feat: asset custom protocol to access local file system (#2104)

Author: Ngo Iok Ui (Wu Yu Wei)

.changes/asset-protocol.md

@@ -0,0 +1,5 @@
+---
+"api": patch
+---
+
+Add asset custom protocol to access local file system.

core/tauri/Cargo.toml

@@ -33,7 +33,7 @@ normal = [ "attohttpc" ]
 [dependencies]
 serde_json = { version = "1.0", features = [ "raw_value" ] }
 serde = { version = "1.0", features = [ "derive" ] }
-tokio = { version = "1.7", features = [ "rt", "rt-multi-thread", "sync" ] }
+tokio = { version = "1.7", features = [ "rt", "rt-multi-thread", "sync", "fs" ] }
 futures = "0.3"
 uuid = { version = "0.8", features = [ "v4" ] }
 thiserror = "1.0"

core/tauri/src/manager.rs

@@ -343,6 +343,15 @@ impl<P: Params> WindowManager<P> {
         current_window_label = label.to_js_string()?,
       ));
 
+    webview_attributes.uri_scheme_protocols.insert(
+      "asset".into(),
+      Box::new(move |url| {
+        let path = url.replace("asset://", "");
+        let data = crate::async_runtime::block_on(async move { tokio::fs::read(path).await })?;
+        Ok(data)
+      }),
+    );
+
     #[cfg(dev)]
     {
       webview_attributes = webview_attributes.initialization_script(&format!(