Add the platform video player composable

Author: colemancda

Demo/swiftui/src/androidMain/kotlin/com/pureswift/swiftui/VideoPlayer.android.kt

@@ -0,0 +1,35 @@
+package com.pureswift.swiftui
+
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.remember
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.viewinterop.AndroidView
+import androidx.compose.ui.unit.dp
+import androidx.media3.common.MediaItem
+import androidx.media3.exoplayer.ExoPlayer
+import androidx.media3.ui.PlayerView
+
+/// Hosts a Media3 player with its standard controls. The player prepares
+/// paused on the first frame; the user starts playback from the controls.
+@Composable
+internal actual fun RenderVideoPlayer(node: ViewNode) {
+    val url = node.string("url") ?: return
+    val context = LocalContext.current
+    val player = remember(node.id, url) {
+        ExoPlayer.Builder(context).build().apply {
+            setMediaItem(MediaItem.fromUri(url))
+            playWhenReady = false
+            prepare()
+        }
+    }
+    DisposableEffect(node.id, url) {
+        onDispose { player.release() }
+    }
+    AndroidView(
+        factory = { PlayerView(it).apply { this.player = player } },
+        modifier = node.composeModifiers().fillMaxWidth().height(220.dp),
+    )
+}

Demo/swiftui/src/commonMain/kotlin/com/pureswift/swiftui/VideoPlayer.kt

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+package com.pureswift.swiftui
+
+import androidx.compose.runtime.Composable
+
+/// A video player for the node's `url`. Platform-specific: Android hosts a
+/// system player view with playback controls; the desktop rig shows a
+/// placeholder.
+@Composable
+internal expect fun RenderVideoPlayer(node: ViewNode)

Demo/swiftui/src/desktopMain/kotlin/com/pureswift/swiftui/VideoPlayer.desktop.kt

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+package com.pureswift.swiftui
+
+import androidx.compose.foundation.background
+import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.graphics.Color
+import androidx.compose.material3.Text
+import androidx.compose.ui.unit.dp
+
+/// The desktop rig has no media stack; show a labeled placeholder.
+@Composable
+internal actual fun RenderVideoPlayer(node: ViewNode) {
+    Box(
+        contentAlignment = Alignment.Center,
+        modifier = node.composeModifiers().fillMaxWidth().height(220.dp).background(Color.Black),
+    ) {
+        Text("▶ ${node.string("url") ?: ""}", color = Color.White)
+    }
+}