Handle capture reset via listener

When the capture source becomes "invalid" (because the display size
changes for example), a reset request is performed to restart the
encoder.

The reset state was stored in SurfaceCapture. The capture implementation
set the flag, and the encoder consumed it.

However, this mechanism did not allow a reset request to _interrupt_ the
encoder, which may be waiting on a blocking call (until a new frame is
produced).

To be able to interrupt the encoder, a reset request must not only set a
flag, but run a callback provided by the encoder. For that purpose,
introduce the CaptureListener interface, which is notified by the
SurfaceCapture implementation whenever the capture is invalidated.

For now, the listener implementation just set a flag as before, so the
behavior is unchanged. It lays the groundwork for the next commits.

PR #5432 <https://github.com/Genymobile/scrcpy/pull/5432>

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

@@ -68,7 +68,7 @@ public class CameraCapture extends SurfaceCapture {
     }
 
     @Override
-    public void init() throws IOException {
+    protected void init() throws IOException {
         cameraThread = new HandlerThread("camera");
         cameraThread.start();
         cameraHandler = new Handler(cameraThread.getLooper());
@@ -256,7 +256,7 @@ public class CameraCapture extends SurfaceCapture {
             public void onDisconnected(CameraDevice camera) {
                 Ln.w("Camera disconnected");
                 disconnected.set(true);
-                requestReset();
+                invalidate();
             }
 
             @Override

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

@@ -0,0 +1,21 @@
+package com.genymobile.scrcpy.video;
+
+import java.util.concurrent.atomic.AtomicBoolean;
+
+public class CaptureReset implements SurfaceCapture.CaptureListener {
+
+    private final AtomicBoolean reset = new AtomicBoolean();
+
+    public boolean consumeReset() {
+        return reset.getAndSet(false);
+    }
+
+    public void reset() {
+        reset.set(true);
+    }
+
+    @Override
+    public void onInvalidated() {
+        reset();
+    }
+}

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

@@ -46,7 +46,7 @@ public class NewDisplayCapture extends SurfaceCapture {
     }
 
     @Override
-    public void init() {
+    protected void init() {
         size = newDisplay.getSize();
         dpi = newDisplay.getDpi();
         if (size == null || dpi == 0) {

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

@@ -85,7 +85,7 @@ public class ScreenCapture extends SurfaceCapture {
                         Ln.v("ScreenCapture: requestReset(): " + getSessionDisplaySize() + " -> (unknown)");
                     }
                     setSessionDisplaySize(null);
-                    requestReset();
+                    invalidate();
                 } else {
                     Size size = di.getSize();
 
@@ -102,7 +102,7 @@ public class ScreenCapture extends SurfaceCapture {
                         // Set the new size immediately, so that a future onDisplayChanged() event called before the asynchronous prepare()
                         // considers that the current size is the requested size (to avoid a duplicate requestReset())
                         setSessionDisplaySize(size);
-                        requestReset();
+                        invalidate();
                     } else if (Ln.isEnabled(Ln.Level.VERBOSE)) {
                         Ln.v("ScreenCapture: Size not changed (" + size + "): do not requestReset()");
                     }
@@ -246,7 +246,7 @@ public class ScreenCapture extends SurfaceCapture {
                 if (Ln.isEnabled(Ln.Level.VERBOSE)) {
                     Ln.v("ScreenCapture: onRotationChanged(" + rotation + ")");
                 }
-                requestReset();
+                invalidate();
             }
         };
         ServiceManager.getWindowManager().registerRotationWatcher(rotationWatcher, displayId);
@@ -272,7 +272,7 @@ public class ScreenCapture extends SurfaceCapture {
                     // Ignore events related to other display ids
                     return;
                 }
-                requestReset();
+                invalidate();
             }
         };
         ServiceManager.getWindowManager().registerDisplayFoldListener(displayFoldListener);

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

@@ -6,36 +6,37 @@ import com.genymobile.scrcpy.device.Size;
 import android.view.Surface;
 
 import java.io.IOException;
-import java.util.concurrent.atomic.AtomicBoolean;
 
 /**
  * A video source which can be rendered on a Surface for encoding.
  */
 public abstract class SurfaceCapture {
 
-    private final AtomicBoolean resetCapture = new AtomicBoolean();
-
-    /**
-     * Request the encoding session to be restarted, for example if the capture implementation detects that the video source size has changed (on
-     * device rotation for example).
-     */
-    protected void requestReset() {
-        resetCapture.set(true);
+    public interface CaptureListener {
+        void onInvalidated();
     }
 
+    private CaptureListener listener;
+
     /**
-     * Consume the reset request (intended to be called by the encoder).
-     *
-     * @return {@code true} if a reset request was pending, {@code false} otherwise.
+     * Notify the listener that the capture has been invalidated (for example, because its size changed).
      */
-    public boolean consumeReset() {
-        return resetCapture.getAndSet(false);
+    protected void invalidate() {
+        listener.onInvalidated();
     }
 
     /**
      * Called once before the first capture starts.
      */
-    public abstract void init() throws ConfigurationException, IOException;
+    public final void init(CaptureListener listener) throws ConfigurationException, IOException {
+        this.listener = listener;
+        init();
+    }
+
+    /**
+     * Called once before the first capture starts.
+     */
+    protected abstract void init() throws ConfigurationException, IOException;
 
     /**
      * Called after the last capture ends (if and only if {@link #init()} has been called).

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

@@ -49,6 +49,8 @@ public class SurfaceEncoder implements AsyncProcessor {
     private Thread thread;
     private final AtomicBoolean stopped = new AtomicBoolean();
 
+    private final CaptureReset reset = new CaptureReset();
+
     public SurfaceEncoder(SurfaceCapture capture, Streamer streamer, int videoBitRate, float maxFps, List<CodecOption> codecOptions,
             String encoderName, boolean downsizeOnError) {
         this.capture = capture;
@@ -65,14 +67,14 @@ public class SurfaceEncoder implements AsyncProcessor {
         MediaCodec mediaCodec = createMediaCodec(codec, encoderName);
         MediaFormat format = createFormat(codec.getMimeType(), videoBitRate, maxFps, codecOptions);
 
-        capture.init();
+        capture.init(reset);
 
         try {
             boolean alive;
             boolean headerWritten = false;
 
             do {
-                capture.consumeReset(); // If a capture reset was requested, it is implicitly fulfilled
+                reset.consumeReset(); // If a capture reset was requested, it is implicitly fulfilled
                 capture.prepare();
                 Size size = capture.getSize();
                 if (!headerWritten) {
@@ -168,14 +170,14 @@ public class SurfaceEncoder implements AsyncProcessor {
         boolean alive = true;
         MediaCodec.BufferInfo bufferInfo = new MediaCodec.BufferInfo();
 
-        while (!capture.consumeReset() && !eof) {
+        while (!reset.consumeReset() && !eof) {
             if (stopped.get()) {
                 alive = false;
                 break;
             }
             int outputBufferId = codec.dequeueOutputBuffer(bufferInfo, -1);
             try {
-                if (capture.consumeReset()) {
+                if (reset.consumeReset()) {
                     // must restart encoding with new size
                     break;
                 }