Feature: ScrollView automaticallyAdjustKeyboardInsets (#31402)

Summary:
Retrying D30015799 (6e903b0) with a fix where ScrollViewNativeComponent was missing the automaticallyAdjustKeyboardInsets prop.
----- Original Summary
Currently, ScrollViews provide the prop `keyboardDismissMode` which lets you choose `"interactive"`. However when the keyboard is shown, it will be rendered above the ScrollView, potentially blocking content.

With the `automaticallyAdjustKeyboardInsets` prop the ScrollView will automatically adjust it's `contentInset`, `scrollIndicatorInsets` and `contentOffset` (scroll Y) props to push the content up so nothing gets blocked.

* The animation curve and duration of the Keyboard is exactly matched.
* The absolute position of the ScrollView is respected, so if the Keyboard only overlaps 10 pixels of the ScrollView, it will only get inset by 10 pixels.
* By respecting the absolute position on screen, this automatically makes it fully compatible with phones with notches (custom safe areas)
* By using the keyboard frame, this also works for different sized keyboards and even `<InputAccessoryView>`s
* This also supports `maintainVisibleContentPosition` and `autoscrollToTopThreshold`.
* I also fixed an issue with the `maintainVisibleContentPosition` (`autoscrollToTopThreshold`) prop(s), so they behave more reliably when `contentInset`s are applied. (This makes automatically scrolling to new items fully compatible with `automaticallyAdjustKeyboardInsets`)

## Changelog

* [iOS] [Added] - ScrollView: `automaticallyAdjustKeyboardInsets` prop: Automatically animate `contentInset`, `scrollIndicatorInsets` and `contentOffset` (scroll Y) to avoid the Keyboard. (respecting absolute position on screen and safe-areas)
* [iOS] [Fixed] - ScrollView: Respect `contentInset` when animating new items with `autoscrollToTopThreshold`, make `automaticallyAdjustKeyboardInsets` work with `autoscrollToTopThreshold` (includes vertical, vertical-inverted, horizontal and horizontal-inverted ScrollViews)

Pull Request resolved: #31402

Test Plan:
<table>
<tr>
<th>Before</th>
<th>After</th>
</tr>
<tr>
<td>

https://user-images.githubusercontent.com/15199031/115708680-9700aa80-a370-11eb-8016-e75d81a92cd7.MP4

</td>

<td>

https://user-images.githubusercontent.com/15199031/115708699-9b2cc800-a370-11eb-976f-c4010cd96d55.MP4

</td>
</table>

### "Why not just use `<KeyboardAvoidingView>`?"

<table>
<tr>
<th>Before (with <code>&lt;KeyboardAvoidingView&gt;</code>)</th>
<th>After (with <code>automaticallyAdjustKeyboardInsets</code>)</th>
</tr>
<tr>
<td>

https://user-images.githubusercontent.com/15199031/115708749-abdd3e00-a370-11eb-8e09-a27ffaef12b8.MP4

</td>

<td>

https://user-images.githubusercontent.com/15199031/115708777-b3044c00-a370-11eb-9b7a-e040ccb3ef8c.MP4

</td>
</table>

> Also notice how the `<KeyboardAvoidingView>` does not match the animation curve of the Keyboard

### Usage

```jsx
export const ChatPage = ({
  flatListProps,
  textInputProps
}: Props): React.ReactElement => (
  <>
    <FlatList
      {...flatListProps}
      keyboardDismissMode="interactive"
      automaticallyAdjustContentInsets={false}
      contentInsetAdjustmentBehavior="never"
      maintainVisibleContentPosition={{ minIndexForVisible: 0, autoscrollToTopThreshold: 100 }}
      automaticallyAdjustKeyboardInsets={true}
    />
    <InputAccessoryView backgroundColor={colors.white}>
      <ChatInput {...textInputProps} />
    </InputAccessoryView>
  </>
);
```

## Related Issues

* Fixes #31394
* Fixes #13073

Reviewed By: yungsters

Differential Revision: D32578661

Pulled By: sota000

fbshipit-source-id: 45985e2844275fe96304eccfd1901907dc4f9279

Author: mrousavy

Libraries/Components/ScrollView/ScrollView.js

@@ -171,6 +171,12 @@ type IOSProps = $ReadOnly<{|
    * @platform ios
    */
   automaticallyAdjustContentInsets?: ?boolean,
+  /**
+   * Controls whether the ScrollView should automatically adjust it's contentInset
+   * and scrollViewInsets when the Keyboard changes it's size. The default value is false.
+   * @platform ios
+   */
+  automaticallyAdjustKeyboardInsets?: ?boolean,
   /**
    * Controls whether iOS should automatically adjust the scroll indicator
    * insets. The default value is true. Available on iOS 13 and later.

