Key, KeyLocation, ModifiersState, NamedKey, PhysicalKey};
 
 bitflags::bitflags! {
@@ -68,14 +69,14 @@ pub fn mouse_button(event: &MouseEvent) -> Option<MouseButton> {
 }
 
 impl MouseButton {
-    pub fn to_id(self) -> u32 {
+    pub fn to_id(self) -> u16 {
         match self {
             MouseButton::Left => 0,
             MouseButton::Right => 1,
             MouseButton::Middle => 2,
             MouseButton::Back => 3,
             MouseButton::Forward => 4,
-            MouseButton::Other(value) => value.into(),
+            MouseButton::Other(value) => value,
         }
     }
 }
@@ -160,6 +161,14 @@ pub fn mouse_scroll_delta(
     }
 }
 
+pub fn pointer_type(event: &PointerEvent, pointer_id: i32) -> PointerKind {
+    match event.pointer_type().as_str() {
+        "mouse" => PointerKind::Mouse,
+        "touch" => PointerKind::Touch(FingerId::new(pointer_id, event.is_primary()).into()),
+        _ => PointerKind::Unknown,
+    }
+}
+
 pub fn key_code(event: &KeyboardEvent) -> PhysicalKey {
     let code = event.code();
     PhysicalKey::from_key_code_attribute_value(&code)