feat(core): add asset_resolver API (#2879)

.changes/asset-resolver.md

@@ -0,0 +1,5 @@
+---
+"tauri": patch
+---
+
+Expose the `asset_resolver` API on the `App` and `AppHandle` structs.

core/tauri/src/app.rs

@@ -8,7 +8,7 @@ pub(crate) mod tray;
 use crate::{
   command::{CommandArg, CommandItem},
   hooks::{InvokeHandler, OnPageLoad, PageLoadPayload, SetupHook},
-  manager::{CustomProtocol, WindowManager},
+  manager::{Asset, CustomProtocol, WindowManager},
   plugin::{Plugin, PluginStore},
   runtime::{
     http::{Request as HttpRequest, Response as HttpResponse},
@@ -169,6 +169,19 @@ impl PathResolver {
   }
 }
 
+/// The asset resolver is a helper to access the [`tauri_utils::assets::Assets`] interface.
+#[derive(Debug, Clone)]
+pub struct AssetResolver<R: Runtime> {
+  manager: WindowManager<R>,
+}
+
+impl<R: Runtime> AssetResolver<R> {
+  /// Gets the app asset associated with the given path.
+  pub fn get(&self, path: String) -> Option<Asset> {
+    self.manager.get_asset(path).ok()
+  }
+}
+
 /// A handle to the currently running application.
 ///
 /// This type implements [`Manager`] which allows for manipulation of global application items.
@@ -400,6 +413,13 @@ macro_rules! shared_app_impl {
       pub fn package_info(&self) -> &PackageInfo {
         self.manager.package_info()
       }
+
+      /// The application's asset resolver.
+      pub fn asset_resolver(&self) -> AssetResolver<R> {
+        AssetResolver {
+          manager: self.manager.clone(),
+        }
+      }
     }
   };
 }

core/tauri/src/lib.rs

@@ -86,11 +86,14 @@ pub use {
   self::window::menu::MenuEvent,
 };
 pub use {
-  self::app::{App, AppHandle, Builder, CloseRequestApi, Event, GlobalWindowEvent, PathResolver},
+  self::app::{
+    App, AppHandle, AssetResolver, Builder, CloseRequestApi, Event, GlobalWindowEvent, PathResolver,
+  },
   self::hooks::{
     Invoke, InvokeError, InvokeHandler, InvokeMessage, InvokeResolver, InvokeResponse, OnPageLoad,
     PageLoadPayload, SetupHook,
   },
+  self::manager::Asset,
   self::runtime::{
     webview::{WebviewAttributes, WindowBuilder},
     window::{

core/tauri/src/manager.rs

@@ -95,6 +95,14 @@ impl<R: Runtime> fmt::Debug for InnerWindowManager<R> {
   }
 }
 
+/// A resolved asset.
+pub struct Asset {
+  /// The asset bytes.
+  pub bytes: Vec<u8>,
+  /// The asset's mime type.
+  pub mime_type: String,
+}
+
 /// Uses a custom URI scheme handler to resolve file requests
 pub struct CustomProtocol<R: Runtime> {
   /// Handler for protocol
@@ -371,22 +379,8 @@ impl<R: Runtime> WindowManager<R> {
     })
   }
 
-  #[allow(clippy::type_complexity)]
-  fn prepare_uri_scheme_protocol(
-    &self,
-  ) -> Box<dyn Fn(&HttpRequest) -> Result<HttpResponse, Box<dyn std::error::Error>> + Send + Sync>
-  {
-    let assets = self.inner.assets.clone();
-    let manager = self.clone();
-    Box::new(move |request| {
-      let mut path = request
-        .uri()
-        .split(&['?', '#'][..])
-        // ignore query string
-        .next()
-        .unwrap()
-        .to_string()
-        .replace("tauri://localhost", "");
+  pub fn get_asset(&self, mut path: String) -> Result<Asset, Box<dyn std::error::Error>> {
+    let assets = &self.inner.assets;
     if path.ends_with('/') {
       path.pop();
     }
@@ -421,20 +415,18 @@ impl<R: Runtime> WindowManager<R> {
             .into_owned()
             .replacen(
               "__TAURI__INVOKE_KEY_TOKEN__",
-                &manager.generate_invoke_key().to_string(),
+              &self.generate_invoke_key().to_string(),
               1,
             )
             .as_bytes()
             .to_vec(),
           false => asset,
         };
-
         let mime_type = MimeType::parse(&final_data, &path);
-          Ok(
-            HttpResponseBuilder::new()
-              .mimetype(&mime_type)
-              .body(final_data)?,
-          )
+        Ok(Asset {
+          bytes: final_data,
+          mime_type,
+        })
       }
       Err(e) => {
         #[cfg(debug_assertions)]
@@ -442,6 +434,27 @@ impl<R: Runtime> WindowManager<R> {
         Err(Box::new(e))
       }
     }
+  }
+
+  #[allow(clippy::type_complexity)]
+  fn prepare_uri_scheme_protocol(
+    &self,
+  ) -> Box<dyn Fn(&HttpRequest) -> Result<HttpResponse, Box<dyn std::error::Error>> + Send + Sync>
+  {
+    let manager = self.clone();
+    Box::new(move |request| {
+      let path = request
+        .uri()
+        .split(&['?', '#'][..])
+        // ignore query string
+        .next()
+        .unwrap()
+        .to_string()
+        .replace("tauri://localhost", "");
+      let asset = manager.get_asset(path)?;
+      HttpResponseBuilder::new()
+        .mimetype(&asset.mime_type)
+        .body(asset.bytes)
     })
   }