Libraries/Components/ScrollView/ScrollViewNativeComponent.js

@@ -25,6 +25,7 @@ const ScrollViewNativeComponent: HostComponent<Props> =
       alwaysBounceHorizontal: true,
       alwaysBounceVertical: true,
       automaticallyAdjustContentInsets: true,
+      automaticallyAdjustKeyboardInsets: true,
       automaticallyAdjustsScrollIndicatorInsets: true,
       bounces: true,
       bouncesZoom: true,

Libraries/Components/ScrollView/ScrollViewNativeComponentType.js

@@ -21,6 +21,7 @@ export type ScrollViewNativeProps = $ReadOnly<{
   alwaysBounceHorizontal?: ?boolean,
   alwaysBounceVertical?: ?boolean,
   automaticallyAdjustContentInsets?: ?boolean,
+  automaticallyAdjustKeyboardInsets?: ?boolean,
   automaticallyAdjustsScrollIndicatorInsets?: ?boolean,
   bounces?: ?boolean,
   bouncesZoom?: ?boolean,

Libraries/Components/ScrollView/ScrollViewViewConfig.js

@@ -24,6 +24,7 @@ const ScrollViewViewConfig = {
     alwaysBounceHorizontal: true,
     alwaysBounceVertical: true,
     automaticallyAdjustContentInsets: true,
+    automaticallyAdjustKeyboardInsets: true,
     automaticallyAdjustsScrollIndicatorInsets: true,
     bounces: true,
     bouncesZoom: true,

React/Views/ScrollView/RCTScrollView.h

@@ -35,6 +35,7 @@
 
 @property (nonatomic, assign) UIEdgeInsets contentInset;
 @property (nonatomic, assign) BOOL automaticallyAdjustContentInsets;
+@property (nonatomic, assign) BOOL automaticallyAdjustKeyboardInsets;
 @property (nonatomic, assign) BOOL DEPRECATED_sendUpdatedChildFrames;
 @property (nonatomic, assign) NSTimeInterval scrollEventThrottle;
 @property (nonatomic, assign) BOOL centerContent;

React/Views/ScrollView/RCTScrollView.m

@@ -274,11 +274,80 @@ @implementation RCTScrollView {
   NSHashTable *_scrollListeners;
 }
 
