我可以使用 chrome web 藍牙低能量 android 將來自樹莓派的圖像的 stream 發送到 android 嗎？

Question

Currently I have a HTML/Javascript web application working on my Android that can pair with a raspberry pi using the Chrome web bluetooth api. 我知道通過 GATT 特性最多可以發送 512 個字節，這對於我的目的來說太小了。 Is there a way to send a stream of images (or even just one image for now) from the pi to my android over BLE with this web bluetooth api?

下面是請求樹莓派的 javascript 代碼。 我在 pi 上運行 python 腳本來宣傳自己及其服務/特征。 目前我有一個自定義的 GATT 特性，但由於 512 字節的限制，我無法通過它發送圖像。 使用 API 查找/連接到 pi 后，是否有另一種方法可以將圖像從 pi 發送回 android？

    //device and characteristic variables

    var bluetoothDevice;

    var imageCharacteristic;



    //decoder for array buffer -> string

    var enc = new TextDecoder("utf-8");



    //UUIDs

    //service uuid 

    const serviceUUID = '00000001-710e-4a5b-8d75-3e5b444bc3cf'


    //write characteristic for taking an image on the pi

    const imageCharacteristicUUID = '00000007-710e-4a5b-8d75-3e5b444bc3cf'



    //button 1: change connect/disconnect button when clicked

    connectButton.addEventListener('click', function handleClick() {

        const initialText = 'Connect';



        if (connectButton.innerText.includes(initialText)) { //user clicks 'connect'

            //check if see if bluetooth device has already been requested

            return (bluetoothDevice ? Promise.resolve() : requestDevice())

            .then(connectDevice)

            .then(_ => {

                connectButton.innerText = 'Disconnect';

                document.getElementById("status").innerHTML = 'BT Connected';

            })

            .catch(error => {

                console.log('error' + error);

            });

        } else { //user clicks 'disconnect'

            if (bluetoothDevice.gatt.connected) { //error handling to ensure device is actually connected

                console.log('disconnecting...')

                bluetoothDevice.gatt.disconnect();

            } else {

                console.log('Bluetooth Device is already disconnected');

            }

        }

    })



    //request device using web bluetooth api

    function requestDevice() {

        return navigator.bluetooth.requestDevice({

            //filter to search for one device

            filters: [

                {name: 'rasPi'},

                {services: [serviceUUID]}

            ]

        })

        .then(device => {

            bluetoothDevice = device;

        })

    }



    //connect to device and register services and characteristics

    function connectDevice() {

        if (bluetoothDevice.gatt.connected) {

            return Promise.resolve();

        }

        console.log("connected");

        return bluetoothDevice.gatt.connect()

        .then(server => server.getPrimaryService(serviceUUID))

        .then(service => service.getCharacteristics())

        .then(characteristics => {

            //start a queue to gather each characteristic

            let queue = Promise.resolve();

            characteristics.forEach(characteristic => {

                switch (characteristic.uuid) {

                    case BluetoothUUID.getCharacteristic(imageCharacteristicUUID) :

                        queue = queue.then(_ => {

                            imageCharacteristic = characteristic;

                        })

                        break;

                    default : console.log('Unknown Characteristic: ' + characteristic.uuid);

                }

            });

            return queue;

        })

    }

Answer 1

已解決：我最終將圖像轉換為字符串並通過一個循環發送它。 我的 web 頁面啟動特征通知並一次獲取 512 個字節，然后串在一起並顯示圖像。