// Copyright 2017 Paul Nettle.
//
// This file is part of Gobbledegook.
//
// Gobbledegook is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Gobbledegook is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with Gobbledegook. If not, see .
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// >>
// >>> INSIDE THIS FILE
// >>
//
// This is our representation of a GATT Characteristic which is intended to be used in our server description
//
// >>
// >>> DISCUSSION
// >>
//
// A GATT descriptor is the component within the Bluetooth LE standard that holds and serves metadata about a Characteristic over
// Bluetooth. This class is intended to be used within the server description. For an explanation of how this class is used, see the
// detailed discussion in Server.cpp.
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#include "GattDescriptor.h"
#include "GattProperty.h"
#include "DBusObject.h"
#include "Utils.h"
#include "Logger.h"
namespace ggk {
//
// Standard constructor
//
// Construct a GattDescriptor
//
// Genreally speaking, these objects should not be constructed directly. Rather, use the `gattDescriptorBegin()` method
// in `GattCharacteristic`.
GattDescriptor::GattDescriptor(DBusObject &owner, GattCharacteristic &characteristic, const std::string &name)
: GattInterface(owner, name), characteristic(characteristic), pOnUpdatedValueFunc(nullptr)
{
}
// Returning the owner pops us one level up the hierarchy
//
// This method compliments `GattCharacteristic::gattDescriptorBegin()`
GattCharacteristic &GattDescriptor::gattDescriptorEnd()
{
return characteristic;
}
//
// D-Bus interface methods
//
// Locates a D-Bus method within this D-Bus interface
bool GattDescriptor::callMethod(const std::string &methodName, GDBusConnection *pConnection, GVariant *pParameters, GDBusMethodInvocation *pInvocation, gpointer pUserData) const
{
for (const DBusMethod &method : methods)
{
if (methodName == method.getName())
{
method.call(pConnection, getPath(), getName(), methodName, pParameters, pInvocation, pUserData);
return true;
}
}
return false;
}
// Adds an event to the descriptor and returns a refereence to 'this` to enable method chaining in the server description
//
// NOTE: We specifically overload this method in order to accept our custom EventCallback type and transform it into a
// TickEvent::Callback type. We also return our own type. This simplifies the server description by allowing call to chain.
GattDescriptor &GattDescriptor::onEvent(int tickFrequency, void *pUserData, EventCallback callback)
{
events.push_back(TickEvent(this, tickFrequency, reinterpret_cast(callback), pUserData));
return *this;
}
// Ticks events within this descriptor
//
// Note: we specifically override this method in order to translate the generic TickEvent::Callback into our own EventCallback
void GattDescriptor::tickEvents(GDBusConnection *pConnection, void *pUserData) const
{
for (const TickEvent &event : events)
{
event.tick(getPath(), pConnection, pUserData);
}
}
// Specialized support for ReadlValue method
//
// Defined as: array{byte} ReadValue(dict options)
//
// D-Bus breakdown:
//
// Input args: options - "a{sv}"
// Output args: value - "ay"
GattDescriptor &GattDescriptor::onReadValue(MethodCallback callback)
{
// array{byte} ReadValue(dict options)
const char *inArgs[] = {"a{sv}", nullptr};
addMethod("ReadValue", inArgs, "ay", reinterpret_cast(callback));
return *this;
}
// Specialized support for WriteValue method
//
// Defined as: void WriteValue(array{byte} value, dict options)
//
// D-Bus breakdown:
//
// Input args: value - "ay"
// options - "a{sv}"
// Output args: void
GattDescriptor &GattDescriptor::onWriteValue(MethodCallback callback)
{
const char *inArgs[] = {"ay", "a{sv}", nullptr};
addMethod("WriteValue", inArgs, nullptr, reinterpret_cast(callback));
return *this;
}
// Custom support for handling updates to our descriptor's value
//
// Defined as: (NOT defined by Bluetooth or BlueZ - this method is internal only)
//
// This method is called by our framework whenever a Descriptor's value is updated. If you need to perform any actions
// when a value is updatd, this is a good place to do that work.
//
// If you need to perform the same action(s) when a value is updated from the client (via `onWriteValue`) or from this server,
// then it may be beneficial to call this method from within your onWriteValue callback to reduce duplicated code. See
// `callOnUpdatedValue` for more information.
GattDescriptor &GattDescriptor::onUpdatedValue(UpdatedValueCallback callback)
{
pOnUpdatedValueFunc = callback;
return *this;
}
// Calls the onUpdatedValue method, if one was set.
//
// Returns false if there was no method set, otherwise, returns the boolean result of the method call.
//
// If you need to perform the same action(s) when a value is updated from the client (via onWriteValue) or from this server,
// then it may be beneficial to place those actions in the `onUpdatedValue` method and call it from from within your
// `onWriteValue` callback to reduce duplicated code. To call the `onUpdatedValue` method from within your `onWriteValue`, you
// can use this pattern:
//
// .onUpdatedValue(DESCRIPTOR_UPDATED_VALUE_CALLBACK_LAMBDA
// {
// // Update your value
// ...
//
// // Call the onUpdateValue method that was set in the same Descriptor
// self.callOnUpdatedValue(pConnection, pUserData);
// })
bool GattDescriptor::callOnUpdatedValue(GDBusConnection *pConnection, void *pUserData) const
{
if (nullptr == pOnUpdatedValueFunc)
{
return false;
}
Logger::debug(SSTR << "Calling OnUpdatedValue function for interface at path '" << getPath() << "'");
return pOnUpdatedValueFunc(*this, pConnection, pUserData);
}
}; // namespace ggk