前言

jetpack compose 真的是个好东西，以前老费劲才能弄出来的效果，用它几行代码就能实现了，真香。

依赖

我这边加载网络图片使用的是coil，因为它出了兼容compose的版本。

// 图片加载
implementation("io.coil-kt:coil:1.4.0")
implementation("io.coil-kt:coil-compose:1.4.0")

代码

全屏显示图片的组件

import androidx.compose.foundation.Image
import androidx.compose.foundation.gestures.detectDragGestures
import androidx.compose.foundation.gestures.detectTapGestures
import androidx.compose.foundation.gestures.rememberTransformableState
import androidx.compose.foundation.gestures.transformable
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.material.Surface
import androidx.compose.runtime.*
import androidx.compose.ui.Modifier
import androidx.compose.ui.geometry.Offset
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.graphicsLayer
import androidx.compose.ui.input.pointer.pointerInput
import coil.compose.rememberImagePainter

/**
 * 全屏图片查看
 * @param modifier Modifier
 * @param url String
 * @param onClick Function0<Unit>  单击图片
 */
@Composable
fun FullScreenImage(
    modifier: Modifier = Modifier,
    url: String,
    onClick: () -> Unit = {}
) {

    var scale by remember { mutableStateOf(1f) }
    var offset by remember { mutableStateOf(Offset.Zero) }
    val state = rememberTransformableState { zoomChange, _, _ ->
        scale = (zoomChange * scale) .coerceAtLeast(1f)
    }

    Surface(
        color = Color.DarkGray,
        modifier = modifier
            .fillMaxSize()
            .pointerInput(Unit) {
                detectTapGestures(
                    onDoubleTap = {
                        scale = 1f
                        offset = Offset.Zero
                    },
                    onTap = {
                        onClick.invoke()
                    }
                )
            }
    ) {
        Image(
            painter = rememberImagePainter(url),
            contentDescription = "",
            modifier = Modifier
                .fillMaxSize()
                .transformable(state = state)
                .graphicsLayer(
                    scaleX = scale,
                    scaleY = scale,
                    translationX = offset.x,
                    translationY = offset.y
                )
                .pointerInput(Unit) {
                    detectDragGestures { _, dragAmount ->
                        offset += dragAmount
                    }
                }

        )
    }
}

使用

// 是否全屏显示图片
var isShowImageFullScreen by remember {
    mutableStateOf(false)
}
Column(
    modifier = Modifier
        .fillMaxSize()
        .background(lightBackground)
        .navigationBarsPadding()
) {
	Button(onClick = { isShowImageFullScreen = true }) {
        Text(text = "显示图片")
    }
}
if (isShowImageFullScreen) {
    FullScreenImage(url = "https://profile.csdnimg.cn/A/0/9/1_sinat_38184748") {
    	// 点击图片关闭显示
        isShowImageFullScreen = false
    }
}