class Thumbnailer : public QObject
{
    Q_OBJECT

public:
    Thumbnailer(const QUrl &url);

Q_SIGNALS:
    void finished();

private Q_SLOTS:
    void render();

private:
    QWebPage page;

};

Thumbnailer::Thumbnailer(const QUrl &url)
{
    page.mainFrame()->load(url);
    connect(&page, SIGNAL(loadFinished(bool)),
        this, SLOT(render()));
}

void Thumbnailer::render()
{
    page.setViewportSize(page.mainFrame()->contentsSize());
    QImage image(page.viewportSize(), QImage::Format_ARGB32);
    QPainter painter(&image);

    page.mainFrame()->render(&painter);
    painter.end();

    QImage thumbnail = image.scaled(400, 400);
    thumbnail.save("thumbnail.png");

    emit finished();
}

Member Function Documentation

QWebPage::​QWebPage(QObject * parent = 0)

Constructs an empty QWebPage with parent parent.

QWebPage::​~QWebPage()

Destroys the web page.

[virtual protected] bool QWebPage::​acceptNavigationRequest(QWebFrame * frame, const QNetworkRequest & request, NavigationType type)

This function is called whenever WebKit requests to navigate frame to the resource specified by request by means of the specified navigation type type.

If frame is a null pointer then navigation to a new window is requested. If the request is accepted createWindow() will be called.

The default implementation interprets the page's linkDelegationPolicy and emits linkClicked accordingly or returns true to let QWebPage handle the navigation itself.

See also createWindow().

QAction * QWebPage::​action(WebAction action) const

Returns a QAction for the specified WebAction action.

The action is owned by the QWebPage but you can customize the look by changing its properties.

QWebPage also takes care of implementing the action, so that upon triggering the corresponding action is performed on the page.

See also triggerAction().

[signal] void QWebPage::​applicationCacheQuotaExceeded(QWebSecurityOrigin * origin, quint64 defaultOriginQuota, quint64 totalSpaceNeeded)

This signal is emitted whenever the web site is asking to store data to the application cache database databaseName and the quota allocated to that web site is exceeded.

quint64 QWebPage::​bytesReceived() const

Returns the number of bytes that were received from the network to render the current page.

See also totalBytes() and loadProgress().

[virtual protected] QString QWebPage::​chooseFile(QWebFrame * parentFrame, const QString & suggestedFile)

This function is called when the web content requests a file name, for example as a result of the user clicking on a "file upload" button in a HTML form.

A suggested filename may be provided in suggestedFile. The frame originating the request is provided as parentFrame.

See also ChooseMultipleFilesExtension.

[signal] void QWebPage::​contentsChanged()

This signal is emitted whenever the text in form elements changes as well as other editable content.

This function was introduced in Qt 4.5.

See also contentEditable, modified, QWebFrame::toHtml(), and QWebFrame::toPlainText().

[virtual protected] QObject * QWebPage::​createPlugin(const QString & classid, const QUrl & url, const QStringList & paramNames, const QStringList & paramValues)

This function is called whenever WebKit encounters a HTML object element with type "application/x-qt-plugin". It is called regardless of the value of QWebSettings::PluginsEnabled. The classid, url, paramNames and paramValues correspond to the HTML object element attributes and child elements to configure the embeddable object.

QMenu * QWebPage::​createStandardContextMenu()

This function creates the standard context menu which is shown when the user clicks on the web page with the right mouse button. It is called from the default contextMenuEvent() handler. The popup menu's ownership is transferred to the caller.

This function was introduced in Qt 4.5.

[virtual protected] QWebPage * QWebPage::​createWindow(WebWindowType type)

This function is called whenever WebKit wants to create a new window of the given type, for example when a JavaScript program requests to open a document in a new window.

If the new window can be created, the new window's QWebPage is returned; otherwise a null pointer is returned.

If the view associated with the web page is a QWebView object, then the default implementation forwards the request to QWebView's createWindow() function; otherwise it returns a null pointer.

If type is WebModalDialog, the application must call setWindowModality(Qt::ApplicationModal) on the new window.

