wip: multi-controller session and pad bridge changes

app/src/main/java/com/droiddeck/launcher/SessionActivity.kt

@@ -138,6 +138,8 @@ class SessionActivity : ComponentActivity(), SurfaceHolder.Callback {
     private fun openDeckRing(why: String) {
         val deck = SessionState.deckPad
         val opened = if (deck) padBridge?.start() else null
+        // Every pad already connected is a player from the start, before its first press.
+        padBridge?.claimConnected()
         Log.i(TAG, "deck ring ($why): deck pad $deck" + when (opened) {
             null -> ", left for first input"
             true -> ", ring open"
@@ -310,6 +312,7 @@ class SessionActivity : ComponentActivity(), SurfaceHolder.Callback {
     private val deviceListener = object : InputManager.InputDeviceListener {
         override fun onInputDeviceAdded(deviceId: Int) {
             logInputDevice("connected", deviceId)
+            padBridge?.claimConnected()
             updateOnScreenControls()
             updatePointerCapture()
         }

app/src/main/java/com/droiddeck/launcher/input/PadBridge.java

@@ -29,7 +29,9 @@ import java.util.concurrent.atomic.AtomicIntegerArray;
  * Guide-then-A chord the client itself answers.
  *
  * <p>Each further controller is another player: slots 1 to 3, an Xbox 360 pad each, which in a
- * Steam session only the client reads (libfakeinput) and hands games through Steam Input.
+ * Steam session only the client reads (libfakeinput) and hands games through Steam Input. Slot 0
+ * is the device's own controls wherever it has them: a Bluetooth pad pressed first used to take
+ * it, and played as the handheld while its built-in pad became player 2.
  */
 public final class PadBridge {
     private static final String TAG = "PadBridge";
@@ -101,6 +103,17 @@ public final class PadBridge {
 
     /** No physical controller is driving the pad: nothing yet, or the on-screen controls were last. */
     public static final int NO_CONTROLLER = -1;
+
+    // AYN's handhelds (the Thor) present their own pad as a USB device Android calls external,
+    // beside the 2020:0111 it re-presents each Bluetooth Xbox pad as.
+    private static final int AYN_VENDOR = 0x2020;
+    private static final int AYN_BUILT_IN_PAD = 0x0112;
+
+    /** Whether this controller is the device's own controls rather than a pad connected to it. */
+    static boolean isBuiltIn(InputDevice device) {
+        return !device.isExternal()
+                || (device.getVendorId() == AYN_VENDOR && device.getProductId() == AYN_BUILT_IN_PAD);
+    }
     /**
      * The Android input device id of the physical controller that last drove any slot, or
      * {@link #NO_CONTROLLER}: where rumble goes when it names no slot of ours (RumbleComponent).
@@ -411,6 +424,19 @@ public final class PadBridge {
         }
     }
 
+    /**
+     * Gives every connected controller its slot now, so the client lists each one as it is
+     * connected instead of on its first press: a further player's pad is plugged in, at rest.
+     */
+    public synchronized void claimConnected() {
+        for (int id : InputDevice.getDeviceIds()) {
+            InputDevice device = InputDevice.getDevice(id);
+            if (!isFromController(device)) continue;
+            int slot = slotFor(device);
+            if (slot > 0 && playerWriters[slot] == null) publish(slot);
+        }
+    }
+
     /** A controller went away: its player's buttons are let go, and a further player's pad is unplugged. */
     public synchronized void onDeviceRemoved(int deviceId) {
         for (int slot = 0; slot < SLOTS; slot++) {
@@ -471,23 +497,55 @@ public final class PadBridge {
         publish();
     }
 
-    /** The slot this controller plays in: the one it has, else the first free one, else player 1's. */
+    /**
+     * The slot this controller plays in: the one it has, else slot 0 for the device's own controls
+     * and a further player's slot for a connected pad (slot 0 too while the device has no controls
+     * of its own), else player 1's.
+     */
     private int slotFor(InputDevice device) {
         int id = device.getId();
-        if (owners[0] == id) return 0;
-        for (int slot = 1; slot < SLOTS; slot++) {
+        for (int slot = 0; slot < SLOTS; slot++) {
             if (owners[slot] == id) return slot;
         }
         for (int slot = 0; slot < SLOTS; slot++) {
             if (owners[slot] != NO_CONTROLLER && InputDevice.getDevice(owners[slot]) == null) free(slot);
         }
-        for (int slot = 0; slot < SLOTS; slot++) {
+        if (isBuiltIn(device)) {
+            // A connected pad playing as the device's own controls moves to a player's slot of its own.
+            int was = owners[0];
+            if (was != NO_CONTROLLER) {
+                free(0);
+                InputDevice other = InputDevice.getDevice(was);
+                if (other != null && !isBuiltIn(other)) {
+                    int to = claim(other, 1);
+                    if (to > 0) publish(to);
+                }
+            }
+            owners[0] = id;
+            Log.i(TAG, "\"" + device.getName() + "\" (id " + id + ") is player 1, the device's own controls");
+            return 0;
+        }
+        int slot = claim(device, builtInConnected() ? 1 : 0);
+        return slot >= 0 ? slot : 0;
+    }
+
+    /** Takes the first free slot from {@code from} for this controller, or -1 if none is free. */
+    private int claim(InputDevice device, int from) {
+        for (int slot = from; slot < SLOTS; slot++) {
             if (owners[slot] != NO_CONTROLLER) continue;
-            owners[slot] = id;
-            Log.i(TAG, "\"" + device.getName() + "\" (id " + id + ") is player " + (slot + 1));
+            owners[slot] = device.getId();
+            Log.i(TAG, "\"" + device.getName() + "\" (id " + device.getId() + ") is player " + (slot + 1));
             return slot;
         }
-        return 0;
+        return -1;
+    }
+
+    private static boolean builtInConnected() {
+        for (int id : InputDevice.getDeviceIds()) {
+            InputDevice device = InputDevice.getDevice(id);
+            if (isFromController(device) && isBuiltIn(device)) return true;
+        }
+        return false;
     }
 
     private PadState stateFor(int slot) {