[BREAKING] - Refactor NimBLEScan

* General code cleanup
* `NimBLEScan::start` will no longer clear cache or results if scanning is already in progress.
* `NimBLEScan::clearResults` will now reset the vector capacity to 0.
* `NimBLEScan::stop` will no longer call the `onScanEnd` callback as the caller should know its been stopped when this is called.
* `NimBLEScan::clearDuplicateCache` has been removed as it was problematic and only for the esp32. Stop and start the scanner for the same effect.
* `NimBLEScan::start` takes a new bool parameter `restart`, default `true`, that will restart an already in progress scan and clear the duplicate filter so all devices will be discovered again.
* Scan response data that is received without advertisement first will now create the device and send a callback.
* Added new method: `NimBLEAdvertisedDevice::isScannable()` that returns true if the device is scannable.
* Added default callbacks for `NimBLEScanCallbacks`
* `NimBLEScanCallbacks` function signatures updated:
* - `onDiscovered` now takes a `const NimBLEAdvertisedDevice*`
* - `onResult` now takes a `const NimBLEAdvertisedDevice*`
* - `onScanEnd` now takes a `const NimBLEScanResults&` and `int reason`
* Added new erase overload: `NimBLEScan::erase(const NimBLEAdvertisedDevice* device)`
* `NimBLEScanResults::getDevice` methods now return `const NimBLEAdvertisedDevice*`
* `NimBLEScanResults` iterators are now `const_iterator`

examples/Advanced/NimBLE_Client/main/main.cpp

@@ -11,7 +11,7 @@
 
 extern "C" {void app_main(void);}
 
-static NimBLEAdvertisedDevice* advDevice;
+static const NimBLEAdvertisedDevice* advDevice;
 
 static bool doConnect = false;
 static uint32_t scanTime = 0; /** scan time in milliseconds, 0 = scan forever */
@@ -67,7 +67,7 @@ class ClientCallbacks : public NimBLEClientCallbacks {
 
 /** Define a class to handle the callbacks when advertisments are received */
 class scanCallbacks: public NimBLEScanCallbacks {
-    void onResult(NimBLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) {
         printf("Advertised Device found: %s\n", advertisedDevice->toString().c_str());
         if(advertisedDevice->isAdvertisingService(NimBLEUUID("DEAD")))
         {
@@ -82,8 +82,8 @@ class scanCallbacks: public NimBLEScanCallbacks {
     }
 
     /** Callback to process the results of the completed scan or restart it */
-    void onScanEnd(NimBLEScanResults results) {
-        printf("Scan Ended\n");
+    void onScanEnd(const NimBLEScanResults& results, int reason) {
+        printf("Scan Ended, reason: %d, device count: %d\n", reason, results.getCount());
     }
 };
 

examples/Continuous_scan/CMakeLists.txt

@@ -0,0 +1,6 @@
+# The following lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(Continuous_scan)

examples/Continuous_scan/main/CMakeLists.txt

@@ -0,0 +1,4 @@
+set(COMPONENT_SRCS "main.cpp")
+set(COMPONENT_ADD_INCLUDEDIRS ".")
+
+register_component()

