Qt 4.8: QWebSettings Class Reference

Qt Reference Documentation

# QWebSettings Class Reference

The QWebSettings class provides an object to store the settings used by QWebPage and QWebFrame. More...

     #include <QWebSettings>

This class was introduced in Qt 4.4.

- List of all members, including inherited members

## Public Types

enum | FontFamily { StandardFont, FixedFont, SerifFont, SansSerifFont, CursiveFont, FantasyFont }
enum | FontSize { MinimumFontSize, MinimumLogicalFontSize, DefaultFontSize, DefaultFixedFontSize }
enum | WebAttribute { AutoLoadImages, DnsPrefetchEnabled, JavascriptEnabled, JavaEnabled, ..., SiteSpecificQuirksEnabled }
enum | WebGraphic { MissingImageGraphic, MissingPluginGraphic, DefaultFrameIconGraphic, TextAreaSizeGripCornerGraphic, ..., SearchCancelButtonPressedGraphic }

## Public Functions

QString | defaultTextEncoding () const
QString | fontFamily ( FontFamily which ) const
int | fontSize ( FontSize type ) const
QString | localStoragePath () const
void | resetAttribute ( WebAttribute attribute )
void | resetFontFamily ( FontFamily which )
void | resetFontSize ( FontSize type )
void | setAttribute ( WebAttribute attribute, bool on )
void | setDefaultTextEncoding ( const QString & encoding )
void | setFontFamily ( FontFamily which, const QString & family )
void | setFontSize ( FontSize type, int size )
void | setLocalStoragePath ( const QString & path )
void | setUserStyleSheetUrl ( const QUrl & location )
bool | testAttribute ( WebAttribute attribute ) const
QUrl | userStyleSheetUrl () const

## Static Public Members

void | clearIconDatabase ()
void | clearMemoryCaches ()
void | enablePersistentStorage ( const QString & path = QString() )
QWebSettings * | globalSettings ()
QString | iconDatabasePath ()
QIcon | iconForUrl ( const QUrl & url )
int | maximumPagesInCache ()
qint64 | offlineStorageDefaultQuota ()
QString | offlineStoragePath ()
QString | offlineWebApplicationCachePath ()
qint64 | offlineWebApplicationCacheQuota ()
void | setIconDatabasePath ( const QString & path )
void | setMaximumPagesInCache ( int pages )
void | setObjectCacheCapacities ( int cacheMinDeadCapacity, int cacheMaxDead, int totalCapacity )
void | setOfflineStorageDefaultQuota ( qint64 maximumSize )
void | setOfflineStoragePath ( const QString & path )
void | setOfflineWebApplicationCachePath ( const QString & path )
void | setOfflineWebApplicationCacheQuota ( qint64 maximumSize )
void | setWebGraphic ( WebGraphic type, const QPixmap & graphic )
QPixmap | webGraphic ( WebGraphic type )

## Detailed Description

The QWebSettings class provides an object to store the settings used by QWebPage and QWebFrame.

Each QWebPage object has its own QWebSettings object, which configures the settings for that page. If a setting is not configured, then it is looked up in the global settings object, which can be accessed using globalSettings().

QWebSettings allows configuration of browser properties, such as font sizes and families, the location of a custom style sheet, and generic attributes like JavaScript and plugins. Individual attributes are set using the setAttribute() function. The WebAttribute enum further describes each attribute.

QWebSettings also configures global properties such as the web page memory cache, icon database, local database storage and offline applications storage.

### Enabling Plugins

Support for browser plugins can enabled by setting the PluginsEnabled attribute. For many applications, this attribute is enabled for all pages by setting it on the global settings object. QtWebKit will always ignore this setting when processing Qt plugins. The decision to allow a Qt plugin is made by the client in its reimplementation of QWebPage::createPlugin().

### Web Application Support

WebKit provides support for features specified in HTML 5 that improve the performance and capabilities of Web applications. These include client-side (offline) storage and the use of a Web application cache.

Client-side (offline) storage is an improvement over the use of cookies to store persistent data in Web applications. Applications can configure and enable the use of an offline storage database by calling the setOfflineStoragePath() with an appropriate file path, and can limit the quota for each application by calling setOfflineStorageDefaultQuota().

