RN: Add NativeImageSource Flow Type

Reviewed By: TheSavior

Differential Revision: D6869985

fbshipit-source-id: 836134ae0919d49b161d1a75d5743e977e6eb3f4

Author: yungsters

Libraries/Image/nativeImageSource.js

@@ -10,47 +10,60 @@
  * @flow
  * @format
  */
+
 'use strict';
 
 const Platform = require('Platform');
 
-type SourceSpec = {
-  ios?: string,
-  android?: string,
+// TODO: Change `nativeImageSource` to return this type.
+export type NativeImageSource = {|
+  +deprecated: true,
+  +height: number,
+  +uri: string,
+  +width: number,
+|};
+
+type NativeImageSourceSpec = {|
+  +android?: string,
+  +ios?: string,
 
   // For more details on width and height, see
   // http://facebook.github.io/react-native/docs/images.html#why-not-automatically-size-everything
-  width: number,
-  height: number,
-};
+  +height: number,
+  +width: number,
+|};
 
 /**
- * In hybrid apps, use `nativeImageSource` to access images that are already available
- * on the native side, for example in Xcode Asset Catalogs or Android's drawable folder.
+ * In hybrid apps, use `nativeImageSource` to access images that are already
+ * available on the native side, for example in Xcode Asset Catalogs or
+ * Android's drawable folder.
  *
- * However, keep in mind that React Native Packager does not guarantee that the image exists. If
- * the image is missing you'll get an empty box. When adding new images your app needs to be
- * recompiled.
+ * However, keep in mind that React Native Packager does not guarantee that the
+ * image exists. If the image is missing you'll get an empty box. When adding
+ * new images your app needs to be recompiled.
  *
- * Prefer Static Image Resources system which provides more guarantees, automates measurements and
- * allows adding new images without rebuilding the native app. For more details visit:
+ * Prefer Static Image Resources system which provides more guarantees,
+ * automates measurements and allows adding new images without rebuilding the
+ * native app. For more details visit:
  *
  *   http://facebook.github.io/react-native/docs/images.html
  *
  */
-function nativeImageSource(spec: SourceSpec): Object {
-  const uri = Platform.select(spec);
-  if (!uri) {
+function nativeImageSource(spec: NativeImageSourceSpec): Object {
+  let uri = Platform.select(spec);
+  if (uri == null) {
     console.warn(
-      `No image name given for ${Platform.OS}: ${JSON.stringify(spec)}`,
+      'nativeImageSource(...): No image name supplied for `%s`:\n%s',
+      Platform.OS,
+      JSON.stringify(spec, null, 2),
     );
+    uri = '';
   }
-
   return {
+    deprecated: true,
+    height: spec.height,
     uri,
     width: spec.width,
-    height: spec.height,
-    deprecated: true,
   };
 }