Qt/WebKit::插件设计(下)

在Qt/WebKit::插件设计(上)已经介绍了QtWebKit插件设计中MIME类型为application/x-qt-plugin或者application/x-qt-styled-widget的情况，本文主要介绍另一种情形，即不限制MIME类型，这种方法相比第一种情形应用更加灵活，扩展性也更好。

main.cpp

#include <QtGui/QApplication>
#include "pluginexample.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    PluginExample pE;
    pE.show();

    return app.exec();
}

pluginexample.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QtGui/QMainWindow>
#include <QtCore/QDir>
#include <QtCore/QUrl>

#include <QtGui/QWidget>
#include <QtGui/QVBoxLayout>
#include <QtGui/QFrame>
#include <QtGui/QDesktopServices>

#include <QtWebKit/QWebView>
#include <QtWebKit/QWebPage>
#include <QtWebKit/QWebFrame>
#include <QtWebKit/QWebSettings>

#include <QtCore/QDebug>

#include "webpluginfactory.h"

class QWebView;

class PluginExample : public QMainWindow
{
    Q_OBJECT

public:
    PluginExample(QWidget *parent = 0);
    ~PluginExample();

private:
    QWebView* m_webView;
    QWebView* createWebView();
};


#endif // MAINWINDOW_H

pluginexample.cpp

#include "pluginexample.h"

/**
 * Plug-in example main class.
 */
PluginExample::PluginExample(QWidget *parent)
    : QMainWindow(parent)
{
    // Create the central widget and set it.
    QFrame* cW = new QFrame(this);
    setCentralWidget(cW);

    // Set the layout to the central widget.
    QVBoxLayout* layout = new QVBoxLayout(cW);
    cW->setLayout(layout);
    layout->setMargin(0);
    layout->setSpacing(0);

    // Create the webview which will be used to display the page.
    m_webView = createWebView();

    // Add it to the layout.
    layout->addWidget(m_webView);

    m_webView->show();
}

PluginExample::~PluginExample()
{

}

/**
 * Creates a new webview
 */
QWebView* PluginExample::createWebView()
{
    //使能QWebView的Javascript和Plugins属性
    QWebSettings* defaultSettings = QWebSettings::globalSettings();
    // We use JavaScript, so set it to be enabled.
    defaultSettings->setAttribute(QWebSettings::JavascriptEnabled, true);
    // Plugins must be set to be enabled to use plug-ins.
    defaultSettings->setAttribute(QWebSettings::PluginsEnabled,true);

    QWebView* webView = new QWebView(this);

    /*
     * We also pass the web plugin factory to the webview.
     */
    WebPluginFactory* factory = new WebPluginFactory(this);
    webView->page()->setPluginFactory(factory);

    webView->load(QUrl("index.html"));
    return webView;
}

WebPluginFactory是插件工厂类，主要需要实现的就是QWebPluginFactory中的两个虚函数: 

virtual QObject *create(const QString &mimeType, const QUrl &url,

const QStringList &argumentNames,const QStringList & argumentValues )const = 0;

virtual QList plugins () const = 0;

create() 方法则根据mimeType等参数来决定创建相应的插件，而plugins()方法是获取所有可用的插件列表。

webpluginfactory.h

#ifndef WEBPLUGINFACTORY_H
#define WEBPLUGINFACTORY_H

#include <QWebPluginFactory>

#include <QLabel>

#include <QDebug>
#include <QUrl>
#include <QWebView>
#include <QWebFrame>

class WebPluginFactory : public QWebPluginFactory
{
    Q_OBJECT
public:
    explicit WebPluginFactory(QObject *parent = 0);
    QObject * create(const QString & mimeType,
                     const QUrl & url,
                     const QStringList & argumentNames,
                     const QStringList & argumentValues) const;
    QList<QWebPluginFactory::Plugin> plugins () const;

signals:

public slots:

private:
    QList<QWebPluginFactory::Plugin> _plugins;
};

#endif // WEBPLUGINFACTORY_H

webpluginfactory.cpp

#include <QtDebug>
#include "webpluginfactory.h"

WebPluginFactory::WebPluginFactory(QObject *parent) :
    QWebPluginFactory(parent)
{
    // initialise the _plugins QList
    // so that we can use it later in the plugins() method
    QWebPluginFactory::Plugin plugin;
    plugin.name = "Qt webkit Plugin";

    QWebPluginFactory::MimeType mimetype;
    mimetype.description = "Embedded Qt Widget";
    mimetype.fileExtensions = QStringList();
    mimetype.name = "application/x-qt-exampleplugin";
    plugin.mimeTypes.append(mimetype);

    _plugins.append(plugin);
}

QObject * WebPluginFactory::create(const QString & mimeType,
                 const QUrl & url,
                 const QStringList & argumentNames,
                 const QStringList & argumentValues) const
{
    Q_UNUSED(url);

    if (("application/x-qt-exampleplugin" != mimeType)) {
        return new QObject();
    }
    /*
    *** 对plugin的相应操作 ****
    */
    Q_UNUSED(argumentNames);
    Q_UNUSED(argumentValues);

    qDebug()<<"This is an MIME=application/x-qt-exampleplugin.";
    qDebug()<<"All the parameters is:"<<argumentNames<<" and "<<argumentValues;

    return NULL;
}

/**
 * Returns supported plug-ins.
 * Currently, this function is only called when JavaScript
 * programs access the global plug-ins or MIME type objects.
 */
QList<QWebPluginFactory::Plugin> WebPluginFactory::plugins () const
{
    return _plugins;
}

pluginexample.pro

QT += core \
      gui \
      webkit

TARGET = pluginexample
TEMPLATE = app

SOURCES += main.cpp\
        pluginexample.cpp \
    webpluginfactory.cpp

HEADERS  += pluginexample.h \
    webpluginfactory.h

测试页面index.html

<html>
    <head>
        <title>Plugin example page</title>
    </head>

    <body id="body">
            <h2>QtWebKit plugin</h2>
            <object id="describePlugin"
                    type="application/x-qt-exampleplugin"
                    width="100%" height="80%">
            </object>

    </body>
</html>

编译运行程序

qmake

make

./pluginexample