Note: In the cases when the window creation is being triggered by JavaScript, apart from reimplementing this method application must also set the JavaScriptCanOpenWindows attribute of QWebSettings to true in order for it to get called.

See also acceptNavigationRequest() and QWebView::createWindow().

QWebFrame * QWebPage::​currentFrame() const

Returns the frame currently active.

See also mainFrame() and frameCreated().

[signal] void QWebPage::​databaseQuotaExceeded(QWebFrame * frame, QString databaseName)

This signal is emitted whenever the web site shown in frame is asking to store data to the database databaseName and the quota allocated to that web site is exceeded.

This function was introduced in Qt 4.5.

See also QWebDatabase.

[signal] void QWebPage::​downloadRequested(const QNetworkRequest & request)

This signal is emitted when the user decides to download a link. The url of the link as well as additional meta-information is contained in request.

See also unsupportedContent().

[virtual] bool QWebPage::​event(QEvent * ev)

Reimplemented from QObject::event().

[virtual] bool QWebPage::​extension(Extension extension, const ExtensionOption * option = 0, ExtensionReturn * output = 0)

This virtual function can be reimplemented in a QWebPage subclass to provide support for extensions. The option argument is provided as input to the extension; the output results can be stored in output.

The behavior of this function is determined by extension. The option and output values are typically casted to the corresponding types (for example, ChooseMultipleFilesExtensionOption and ChooseMultipleFilesExtensionReturn for ChooseMultipleFilesExtension).

You can call supportsExtension() to check if an extension is supported by the page.

Returns true if the extension was called successfully; otherwise returns false.

See also supportsExtension() and Extension.

[signal] void QWebPage::​featurePermissionRequestCanceled(QWebFrame * frame, QWebPage::Feature feature)

[signal] void QWebPage::​featurePermissionRequested(QWebFrame * frame, QWebPage::Feature feature)

bool QWebPage::​findText(const QString & subString, FindFlags options = 0)

Finds the specified string, subString, in the page, using the given options.

If the HighlightAllOccurrences flag is passed, the function will highlight all occurrences that exist in the page. All subsequent calls will extend the highlight, rather than replace it, with occurrences of the new string.

If the HighlightAllOccurrences flag is not passed, the function will select an occurrence and all subsequent calls will replace the current occurrence with the next one.

To clear the selection, just pass an empty string.

Returns true if subString was found; otherwise returns false.

bool QWebPage::​focusNextPrevChild(bool next)

Similar to QWidget::focusNextPrevChild() it focuses the next focusable web element if next is true; otherwise the previous element is focused.

Returns true if it can find a new focusable element, or false if it can't.

QWebFrame * QWebPage::​frameAt(const QPoint & pos) const

Returns the frame at the given point pos, or 0 if there is no frame at that position.

This function was introduced in Qt 4.6.

See also mainFrame() and currentFrame().

[signal] void QWebPage::​frameCreated(QWebFrame * frame)

This signal is emitted whenever the page creates a new frame.

See also currentFrame().

[signal] void QWebPage::​geometryChangeRequested(const QRect & geom)

This signal is emitted whenever the document wants to change the position and size of the page to geom. This can happen for example through JavaScript.

QWebHistory * QWebPage::​history() const

Returns a pointer to the view's history of navigated web pages.

QVariant QWebPage::​inputMethodQuery(Qt::InputMethodQuery property) const

This method is used by the input method to query a set of properties of the page to be able to support complex input method operations as support for surrounding text and reconversions.

property specifies which property is queried.

See also QWidget::inputMethodEvent(), QInputMethodEvent, and QInputContext.

[virtual protected] void QWebPage::​javaScriptAlert(QWebFrame * frame, const QString & msg)

This function is called whenever a JavaScript program running inside frame calls the alert() function with the message msg.

The default implementation shows the message, msg, with QMessageBox::information.

[virtual protected] bool QWebPage::​javaScriptConfirm(QWebFrame * frame, const QString & msg)

This function is called whenever a JavaScript program running inside frame calls the confirm() function with the message, msg. Returns true if the user confirms the message; otherwise returns false.

