Remove native and web features from dioxus-html (#3006)

* remove native and web features from dioxus-html

* Fix downcasting web events

* Fix desktop with tokio disabled

packages/web/src/file_engine.rs

@@ -0,0 +1,133 @@
+use std::any::Any;
+
+use dioxus_html::FileEngine;
+use futures_channel::oneshot;
+use js_sys::Uint8Array;
+use wasm_bindgen::{prelude::Closure, JsCast};
+use web_sys::{File, FileList, FileReader};
+
+/// A file engine for the web platform
+pub struct WebFileEngine {
+    file_reader: FileReader,
+    file_list: FileList,
+}
+
+impl WebFileEngine {
+    /// Create a new file engine from a file list
+    pub fn new(file_list: FileList) -> Option<Self> {
+        Some(Self {
+            file_list,
+            file_reader: FileReader::new().ok()?,
+        })
+    }
+
+    fn len(&self) -> usize {
+        self.file_list.length() as usize
+    }
+
+    fn get(&self, index: usize) -> Option<File> {
+        self.file_list.item(index as u32)
+    }
+
+    fn find(&self, name: &str) -> Option<File> {
+        (0..self.len())
+            .filter_map(|i| self.get(i))
+            .find(|f| f.name() == name)
+    }
+}
+
+#[async_trait::async_trait(?Send)]
+impl FileEngine for WebFileEngine {
+    fn files(&self) -> Vec<String> {
+        (0..self.len())
+            .filter_map(|i| self.get(i).map(|f| f.name()))
+            .collect()
+    }
+
+    async fn file_size(&self, file: &str) -> Option<u64> {
+        let file = self.find(file)?;
+        Some(file.size() as u64)
+    }
+
+    // read a file to bytes
+    async fn read_file(&self, file: &str) -> Option<Vec<u8>> {
+        let file = self.find(file)?;
+
+        let file_reader = self.file_reader.clone();
+        let (rx, tx) = oneshot::channel();
+        let on_load: Closure<dyn FnMut()> = Closure::new({
+            let mut rx = Some(rx);
+            move || {
+                let result = file_reader.result();
+                let _ = rx
+                    .take()
+                    .expect("multiple files read without refreshing the channel")
+                    .send(result);
+            }
+        });
+
+        self.file_reader
+            .set_onload(Some(on_load.as_ref().unchecked_ref()));
+        on_load.forget();
+        self.file_reader.read_as_array_buffer(&file).ok()?;
+
+        if let Ok(Ok(js_val)) = tx.await {
+            let as_u8_arr = Uint8Array::new(&js_val);
+            let as_u8_vec = as_u8_arr.to_vec();
+
+            Some(as_u8_vec)
+        } else {
+            None
+        }
+    }
+
+    // read a file to string
+    async fn read_file_to_string(&self, file: &str) -> Option<String> {
+        let file = self.find(file)?;
+
+        let file_reader = self.file_reader.clone();
+        let (rx, tx) = oneshot::channel();
+        let on_load: Closure<dyn FnMut()> = Closure::new({
+            let mut rx = Some(rx);
+            move || {
+                let result = file_reader.result();
+                let _ = rx
+                    .take()
+                    .expect("multiple files read without refreshing the channel")
+                    .send(result);
+            }
+        });
+
+        self.file_reader
+            .set_onload(Some(on_load.as_ref().unchecked_ref()));
+        on_load.forget();
+        self.file_reader.read_as_text(&file).ok()?;
+
+        if let Ok(Ok(js_val)) = tx.await {
+            js_val.as_string()
+        } else {
+            None
+        }
+    }
+
+    async fn get_native_file(&self, file: &str) -> Option<Box<dyn Any>> {
+        let file = self.find(file)?;
+        Some(Box::new(file))
+    }
+}
+
+/// Helper trait for WebFileEngine
+#[async_trait::async_trait(?Send)]
+pub trait WebFileEngineExt {
+    /// returns web_sys::File
+    async fn get_web_file(&self, file: &str) -> Option<web_sys::File>;
+}
+
+#[async_trait::async_trait(?Send)]
+impl WebFileEngineExt for std::sync::Arc<dyn FileEngine> {
+    async fn get_web_file(&self, file: &str) -> Option<web_sys::File> {
+        let native_file = self.get_native_file(file).await?;
+        let ret = native_file.downcast::<web_sys::File>().ok()?;
+        Some(*ret)
+    }
+}