feat(android): install on Android TV, and take a remote's keys in the player

The app is listed in the TV launcher with a banner, and neither a touch
screen nor leanback is required. While the controls are down the player
takes D-pad left and right as a ten-second seek, the middle button as
bringing the controls up, and play/pause and space as they say.

android/app/src/main/AndroidManifest.xml

@@ -7,6 +7,13 @@
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_DATA_SYNC" />
     <uses-permission android:name="android.permission.FOREGROUND_SERVICE_MEDIA_PLAYBACK" />
 
+    <!--
+      Android TV: listed in its launcher, and installable without a touch
+      screen. Neither is required, so phones are offered the same build.
+    -->
+    <uses-feature android:name="android.software.leanback" android:required="false" />
+    <uses-feature android:name="android.hardware.touchscreen" android:required="false" />
+
     <application
         android:name=".ProtonStreamApplication"
         android:allowBackup="false"
@@ -14,6 +21,7 @@
         android:enableOnBackInvokedCallback="true"
         tools:targetApi="33"
         android:icon="@mipmap/ic_launcher"
+        android:banner="@drawable/tv_banner"
         android:label="@string/app_name"
         android:supportsRtl="true"
         android:theme="@style/Theme.ProtonStream">
@@ -39,6 +47,7 @@
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
+                <category android:name="android.intent.category.LEANBACK_LAUNCHER" />
             </intent-filter>
             <!--
               Proton Drive public links. autoVerify="false", said explicitly:

android/app/src/main/java/io/narl/protonstream/playback/PlayerScreen.kt

@@ -68,6 +68,14 @@ import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.rememberUpdatedState
 import androidx.compose.foundation.gestures.detectTapGestures
+import androidx.compose.ui.focus.FocusRequester
+import androidx.compose.ui.focus.focusRequester
+import androidx.compose.foundation.focusable
+import androidx.compose.ui.input.key.Key
+import androidx.compose.ui.input.key.KeyEventType
+import androidx.compose.ui.input.key.key
+import androidx.compose.ui.input.key.onKeyEvent
+import androidx.compose.ui.input.key.type
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.semantics.onClick
 import androidx.compose.ui.semantics.semantics
@@ -444,12 +452,46 @@ fun PlayerScreen(
         }
     }
     val current by rememberUpdatedState(state)
+    // Where a remote's keys land while the controls are down. Once they are
+    // up, the D-pad moves between their buttons as it does anywhere else.
+    val keys = remember { FocusRequester() }
+    LaunchedEffect(showControls) { if (!showControls) runCatching { keys.requestFocus() } }
     if (minimized) return
 
     Box(
         Modifier
             .fillMaxSize()
             .background(Color.Black)
+            // A TV remote, a keyboard: left and right seek as a double tap
+            // does, the middle button brings the controls up, and play/pause
+            // and space do what they say.
+            .focusRequester(keys)
+            .onKeyEvent { event ->
+                if (event.type != KeyEventType.KeyDown) return@onKeyEvent false
+                when (event.key) {
+                    Key.DirectionLeft, Key.DirectionRight -> {
+                        if (showControls) return@onKeyEvent false
+                        val seconds = if (event.key == Key.DirectionLeft) -DOUBLE_TAP_SECONDS else DOUBLE_TAP_SECONDS
+                        host.seek((current.position + seconds).coerceAtLeast(0.0))
+                        nudge = seconds to (nudge?.second ?: 0) + 1
+                        true
+                    }
+                    Key.DirectionCenter, Key.Enter, Key.NumPadEnter, Key.DirectionUp, Key.DirectionDown -> {
+                        if (showControls) return@onKeyEvent false
+                        showControls = true
+                        true
+                    }
+                    Key.MediaPlayPause, Key.Spacebar -> {
+                        host.setPaused(!current.paused)
+                        showControls = true
+                        true
+                    }
+                    Key.MediaPlay -> { host.setPaused(false); true }
+                    Key.MediaPause -> { host.setPaused(true); true }
+                    else -> false
+                }
+            }
+            .focusable()
             // Double-tap a side to seek ten seconds, as every phone video
             // player has taught; the middle plays or pauses. A single tap
             // waits out the double-tap timeout, which is the price of both.

docs/ANDROID.md

@@ -7,6 +7,18 @@ screens, while UniFFI exposes the existing catalog, share, streaming, watch-stat
 and offline logic. Keep reusable behavior in the Rust crates rather than
 reimplementing it in Kotlin.
 
+## Android TV
+
+The same build installs on Android TV: it is listed in the TV launcher
+(`LEANBACK_LAUNCHER`, with the banner `scripts/render-tv-banner.sh` renders)
+and requires neither a touch screen nor leanback. Every screen is Compose
+`clickable`s, which the D-pad already moves between. The player takes a
+remote's keys while its controls are down: left and right seek ten seconds,
+the middle button brings the controls up, and play/pause works as on a
+keyboard. There is no TV-specific layout yet, and none of it has been run on a
+TV. Signing in to an account, so that shares arrive through sync, is the way
+to set one up without typing a share link on a remote.
+
 ## Toolchain
 
 Install JDK 17, Android SDK Platform/Build Tools 36, NDK

scripts/render-tv-banner.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+# Render the Android TV launcher banner, 320 by 180 dp, from the iOS icon: its
+# canvas widened to 16:9 with the face gradient run across the whole width,
+# and the play mark a little smaller, since a banner is shown as is rather
+# than cut down by a mask. Twice the size, in drawable-nodpi: one file for
+# every screen, which the launcher scales to its slot, sharp on a 4K one.
+set -euo pipefail
+
+script_dir="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+icon="$script_dir/../ios/ProtonStream/Resources/AppIcon.svg"
+out="$script_dir/../android/app/src/main/res/drawable-nodpi/tv_banner.png"
+
+command -v rsvg-convert >/dev/null || { echo "rsvg-convert is required (librsvg)" >&2; exit 1; }
+command -v magick >/dev/null || { echo "magick is required (ImageMagick)" >&2; exit 1; }
+mkdir -p "$(dirname "$out")"
+sed -e 's/width="1024" height="1024" viewBox="0 0 108 108"/width="320" height="180" viewBox="-42 0 192 108"/' \
+    -e 's/<rect width="108" height="108"/<rect x="-42" width="192" height="108"/' \
+    -e 's/x1="0" y1="0" x2="108" y2="108"/x1="-42" y1="0" x2="150" y2="108"/' \
+    -e 's/scale(1.5)/scale(1.15)/' \
+    "$icon" | rsvg-convert -w 640 -h 360 | magick - -alpha off -strip "$out"
+echo "wrote $out"