1 /*
2 * Copyright (C) 2022 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 #pragma once
18
19 #include <cstdint>
20 #include <memory>
21 #include <mutex>
22 #include <string>
23 #include <unordered_map>
24
25 #include <android-base/result.h>
26 #include <android-base/thread_annotations.h>
27 #include <android/sysprop/InputProperties.sysprop.h>
28 #include <input/Input.h>
29 #include <input/MotionPredictorMetricsManager.h>
30 #include <input/TfLiteMotionPredictor.h>
31 #include <utils/Timers.h> // for nsecs_t
32
33 namespace android {
34
isMotionPredictionEnabled()35 static inline bool isMotionPredictionEnabled() {
36 return sysprop::InputProperties::enable_motion_prediction().value_or(true);
37 }
38
39 /**
40 * Given a set of MotionEvents for the current gesture, predict the motion. The returned MotionEvent
41 * contains a set of samples in the future.
42 *
43 * The typical usage is like this:
44 *
45 * MotionPredictor predictor(offset = MY_OFFSET);
46 * predictor.record(DOWN_MOTION_EVENT);
47 * predictor.record(MOVE_MOTION_EVENT);
48 * prediction = predictor.predict(futureTime);
49 *
50 * The resulting motion event will have eventTime <= (futureTime + MY_OFFSET). It might contain
51 * historical data, which are additional samples from the latest recorded MotionEvent's eventTime
52 * to the futureTime + MY_OFFSET.
53 *
54 * The offset is used to provide additional flexibility to the caller, in case the default present
55 * time (typically provided by the choreographer) does not account for some delays, or to simply
56 * reduce the aggressiveness of the prediction. Offset can be positive or negative.
57 */
58 class MotionPredictor {
59 public:
60 /**
61 * Parameters:
62 * predictionTimestampOffsetNanos: additional, constant shift to apply to the target
63 * prediction time. The prediction will target the time t=(prediction time +
64 * predictionTimestampOffsetNanos).
65 *
66 * modelPath: filesystem path to a TfLiteMotionPredictorModel flatbuffer, or nullptr to use the
67 * default model path.
68 *
69 * checkEnableMotionPredition: the function to check whether the prediction should run. Used to
70 * provide an additional way of turning prediction on and off. Can be toggled at runtime.
71 */
72 MotionPredictor(nsecs_t predictionTimestampOffsetNanos,
73 std::function<bool()> checkEnableMotionPrediction = isMotionPredictionEnabled);
74
75 /**
76 * Record the actual motion received by the view. This event will be used for calculating the
77 * predictions.
78 *
79 * @return empty result if the event was processed correctly, error if the event is not
80 * consistent with the previously recorded events.
81 */
82 android::base::Result<void> record(const MotionEvent& event);
83
84 std::unique_ptr<MotionEvent> predict(nsecs_t timestamp);
85
86 bool isPredictionAvailable(int32_t deviceId, int32_t source);
87
88 private:
89 const nsecs_t mPredictionTimestampOffsetNanos;
90 const std::function<bool()> mCheckMotionPredictionEnabled;
91
92 std::unique_ptr<TfLiteMotionPredictorModel> mModel;
93
94 std::unique_ptr<TfLiteMotionPredictorBuffers> mBuffers;
95 std::optional<MotionEvent> mLastEvent;
96
97 std::optional<MotionPredictorMetricsManager> mMetricsManager;
98 };
99
100 } // namespace android
101