62 lines
2.0 KiB
Markdown
62 lines
2.0 KiB
Markdown
---
|
|
title: Animate Transform and Opacity Instead of Layout Properties
|
|
impact: HIGH
|
|
impactDescription: GPU-accelerated animations, no layout recalculation
|
|
tags: animation, performance, reanimated, transform, opacity
|
|
---
|
|
|
|
## Animate Transform and Opacity Instead of Layout Properties
|
|
|
|
Avoid animating `width`, `height`, `top`, `left`, `margin`, or `padding`. These trigger layout recalculation on every frame. Instead, use `transform` (scale, translate) and `opacity` which run on the GPU without triggering layout.
|
|
|
|
**Incorrect (animates height, triggers layout every frame):**
|
|
|
|
```tsx
|
|
import Animated, { useAnimatedStyle, withTiming } from "react-native-reanimated";
|
|
|
|
function CollapsiblePanel({ expanded }: { expanded: boolean }) {
|
|
const animatedStyle = useAnimatedStyle(() => ({
|
|
height: withTiming(expanded ? 200 : 0), // triggers layout on every frame
|
|
overflow: "hidden",
|
|
}));
|
|
|
|
return <Animated.View style={animatedStyle}>{children}</Animated.View>;
|
|
}
|
|
```
|
|
|
|
**Correct (animates scaleY, GPU-accelerated):**
|
|
|
|
```tsx
|
|
import Animated, { useAnimatedStyle, withTiming } from "react-native-reanimated";
|
|
|
|
function CollapsiblePanel({ expanded }: { expanded: boolean }) {
|
|
const animatedStyle = useAnimatedStyle(() => ({
|
|
transform: [{ scaleY: withTiming(expanded ? 1 : 0) }],
|
|
opacity: withTiming(expanded ? 1 : 0),
|
|
}));
|
|
|
|
return (
|
|
<Animated.View style={[{ height: 200, transformOrigin: "top" }, animatedStyle]}>
|
|
{children}
|
|
</Animated.View>
|
|
);
|
|
}
|
|
```
|
|
|
|
**Correct (animates translateY for slide animations):**
|
|
|
|
```tsx
|
|
import Animated, { useAnimatedStyle, withTiming } from "react-native-reanimated";
|
|
|
|
function SlideIn({ visible }: { visible: boolean }) {
|
|
const animatedStyle = useAnimatedStyle(() => ({
|
|
transform: [{ translateY: withTiming(visible ? 0 : 100) }],
|
|
opacity: withTiming(visible ? 1 : 0),
|
|
}));
|
|
|
|
return <Animated.View style={animatedStyle}>{children}</Animated.View>;
|
|
}
|
|
```
|
|
|
|
GPU-accelerated properties: `transform` (translate, scale, rotate), `opacity`. Everything else triggers layout.
|