ShimmeringActivity.kt

package com.leonidivankin.draftandroid.articles.shimmering

import android.os.Bundle
import androidx.activity.compose.setContent
import androidx.appcompat.app.AppCompatActivity
import androidx.compose.animation.core.*
import androidx.compose.foundation.background
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.shape.RoundedCornerShape
import androidx.compose.runtime.Composable
import androidx.compose.runtime.getValue
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Brush
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalConfiguration
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp

class ShimmeringActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContent {
            ShimmeringCompose(
                modifier = Modifier
                    .width(300.dp)
                    .height(150.dp),
                cornerRadius = 16.dp
            )
        }
    }
}

@Composable
fun ShimmeringCompose(
    modifier: Modifier,
    cornerRadius: Dp
) {
    val screenWidth = LocalConfiguration.current.screenWidthDp.dp

    val translateAnim by rememberInfiniteTransition().animateFloat(
        initialValue = 0f,
        targetValue = screenWidth.px,
        animationSpec = infiniteRepeatable(
            animation = tween(durationMillis = 1500, easing = FastOutSlowInEasing)
        )
    )

    val shimmerColorShades = listOf(Color(0xFFF37F19), Color(0xFF007CFF), Color(0xFFF37F19))

    val brush = Brush.linearGradient(
        colors = shimmerColorShades,
        start = Offset(translateAnim, translateAnim),
        end = Offset(translateAnim + 70.dp.px, translateAnim + 35.dp.px)
    )

    Box(modifier = modifier.background(brush = brush, shape = RoundedCornerShape(cornerRadius)))
}

val Dp.px: Float
    @Composable
    get() = with(LocalDensity.current) { this@px.toPx() }