See also QWebPage::settings(), QWebView::settings(), and Web Browser.

## Member Type Documentation

### enum QWebSettings::FontFamily

This enum describes the generic font families defined by CSS 2. For more information see the CSS standard.

Constant | Value
--- | ---
`QWebSettings::StandardFont` | `0`
`QWebSettings::FixedFont` | `1`
`QWebSettings::SerifFont` | `2`
`QWebSettings::SansSerifFont` | `3`
`QWebSettings::CursiveFont` | `4`
`QWebSettings::FantasyFont` | `5`

### enum QWebSettings::FontSize

This enum describes the font sizes configurable through QWebSettings.

Constant | Value | Description
--- | --- | ---
`QWebSettings::MinimumFontSize` | `0` | The hard minimum font size.
`QWebSettings::MinimumLogicalFontSize` | `1` | The minimum logical font size that is applied when zooming out with QWebFrame::setTextSizeMultiplier().
`QWebSettings::DefaultFontSize` | `2` | The default font size for regular text.
`QWebSettings::DefaultFixedFontSize` | `3` | The default font size for fixed-pitch text.

### enum QWebSettings::WebAttribute

This enum describes various attributes that are configurable through QWebSettings.

Constant | Value | Description
--- | --- | ---
`QWebSettings::AutoLoadImages` | `0` | Specifies whether images are automatically loaded in web pages. This is enabled by default.
`QWebSettings::DnsPrefetchEnabled` | ? | Specifies whether QtWebkit will try to pre-fetch DNS entries to speed up browsing. This only works as a global attribute. Only for Qt 4.6 and later. This is disabled by default.
`QWebSettings::JavascriptEnabled` | `1` | Enables or disables the running of JavaScript programs. This is enabled by default
`QWebSettings::JavaEnabled` | `2` | Enables or disables Java applets. Currently Java applets are not supported.
`QWebSettings::PluginsEnabled` | `3` | Enables or disables plugins in Web pages (e.g. using NPAPI). Qt plugins with a mimetype such as "application/x-qt-plugin" are not affected by this setting. This is disabled by default.
`QWebSettings::PrivateBrowsingEnabled` | `4` | Private browsing prevents WebKit from recording visited pages in the history and storing web page icons. This is disabled by default.
`QWebSettings::JavascriptCanOpenWindows` | `5` | Specifies whether JavaScript programs can open new windows. This is disabled by default.
`QWebSettings::JavascriptCanCloseWindows` | ? | Specifies whether JavaScript programs can close windows. This is disabled by default.
`QWebSettings::JavascriptCanAccessClipboard` | `6` | Specifies whether JavaScript programs can read or write to the clipboard. This is disabled by default.
`QWebSettings::DeveloperExtrasEnabled` | `7` | Enables extra tools for Web developers. Currently this enables the "Inspect" element in the context menu as well as the use of QWebInspector which controls the web inspector for web site debugging. This is disabled by default.
`QWebSettings::SpatialNavigationEnabled` | ? | Enables or disables the Spatial Navigation feature, which consists in the ability to navigate between focusable elements in a Web page, such as hyperlinks and form controls, by using Left, Right, Up and Down arrow keys. For example, if a user presses the Right key, heuristics determine whether there is an element he might be trying to reach towards the right and which element he probably wants. This is disabled by default.
`QWebSettings::LinksIncludedInFocusChain` | `8` | Specifies whether hyperlinks should be included in the keyboard focus chain. This is enabled by default.
`QWebSettings::ZoomTextOnly` | `9` | Specifies whether the zoom factor on a frame applies only to the text or to all content. This is disabled by default.
`QWebSettings::PrintElementBackgrounds` | `10` | Specifies whether the background color and images are also drawn when the page is printed. This is enabled by default.
`QWebSettings::OfflineStorageDatabaseEnabled` | `11` | Specifies whether support for the HTML 5 offline storage feature is enabled or not. This is disabled by default.
`QWebSettings::OfflineWebApplicationCacheEnabled` | `12` | Specifies whether support for the HTML 5 web application cache feature is enabled or not. This is disabled by default.
`QWebSettings::LocalStorageEnabled` | `13` | Specifies whether support for the HTML 5 local storage feature is enabled or not. This is disabled by default. (This value was introduced in 4.6.)
`QWebSettings::LocalStorageDatabaseEnabled` | `LocalStorageEnabled` | This enum value is deprecated. Use QWebSettings::LocalStorageEnabled instead.
`QWebSettings::LocalContentCanAccessRemoteUrls` | ? | Specifies whether locally loaded documents are allowed to access remote urls. This is disabled by default. For more information about security origins and local vs. remote content see QWebSecurityOrigin. (This value was introduced in 4.6.)
`QWebSettings::LocalContentCanAccessFileUrls` | ? | Specifies whether locally loaded documents are allowed to access other local urls. This is enabled by default. For more information about security origins and local vs. remote content see QWebSecurityOrigin.
`QWebSettings::XSSAuditingEnabled` | ? | Specifies whether load requests should be monitored for cross-site scripting attempts. Suspicious scripts will be blocked and reported in the inspector's JavaScript console. Enabling this feature might have an impact on performance and it is disabled by default.
`QWebSettings::AcceleratedCompositingEnabled` | ? | This feature, when used in conjunction with QGraphicsWebView, accelerates animations of web content. CSS animations of the transform and opacity properties will be rendered by composing the cached content of the animated elements. This is enabled by default.
`QWebSettings::TiledBackingStoreEnabled` | ? | This setting enables the tiled backing store feature for a QGraphicsWebView. With the tiled backing store enabled, the web page contents in and around the current visible area is speculatively cached to bitmap tiles. The tiles are automatically kept in sync with the web page as it changes. Enabling tiling can significantly speed up painting heavy operations like scrolling. Enabling the feature increases memory consumption. It does not work well with contents using CSS fixed positioning (see also resizesToContents property). tiledBackingStoreFrozen property allows application to temporarily freeze the contents of the backing store. This is disabled by default.
`QWebSettings::FrameFlatteningEnabled` | ? | With this setting each subframe is expanded to its contents. On touch devices, it is desired to not have any scrollable sub parts of the page as it results in a confusing user experience, with scrolling sometimes scrolling sub parts and at other times scrolling the page itself. For this reason iframes and framesets are barely usable on touch devices. This will flatten all the frames to become one scrollable page. This is disabled by default.
`QWebSettings::SiteSpecificQuirksEnabled` | ? | This setting enables WebKit's workaround for broken sites. It is enabled by default.

