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/********************************************************************************
* *
* I n t e r - T h r e a d M e s s a g i n g C h a n n e l *
* *
*********************************************************************************
* Copyright (C) 2006,2022 by Jeroen van der Zijp. All Rights Reserved. *
*********************************************************************************
* This library 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. *
* *
* This library 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 Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/> *
********************************************************************************/
#ifndef FXMESSAGECHANNEL_H
#define FXMESSAGECHANNEL_H
#ifndef FXOBJECT_H
#include "FXObject.h"
#endif
namespace FX {
class FXApp;
/**
* FXMessageChannel manages a messaging channel between a worker thread and the main
* user-interface thread.
* When an FXMessageChannel is constructed, it automatically calls addInput() function to
* register itself as the message handler for the SEL_IO_READ message from FXApp.
* Likewise, when FXMessageChannel is destroyed, it calls removeInput() to remove itself
* as the message handler for the SEL_IO_READ message from FXApp.
* When a worker thread calls the message() API, the target and message, as well
* as optional message data, are written into the message channel.
* The main user-interface thread is awakened and subsequently dispatches to the
* onMessage handler of FXMessageChannel, which reads the target, selector, and optional
* message data from the channel and then dispatches to this target using the given
* selector.
* Thus, FXMessageChannel provides a worker thread with a way to asynchronously invoke
* any message handler in the context of the main user-interface thread.
* If the size of the optional data is zero, the message handler will be passed a
* NULL pointer.
* The maximum payload size passed with message() is 8192 bytes.
*/
class FXAPI FXMessageChannel : public FXObject {
FXDECLARE(FXMessageChannel)
private:
FXApp *app;
protected:
FXInputHandle h[3];
FXMutex m;
protected:
FXMessageChannel();
private:
FXMessageChannel(const FXMessageChannel&);
FXMessageChannel& operator=(const FXMessageChannel&);
public:
enum{
ID_IO_READ=1,
ID_LAST
};
public:
long onMessage(FXObject*,FXSelector,void*);
public:
/**
* Initialize message channel.
* Adds the message channel to FXApp's input watch set.
*/
FXMessageChannel(FXApp* a);
/**
* Get application pointer.
*/
FXApp* getApp() const { return app; }
/**
* Send a message msg comprising of FXSEL(type,id) to a target tgt, and pass optional
* data of size bytes.
* This asynchronously calls the indicated handler in the context of the main GUI
* thread's event loop.
* Up to 8192 bytes may be passed along.
*/
FXbool message(FXObject* tgt,FXSelector msg,const void* data=nullptr,FXint size=0);
/**
* Clean up message channel.
* Removes the message channel from FXApp's input watch set.
*/
virtual ~FXMessageChannel();
};
}
#endif
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