SwipeRefreshCustomIndicatorSample.kt

/*
 * Copyright 2021 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

@file:Suppress("DEPRECATION")

package com.google.accompanist.sample.swiperefresh

import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.animation.core.FastOutSlowInEasing
import androidx.compose.foundation.Image
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Row
import androidx.compose.foundation.layout.Spacer
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.layout.fillMaxWidth
import androidx.compose.foundation.layout.height
import androidx.compose.foundation.layout.padding
import androidx.compose.foundation.layout.size
import androidx.compose.foundation.layout.width
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.material.LinearProgressIndicator
import androidx.compose.material.MaterialTheme
import androidx.compose.material.Scaffold
import androidx.compose.material.Text
import androidx.compose.material.TopAppBar
import androidx.compose.runtime.Composable
import androidx.compose.runtime.LaunchedEffect
import androidx.compose.runtime.getValue
import androidx.compose.runtime.mutableStateOf
import androidx.compose.runtime.remember
import androidx.compose.runtime.setValue
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.drawWithCache
import androidx.compose.ui.graphics.Brush
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.platform.LocalDensity
import androidx.compose.ui.res.painterResource
import androidx.compose.ui.res.stringResource
import androidx.compose.ui.unit.Dp
import androidx.compose.ui.unit.dp
import com.google.accompanist.sample.AccompanistSampleTheme
import com.google.accompanist.sample.R
import com.google.accompanist.swiperefresh.SwipeRefresh
import com.google.accompanist.swiperefresh.SwipeRefreshState
import com.google.accompanist.swiperefresh.rememberSwipeRefreshState
import kotlinx.coroutines.delay

class SwipeRefreshCustomIndicatorSample : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContent {
            AccompanistSampleTheme {
                Sample()
            }
        }
    }
}

@Suppress("DEPRECATION")
@Composable
private fun Sample() {
    Scaffold(
        topBar = {
            TopAppBar(
                title = { Text(stringResource(R.string.swiperefresh_title_custom)) },
                backgroundColor = MaterialTheme.colors.surface,
            )
        },
        modifier = Modifier.fillMaxSize()
    ) { padding ->
        // Simulate a fake 2-second 'load'. Ideally this 'refreshing' value would
        // come from a ViewModel or similar
        var refreshing by remember { mutableStateOf(false) }
        LaunchedEffect(refreshing) {
            if (refreshing) {
                delay(2000)
                refreshing = false
            }
        }

        SwipeRefresh(
            state = rememberSwipeRefreshState(isRefreshing = refreshing),
            onRefresh = { refreshing = true },
            indicator = { state, trigger ->
                GlowIndicator(
                    swipeRefreshState = state,
                    refreshTriggerDistance = trigger
                )
            },
        ) {
            LazyColumn(contentPadding = padding) {
                items(30) {
                    Row(Modifier.padding(16.dp)) {
                        Image(
                            painter = painterResource(R.drawable.placeholder),
                            contentDescription = null,
                            modifier = Modifier.size(64.dp),
                        )

                        Spacer(Modifier.width(8.dp))

                        Text(
                            text = "Text",
                            style = MaterialTheme.typography.subtitle2,
                            modifier = Modifier
                                .weight(1f)
                                .align(Alignment.CenterVertically)
                        )
                    }
                }
            }
        }
    }
}

/**
 * A custom indicator which displays a glow and progress indicator
 */
@Composable
fun GlowIndicator(
    swipeRefreshState: SwipeRefreshState,
    refreshTriggerDistance: Dp,
    color: Color = MaterialTheme.colors.primary,
) {
    Box(
        Modifier
            .drawWithCache {
                onDrawBehind {
                    val distance = refreshTriggerDistance.toPx()
                    val progress = (swipeRefreshState.indicatorOffset / distance).coerceIn(0f, 1f)
                    // We draw a translucent glow
                    val brush = Brush.verticalGradient(
                        0f to color.copy(alpha = 0.45f),
                        1f to color.copy(alpha = 0f)
                    )
                    // And fade the glow in/out based on the swipe progress
                    drawRect(brush = brush, alpha = FastOutSlowInEasing.transform(progress))
                }
            }
            .fillMaxWidth()
            .height(72.dp)
    ) {
        if (swipeRefreshState.isRefreshing) {
            // If we're refreshing, show an indeterminate progress indicator
            LinearProgressIndicator(Modifier.fillMaxWidth())
        } else {
            // Otherwise we display a determinate progress indicator with the current swipe progress
            val trigger = with(LocalDensity.current) { refreshTriggerDistance.toPx() }
            val progress = (swipeRefreshState.indicatorOffset / trigger).coerceIn(0f, 1f)
            LinearProgressIndicator(
                progress = progress,
                modifier = Modifier.fillMaxWidth(),
            )
        }
    }
}