### enum QWebSettings::WebGraphic

This enums describes the standard graphical elements used in webpages.

Constant | Value | Description
--- | --- | ---
`QWebSettings::MissingImageGraphic` | `0` | The replacement graphic shown when an image could not be loaded.
`QWebSettings::MissingPluginGraphic` | `1` | The replacement graphic shown when a plugin could not be loaded.
`QWebSettings::DefaultFrameIconGraphic` | `2` | The default icon for QWebFrame::icon().
`QWebSettings::TextAreaSizeGripCornerGraphic` | `3` | The graphic shown for the size grip of text areas.
`QWebSettings::DeleteButtonGraphic` | `4` | The graphic shown for the WebKit-Editing-Delete-Button in Deletion UI.
`QWebSettings::InputSpeechButtonGraphic` | `5` | The graphic shown in input fields that support speech recognition.
`QWebSettings::SearchCancelButtonGraphic` | `6` | The graphic shown for clearing the text in a search field.
`QWebSettings::SearchCancelButtonPressedGraphic` | `7` | The graphic shown when SearchCancelButtonGraphic is pressed.

## Member Function Documentation

### void QWebSettings::clearIconDatabase ()`[static]`

Clears the icon database.

### void QWebSettings::clearMemoryCaches ()`[static]`

Frees up as much memory as possible by cleaning all memory caches such as page, object and font cache.

This function was introduced in Qt 4.6.

### QString QWebSettings::defaultTextEncoding () const

Returns the default text encoding.

This function was introduced in Qt 4.6.

See also setDefaultTextEncoding().