examples/Continuous_scan/main/main.cpp

@@ -0,0 +1,45 @@
+/**
+ *  Continuous Scan Example
+ *
+ *  This example demonstrates how to continuously scan for BLE devices.
+ *  When devices are found the onDiscovered and onResults callbacks will be called with the device data.
+ *  The scan will not store the results, only the callbacks will be used
+ *  When the scan timeout is reached the onScanEnd callback will be called and the scan will be restarted.
+ *  This will clear the duplicate cache in the controller and allow the same devices to be reported again.
+ *
+ *  Created: on March 24 2020
+ *      Author: H2zero
+ *
+ */
+
+#include "NimBLEDevice.h"
+
+static constexpr uint32_t scanTime = 30 * 1000; // 30 seconds scan time.
+
+class scanCallbacks : public NimBLEScanCallbacks {
+    // Initial discovery, advertisement data only.
+    void onDiscovered(const NimBLEAdvertisedDevice* advertisedDevice) override {
+        printf("Discovered Device: %s\n", advertisedDevice->toString().c_str());
+    }
+
+    // If active scanning the result here will have the scan response data.
+    // If not active scanning then this will be the same as onDiscovered.
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) override {
+        printf("Device result: %s\n", advertisedDevice->toString().c_str());
+    }
+
+    void onScanEnd(const NimBLEScanResults& results, int reason) override {
+        printf("Scan ended reason = %d; restarting scan\n", reason);
+        NimBLEDevice::getScan()->start(scanTime, false, true);
+    }
+} scanCallbacks; // create a callback class instance.
+
+extern "C" void app_main() {
+    NimBLEDevice::init("");                         // Initialize the device, you can specify a device name if you want.
+    NimBLEScan* pBLEScan = NimBLEDevice::getScan(); // Create the scan object.
+    pBLEScan->setScanCallbacks(&scanCallbacks, false); // Set the callback for when devices are discovered, no duplicates.
+    pBLEScan->setActiveScan(true);          // Set active scanning, this will get more data from the advertiser.
+    pBLEScan->setMaxResults(0);             // Do not store the scan results, use callback only.
+    pBLEScan->start(scanTime, false, true); // duration, not a continuation of last scan, restart to get all devices again.
+    printf("Scanning...\n");
+}

examples/Continuous_scan/sdkconfig.defaults

@@ -0,0 +1,12 @@
+# Override some defaults so BT stack is enabled
+# in this example
+
+#
+# BT config
+#
+CONFIG_BT_ENABLED=y
+CONFIG_BTDM_CTRL_MODE_BLE_ONLY=y
+CONFIG_BTDM_CTRL_MODE_BR_EDR_ONLY=n
+CONFIG_BTDM_CTRL_MODE_BTDM=n
+CONFIG_BT_BLUEDROID_ENABLED=n
+CONFIG_BT_NIMBLE_ENABLED=y

examples/NimBLE_Async_Client/main/main.cpp

@@ -25,7 +25,7 @@ class ClientCallbacks : public NimBLEClientCallbacks {
 } clientCB;
 
 class scanCallbacks : public NimBLEScanCallbacks {
-    void onResult(NimBLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const NimBLEAdvertisedDevice* advertisedDevice) {
         printf("Advertised Device found: %s\n", advertisedDevice->toString().c_str());
         if (advertisedDevice->haveName() && advertisedDevice->getName() == "NimBLE-Server") {
             printf("Found Our Device\n");

examples/basic/BLE_client/main/main.cpp

@@ -24,7 +24,7 @@ static bool doConnect = false;
 static bool connected = false;
 static bool doScan = false;
 static BLERemoteCharacteristic* pRemoteCharacteristic;
-static BLEAdvertisedDevice* myDevice;
+static const BLEAdvertisedDevice* myDevice;
 
 static void notifyCallback(
   BLERemoteCharacteristic* pBLERemoteCharacteristic,
@@ -137,7 +137,7 @@ class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
 
 /*** Only a reference to the advertised device is passed now
   void onResult(BLEAdvertisedDevice advertisedDevice) { **/
-  void onResult(BLEAdvertisedDevice* advertisedDevice) {
+  void onResult(const BLEAdvertisedDevice* advertisedDevice) {
     printf("BLE Advertised Device found: %s\n", advertisedDevice->toString().c_str());
 
     // We have found a device, let us now see if it contains the service we are looking for.

examples/basic/BLE_scan/main/main.cpp

@@ -21,7 +21,7 @@ int scanTime = 5 * 1000; // In milliseconds, 0 = scan forever
 BLEScan* pBLEScan;
 
 class MyAdvertisedDeviceCallbacks: public BLEAdvertisedDeviceCallbacks {
-    void onResult(BLEAdvertisedDevice* advertisedDevice) {
+    void onResult(const BLEAdvertisedDevice* advertisedDevice) {
       printf("Advertised Device: %s \n", advertisedDevice->toString().c_str());
     }
 };
@@ -35,7 +35,7 @@ void scanTask (void * parameter){
         pBLEScan->clearResults();   // delete results fromBLEScan buffer to release memory
         vTaskDelay(2000/portTICK_PERIOD_MS); // Delay a second between loops.
     }
-    
+
     vTaskDelete(NULL);
 }