Move RCTTest & takeSnapshot to RNTester (#23721)

Summary:
Part of: #23313.

This moves the `RCTTest` lib from `Libraries/RCTTest` to `RNTester/RCTTest`. This also removes `takeSnapshot` from React Native, and implements it as a standalone module in RNTester called `ScreenshotManager`.

[General] [Removed] - RCTTest & ReactNative.takeSnapshot
Pull Request resolved: https://github.com/facebook/react-native/pull/23721

Differential Revision: D14434796

Pulled By: PeteTheHeat

fbshipit-source-id: d6e103a0ea0b6702701cdb5ce8449163ca4628ce

RNTester/NativeModuleExample/NativeScreenshotManager.js

@@ -0,0 +1,28 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow
+ * @format
+ */
+
+'use strict';
+
+import type {TurboModule} from 'RCTExport';
+import * as TurboModuleRegistry from 'TurboModuleRegistry';
+
+export interface Spec extends TurboModule {
+  +getConstants: () => {||};
+  takeSnapshot(id: string): Promise<string>;
+}
+
+const NativeModule = TurboModuleRegistry.get<Spec>('ScreenshotManager');
+
+export function takeSnapshot(id: string): Promise<string> {
+  if (NativeModule != null) {
+    return NativeModule.takeSnapshot(id);
+  }
+  return Promise.reject();
+}

RNTester/NativeModuleExample/Screenshot.h

@@ -0,0 +1,12 @@
+//
+//  RNTTakeScreenshot.h
+//  RNTester
+//
+//  Created by Eric Lewis on 3/1/19.
+//  Copyright © 2019 Facebook. All rights reserved.
+//
+
+#import <React/RCTViewManager.h>
+
+@interface ScreenshotManager : RCTViewManager
+@end

RNTester/NativeModuleExample/Screenshot.m

@@ -0,0 +1,84 @@
+//
+//  RNTTakeScreenshot.m
+//  RNTester
+//
+//  Created by Eric Lewis on 3/1/19.
+//  Copyright © 2019 Facebook. All rights reserved.
+//
+
+#import "Screenshot.h"
+
+#import <React/RCTUIManager.h>
+
+@implementation ScreenshotManager
+
+RCT_EXPORT_MODULE();
+
+RCT_EXPORT_METHOD(takeScreenshot:(id /* NSString or NSNumber */)target
+                  withOptions:(NSDictionary *)options
+                  resolve:(RCTPromiseResolveBlock)resolve
+                  reject:(RCTPromiseRejectBlock)reject)
+{
+  [self.bridge.uiManager addUIBlock:^(__unused RCTUIManager *uiManager, NSDictionary<NSNumber *, UIView *> *viewRegistry) {
+
+    // Get view
+    UIView *view;
+    if (target == nil || [target isEqual:@"window"]) {
+      view = RCTKeyWindow();
+    } else if ([target isKindOfClass:[NSNumber class]]) {
+      view = viewRegistry[target];
+      if (!view) {
+        RCTLogError(@"No view found with reactTag: %@", target);
+        return;
+      }
+    }
+
+    // Get options
+    CGSize size = [RCTConvert CGSize:options];
+    NSString *format = [RCTConvert NSString:options[@"format"] ?: @"png"];
+
+    // Capture image
+    if (size.width < 0.1 || size.height < 0.1) {
+      size = view.bounds.size;
+    }
+    UIGraphicsBeginImageContextWithOptions(size, NO, 0);
+    BOOL success = [view drawViewHierarchyInRect:(CGRect){CGPointZero, size} afterScreenUpdates:YES];
+    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+
+    if (!success || !image) {
+      reject(RCTErrorUnspecified, @"Failed to capture view snapshot.", nil);
+      return;
+    }
+
+    // Convert image to data (on a background thread)
+    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
+
+      NSData *data;
+      if ([format isEqualToString:@"png"]) {
+        data = UIImagePNGRepresentation(image);
+      } else if ([format isEqualToString:@"jpeg"]) {
+        CGFloat quality = [RCTConvert CGFloat:options[@"quality"] ?: @1];
+        data = UIImageJPEGRepresentation(image, quality);
+      } else {
+        RCTLogError(@"Unsupported image format: %@", format);
+        return;
+      }
+
+      // Save to a temp file
+      NSError *error = nil;
+      NSString *tempFilePath = RCTTempFilePath(format, &error);
+      if (tempFilePath) {
+        if ([data writeToFile:tempFilePath options:(NSDataWritingOptions)0 error:&error]) {
+          resolve(tempFilePath);
+          return;
+        }
+      }
+
+      // If we reached here, something went wrong
+      reject(RCTErrorUnspecified, error.localizedDescription, error);
+    });
+  }];
+}
+
+@end