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 
AETriggerResult()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
update(CaptureResultProxy result)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      */
get()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      */
get(long timeout, TimeUnit timeUnit)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