Listen to display changed events

Replace RotationWatcher and DisplayFoldListener by a single
DisplayListener, which is notified whenever the display size or dpi
changes.

Still use the old version specifically for Android 14, where
DisplayListener may be broken (it is fixed in recent Android 14
upgrades), until we receive the first DisplayListener event (which
proves that it works).

Refs #4469 <https://github.com/Genymobile/scrcpy/pull/4469>

Co-authored-by: Simon Chan <1330321+yume-chan@users.noreply.github.com>

server/src/main/java/com/genymobile/scrcpy/video/ScreenCapture.java

@@ -6,12 +6,15 @@ import com.genymobile.scrcpy.device.DisplayInfo;
 import com.genymobile.scrcpy.device.Size;
 import com.genymobile.scrcpy.util.Ln;
 import com.genymobile.scrcpy.util.LogUtils;
+import com.genymobile.scrcpy.wrappers.DisplayManager;
 import com.genymobile.scrcpy.wrappers.ServiceManager;
 import com.genymobile.scrcpy.wrappers.SurfaceControl;
 
 import android.graphics.Rect;
 import android.hardware.display.VirtualDisplay;
 import android.os.Build;
+import android.os.Handler;
+import android.os.HandlerThread;
 import android.os.IBinder;
 import android.view.IDisplayFoldListener;
 import android.view.IRotationWatcher;
@@ -31,6 +34,13 @@ public class ScreenCapture extends SurfaceCapture {
     private IBinder display;
     private VirtualDisplay virtualDisplay;
 
+    private DisplayManager.DisplayListenerHandle displayListenerHandle;
+    private HandlerThread handlerThread;
+
+    // On Android 14, the DisplayListener may be broken (it never send events). This is fixed in recent Android 14 upgrades, but we can't really know.
+    // So register a RotationWatcher and a DisplayFoldListener as a fallback, until we receive the first event from DisplayListener (which proves
+    // that it works).
+    private boolean displayListenerWorks; // only accessed from the display listener thread
     private IRotationWatcher rotationWatcher;
     private IDisplayFoldListener displayFoldListener;
 
@@ -44,30 +54,25 @@ public class ScreenCapture extends SurfaceCapture {
 
     @Override
     public void init() {
-        if (displayId == 0) {
+        if (Build.VERSION.SDK_INT == AndroidVersions.API_34_ANDROID_14) {
-            rotationWatcher = new IRotationWatcher.Stub() {
+            registerDisplayListenerFallbacks();
-                @Override
-                public void onRotationChanged(int rotation) {
-                    requestReset();
-                }
-            };
-            ServiceManager.getWindowManager().registerRotationWatcher(rotationWatcher, displayId);
         }
 
-        if (Build.VERSION.SDK_INT >= AndroidVersions.API_29_ANDROID_10) {
+        handlerThread = new HandlerThread("DisplayListener");
-            displayFoldListener = new IDisplayFoldListener.Stub() {
+        handlerThread.start();
-                @Override
+        Handler handler = new Handler(handlerThread.getLooper());
-                public void onDisplayFoldChanged(int displayId, boolean folded) {
+        displayListenerHandle = ServiceManager.getDisplayManager().registerDisplayListener(displayId -> {
-                    if (ScreenCapture.this.displayId != displayId) {
+            if (Build.VERSION.SDK_INT == AndroidVersions.API_34_ANDROID_14) {
-                        // Ignore events related to other display ids
+                if (!displayListenerWorks) {
-                        return;
+                    // On the first display listener event, we know it works, we can unregister the fallbacks
-                    }
+                    displayListenerWorks = true;
-
+                    unregisterDisplayListenerFallbacks();
-                    requestReset();
                 }
-            };
+            }
-            ServiceManager.getWindowManager().registerDisplayFoldListener(displayFoldListener);
+            if (this.displayId == displayId) {
-        }
+                requestReset();
+            }
+        }, handler);
     }
 
     @Override
@@ -137,12 +142,11 @@ public class ScreenCapture extends SurfaceCapture {
 
