Add ElectronStorageHelper to load bundled assets

src/.eslintrc.js

@@ -4,5 +4,7 @@ module.exports = {
         node: true
     },
     extends: ['scratch', 'scratch/es6'],
-    globals: ['__static']
+    globals: {
+        __static: false // electron-webpack provides this constant to access bundled static assets
+    }
 };

src/common/ElectronStorageHelper.js

@@ -0,0 +1,40 @@
+const fs = require('fs');
+const path = require('path');
+
+const staticAssets = path.resolve(__static, 'assets');
+
+/**
+ * Allow the storage module to load files bundled in the Electron application.
+ */
+class ElectronStorageHelper {
+    constructor (storageInstance) {
+        this.parent = storageInstance;
+    }
+
+    /**
+     * Fetch an asset but don't process dependencies.
+     * @param {AssetType} assetType - The type of asset to fetch.
+     * @param {string} assetId - The ID of the asset to fetch: a project ID, MD5, etc.
+     * @param {DataFormat} dataFormat - The file format / file extension of the asset to fetch: PNG, JPG, etc.
+     * @return {Promise.<Asset>} A promise for the contents of the asset.
+     */
+    load (assetType, assetId, dataFormat) {
+        assetId = path.basename(assetId);
+        dataFormat = path.basename(dataFormat);
+
+        return new Promise((resolve, reject) => {
+            fs.readFile(
+                path.resolve(staticAssets, `${assetId}.${dataFormat}`),
+                (err, data) => {
+                    if (err) {
+                        reject(err);
+                    } else {
+                        resolve(new this.parent.Asset(assetType, assetId, dataFormat, data));
+                    }
+                }
+            );
+        });
+    }
+}
+
+module.exports = ElectronStorageHelper;

src/renderer/index.js

@@ -4,6 +4,8 @@ import ReactDOM from 'react-dom';
 import GUI, {AppStateHOC} from 'scratch-gui';
 import styles from 'scratch-gui/src/playground/index.css';
 
+import ElectronStorageHelper from '../common/ElectronStorageHelper';
+
 // Register "base" page view
 // analytics.pageview('/');
 
@@ -19,5 +21,10 @@ if (process.env.NODE_ENV === 'production' && typeof window === 'object') {
     window.onbeforeunload = () => true;
 }
 
-const wrappedGui = React.createElement(WrappedGui);
+const onStorageInit = storageInstance => {
+    storageInstance.addHelper(new ElectronStorageHelper(storageInstance));
+    // storageInstance.addOfficialScratchWebStores(); // TODO: do we want this?
+};
+
+const wrappedGui = React.createElement(WrappedGui, {onStorageInit});
 ReactDOM.render(wrappedGui, appTarget);