The default implementation executes the query using QMessageBox::information with QMessageBox::Ok and QMessageBox::Cancel buttons.

[virtual protected] void QWebPage::​javaScriptConsoleMessage(const QString & message, int lineNumber, const QString & sourceID)

This function is called whenever a JavaScript program tries to print a message to the web browser's console.

For example in case of evaluation errors the source URL may be provided in sourceID as well as the lineNumber.

The default implementation prints nothing.

[virtual protected] bool QWebPage::​javaScriptPrompt(QWebFrame * frame, const QString & msg, const QString & defaultValue, QString * result)

This function is called whenever a JavaScript program running inside frame tries to prompt the user for input. The program may provide an optional message, msg, as well as a default value for the input in defaultValue.

If the prompt was cancelled by the user the implementation should return false; otherwise the result should be written to result and true should be returned. If the prompt was not cancelled by the user, the implementation should return true and the result string must not be null.

The default implementation uses QInputDialog::getText().

[signal] void QWebPage::​linkClicked(const QUrl & url)

This signal is emitted whenever the user clicks on a link and the page's linkDelegationPolicy property is set to delegate the link handling for the specified url.

By default no links are delegated and are handled by QWebPage instead.

Note: This signal possibly won't be emitted for clicked links which use JavaScript to trigger navigation.

See also linkHovered().

[signal] void QWebPage::​linkHovered(const QString & link, const QString & title, const QString & textContent)

This signal is emitted when the mouse hovers over a link.

link contains the link url. title is the link element's title, if it is specified in the markup. textContent provides text within the link element, e.g., text inside an HTML anchor tag.

When the mouse leaves the link element the signal is emitted with empty parameters.

See also linkClicked().

[signal] void QWebPage::​loadFinished(bool ok)

This signal is emitted when the page finishes loading content. This signal is independant of script execution or page rendering. ok will indicate whether the load was successful or any error occurred.

See also loadStarted() and ErrorPageExtension.

[signal] void QWebPage::​loadProgress(int progress)

This signal is emitted when the global progress status changes. The current value is provided by progress and scales from 0 to 100, which is the default range of QProgressBar. It accumulates changes from all the child frames.

See also bytesReceived().

[signal] void QWebPage::​loadStarted()

This signal is emitted when a page starts loading content.

See also loadFinished().

QWebFrame * QWebPage::​mainFrame() const

Returns the main frame of the page.

The main frame provides access to the hierarchy of sub-frames and is also needed if you want to explicitly render a web page into a given painter.

See also currentFrame().

[signal] void QWebPage::​menuBarVisibilityChangeRequested(bool visible)

This signal is emitted whenever the visibility of the menubar in a web browser window that hosts QWebPage should be changed to visible.

[signal] void QWebPage::​microFocusChanged()

This signal is emitted when for example the position of the cursor in an editable form element changes. It is used to inform input methods about the new on-screen position where the user is able to enter text. This signal is usually connected to the QWidget::updateMicroFocus() slot.

QNetworkAccessManager * QWebPage::​networkAccessManager() const

Returns the QNetworkAccessManager that is responsible for serving network requests for this QWebPage.

See also setNetworkAccessManager().

QWebPluginFactory * QWebPage::​pluginFactory() const

Returns the QWebPluginFactory that is responsible for creating plugins embedded into this QWebPage. If no plugin factory is installed a null pointer is returned.

See also setPluginFactory().

[signal] void QWebPage::​printRequested(QWebFrame * frame)

This signal is emitted whenever the page requests the web browser to print frame, for example through the JavaScript window.print() call.

See also QWebFrame::print() and QPrintPreviewDialog.

[signal] void QWebPage::​repaintRequested(const QRect & dirtyRect)

This signal is emitted whenever this QWebPage should be updated. It's useful when rendering a QWebPage without a QWebView or QGraphicsWebView. dirtyRect contains the area that needs to be updated. To paint the QWebPage get the mainFrame() and call the render(QPainter*, const QRegion&) method with the dirtyRect as the second parameter.

