mirror of
https://github.com/facebook/react-native.git
synced 2025-11-01 09:14:26 +00:00
Samuel Susla
3265519920
Summary:
Changelog: [Internal]
If you look at implementation of hit testing in `RCTViewComponentView`
```
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
if (UIEdgeInsetsEqualToEdgeInsets(self.hitTestEdgeInsets, UIEdgeInsetsZero)) {
return [super pointInside:point withEvent:event];
}
CGRect hitFrame = UIEdgeInsetsInsetRect(self.bounds, self.hitTestEdgeInsets);
return CGRectContainsPoint(hitFrame, point);
}
```
you will notice that we use `UIEdgeInsetsInsetRect` to calculate hitFrame. The input for this function is bounds and `hitTestEdgeInsets`. `hitTestEdgeInsets` is our hitSlop.
Look at documentation of `UIEdgeInsetsInsetRect`, it says "Adjusts a rectangle by the given edge insets.".
So if you give it a positive edge insets, it will make the rect smaller.
That's why we need to reverse values of hitSlop to negative before assigning it to `hitTestEdgeInsets`.
Paper does the same thing here https://github.com/facebook/react-native/blob/d0871d0a9a373e1d3ac35da46c85c0d0e793116d/React/Views/RCTViewManager.m#L304-L305
Reviewed By: mdvacca
Differential Revision: D21661894
fbshipit-source-id: c3dd6c55b68e4fdef8589ca8f0484e2837b4136c