+- (void)_registerKeyboardListener
+{
+  [[NSNotificationCenter defaultCenter] addObserver:self
+                                           selector:@selector(_keyboardWillChangeFrame:)
+                                               name:UIKeyboardWillChangeFrameNotification
+                                             object:nil];
+}
+
+- (void)_unregisterKeyboardListener
+{
+  [[NSNotificationCenter defaultCenter] removeObserver:self name:UIKeyboardWillChangeFrameNotification object:nil];
+}
+
+static inline UIViewAnimationOptions animationOptionsWithCurve(UIViewAnimationCurve curve)
+{
+  // UIViewAnimationCurve #7 is used for keyboard and therefore private - so we can't use switch/case here.
+  // source: https://stackoverflow.com/a/7327374/5281431
+  RCTAssert(
+      UIViewAnimationCurveLinear << 16 == UIViewAnimationOptionCurveLinear,
+      @"Unexpected implementation of UIViewAnimationCurve");
+  return curve << 16;
+}
+
+- (void)_keyboardWillChangeFrame:(NSNotification *)notification
+{
+  if (![self automaticallyAdjustKeyboardInsets]) {
+    return;
+  }
+  if ([self isHorizontal:_scrollView]) {
+    return;
+  }
+
+  double duration = [notification.userInfo[UIKeyboardAnimationDurationUserInfoKey] doubleValue];
+  UIViewAnimationCurve curve =
+      (UIViewAnimationCurve)[notification.userInfo[UIKeyboardAnimationCurveUserInfoKey] unsignedIntegerValue];
+  CGRect beginFrame = [notification.userInfo[UIKeyboardFrameBeginUserInfoKey] CGRectValue];
+  CGRect endFrame = [notification.userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
+
+  CGPoint absoluteViewOrigin = [self convertPoint:self.bounds.origin toView:nil];
+  CGFloat scrollViewLowerY = self.inverted ? absoluteViewOrigin.y : absoluteViewOrigin.y + self.bounds.size.height;
+
+  UIEdgeInsets newEdgeInsets = _scrollView.contentInset;
+  CGFloat inset = MAX(scrollViewLowerY - endFrame.origin.y, 0);
+  if (self.inverted) {
+    newEdgeInsets.top = MAX(inset, _contentInset.top);
+  } else {
+    newEdgeInsets.bottom = MAX(inset, _contentInset.bottom);
+  }
+
+  CGPoint newContentOffset = _scrollView.contentOffset;
+  CGFloat contentDiff = endFrame.origin.y - beginFrame.origin.y;
+  if (self.inverted) {
+    newContentOffset.y += contentDiff;
+  } else {
+    newContentOffset.y -= contentDiff;
+  }
+
+  [UIView animateWithDuration:duration
+                        delay:0.0
+                      options:animationOptionsWithCurve(curve)
+                   animations:^{
+                     self->_scrollView.contentInset = newEdgeInsets;
+                     self->_scrollView.scrollIndicatorInsets = newEdgeInsets;
+                     [self scrollToOffset:newContentOffset animated:NO];
+                   }
+                   completion:nil];
+}
+
 - (instancetype)initWithEventDispatcher:(id<RCTEventDispatcherProtocol>)eventDispatcher
 {
   RCTAssertParam(eventDispatcher);
 
   if ((self = [super initWithFrame:CGRectZero])) {
+    [self _registerKeyboardListener];
     _eventDispatcher = eventDispatcher;
 
     _scrollView = [[RCTCustomScrollView alloc] initWithFrame:CGRectZero];
@@ -396,6 +465,7 @@ - (void)dealloc
 {
   _scrollView.delegate = nil;
   [_eventDispatcher.bridge.uiManager.observerCoordinator removeObserver:self];
+  [self _unregisterKeyboardListener];
 }
 
