ZoomControl.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.camera2.internal;
import android.graphics.Rect;
import android.hardware.camera2.CameraCharacteristics;
import android.hardware.camera2.CaptureRequest;
import android.hardware.camera2.TotalCaptureResult;
import android.os.Looper;
import androidx.annotation.FloatRange;
import androidx.annotation.GuardedBy;
import androidx.annotation.NonNull;
import androidx.annotation.VisibleForTesting;
import androidx.annotation.WorkerThread;
import androidx.camera.core.CameraControl.OperationCanceledException;
import androidx.camera.core.ZoomState;
import androidx.camera.core.impl.utils.futures.Futures;
import androidx.camera.core.internal.ImmutableZoomState;
import androidx.concurrent.futures.CallbackToFutureAdapter;
import androidx.lifecycle.LifecycleOwner;
import androidx.lifecycle.LiveData;
import androidx.lifecycle.MutableLiveData;
import androidx.lifecycle.Observer;
import com.google.common.util.concurrent.ListenableFuture;
/**
* Implementation of zoom control used within CameraControl and CameraInfo.
*
* <p>It consists of setters and getters. Setters like {@link #setZoomRatio(float)} and
* {@link #setLinearZoom(float)} return a {@link ListenableFuture} which apps can
* use to await the async result. The {@link #getZoomState()} getter returns a {@link LiveData}
* which apps can get immediate value from by
* {@link LiveData#getValue()} or observe the changes by
* {@link LiveData#observe(LifecycleOwner, Observer)}.
*
* <p>{@link #setZoomRatio(float)} accepts zoom ratio from {@link ZoomState#getMinZoomRatio()} to
* {@link ZoomState#getMaxZoomRatio()}. Alternatively, app can call {@link #setLinearZoom(float)} to
* specify the zoom by a [0..1] percentage. The linearZoom value is a float ranging from 0 to 1
* representing the minimum zoom to maximum zoom respectively. The benefits of using linear zoom
* is it ensures the FOV width/height is changed linearly.
*
* <p>The operation (the setters) will throw {@link IllegalStateException} if {@link ZoomControl} is
* not active. All states are reset to default values once it is inactive. We should set active
* on {@link ZoomControl} when apps are ready to accept zoom operations and set inactive if camera
* is closing or closed.
*/
final class ZoomControl {
private static final String TAG = "ZoomControl";
public static final float DEFAULT_ZOOM_RATIO = 1.0f;
public static final float MIN_ZOOM = DEFAULT_ZOOM_RATIO;
private final Camera2CameraControl mCamera2CameraControl;
@GuardedBy("mActiveLock")
private final ZoomStateImpl mCurrentZoomState;
private final MutableLiveData<ZoomState> mZoomStateLiveData;
@SuppressWarnings("WeakerAccess") /* synthetic accessor */
final Object mCompleterLock = new Object();
@GuardedBy("mCompleterLock")
@SuppressWarnings("WeakerAccess") /* synthetic accessor */
CallbackToFutureAdapter.Completer<Void> mPendingZoomRatioCompleter;
@SuppressWarnings("WeakerAccess") /* synthetic accessor */
@GuardedBy("mCompleterLock")
Rect mPendingZoomCropRegion = null;
final Object mActiveLock = new Object();
/**
* true if it is ready to accept zoom operation. Any zoom operation during inactive state will
* throw{@link IllegalStateException}.
*/
@GuardedBy("mActiveLock")
private boolean mIsActive = false;
ZoomControl(@NonNull Camera2CameraControl camera2CameraControl,
@NonNull CameraCharacteristics cameraCharacteristics) {
mCamera2CameraControl = camera2CameraControl;
mCurrentZoomState = new ZoomStateImpl(getMaxDigitalZoom(cameraCharacteristics), MIN_ZOOM);
mCurrentZoomState.setZoomRatio(DEFAULT_ZOOM_RATIO);
mZoomStateLiveData = new MutableLiveData<>(ImmutableZoomState.create(mCurrentZoomState));
camera2CameraControl.addCaptureResultListener(mCaptureResultListener);
}
/**
* Set current active state. Set active if it is ready to accept zoom operations.