### void QWebSettings::enablePersistentStorage ( const QString & path = QString() )`[static]`

Enables WebKit data persistence and sets the path to path. If path is empty, the user-specific data location specified by DataLocation will be used instead.

This method will simultaneously set and enable the iconDatabasePath(), localStoragePath(), offlineStoragePath() and offlineWebApplicationCachePath().

This function was introduced in Qt 4.6.

See also localStoragePath().

### QString QWebSettings::fontFamily ( FontFamily which ) const

Returns the actual font family for the specified generic font family, which.

See also setFontFamily().

### int QWebSettings::fontSize ( FontSize type ) const

Returns the default font size for type.

See also setFontSize().

### QWebSettings * QWebSettings::globalSettings ()`[static]`

Returns the global settings object.

Any setting changed on the default object is automatically applied to all QWebPage instances where the particular setting is not overriden already.

### QString QWebSettings::iconDatabasePath ()`[static]`

Returns the path of the icon database or an empty string if the icon database is disabled.

See also setIconDatabasePath() and clearIconDatabase().

### QIcon QWebSettings::iconForUrl ( const QUrl & url )`[static]`

Returns the web site's icon for url.

If the web site does not specify an icon OR if the icon is not in the database, a null QIcon is returned.

Note: The returned icon's size is arbitrary.

See also setIconDatabasePath().

### QString QWebSettings::localStoragePath () const

Returns the path for HTML5 local storage.

This function was introduced in Qt 4.6.

See also setLocalStoragePath().

### int QWebSettings::maximumPagesInCache ()`[static]`

Returns the maximum number of web pages that are kept in the memory cache.

See also setMaximumPagesInCache().

### qint64 QWebSettings::offlineStorageDefaultQuota ()`[static]`

Returns the value of the default quota for new offline storage databases.

This function was introduced in Qt 4.5.

See also setOfflineStorageDefaultQuota().

### QString QWebSettings::offlineStoragePath ()`[static]`

Returns the path of the HTML5 client-side database storage or an empty string if the feature is disabled.

This function was introduced in Qt 4.5.

See also setOfflineStoragePath().

### QString QWebSettings::offlineWebApplicationCachePath ()`[static]`

Returns the path of the HTML5 offline web application cache storage or an empty string if the feature is disabled.

This function was introduced in Qt 4.6.

See also setOfflineWebApplicationCachePath().

### qint64 QWebSettings::offlineWebApplicationCacheQuota ()`[static]`

Returns the value of the quota for the offline web application cache.

This function was introduced in Qt 4.6.

See also setOfflineWebApplicationCacheQuota().

### void QWebSettings::resetAttribute ( WebAttribute attribute )

Resets the setting of attribute to the value specified in the global QWebSettings instance.

This function has no effect on the global QWebSettings instance.

See also globalSettings().

### void QWebSettings::resetFontFamily ( FontFamily which )

Resets the actual font family specified by which to the one set in the global QWebSettings instance.

This function has no effect on the global QWebSettings instance.

### void QWebSettings::resetFontSize ( FontSize type )

Resets the font size for type to the size specified in the global settings object.

This function has no effect on the global QWebSettings instance.

### void QWebSettings::setAttribute ( WebAttribute attribute, bool on )

Enables or disables the specified attribute feature depending on the value of on.

### void QWebSettings::setDefaultTextEncoding ( const QString & encoding )

Specifies the default text encoding system.

The encoding, must be a string describing an encoding such as "utf-8", "iso-8859-1", etc. If left empty a default value will be used. For a more extensive list of encoding names see QTextCodec

This function was introduced in Qt 4.6.

See also defaultTextEncoding().

### void QWebSettings::setFontFamily ( FontFamily which, const QString & family )

Sets the actual font family to family for the specified generic family, which.

See also fontFamily().

### void QWebSettings::setFontSize ( FontSize type, int size )

Sets the font size for type to size.

See also fontSize().

### void QWebSettings::setIconDatabasePath ( const QString & path )`[static]`

Sets the path of the icon database to path. The icon database is used to store "favicons" associated with web sites.

path must point to an existing directory.

Setting an empty path disables the icon database.

See also iconDatabasePath() and clearIconDatabase().

