BLE: Scanned/Connected/Disconnected/Data Received callback in C++ style

[XuGuohui]

This PR is targeting to the feature/ble_scan_filter/ch37224 branch.

Problem

The existing wiring BLE APIs only support c style callback.

Solution

Using function wrapper to support c++ style callback.

Example App

1. Central side:

#include "Particle.h"

SYSTEM_MODE(MANUAL);

SerialLogHandler log(LOG_LEVEL_INFO);

BleCharacteristic peerTxChar;

void onBleScanCallbackWrapper(const BleScanResult& result) {
    Log.info("I'm a normal function.");
}

void onBleScanCallbackWithName(const char* name, const BleScanResult& result, void* context) {
    Log.info("I'm a normal function with context: %s", name);
}

class Test {
public:
    void scanHandler(const BleScanResult& result) {
        Log.info("Test::scanHandler()");
    }

    void dataHandler(const uint8_t* buf, size_t len) {
        Log.info("Test::dataHandler(), Data received:");
        for (uint8_t i = 0; i < len; i++) {
            Serial.printf("0x%02X ", buf[i]);
        }
        Serial.println("");
    }

    void disconnectHandler(const BlePeerDevice& peer) {
        Log.info("Test::disconnectHandler(), Disconnected by peer device.");
    }
};

Test test;

void setup() {
    while (!Serial.isConnected());
    delay(1s);

    Log.info("Start scanning...");
    BLE.scan(onBleScanCallbackWrapper);
    Log.info("Scan stopped\r\n");

    delay(3s);

    Log.info("Start scanning...");
    BLE.scan([](const BleScanResult& result) {
        Log.info("I'm a lambda.");
    });
    Log.info("Scan stopped\r\n");

    delay(3s);

    Log.info("Start scanning...");
    BLE.scan(std::bind(onBleScanCallbackWithName, "BindCallback", std::placeholders::_1, nullptr));
    Log.info("Scan stopped\r\n");

    Log.info("Start scanning...");
    BLE.scan(&Test::scanHandler, &test);
    Log.info("Scan stopped\r\n");

    delay(3s);

    // auto dataCb = [](const uint8_t* buf, size_t len, BleCharacteristic* characteristic) {
    //     Log.info("Data received from %s: ", characteristic->UUID().toString().c_str());
    //     for (uint8_t i = 0; i < len; i++) {
    //         Serial.printf("0x%02X ", buf[i]);
    //     }
    //     Serial.println("");
    // };
    // peerTxChar.onDataReceived(std::bind(dataCb, std::placeholders::_1, std::placeholders::_2, &peerTxChar));
    peerTxChar.onDataReceived(&Test::dataHandler, &test);

    // BLE.onDisconnected([](const BlePeerDevice& peer) {
    //     Log.info("Disconnected by peer device.");
    // });
    BLE.onDisconnected(&Test::disconnectHandler, &test);
}

void loop() {
    if (!BLE.connected()) {
        Log.info("Start scanning...");
        auto results = BLE.scan();
        for (const auto& result : results) {
            BleUuid foundServiceUUID;
            size_t svcCount = result.advertisingData.serviceUUID(&foundServiceUUID, 1);
            if (svcCount > 0 && foundServiceUUID == "6E400001-B5A3-F393-E0A9-E50E24DCCA9E") {
                Log.info("Connecting...");
                BlePeerDevice peer = BLE.connect(result.address);
                if (peer.connected()) {
                    Log.info("Connected.");
                    peer.getCharacteristicByUUID(peerTxChar, "6E400003-B5A3-F393-E0A9-E50E24DCCA9E");
                    if (!peerTxChar.valid()) {
                        Log.error("TX characteristic not found.");
                    }
                }
                break;
            }
        }
    }
}

2. Peripheral side:

• user/tests/app/ble/uart_peripheral

References

N/A

---

Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)

[avtolstoy]

@XuGuohui OK, but if possible let's refactor and just use std::function everywhere.

[avtolstoy]

Nit: probably fine without wiring prefix :)

[XuGuohui]

Renamed.