*
* <p>Any zoom operation during inactive state will do nothing and report a error in
* ListenableFuture. All zoom states are reset to default once it is changed to inactive state.
*/
@WorkerThread
void setActive(boolean isActive) {
CallbackToFutureAdapter.Completer<Void> completerToSetException = null;
boolean shouldResetDefault = false;
// Only do variable assignment within the synchronized block to prevent form dead lock.
synchronized (mActiveLock) {
if (mIsActive == isActive) {
return;
}
mIsActive = isActive;
if (!mIsActive) {
// Fails the pending ListenableFuture.
synchronized (mCompleterLock) {
if (mPendingZoomRatioCompleter != null) {
completerToSetException = mPendingZoomRatioCompleter;
mPendingZoomRatioCompleter = null;
mPendingZoomCropRegion = null;
}
}
// Reset all values if zoomControl is inactive.
shouldResetDefault = true;
mCurrentZoomState.setZoomRatio(DEFAULT_ZOOM_RATIO);
updateLiveData(ImmutableZoomState.create(mCurrentZoomState));
}
}
if (shouldResetDefault) {
mCamera2CameraControl.setCropRegion(null);
}
if (completerToSetException != null) {
completerToSetException
.setException(new OperationCanceledException("Camera is not active."));
}
}
private Camera2CameraControl.CaptureResultListener mCaptureResultListener =
new Camera2CameraControl.CaptureResultListener() {
@WorkerThread
@Override
public boolean onCaptureResult(@NonNull TotalCaptureResult captureResult) {
// Compare the requested crop region, not the result's crop region because HAL
// could modify the requested crop region.
CallbackToFutureAdapter.Completer<Void> completerToSet = null;
synchronized (mCompleterLock) {
if (mPendingZoomRatioCompleter != null) {
CaptureRequest request = captureResult.getRequest();
Rect cropRect = (request == null) ? null :
request.get(CaptureRequest.SCALER_CROP_REGION);
if (mPendingZoomCropRegion != null
&& mPendingZoomCropRegion.equals(cropRect)) {
completerToSet = mPendingZoomRatioCompleter;
mPendingZoomRatioCompleter = null;
mPendingZoomCropRegion = null;
}
}
}
if (completerToSet != null) {
completerToSet.set(null);
}
return false; // continue checking
}
};
/**
* Sets current zoom by ratio.
*
* <p>It modifies both current zoomRatio and linearZoom so if apps are observing
* zoomRatio or linearZoom, they will get the update as well. If the ratio is
* smaller than {@link ZoomState#getMinZoomRatio()} or larger than
* {@link ZoomState#getMaxZoomRatio()} ()}, the returned {@link ListenableFuture} will fail with
* {@link IllegalArgumentException} and it won't modify current zoom ratio. It is the
* applications' duty to clamp the ratio.
*
* @return a {@link ListenableFuture} which is finished when current repeating request
* result contains the requested zoom ratio. It fails with
* {@link OperationCanceledException} if there is newer value being set or camera is closed. If
* the ratio is out of range, it fails with {@link IllegalArgumentException}.
*/
@NonNull
ListenableFuture<Void> setZoomRatio(float ratio) {
// Wrapping the whole method in synchronized block in case mActive is changed to false in
// the middle of the method. To avoid the deadlock problem, we only perform variable
// assignment in the setActive() synchronized block.
synchronized (mActiveLock) {
if (!mIsActive) {
return Futures.immediateFailedFuture(
new OperationCanceledException("Camera is not active."));
}
// If the requested ratio is out of range, it will not modify zoom value but report
// IllegalArgumentException in returned ListenableFuture.
try {
mCurrentZoomState.setZoomRatio(ratio);
} catch (IllegalArgumentException e) {
return Futures.immediateFailedFuture(e);
}
updateLiveData(ImmutableZoomState.create(mCurrentZoomState));
return submitCameraZoomRatio(ratio);
}
}
@NonNull
@VisibleForTesting
static Rect getCropRectByRatio(@NonNull Rect sensorRect, float ratio) {
float cropWidth = (sensorRect.width() / ratio);
float cropHeight = (sensorRect.height() / ratio);
float left = ((sensorRect.width() - cropWidth) / 2.0f);
float top = ((sensorRect.height() - cropHeight) / 2.0f);
return new Rect((int) left, (int) top, (int) (left + cropWidth),
(int) (top + cropHeight));
}
/**
* Submits the request for updating the zoom ratio of the underlying camera instance.