See also mainFrame() and view().

[signal] void QWebPage::​restoreFrameStateRequested(QWebFrame * frame)

This signal is emitted when the load of frame is finished and the application may now update its state accordingly.

This function was introduced in Qt 4.5.

[signal] void QWebPage::​saveFrameStateRequested(QWebFrame * frame, QWebHistoryItem * item)

This signal is emitted shortly before the history of navigated pages in frame is changed, for example when navigating back in the history.

The provided QWebHistoryItem, item, holds the history entry of the frame before the change.

A potential use-case for this signal is to store custom data in the QWebHistoryItem associated to the frame, using QWebHistoryItem::setUserData().

This function was introduced in Qt 4.5.

[signal] void QWebPage::​scrollRequested(int dx, int dy, const QRect & rectToScroll)

This signal is emitted whenever the content given by rectToScroll needs to be scrolled dx and dy downwards and no view was set.

See also view().

[signal] void QWebPage::​selectionChanged()

This signal is emitted whenever the selection changes, either interactively or programmatically (e.g. by calling triggerAction() with a selection action).

See also selectedText().

void QWebPage::​setActualVisibleContentRect(const QRect & rect) const

void QWebPage::​setFeaturePermission(QWebFrame * frame, Feature feature, PermissionPolicy policy)

void QWebPage::​setNetworkAccessManager(QNetworkAccessManager * manager)

Sets the QNetworkAccessManager manager responsible for serving network requests for this QWebPage.

Note: It is currently not supported to change the network access manager after the QWebPage has used it. The results of doing this are undefined.

See also networkAccessManager().

void QWebPage::​setPluginFactory(QWebPluginFactory * factory)

Sets the QWebPluginFactory factory responsible for creating plugins embedded into this QWebPage.

Note: The plugin factory is only used if the QWebSettings::PluginsEnabled attribute is enabled.

See also pluginFactory().

void QWebPage::​setView(QWidget * view)

Sets the view that is associated with the web page.

See also view().

QWebSettings * QWebPage::​settings() const

Returns a pointer to the page's settings object.

See also QWebSettings::globalSettings().

[virtual] bool QWebPage::​shouldInterruptJavaScript()

This function is called when a JavaScript program is running for a long period of time.

If the user wanted to stop the JavaScript the implementation should return true; otherwise false.

The default implementation executes the query using QMessageBox::information with QMessageBox::Yes and QMessageBox::No buttons.

This function was introduced in Qt 4.6.

[signal] void QWebPage::​statusBarMessage(const QString & text)

This signal is emitted when the statusbar text is changed by the page.

[signal] void QWebPage::​statusBarVisibilityChangeRequested(bool visible)

This signal is emitted whenever the visibility of the statusbar in a web browser window that hosts QWebPage should be changed to visible.

QStringList QWebPage::​supportedContentTypes() const

Returns the list of all content types supported by QWebPage.

bool QWebPage::​supportsContentType(const QString & mimeType) const

Returns true if QWebPage can handle the given mimeType; otherwise, returns false.

[virtual] bool QWebPage::​supportsExtension(Extension extension) const

This virtual function returns true if the web page supports extension; otherwise false is returned.

See also extension().

bool QWebPage::​swallowContextMenuEvent(QContextMenuEvent * event)

Filters the context menu event, event, through handlers for scrollbars and custom event handlers in the web page. Returns true if the event was handled; otherwise false.

A web page may swallow a context menu event through a custom event handler, allowing for context menus to be implemented in HTML/JavaScript. This is used by Google Maps, for example.

[signal] void QWebPage::​toolBarVisibilityChangeRequested(bool visible)

This signal is emitted whenever the visibility of the toolbar in a web browser window that hosts QWebPage should be changed to visible.

quint64 QWebPage::​totalBytes() const

Returns the total number of bytes that were received from the network to render the current page, including extra content such as embedded images.

See also bytesReceived().

[virtual] void QWebPage::​triggerAction(WebAction action, bool checked = false)

This function can be called to trigger the specified action. It is also called by Qt WebKit if the user triggers the action, for example through a context menu item.

