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# QNPlugin Class Reference

The QNPlugin class provides the main factory for plugin objects. More...

This class is part of the Qt Netscape Extension.

`#include <qnp.h>`

List of all member functions.

## Public Members

- virtual ~QNPlugin ()
- void getVersionInfo ( int & plugin_major, int & plugin_minor, int & browser_major, int & browser_minor )
- virtual QNPInstance * newInstance () = 0
- virtual const char * getMIMEDescription () const = 0
- virtual const char * getPluginNameString () const = 0
- virtual const char * getPluginDescriptionString () const = 0
- virtual void * getJavaClass ()
- virtual void unuseJavaClass ()
- void * getJavaEnv () const

## Static Public Members

- QNPlugin * create ()
- QNPlugin * actual ()

## Protected Members

- QNPlugin ()

## Detailed Description

This class is defined in the Qt Netscape Extension, which can be found in the `qt/extensions` directory. It is not included in the main Qt API.

The QNPlugin class provides the main factory for plugin objects.

This class is the heart of the plugin. One instance of this object is created when the plugin is first needed, by calling QNPlugin::create(), which must be implemented in your plugin code to return some derived class of QNPlugin. The one QNPlugin object creates all QNPInstance instances for a web browser running in a single process.

Additionally, if Qt is linked to the plugin as a dynamic library, only one instance of QApplication will exist across all plugins that have been made with Qt. So, your plugin should tread lightly on global settings. Do not, for example, use QApplication::setFont() - that will change the font in every widget of every Qt-based plugin currently loaded!

## Member Function Documentation

### QNPlugin::QNPlugin ()`[protected]`

Creates a QNPlugin. This may only be used by the constructor of the class, derived from QNPlugin, that is returned by your plugin's implementation of the QNPlugin::create() function.

### QNPlugin::~QNPlugin ()`[virtual]`

Destroys the QNPlugin. This is called by the plugin binding code just before the plugin is about to be unloaded from memory. If newWindow() has been called, a QApplication will still exist at this time, but will be deleted shortly after, just before the plugin is deleted.

### QNPlugin * QNPlugin::actual ()`[static]`

Returns the plugin most recently returned by QNPlugin::create().

### QNPlugin * QNPlugin::create ()`[static]`

This function must be implemented by your plugin code. It should return a derived class of QNPlugin.

### void * QNPlugin::getJavaClass ()`[virtual]`

Override this function to return a reference to the Java class that represents the plugin. The default returns 0, indicating no class.

If you override this class, you must also override QNPlugin::unuseJavaClass().

The return value is actually a `jref`; we use `void*` so as to avoid burdening plugins which do not require Java.

See also getJavaEnv() and QNPInstance::getJavaPeer().

### void * QNPlugin::getJavaEnv () const

Returns a pointer to the Java execution environment, or 0 if either Java is disabled or an error occurred.

The return value is actually a `JRIEnv*`; we use `void*` so as to avoid burdening plugins which do not require Java.

See also getJavaClass() and QNPInstance::getJavaPeer().

### const char * QNPlugin::getMIMEDescription () const`[pure virtual]`

Override this function to return the MIME description of the data formats supported by your plugin. The format of this string is shown by the following example:

        const char* getMIMEDescription() const
        {
            return "image/x-png:png:PNG Image;"
                   "image/png:png:PNG Image;"
                   "image/x-portable-bitmap:pbm:PBM Image;"
                   "image/x-portable-graymap:pgm:PGM Image;"
                   "image/x-portable-pixmap:ppm:PPM Image;"
                   "image/bmp:bmp:BMP Image;"
                   "image/x-ms-bmp:bmp:BMP Image;"
                   "image/x-xpixmap:xpm:XPM Image;"
                   "image/xpm:xpm:XPM Image";
        }

### const char * QNPlugin::getPluginDescriptionString () const`[pure virtual]`

Returns a pointer to the plain-text description of the plugin.

### const char * QNPlugin::getPluginNameString () const`[pure virtual]`

Returns a pointer to the plain-text name of the plugin.

### void QNPlugin::getVersionInfo ( int & plugin_major, int & plugin_minor, int & browser_major, int & browser_minor )

Populates *plugin_major and *plugin_minor with the version of the plugin API and populates *browser_major and *browser_minor with the version of the web browser.

### QNPInstance * QNPlugin::newInstance ()`[pure virtual]`

Override this function to return an appropriate derived class of QNPInstance.

### void QNPlugin::unuseJavaClass ()`[virtual]`

This function is called when the plugin is shutting down. The function should unuse the Java class returned earlier by getJavaClass().

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