[ScrollView] add onPageChange for scrollView with pagingEnabled=true.

Just like onScroll handle, does it makes sense to add onPageChange handler for ScrollView with pagingEnabled=true?

Wondering how to get a callback when the page changes on pagingEnabled ScrollView’s now.

cc @ide @vjeux

[chirag04]

@ide onMomentumScrollEnd is working. Sharing the code for anyone looking for it. Small core api is what i support so closing this for now.

We should def. document this function though.

onMomentumScrollEnd={this.handlePageChange}

handlePageChange: function(e) {
    var offset = e.nativeEvent.contentOffset;
    if(offset) {
      var page = Math.round(offset.x / WIDTH) + 1;
      if(this.state.page != page) {
        this.setState({page: page});
      }
    }
  },

[chirag04]

@ide I agree with @vjeux. It is annoying to compute right now. Also, i guess you are talking about onMomentumScrollEnd or something. I couldn’t get that working.

onPageChanged makes sense also for anyone with pagingEnabled.

I will go ahead and try to make a PR then.