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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.camera.one.v2.autofocus;
     18 
     19 import android.hardware.camera2.CaptureRequest;
     20 import android.hardware.camera2.CaptureResult;
     21 
     22 import com.android.camera.async.Updatable;
     23 import com.android.camera.one.v2.camera2proxy.CaptureResultProxy;
     24 import com.google.common.base.Objects;
     25 import com.google.common.collect.ImmutableSet;
     26 import com.google.common.util.concurrent.SettableFuture;
     27 
     28 import java.util.Set;
     29 import java.util.concurrent.ExecutionException;
     30 import java.util.concurrent.TimeUnit;
     31 import java.util.concurrent.TimeoutException;
     32 
     33 import javax.annotation.ParametersAreNonnullByDefault;
     34 
     35 /**
     36  * Listens for image metadata and returns the result of an AE scan caused by an
     37  * AE_TRIGGER_START. The result of indicates whether flash is required.
     38  * <p>
     39  * Maintains the current state of auto-exposure scans resulting from explicit
     40  * precapture trigger requests. This maintains the subset of the finite state
     41  * machine of {@link CaptureResult#CONTROL_AE_STATE} which relates to
     42  * CONTROL_AE_PRECAPTURE_TRIGGER
     43  * <p>
     44  * That is, it invokes the given callback when a scan is complete, according to
     45  * the following sequence:
     46  *
     47  * <pre>
     48  * .* CONTROL_AE_PRECAPTURE_TRIGGER_START .*
     49  * (STATE_INACTIVE|STATE_FLASH_REQUIRED|STATE_CONVERGED|STATE_LOCKED)
     50  * </pre>
     51  * <p>
     52  * See the android documentation for {@link CaptureResult#CONTROL_AE_STATE} for
     53  * further documentation on the state machine this class implements.
     54  */
     55 @ParametersAreNonnullByDefault
     56 public final class AETriggerResult implements Updatable<CaptureResultProxy> {
     57     private static final Set<Integer> TRIGGER_DONE_STATES = ImmutableSet.of(
     58             CaptureResult.CONTROL_AE_STATE_INACTIVE,
     59             CaptureResult.CONTROL_AE_STATE_FLASH_REQUIRED,
     60             CaptureResult.CONTROL_AE_STATE_CONVERGED,
     61             CaptureResult.CONTROL_AE_STATE_LOCKED);
     62 
     63     private final TriggerStateMachine mStateMachine;
     64     private final SettableFuture<Boolean> mFutureResult;
     65 
     66     public AETriggerResult() {
     67         mStateMachine = new TriggerStateMachine(
     68                 CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER_START,
     69                 TRIGGER_DONE_STATES);
     70         mFutureResult = SettableFuture.create();
     71     }
     72 
     73     @Override
     74     public void update(CaptureResultProxy result) {
     75         Integer state = result.get(CaptureResult.CONTROL_AE_STATE);
     76         boolean done = mStateMachine.update(
     77                 result.getFrameNumber(),
     78                 result.getRequest().get(CaptureRequest.CONTROL_AE_PRECAPTURE_TRIGGER),
     79                 state);
     80         if (done) {
     81             boolean flashRequired = Objects.equal(state, CaptureResult
     82                     .CONTROL_AE_STATE_FLASH_REQUIRED);
     83             mFutureResult.set(flashRequired);
     84         }
     85     }
     86 
     87     /**
     88      * Blocks until the AE scan is complete.
     89      *
     90      * @return Whether the scene requires flash to be properly exposed.
     91      * @throws InterruptedException
     92      */
     93     public boolean get() throws InterruptedException {
     94         try {
     95             return mFutureResult.get();
     96         } catch (ExecutionException impossible) {
     97             throw new RuntimeException(impossible);
     98         }
     99     }
    100 
    101     /**
    102      * Blocks until the AE scan is complete.
    103      *
    104      * @return Whether the scene requires flash to be properly exposed.
    105      * @throws InterruptedException
    106      */
    107     public boolean get(long timeout, TimeUnit timeUnit) throws InterruptedException,
    108             TimeoutException {
    109         try {
    110             return mFutureResult.get(timeout, timeUnit);
    111         } catch (ExecutionException impossible) {
    112             throw new RuntimeException(impossible);
    113         }
    114     }
    115 }
    116