### void QWebSettings::setLocalStoragePath ( const QString & path )

Sets the path for HTML5 local storage to path.

For more information on HTML5 local storage see the Web Storage standard.

Support for local storage can enabled by setting the LocalStorageEnabled attribute.

This function was introduced in Qt 4.6.

See also localStoragePath().

### void QWebSettings::setMaximumPagesInCache ( int pages )`[static]`

Sets the maximum number of pages to hold in the memory page cache to pages.

The Page Cache allows for a nicer user experience when navigating forth or back to pages in the forward/back history, by pausing and resuming up to pages.

For more information about the feature, please refer to:

http://webkit.org/blog/427/webkit-page-cache-i-the-basics/

See also maximumPagesInCache().

### void QWebSettings::setObjectCacheCapacities ( int cacheMinDeadCapacity, int cacheMaxDead, int totalCapacity )`[static]`

Specifies the capacities for the memory cache for dead objects such as stylesheets or scripts.

The cacheMinDeadCapacity specifies the minimum number of bytes that dead objects should consume when the cache is under pressure.

cacheMaxDead is the maximum number of bytes that dead objects should consume when the cache is not under pressure.

totalCapacity specifies the maximum number of bytes that the cache should consume overall.

The cache is enabled by default. Calling setObjectCacheCapacities(0, 0, 0) will disable the cache. Calling it with one non-zero enables it again.

### void QWebSettings::setOfflineStorageDefaultQuota ( qint64 maximumSize )`[static]`

Sets the value of the default quota for new offline storage databases to maximumSize.

This function was introduced in Qt 4.5.

See also offlineStorageDefaultQuota().

### void QWebSettings::setOfflineStoragePath ( const QString & path )`[static]`

Sets path as the save location for HTML5 client-side database storage data.

path must point to an existing directory.

Setting an empty path disables the feature.

Support for client-side databases can enabled by setting the OfflineStorageDatabaseEnabled attribute.

This function was introduced in Qt 4.5.

See also offlineStoragePath().

### void QWebSettings::setOfflineWebApplicationCachePath ( const QString & path )`[static]`

Sets the path for HTML5 offline web application cache storage to path.

An application cache acts like an HTTP cache in some sense. For documents that use the application cache via JavaScript, the loader engine will first ask the application cache for the contents, before hitting the network.

The feature is described in details at: http://dev.w3.org/html5/spec/Overview.html#appcache

path must point to an existing directory.

Setting an empty path disables the feature.

Support for offline web application cache storage can enabled by setting the OfflineWebApplicationCacheEnabled attribute.

This function was introduced in Qt 4.6.

See also offlineWebApplicationCachePath().

### void QWebSettings::setOfflineWebApplicationCacheQuota ( qint64 maximumSize )`[static]`

Sets the value of the quota for the offline web application cache to maximumSize.

This function was introduced in Qt 4.6.

See also offlineWebApplicationCacheQuota().

### void QWebSettings::setUserStyleSheetUrl ( const QUrl & location )

Specifies the location of a user stylesheet to load with every web page.

The location must be either a path on the local filesystem, or a data URL with UTF-8 and Base64 encoded data, such as:

"data:text/css;charset=utf-8;base64,cCB7IGJhY2tncm91bmQtY29sb3I6IHJlZCB9Ow=="

Note: If the base64 data is not valid, the style will not be applied.

See also userStyleSheetUrl().

### void QWebSettings::setWebGraphic ( WebGraphic type, const QPixmap & graphic )`[static]`

Sets graphic to be drawn when QtWebKit needs to draw an image of the given type.

For example, when an image cannot be loaded, the pixmap specified by MissingImageGraphic is drawn instead.

See also webGraphic().

### bool QWebSettings::testAttribute ( WebAttribute attribute ) const

Returns true if attribute is enabled; otherwise returns false.

### QUrl QWebSettings::userStyleSheetUrl () const

Returns the location of the user stylesheet.

See also setUserStyleSheetUrl().

### QPixmap QWebSettings::webGraphic ( WebGraphic type )`[static]`

Returns a previously set pixmap used to draw replacement graphics of the specified type.

See also setWebGraphic().