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128 lines
4.1 KiB
128 lines
4.1 KiB
/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef _UI_INPUTFLINGER_TOUCH_VIDEO_DEVICE_H
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#define _UI_INPUTFLINGER_TOUCH_VIDEO_DEVICE_H
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#include <android-base/unique_fd.h>
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#include <input/TouchVideoFrame.h>
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#include <stdint.h>
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#include <array>
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#include <optional>
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#include <string>
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#include <vector>
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namespace android {
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/**
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* Represents a video device that uses v4l2 api to report touch heatmap data.
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*/
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class TouchVideoDevice {
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public:
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/**
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* Create a new TouchVideoDevice for the path provided.
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* Return nullptr upon failure.
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*/
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static std::unique_ptr<TouchVideoDevice> create(std::string devicePath);
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~TouchVideoDevice();
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bool hasValidFd() const { return mFd.get() != INVALID_FD; }
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/**
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* Obtain the file descriptor associated with this video device.
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* Could be used for adding to epoll.
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*/
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int getFd() const { return mFd.get(); }
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/**
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* Get the name of this video device.
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*/
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const std::string& getName() const { return mName; }
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/**
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* Get the file path of this video device.
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*/
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const std::string& getPath() const { return mPath; }
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/**
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* Get the height of the heatmap frame
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*/
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uint32_t getHeight() const { return mHeight; }
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/**
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* Get the width of the heatmap frame
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*/
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uint32_t getWidth() const { return mWidth; }
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/**
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* Direct read of the frame. Stores the frame into internal buffer.
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* Return the number of frames that were successfully read.
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*
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* This function should not be called unless buffer is ready!
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* This must be checked with select, poll, epoll, or similar api first.
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* If epoll indicates that there is data ready to read, but this function
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* returns zero, then it is likely an error occurred.
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*/
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size_t readAndQueueFrames();
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/**
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* Return all of the queued frames, and erase them from the local buffer.
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* The returned frames are in the order that they were received from the
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* v4l2 device, with the oldest frame at the index 0.
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*/
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std::vector<TouchVideoFrame> consumeFrames();
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/**
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* Get string representation of this video device.
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*/
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std::string dump() const;
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private:
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android::base::unique_fd mFd;
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std::string mName;
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std::string mPath;
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uint32_t mHeight;
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uint32_t mWidth;
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static constexpr int INVALID_FD = -1;
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/**
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* How many buffers to request for heatmap.
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* The kernel driver will be allocating these buffers for us,
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* and will provide memory locations to read these from.
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*/
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static constexpr size_t NUM_BUFFERS = 3;
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std::array<const int16_t*, NUM_BUFFERS> mReadLocations;
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/**
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* How many buffers to keep for the internal queue. When the internal buffer
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* exceeds this capacity, oldest frames will be dropped.
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*/
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static constexpr size_t MAX_QUEUE_SIZE = 20;
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std::vector<TouchVideoFrame> mFrames;
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/**
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* The constructor is private because opening a v4l2 device requires many checks.
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* To get a new TouchVideoDevice, use 'create' instead.
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*/
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explicit TouchVideoDevice(int fd, std::string&& name, std::string&& devicePath, uint32_t height,
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uint32_t width,
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const std::array<const int16_t*, NUM_BUFFERS>& readLocations);
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/**
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* Read all currently available frames.
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*/
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std::vector<TouchVideoFrame> readFrames();
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/**
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* Read a single frame. May return nullopt if no data is currently available for reading.
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*/
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std::optional<TouchVideoFrame> readFrame();
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};
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} // namespace android
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#endif // _UI_INPUTFLINGER_TOUCH_VIDEO_DEVICE_H
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