Simplify camera startup code

Avoid multiple back-and-forths between the caller thread and the camera
thread.

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

@@ -36,6 +36,7 @@ import android.view.Surface;
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
@@ -78,6 +79,9 @@ public class CameraCapture extends SurfaceCapture {
 
     private final AtomicBoolean disconnected = new AtomicBoolean();
 
+    // Must be accessed only from the camera thread
+    private boolean started;
+
     public CameraCapture(Options options) {
         this.explicitCameraId = options.getCameraId();
         this.cameraFacing = options.getCameraFacing();
@@ -250,6 +254,7 @@ public class CameraCapture extends SurfaceCapture {
         return ratio.getAspectRatio();
     }
 
+    @TargetApi(AndroidVersions.API_28_ANDROID_9)
     @Override
     public void start(Surface surface) throws IOException {
         if (transform != null) {
@@ -261,11 +266,50 @@ public class CameraCapture extends SurfaceCapture {
             surface = glRunner.start(captureSize, videoSize, surface);
         }
 
+        cameraHandler.post(() -> {
+            assertCameraThread();
+            started = true;
+        });
+
+        Surface captureSurface = surface;
+        OutputConfiguration outputConfig = new OutputConfiguration(captureSurface);
+        List<OutputConfiguration> outputs = Collections.singletonList(outputConfig);
+        int sessionType = highSpeed ? SessionConfiguration.SESSION_HIGH_SPEED : SessionConfiguration.SESSION_REGULAR;
+        SessionConfiguration sessionConfig = new SessionConfiguration(sessionType, outputs, cameraExecutor, new CameraCaptureSession.StateCallback() {
+            @Override
+            public void onConfigured(CameraCaptureSession session) {
+                assertCameraThread();
+                if (!started) {
+                    // Stopped on the encoder thread between the call to start() and this callback
+                    return;
+                }
+
+                try {
+                    CaptureRequest.Builder requestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
+                    requestBuilder.addTarget(captureSurface);
+
+                    if (fps > 0) {
+                        requestBuilder.set(CaptureRequest.CONTROL_AE_TARGET_FPS_RANGE, new Range<>(fps, fps));
+                    }
+
+                    CaptureRequest request = requestBuilder.build();
+                    setRepeatingRequest(session, request);
+                } catch (CameraAccessException e) {
+                    Ln.e("Camera error", e);
+                    invalidate();
+                }
+            }
+
+            @Override
+            public void onConfigureFailed(CameraCaptureSession session) {
+                Ln.e("Camera configuration error");
+                invalidate();
+            }
+        });
+
         try {
-            CameraCaptureSession session = createCaptureSession(cameraDevice, surface);
+            cameraDevice.createCaptureSession(sessionConfig);
-            CaptureRequest request = createCaptureRequest(surface);
+        } catch (CameraAccessException e) {
-            setRepeatingRequest(session, request);
-        } catch (CameraAccessException | InterruptedException e) {
             stop();
             throw new IOException(e);
         }
@@ -273,6 +317,11 @@ public class CameraCapture extends SurfaceCapture {
 
     @Override
     public void stop() {
+        cameraHandler.post(() -> {
+            assertCameraThread();
+            started = false;
+        });
+
         if (glRunner != null) {
             glRunner.stopAndRelease();
             glRunner = null;
@@ -353,46 +402,7 @@ public class CameraCapture extends SurfaceCapture {
     }
 
     @TargetApi(AndroidVersions.API_31_ANDROID_12)
-    private CameraCaptureSession createCaptureSession(CameraDevice camera, Surface surface) throws CameraAccessException, InterruptedException {
+    private void setRepeatingRequest(CameraCaptureSession session, CaptureRequest request) throws CameraAccessException {
-        CompletableFuture<CameraCaptureSession> future = new CompletableFuture<>();
-        OutputConfiguration outputConfig = new OutputConfiguration(surface);
-        List<OutputConfiguration> outputs = Arrays.asList(outputConfig);
-
-        int sessionType = highSpeed ? SessionConfiguration.SESSION_HIGH_SPEED : SessionConfiguration.SESSION_REGULAR;
-        SessionConfiguration sessionConfig = new SessionConfiguration(sessionType, outputs, cameraExecutor, new CameraCaptureSession.StateCallback() {
-            @Override
-            public void onConfigured(CameraCaptureSession session) {
-                future.complete(session);
-            }
-
-            @Override
-            public void onConfigureFailed(CameraCaptureSession session) {
-                future.completeExceptionally(new CameraAccessException(CameraAccessException.CAMERA_ERROR));
-            }
-        });
-
-        camera.createCaptureSession(sessionConfig);
-
-        try {
-            return future.get();
-        } catch (ExecutionException e) {
-            throw (CameraAccessException) e.getCause();
-        }
-    }
-
-    private CaptureRequest createCaptureRequest(Surface surface) throws CameraAccessException {
-        CaptureRequest.Builder requestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_RECORD);
-        requestBuilder.addTarget(surface);
-
-        if (fps > 0) {
-            requestBuilder.set(CaptureRequest.CONTROL_AE_TARGET_FPS_RANGE, new Range<>(fps, fps));
-        }
-
-        return requestBuilder.build();
-    }
-
-    @TargetApi(AndroidVersions.API_31_ANDROID_12)
-    private void setRepeatingRequest(CameraCaptureSession session, CaptureRequest request) throws CameraAccessException, InterruptedException {
         CameraCaptureSession.CaptureCallback callback = new CameraCaptureSession.CaptureCallback() {
             @Override
             public void onCaptureStarted(CameraCaptureSession session, CaptureRequest request, long timestamp, long frameNumber) {
@@ -418,4 +428,8 @@ public class CameraCapture extends SurfaceCapture {
     public boolean isClosed() {
         return disconnected.get();
     }
+
+    private void assertCameraThread() {
+        assert Thread.currentThread() == cameraThread;
+    }
 }