If action is a checkable action then checked specified whether the action is toggled or not.

See also action().

QUndoStack * QWebPage::​undoStack() const

Returns a pointer to the undo stack used for editable content.

See also modified.

[signal] void QWebPage::​unsupportedContent(QNetworkReply * reply)

This signal is emitted when WebKit cannot handle a link the user navigated to or a web server's response includes a "Content-Disposition" header with the 'attachment' directive. If "Content-Disposition" is present in reply, the web server is indicating that the client should prompt the user to save the content regardless of content-type. See RFC 2616 sections 19.5.1 for details about Content-Disposition.

At signal emission time the meta-data of the QNetworkReply reply is available.

Note: The receiving slot is responsible for deleting the QNetworkReply reply.

Note: This signal is only emitted if the forwardUnsupportedContent property is set to true.

See also downloadRequested().

void QWebPage::​updatePositionDependentActions(const QPoint & pos)

Updates the page's actions depending on the position pos. For example if pos is over an image element the CopyImageToClipboard action is enabled.

[virtual protected] QString QWebPage::​userAgentForUrl(const QUrl & url) const

This function is called when a user agent for HTTP requests is needed. You can reimplement this function to dynamically return different user agents for different URLs, based on the url parameter.

The default implementation returns the following value:

"Mozilla/5.0 (%Platform%%Security%%Subplatform%) AppleWebKit/%WebKitVersion% (KHTML, like Gecko) %AppVersion Safari/%WebKitVersion%"

In this string the following values are replaced at run-time:

• %Platform% expands to the windowing system followed by "; " if it is not Windows (e.g. "X11; ").
• %Security% expands to "N; " if SSL is disabled.
• %Subplatform% expands to the operating system version (e.g. "Windows NT 6.1" or "Intel Mac OS X 10.5").
• %WebKitVersion% is the version of WebKit the application was compiled against.
• %AppVersion% expands to QCoreApplication::applicationName()/QCoreApplication::applicationVersion() if they're set; otherwise defaulting to Qt and the current Qt version.

QWidget * QWebPage::​view() const

Returns the view widget that is associated with the web page.

See also setView().

ViewportAttributes QWebPage::​viewportAttributesForSize(const QSize & availableSize) const

Computes the optimal viewport configuration given the availableSize, when user interface components are disregarded.

The configuration is also dependent on the device screen size which is obtained automatically. For testing purposes the size can be overridden by setting two environment variables QTWEBKIT_DEVICE_WIDTH and QTWEBKIT_DEVICE_HEIGHT, which both needs to be set.

The ViewportAttributes includes a pixel density ratio, which will also be exposed to the web author though the -webkit-pixel-ratio media feature. This is the ratio between 1 density-independent pixel (DPI) and physical pixels.

A density-independent pixel is equivalent to one physical pixel on a 160 DPI screen, so on our platform assumes that as the baseline density.

The conversion of DIP units to screen pixels is quite simple:

pixels = DIPs * (density / 160).

Thus, on a 240 DPI screen, 1 DIPs would equal 1.5 physical pixels.

An invalid instance will be returned in the case an empty size is passed to the method.

Note: The density is automatically obtained from the DPI of the screen where the page is being shown, but as many X11 servers are reporting wrong DPI, it is possible to override it using QX11Info::setAppDpiY().

[signal] void QWebPage::​viewportChangeRequested()

Page authors can provide the supplied values by using the viewport meta tag. More information about this can be found at Safari Reference Library: Using the Viewport Meta Tag.

This function was introduced in Qt 4.8.

See also QWebPage::ViewportAttributes, setPreferredContentsSize(), and QGraphicsWebView::setScale().

[signal] void QWebPage::​windowCloseRequested()

This signal is emitted whenever the page requests the web browser window to be closed, for example through the JavaScript window.close() call.

#if QTWEBKIT_VERSION >= QTWEBKIT_VERSION_CHECK(2, 1, 0)
// code to use API new in Qt WebKit 2.1.0
#endif