SurfaceViewImplementation.java
/*
* Copyright 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.camera.view;
import android.util.Log;
import android.util.Size;
import android.view.Surface;
import android.view.SurfaceHolder;
import android.widget.FrameLayout;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.UiThread;
import androidx.camera.core.Preview;
import androidx.concurrent.futures.CallbackToFutureAdapter;
import com.google.common.util.concurrent.ListenableFuture;
/**
* The SurfaceView implementation for {@link PreviewView}.
*/
final class SurfaceViewImplementation implements PreviewView.Implementation {
private static final String TAG = "SurfaceViewPreviewView";
// Synthetic Accessor
@SuppressWarnings("WeakerAccess")
TransformableSurfaceView mSurfaceView;
// Synthetic Accessor
@SuppressWarnings("WeakerAccess")
final CompleterWithSizeCallback mCompleterWithSizeCallback =
new CompleterWithSizeCallback();
private Preview.PreviewSurfaceProvider mPreviewSurfaceProvider =
new Preview.PreviewSurfaceProvider() {
@NonNull
@Override
public ListenableFuture<Surface> provideSurface(@NonNull Size resolution,
@NonNull ListenableFuture<Void> surfaceReleaseFuture) {
// No-op on surfaceReleaseFuture because the Surface will be destroyed by
// SurfaceView.
return CallbackToFutureAdapter.getFuture(
completer -> {
// Post to UI thread for thread safety.
mSurfaceView.post(
() -> mCompleterWithSizeCallback.setCompleterAndSize(
completer, resolution));
return "SurfaceViewSurfaceCreation";
});
}
};
/**
* {@inheritDoc}
*/
@Override
public void init(@NonNull FrameLayout parent) {
mSurfaceView = new TransformableSurfaceView(parent.getContext());
mSurfaceView.setLayoutParams(
new FrameLayout.LayoutParams(
FrameLayout.LayoutParams.MATCH_PARENT,
FrameLayout.LayoutParams.MATCH_PARENT));
parent.addView(mSurfaceView);
mSurfaceView.getHolder().addCallback(mCompleterWithSizeCallback);
}
/**
* {@inheritDoc}
*/
@NonNull
@Override
public Preview.PreviewSurfaceProvider getPreviewSurfaceProvider() {
return mPreviewSurfaceProvider;
}
/**
* The {@link SurfaceHolder.Callback} on mSurfaceView.
*
* <p> SurfaceView creates Surface on its own before we can do anything. This class makes
* sure only the Surface with correct size will be returned to Preview.
*/
class CompleterWithSizeCallback implements SurfaceHolder.Callback {
// Target Surface size. Only complete the ListenableFuture when the size of the Surface
// matches this value.
// Guarded by UI thread.
@Nullable
private Size mTargetSize;
// Completer to set when the target size is met.
// Guarded by UI thread.
@Nullable
private CallbackToFutureAdapter.Completer<Surface> mCompleter;
// The cached size of the current Surface.
// Guarded by UI thread.
@Nullable
private Size mCurrentSurfaceSize;
/**
* Sets the completer and the size. The completer will only be set if the current size of
* the Surface matches the target size.
*/
@UiThread
void setCompleterAndSize(CallbackToFutureAdapter.Completer<Surface> completer,
Size targetSize) {
cancelCompleter();
mCompleter = completer;
mTargetSize = targetSize;
if (!tryToComplete()) {
// The current size is incorrect. Wait for it to change.
Log.d(TAG, "Wait for new Surface creation.");
mSurfaceView.getHolder().setFixedSize(targetSize.getWidth(),
targetSize.getHeight());
}
}
/**
* Sets the completer if size matches.
*
* @return true if the completer is set.
*/
@UiThread
private boolean tryToComplete() {
Surface surface = mSurfaceView.getHolder().getSurface();
if (mCompleter != null && mTargetSize != null && mTargetSize.equals(
mCurrentSurfaceSize)) {
Log.d(TAG, "Surface set on Preview.");
mCompleter.set(surface);
mCompleter = null;
mTargetSize = null;
return true;
}
return false;
}
@UiThread
private void cancelCompleter() {
if (mCompleter != null) {
Log.d(TAG, "Completer canceled.");
mCompleter.setCancelled();
mCompleter = null;
}
mTargetSize = null;
}
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
Log.d(TAG, "Surface created.");
// No-op. Handling surfaceChanged() is enough because it's always called afterwards.
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int format, int width, int height) {
Log.d(TAG, "Surface changed. Size: " + width + "x" + height);
mCurrentSurfaceSize = new Size(width, height);
tryToComplete();
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
Log.d(TAG, "Surface destroyed.");
mCurrentSurfaceSize = null;
cancelCompleter();
}
}
}