*
* <p>When the returned {@link ListenableFuture} completes, either the zoom ratio will be
* updated or it will have failed, because some other action canceled the updating of the zoom.
*/
@NonNull
@GuardedBy("mActiveLock")
private ListenableFuture<Void> submitCameraZoomRatio(float ratio) {
Rect sensorRect = mCamera2CameraControl.getSensorRect();
Rect targetRegion = getCropRectByRatio(sensorRect, ratio);
mCamera2CameraControl.setCropRegion(targetRegion);
return CallbackToFutureAdapter.getFuture((completer) -> {
CallbackToFutureAdapter.Completer<Void> completerToCancel = null;
synchronized (mCompleterLock) {
if (mPendingZoomRatioCompleter != null) {
completerToCancel = mPendingZoomRatioCompleter;
mPendingZoomRatioCompleter = null;
}
mPendingZoomCropRegion = targetRegion;
mPendingZoomRatioCompleter = completer;
}
if (completerToCancel != null) {
completerToCancel.setException(
new OperationCanceledException("There is a new zoomRatio being set"));
}
return "setZoomRatio";
});
}
/**
* Sets current zoom by a linear zoom value ranging from 0f to 1.0f. LinearZoom 0f represents
* the minimum zoom while linearZoom 1.0f represents the maximum zoom. The advantage of
* linearZoom is that it ensures the field of view (FOV) varies linearly with the linearZoom
* value, for use with slider UI elements (while {@link #setZoomRatio(float)} works well
* for pinch-zoom gestures).
*
* <p>It modifies both current zoomRatio and linearZoom so if apps are observing
* zoomRatio or linearZoom, they will get the update as well. If the linearZoom is not in
* the range [0..1], the returned {@link ListenableFuture} will fail with
* {@link IllegalArgumentException} and it won't modify current linearZoom and zoomRatio. It is
* application's duty to clamp the linearZoom within [0..1].
*
* @return a {@link ListenableFuture} which is finished when current repeating request
* result contains the requested linearZoom. It fails with
* {@link OperationCanceledException} if there is newer value being set or camera is closed.
* If linearZoom is not in range [0..1], it fails with {@link IllegalArgumentException}.
*/
@NonNull
ListenableFuture<Void> setLinearZoom(@FloatRange(from = 0f, to = 1f) float linearZoom) {
// Wrapping the whole method in synchronized block in case mActive is changed to false in
// the middle of the method. To avoid the deadlock problem, we only perform variable
// assignment in the setActive() synchronized block.
synchronized (mActiveLock) {
if (!mIsActive) {
return Futures.immediateFailedFuture(
new OperationCanceledException("Camera is not active."));
}
// If the requested linearZoom is out of range, it will not modify zoom value but
// report IllegalArgumentException in returned ListenableFuture.
try {
mCurrentZoomState.setLinearZoom(linearZoom);
} catch (IllegalArgumentException e) {
return Futures.immediateFailedFuture(e);
}
updateLiveData(ImmutableZoomState.create(mCurrentZoomState));
return submitCameraZoomRatio(mCurrentZoomState.getZoomRatio());
}
}
private void updateLiveData(ZoomState zoomState) {
if (Looper.myLooper() == Looper.getMainLooper()) {
mZoomStateLiveData.setValue(zoomState);
} else {
mZoomStateLiveData.postValue(zoomState);
}
}
/**
* Returns a {@link LiveData} of the current {@link ZoomState}.
*
* <p>Setting the zoom via {@link #setLinearZoom(float)} or {@link #setZoomRatio(float)} will
* trigger a change in the values of the LiveData.
*/
LiveData<ZoomState> getZoomState() {
return mZoomStateLiveData;
}
private static float getMaxDigitalZoom(CameraCharacteristics cameraCharacteristics) {
Float maxZoom = cameraCharacteristics.get(
CameraCharacteristics.SCALER_AVAILABLE_MAX_DIGITAL_ZOOM);
if (maxZoom == null) {
return MIN_ZOOM;
}
return maxZoom;
}
}