Snippet to snapping an image out of a composable and sharing it through a share sheet

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:tools="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android">

    <application>
        <activity
            android:name="..."
            android:exported="true"
            android:label="..."
            android:theme="...">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

        <provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="${applicationId}.provider"
            android:exported="false"
            android:grantUriPermissions="true">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/provider_paths" />
        </provider>
    </application>

</manifest>

Composable.kt

import android.annotation.SuppressLint
import android.content.ClipData
import android.content.Intent
import android.graphics.Bitmap
import android.graphics.Picture
import android.net.Uri
import android.os.Environment
import androidx.compose.foundation.background
import androidx.compose.foundation.border
import androidx.compose.foundation.layout.Arrangement
import androidx.compose.foundation.layout.Box
import androidx.compose.foundation.layout.Column
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.material3.Button
import androidx.compose.material3.Text
import androidx.compose.runtime.Composable
import androidx.compose.runtime.remember
import androidx.compose.ui.Alignment
import androidx.compose.ui.Modifier
import androidx.compose.ui.draw.drawWithCache
import androidx.compose.ui.graphics.Color
import androidx.compose.ui.graphics.drawscope.draw
import androidx.compose.ui.graphics.drawscope.drawIntoCanvas
import androidx.compose.ui.graphics.nativeCanvas
import androidx.compose.ui.platform.LocalContext
import androidx.compose.ui.unit.dp
import androidx.core.content.FileProvider
import com.your.app.id.BuildConfig
import okio.buffer
import okio.sink
import java.io.File

@SuppressLint("NewApi")
@Composable
fun ShareComposable() {
  val context = LocalContext.current
  val picture: Picture = remember { Picture() }
  Box(
    modifier = Modifier
      .fillMaxSize()
      .drawWithCache {
        val width = size.width.toInt()
        val height = size.height.toInt()
        onDrawWithContent {
          val pictureCanvas = androidx.compose.ui.graphics.Canvas(picture.beginRecording(width, height))
          draw(this, layoutDirection, pictureCanvas, size) {
            this@onDrawWithContent.drawContent()
          }
          picture.endRecording()
          drawIntoCanvas { canvas -> canvas.nativeCanvas.drawPicture(picture) }
        }
      },
    contentAlignment = Alignment.Center,
  ) {
    Column(verticalArrangement = Arrangement.spacedBy(16.dp), horizontalAlignment = Alignment.CenterHorizontally) {
      Box(
        contentAlignment = Alignment.Center,
        modifier = Modifier
          .height(64.dp)
          .fillMaxWidth()
          .padding(horizontal = 16.dp)
          .background(Color(0xFFFBEDC5))
          .border(1.dp, Color(0xFFFFBF00)),
      ) {
        Text(text = "Some content", modifier = Modifier.padding(16.dp))
      }
      Button(
        onClick = {
          val photoFile: File = File(
            /* parent = */ context.getExternalFilesDir(Environment.DIRECTORY_PICTURES),
            /* child = */ "IMAGE_${System.currentTimeMillis()}.png",
          )
          val photoUri: Uri = FileProvider.getUriForFile(
            /* context = */ context,
            /* authority = */ "${BuildConfig.APPLICATION_ID}.provider",
            /* file = */ photoFile,
          )
          val bitmap = Bitmap.createBitmap(picture) // Needs API 28+, not sure of alternatives
          photoFile.sink().buffer().use { // From okio
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, it.outputStream()) // PNG or JPEG, not sure
          }
          val sendIntent: Intent = Intent().apply {
            action = Intent.ACTION_SEND
            setType("image/*")
            putExtra(Intent.EXTRA_STREAM, photoUri)
            addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
            clipData = ClipData.newRawUri("image thumbnail", photoUri)
          }
          context.startActivity(Intent.createChooser(sendIntent, "From Compose UI!"))
        },
      ) {
        Text("Share composable")
      }
    }
  }
}

provider_paths.xml

<?xml version="1.0" encoding="utf-8"?>
<paths>
    <external-path
        name="share_pictures"
        path="/" />
</paths>