Add UIManager.measureInWindow to get window coordinates

Summary: When embedding in a hybrid app, we sometimes present new modal views or windows that have a different frame from the original root view. This API allows us to get coordinates in the application's window frame, which should be valid in any fullscreen view.

Reviewed By: majak

Differential Revision: D2939827

fb-gh-sync-id: 06b93cc2cb3519a25819c6efa445c779314dd673
shipit-source-id: 06b93cc2cb3519a25819c6efa445c779314dd673

Libraries/ReactIOS/NativeMethodsMixin.js

@@ -27,6 +27,13 @@ type MeasureOnSuccessCallback = (
   pageY: number
 ) => void
 
+type MeasureInWindowOnSuccessCallback = (
+  x: number,
+  y: number,
+  width: number,
+  height: number,
+) => void
+
 type MeasureLayoutOnSuccessCallback = (
   left: number,
   top: number,
@@ -83,6 +90,28 @@ var NativeMethodsMixin = {
     );
   },
 
+  /**
+   * Determines the location of the given view in the window and returns the
+   * values via an async callback. If the React root view is embedded in
+   * another native view, this will give you the absolute coordinates. If
+   * successful, the callback will be called be called with the following
+   * arguments:
+   *
+   *  - x
+   *  - y
+   *  - width
+   *  - height
+   *
+   * Note that these measurements are not available until after the rendering
+   * has been completed in native.
+   */
+  measureInWindow: function(callback: MeasureInWindowOnSuccessCallback) {
+    UIManager.measureInWindow(
+      findNodeHandle(this),
+      mountSafeCallback(this, callback)
+    );
+  },
+
   /**
    * Like [`measure()`](#measure), but measures the view relative an ancestor,
    * specified as `relativeToNativeNode`. This means that the returned x, y

React/Modules/RCTUIManager.m

@@ -1076,6 +1076,29 @@ - (void)setNeedsLayout
   }];
 }
 
+RCT_EXPORT_METHOD(measureInWindow:(nonnull NSNumber *)reactTag
+                  callback:(RCTResponseSenderBlock)callback)
+{
+  [self addUIBlock:^(__unused RCTUIManager *uiManager, NSDictionary<NSNumber *, UIView *> *viewRegistry) {
+    UIView *view = viewRegistry[reactTag];
+    if (!view) {
+      // this view was probably collapsed out
+      RCTLogWarn(@"measure cannot find view with tag #%@", reactTag);
+      callback(@[]);
+      return;
+    }
+
+    // Return frame coordinates in window
+    CGRect windowFrame = [view.window convertRect:view.frame fromView:view.superview];
+    callback(@[
+      @(windowFrame.origin.x),
+      @(windowFrame.origin.y),
+      @(windowFrame.size.width),
+      @(windowFrame.size.height),
+    ]);
+  }];
+}
+
 static void RCTMeasureLayout(RCTShadowView *view,
                              RCTShadowView *ancestor,
                              RCTResponseSenderBlock callback)