[英]What are the implications of using interpolation over multiple Animated.Values?
[英]React Native - How to compare two Animated.Values in shouldComponentUpdate?
我正在優化我的平面列表項(漸進式圖像)並避免擴展 React.PureComponent 我決定實現我自己的 shouldComponentUpdate 生命周期方法。
我的漸進式圖像有兩個動畫值:
1. thumbnailOpacity 2. imageOpacity
我的應該組件更新必須如下所示:
state = {
isLoading: true,
thumbnailOpacity: new Animated.Value(0),
imageOpacity: new Animated.Value(0)
}
shouldComponentUpdate(nextProps, nextState) {
/*
React's PureComponent implement a shouldComponentUpdate with shallow comparison.
This is expensive here, because it need to check all our props. For a good bit-level performance,
use the strictest rules for our list item.
This component must re-render only when the state change.
*/
return (
nextState.isLoading !== this.state.isLoading ||
nextState.thumbnailOpacity !== this.state.thumbnailOpacity ||
nextState.imageOpacity !== this.state.imageOpacity
);
}
但是由於動畫值不是原始數據類型,如果沒有淺層比較,我不知道如何做到這一點。
有任何想法嗎? 謝謝你。
從您的狀態初始化:
state = {
...
thumbnailOpacity: new Animated.Value(0),
imageOpacity: new Animated.Value(0)
}
您應該能夠像這樣訪問它:
this.state.thumbnailOpacity._value
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