feat: add "WindowDrag" component

Author: aleclarson

@types/index.d.ts

@@ -8424,6 +8424,14 @@ declare class SwitchComponent extends React.Component<SwitchProps> {}
 declare const SwitchBase: Constructor<NativeMethodsMixin> & typeof SwitchComponent;
 export class Switch extends SwitchBase {}
 
+/**
+ * The `WindowDrag` component provides an area where the mouse can left-click
+ * and then drag in order to move the native `RCTWindow` that contains this view.
+ *
+ * @platform macos
+ */
+export class WindowDrag extends React.Component<ViewProps> {}
+
 /**
  * NOTE: `VibrationIOS` is being deprecated. Use `Vibration` instead.
  *

Libraries/Components/Window/WindowDrag.js

@@ -0,0 +1,39 @@
+/**
+ * Copyright (c) 2015-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @providesModule WindowDrag
+ * @noflow
+ */
+'use strict';
+
+const React = require('react');
+const ReactNative = require('ReactNative');
+const TouchableWithoutFeedback = require('TouchableWithoutFeedback');
+const UIManager = require('UIManager');
+const View = require('View');
+
+const DRAG_REF = 'drag';
+
+class WindowDrag extends React.Component {
+  render() {
+    return (
+      <TouchableWithoutFeedback
+        onPressIn={() => (
+          UIManager.dispatchViewManagerCommand(
+            ReactNative.findNodeHandle(this.refs[DRAG_REF]),
+            UIManager.RCTView.Commands.performWindowDrag,
+            null
+          )
+        )}>
+        <View ref={DRAG_REF} {...this.props} />
+      </TouchableWithoutFeedback>
+    );
+  }
+}
+
+module.exports = WindowDrag;

Libraries/react-native/react-native-implementation.js

@@ -60,6 +60,7 @@ const ReactNative = {
   get ViewPagerAndroid() { return require('ViewPagerAndroid'); },
   get VirtualizedList() { return require('VirtualizedList'); },
   get WebView() { return require('WebView'); },
+  get WindowDrag() { return require('WindowDrag'); },
 
   // APIs
   get ActionSheetIOS() { return require('ActionSheetIOS'); },

React/Views/RCTViewManager.m

@@ -22,6 +22,7 @@
 #import "RCTUIManagerUtils.h"
 #import "RCTUtils.h"
 #import "RCTView.h"
+#import "RCTWindow.h"
 #import "NSView+React.h"
 #import "RCTConvert+Transform.h"
 
@@ -364,4 +365,28 @@ - (RCTShadowView *)shadowView
 
 RCT_EXPORT_SHADOW_PROPERTY(direction, YGDirection)
 
+RCT_EXPORT_METHOD(performWindowDrag:(nonnull NSNumber *)reactTag)
+{
+  [self.bridge.uiManager addUIBlock:
+   ^(__unused RCTUIManager *uiManager, NSDictionary<NSNumber *, RCTView *> *viewRegistry) {
+     
+     RCTView *view = viewRegistry[reactTag];
+     if (!view || ![view isKindOfClass:[RCTView class]]) {
+       RCTLogError(@"Cannot find RCTView with tag #%@", reactTag);
+       return;
+     }
+     
+     RCTWindow *window = (RCTWindow *)view.window;
+     if (!window || ![window isKindOfClass:[RCTWindow class]]) {
+       RCTLogError(@"Expected RCTView.window to be a RCTWindow, but got a %@", window.className);
+       return;
+     }
+     
+     NSEvent *event = window.lastLeftMouseEvent;
+     if (event && event.type != NSLeftMouseUp) {
+       [window performWindowDragWithEvent:window.lastLeftMouseEvent];
+     }
+   }];
+}
+
 @end

React/Views/RCTWindow.h

@@ -24,4 +24,6 @@
 // Only exists between mouseDown and mouseUp events (may not be a React view)
 @property (nullable, strong) NSView *clickOrigin;
 
+@property (nonatomic, readonly) NSEvent *lastLeftMouseEvent;
+
 @end

React/Views/RCTWindow.m

@@ -126,6 +126,7 @@ - (void)sendEvent:(NSEvent *)event
 
   if (_clickTarget) {
     if (type == NSEventTypeLeftMouseDragged) {
+      _lastLeftMouseEvent = event;
       if (_clickType == NSEventTypeLeftMouseDown) {
         [self _sendTouchEvent:@"touchMove"];
       }
@@ -162,6 +163,7 @@ - (void)sendEvent:(NSEvent *)event
       }
 
       if (type == NSEventTypeLeftMouseDown) {
+        _lastLeftMouseEvent = event;
         [self _sendTouchEvent:@"touchStart"];
       }
 
@@ -172,6 +174,8 @@ - (void)sendEvent:(NSEvent *)event
   }
 
   if (type == NSEventTypeLeftMouseUp) {
+    _lastLeftMouseEvent = event;
+    
     if (_clickType == NSEventTypeLeftMouseDown) {
       [self _sendTouchEvent:@"touchEnd"];
       _clickTarget = nil;