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Game Programming Using Qt Beginner's Guide

You're reading from   Game Programming Using Qt Beginner's Guide A complete guide to designing and building fun games with Qt and Qt Quick 2 using associated toolsets

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Product type Paperback
Published in Jan 2016
Publisher
ISBN-13 9781782168874
Length 512 pages
Edition 1st Edition
Tools
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Authors (2):
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Lorenz Haas Lorenz Haas
Author Profile Icon Lorenz Haas
Lorenz Haas
Witold Wysota Witold Wysota
Author Profile Icon Witold Wysota
Witold Wysota
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Toc

Table of Contents (13) Chapters Close

Preface 1. Introduction to Qt FREE CHAPTER 2. Installation 3. Qt GUI Programming 4. Qt Core Essentials 5. Graphics with Qt 6. Graphics View 7. Networking 8. Scripting 9. Qt Quick Basics 10. Qt Quick A. Pop Quiz Answers Index

Time for action – writing the OOP conform code using QSignalMapper


A more elegant way that does not rely on sender() would be to use QSignalMapper and a local hash, in which all replies that are connected to that slot are stored. So, whenever you call QNetworkAccessManager::get(), store the returned pointer in a member variable of the QHash<int, QNetworkReply*> type and set up the mapper. Let's assume that we have the following member variables and that they are set up properly:

QNetworkAccessManager *m_nam;
QSignalMapper *m_mapper;
QHash<int, QNetworkReply*> m_replies;

Then, you connect the finished() signal of a reply this way:

QNetworkReply *reply = m_nam->get(QNetworkRequest(QUrl(/*...*/)));
connect(reply, SIGNAL(finished()), m_mapper, SLOT(map()));
int id = /* unique id, not already used in m_replies*/;
m_replies.insert(id, reply);
m_mapper->setMapping(reply, id);

What just happened?

First, we posted the request and fetched the pointer to QNetworkReply with reply. Then...

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