Move takeSnapshot from React repo to RN

Reviewed By: sophiebits

Differential Revision: D7547298

fbshipit-source-id: 6ab0c0a9e244a2f68d27307b84285b2c8fff1342

Author: sebmarkbage

Libraries/ReactNative/takeSnapshot.js

@@ -0,0 +1,48 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @providesModule takeSnapshot
+ * @format
+ * @flow
+ */
+
+const ReactNative = require('ReactNative');
+const UIManager = require('UIManager');
+
+/**
+ * Capture an image of the screen, window or an individual view. The image
+ * will be stored in a temporary file that will only exist for as long as the
+ * app is running.
+ *
+ * The `view` argument can be the literal string `window` if you want to
+ * capture the entire window, or it can be a reference to a specific
+ * React Native component.
+ *
+ * The `options` argument may include:
+ * - width/height (number) - the width and height of the image to capture.
+ * - format (string) - either 'png' or 'jpeg'. Defaults to 'png'.
+ * - quality (number) - the quality when using jpeg. 0.0 - 1.0 (default).
+ *
+ * Returns a Promise.
+ * @platform ios
+ */
+module.exports = function takeSnapshot(
+  view?: 'window' | React$Element<any> | number,
+  options?: {
+    width?: number,
+    height?: number,
+    format?: 'png' | 'jpeg',
+    quality?: number,
+  },
+): Promise<any> {
+  if (typeof view !== 'number' && view !== 'window') {
+    view = ReactNative.findNodeHandle(view) || 'window';
+  }
+
+  // Call the hidden '__takeSnapshot' method; the main one throws an error to
+  // prevent accidental backwards-incompatible usage.
+  return UIManager.__takeSnapshot(view, options);
+};