     @Override
     public void release() {
-        if (rotationWatcher != null) {
+        if (Build.VERSION.SDK_INT == AndroidVersions.API_34_ANDROID_14) {
-            ServiceManager.getWindowManager().unregisterRotationWatcher(rotationWatcher);
+            unregisterDisplayListenerFallbacks();
-        }
-        if (Build.VERSION.SDK_INT >= AndroidVersions.API_29_ANDROID_10) {
-            ServiceManager.getWindowManager().unregisterDisplayFoldListener(displayFoldListener);
         }
+        handlerThread.quitSafely();
+        ServiceManager.getDisplayManager().unregisterDisplayListener(displayListenerHandle);
         if (display != null) {
             SurfaceControl.destroyDisplay(display);
             display = null;
@@ -182,4 +186,45 @@ public class ScreenCapture extends SurfaceCapture {
             SurfaceControl.closeTransaction();
         }
     }
+
+    private void registerDisplayListenerFallbacks() {
+        if (displayId == 0) {
+            rotationWatcher = new IRotationWatcher.Stub() {
+                @Override
+                public void onRotationChanged(int rotation) {
+                    Ln.i("=== rotation");
+                    requestReset();
+                }
+            };
+            ServiceManager.getWindowManager().registerRotationWatcher(rotationWatcher, displayId);
+        }
+
+        // Build.VERSION.SDK_INT >= AndroidVersions.API_29_ANDROID_10 (but implied by == API_34_ANDROID 14)
+        displayFoldListener = new IDisplayFoldListener.Stub() {
+            @Override
+            public void onDisplayFoldChanged(int displayId, boolean folded) {
+                if (ScreenCapture.this.displayId != displayId) {
+                    // Ignore events related to other display ids
+                    return;
+                }
+
+                requestReset();
+            }
+        };
+        ServiceManager.getWindowManager().registerDisplayFoldListener(displayFoldListener);
+    }
+
+    private void unregisterDisplayListenerFallbacks() {
+        synchronized (this) {
+            if (rotationWatcher != null) {
+                ServiceManager.getWindowManager().unregisterRotationWatcher(rotationWatcher);
+                rotationWatcher = null;
+            }
+            if (displayFoldListener != null) {
+                // Build.VERSION.SDK_INT >= AndroidVersions.API_29_ANDROID_10 (but implied by == API_34_ANDROID 14)
+                ServiceManager.getWindowManager().unregisterDisplayFoldListener(displayFoldListener);
+                displayFoldListener = null;
+            }
+        }
+    }
 }

server/src/main/java/com/genymobile/scrcpy/wrappers/DisplayManager.java

@@ -9,17 +9,40 @@ import com.genymobile.scrcpy.util.Ln;
 import android.annotation.SuppressLint;
 import android.content.Context;
 import android.hardware.display.VirtualDisplay;
+import android.os.Handler;
 import android.view.Display;
 import android.view.Surface;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.Field;
 import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
 @SuppressLint("PrivateApi,DiscouragedPrivateApi")
 public final class DisplayManager {
+
+    // android.hardware.display.DisplayManager.EVENT_FLAG_DISPLAY_CHANGED
+    public static final long EVENT_FLAG_DISPLAY_CHANGED = 1L << 2;
+
+    public interface DisplayListener {
+        /**
+         * Called whenever the properties of a logical {@link android.view.Display},
+         * such as size and density, have changed.
+         *
+         * @param displayId The id of the logical display that changed.
+         */
+        void onDisplayChanged(int displayId);
+    }
+
+    public static final class DisplayListenerHandle {
+        private final Object displayListenerProxy;
+        private DisplayListenerHandle(Object displayListenerProxy) {
+            this.displayListenerProxy = displayListenerProxy;
+        }
+    }
+
     private final Object manager; // instance of hidden class android.hardware.display.DisplayManagerGlobal
     private Method createVirtualDisplayMethod;
 
@@ -137,4 +160,50 @@ public final class DisplayManager {
         android.hardware.display.DisplayManager dm = ctor.newInstance(FakeContext.get());
         return dm.createVirtualDisplay(name, width, height, dpi, surface, flags);
     }
+
+    public DisplayListenerHandle registerDisplayListener(DisplayListener listener, Handler handler) {
+        try {
+            Class<?> displayListenerClass = Class.forName("android.hardware.display.DisplayManager$DisplayListener");
+            Object displayListenerProxy = Proxy.newProxyInstance(
+                    ClassLoader.getSystemClassLoader(),
+                    new Class[] {displayListenerClass},
+                    (proxy, method, args) -> {
+                        if ("onDisplayChanged".equals(method.getName())) {
+                            listener.onDisplayChanged((int) args[0]);
+                        }
+                        return null;
+                    });
+            try {
+                manager.getClass()
+                        .getMethod("registerDisplayListener", displayListenerClass, Handler.class, long.class, String.class)
+                        .invoke(manager, displayListenerProxy, handler, EVENT_FLAG_DISPLAY_CHANGED, FakeContext.PACKAGE_NAME);
+            } catch (NoSuchMethodException e) {
+                try {
+                    manager.getClass()
+                            .getMethod("registerDisplayListener", displayListenerClass, Handler.class, long.class)
+                            .invoke(manager, displayListenerProxy, handler, EVENT_FLAG_DISPLAY_CHANGED);
+                } catch (NoSuchMethodException e2) {
+                    manager.getClass()
+                            .getMethod("registerDisplayListener", displayListenerClass, Handler.class)
+                            .invoke(manager, displayListenerProxy, handler);
+                }
+            }
+
+            return new DisplayListenerHandle(displayListenerProxy);
+        } catch (Exception e) {
+            // Rotation and screen size won't be updated, not a fatal error
+            Ln.e("Could not register display listener", e);
+        }
+
+        return null;
+    }
+
+    public void unregisterDisplayListener(DisplayListenerHandle listener) {
+        try {
+            Class<?> displayListenerClass = Class.forName("android.hardware.display.DisplayManager$DisplayListener");
+            manager.getClass().getMethod("unregisterDisplayListener", displayListenerClass).invoke(manager, listener.displayListenerProxy);
+        } catch (Exception e) {
+            Ln.e("Could not unregister display listener", e);
+        }
+    }
 }