Animation basics (animate*AsState) in Android Kotlin - UI Render Trace

Component - Animation basics (animate*AsState)

This UI component shows a simple animation using animate*AsState in Jetpack Compose. When you tap the button, a box smoothly changes its size and color. This helps you see how animations make UI changes look smooth and natural.

Widget Tree

Column
├── Box
└── Button

The root layout is a vertical Column. Inside it, there is a Box that changes size and color with animation. Below the Box, there is a Button that triggers the animation when clicked.

Render Trace - 3 Steps

Step 1: Column

Step 2: Box

Step 3: Button

State Change - Re-render

Trigger:User taps the 'Animate' button

Before

Box size is 100.dp, color is Red

→

After

Box size animates to 200.dp, color animates to Green

Re-renders:The entire Column recomposes, but only Box's animated properties visually change smoothly

UI Quiz - 3 Questions

What happens when you tap the 'Animate' button?

A The screen background changes color

B The button disappears

C The box smoothly changes size and color

D Nothing happens

Key Insight

Using animate*AsState in Jetpack Compose lets you easily add smooth animations to UI properties like size and color. This makes your app feel more alive and responsive without complex code.