 - (void)layoutSubviews
@@ -832,23 +902,33 @@ - (void)setMaintainVisibleContentPosition:(NSDictionary *)maintainVisibleContent
 - (void)uiManagerWillPerformMounting:(RCTUIManager *)manager
 {
   RCTAssertUIManagerQueue();
-  [manager
-      prependUIBlock:^(__unused RCTUIManager *uiManager, __unused NSDictionary<NSNumber *, UIView *> *viewRegistry) {
-        BOOL horz = [self isHorizontal:self->_scrollView];
-        NSUInteger minIdx = [self->_maintainVisibleContentPosition[@"minIndexForVisible"] integerValue];
-        for (NSUInteger ii = minIdx; ii < self->_contentView.subviews.count; ++ii) {
-          // Find the first entirely visible view. This must be done after we update the content offset
-          // or it will tend to grab rows that were made visible by the shift in position
-          UIView *subview = self->_contentView.subviews[ii];
-          if ((horz ? subview.frame.origin.x >= self->_scrollView.contentOffset.x
-                    : subview.frame.origin.y >= self->_scrollView.contentOffset.y) ||
-              ii == self->_contentView.subviews.count - 1) {
-            self->_prevFirstVisibleFrame = subview.frame;
-            self->_firstVisibleView = subview;
-            break;
-          }
-        }
-      }];
+
+  [manager prependUIBlock:^(
+               __unused RCTUIManager *uiManager, __unused NSDictionary<NSNumber *, UIView *> *viewRegistry) {
+    BOOL horz = [self isHorizontal:self->_scrollView];
+    NSUInteger minIdx = [self->_maintainVisibleContentPosition[@"minIndexForVisible"] integerValue];
+    for (NSUInteger ii = minIdx; ii < self->_contentView.subviews.count; ++ii) {
+      // Find the first entirely visible view. This must be done after we update the content offset
+      // or it will tend to grab rows that were made visible by the shift in position
+      UIView *subview = self->_contentView.subviews[ii];
+      BOOL hasNewView = NO;
+      if (horz) {
+        CGFloat leftInset = self.inverted ? self->_scrollView.contentInset.right : self->_scrollView.contentInset.left;
+        CGFloat x = self->_scrollView.contentOffset.x + leftInset;
+        hasNewView = subview.frame.origin.x > x;
+      } else {
+        CGFloat bottomInset =
+            self.inverted ? self->_scrollView.contentInset.top : self->_scrollView.contentInset.bottom;
+        CGFloat y = self->_scrollView.contentOffset.y + bottomInset;
+        hasNewView = subview.frame.origin.y > y;
+      }
+      if (hasNewView || ii == self->_contentView.subviews.count - 1) {
+        self->_prevFirstVisibleFrame = subview.frame;
+        self->_firstVisibleView = subview;
+        break;
+      }
+    }
+  }];
   [manager addUIBlock:^(__unused RCTUIManager *uiManager, __unused NSDictionary<NSNumber *, UIView *> *viewRegistry) {
     if (self->_maintainVisibleContentPosition == nil) {
       return; // The prop might have changed in the previous UIBlocks, so need to abort here.
@@ -858,25 +938,30 @@ - (void)uiManagerWillPerformMounting:(RCTUIManager *)manager
     if ([self isHorizontal:self->_scrollView]) {
       CGFloat deltaX = self->_firstVisibleView.frame.origin.x - self->_prevFirstVisibleFrame.origin.x;
       if (ABS(deltaX) > 0.1) {
+        CGFloat leftInset = self.inverted ? self->_scrollView.contentInset.right : self->_scrollView.contentInset.left;
+        CGFloat x = self->_scrollView.contentOffset.x + leftInset;
         self->_scrollView.contentOffset =
             CGPointMake(self->_scrollView.contentOffset.x + deltaX, self->_scrollView.contentOffset.y);
         if (autoscrollThreshold != nil) {
           // If the offset WAS within the threshold of the start, animate to the start.
-          if (self->_scrollView.contentOffset.x - deltaX <= [autoscrollThreshold integerValue]) {
-            [self scrollToOffset:CGPointMake(0, self->_scrollView.contentOffset.y) animated:YES];
+          if (x - deltaX <= [autoscrollThreshold integerValue]) {
+            [self scrollToOffset:CGPointMake(-leftInset, self->_scrollView.contentOffset.y) animated:YES];
           }
         }
       }
     } else {
       CGRect newFrame = self->_firstVisibleView.frame;
       CGFloat deltaY = newFrame.origin.y - self->_prevFirstVisibleFrame.origin.y;
       if (ABS(deltaY) > 0.1) {
+        CGFloat bottomInset =
+            self.inverted ? self->_scrollView.contentInset.top : self->_scrollView.contentInset.bottom;
+        CGFloat y = self->_scrollView.contentOffset.y + bottomInset;
         self->_scrollView.contentOffset =
             CGPointMake(self->_scrollView.contentOffset.x, self->_scrollView.contentOffset.y + deltaY);
         if (autoscrollThreshold != nil) {
           // If the offset WAS within the threshold of the start, animate to the start.
-          if (self->_scrollView.contentOffset.y - deltaY <= [autoscrollThreshold integerValue]) {
-            [self scrollToOffset:CGPointMake(self->_scrollView.contentOffset.x, 0) animated:YES];
+          if (y - deltaY <= [autoscrollThreshold integerValue]) {
+            [self scrollToOffset:CGPointMake(self->_scrollView.contentOffset.x, -bottomInset) animated:YES];
           }
         }
       }

React/Views/ScrollView/RCTScrollViewManager.m

@@ -66,6 +66,7 @@ - (UIView *)view
 RCT_EXPORT_VIEW_PROPERTY(centerContent, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(maintainVisibleContentPosition, NSDictionary)
 RCT_EXPORT_VIEW_PROPERTY(automaticallyAdjustContentInsets, BOOL)
+RCT_EXPORT_VIEW_PROPERTY(automaticallyAdjustKeyboardInsets, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(decelerationRate, CGFloat)
 RCT_EXPORT_VIEW_PROPERTY(directionalLockEnabled, BOOL)
 RCT_EXPORT_VIEW_PROPERTY(indicatorStyle, UIScrollViewIndicatorStyle)