An abstract base class for an MVC view that is rendered using a widget. More...

#include <Wt/WViewWidget.h>

Inheritance diagram for Wt::WViewWidget:

Public Member Functions
	WViewWidget ()
	Creates a new view widget.

void	update ()
	Updates the view. More...

virtual void	load () override
	Loads content just before the widget is used. More...

virtual void	render (WFlags< RenderFlag > flags) override
	Renders the widget. More...

virtual void	refresh () override
	Refresh the widget. More...

Public Member Functions inherited from Wt::WWebWidget
	WWebWidget ()
	Construct a WebWidget.

virtual std::vector< WWidget * >	children () const override
	Returns child widgets. More...

Signal &	childrenChanged ()
	Signal emitted when children have been added or removed. More...

virtual void	setPositionScheme (PositionScheme scheme) override
	Sets the CSS position scheme. More...

virtual PositionScheme	positionScheme () const override
	Returns the CSS position scheme. More...

virtual void	setOffsets (const WLength &offset, WFlags< Side > sides=AllSides) override
	Sets CSS offsets for a non-statically positioned widget. More...

virtual WLength	offset (Side s) const override
	Returns a CSS offset. More...

virtual void	resize (const WLength &width, const WLength &height) override
	Resizes the widget. More...

virtual WLength	width () const override
	Returns the width. More...

virtual WLength	height () const override
	Returns the height. More...

virtual void	setMinimumSize (const WLength &width, const WLength &height) override
	Sets a minimum size. More...

virtual WLength	minimumWidth () const override
	Returns the minimum width. More...

virtual WLength	minimumHeight () const override
	Returns the minimum height. More...

virtual void	setMaximumSize (const WLength &width, const WLength &height) override
	Sets a maximum size. More...

virtual WLength	maximumWidth () const override
	Returns the maximum width. More...

virtual WLength	maximumHeight () const override
	Returns the maximum height. More...

virtual void	setLineHeight (const WLength &height) override
	Sets the CSS line height for contained text.

virtual WLength	lineHeight () const override
	Returns the CSS line height for contained text. More...

virtual void	setFloatSide (Side s) override
	Specifies a CSS float side. More...

virtual Side	floatSide () const override
	Returns the CSS float side. More...

virtual void	setClearSides (WFlags< Side > sides) override
	Sets the sides that should be cleared of floats. More...

virtual WFlags< Side >	clearSides () const override
	Returns the sides that should remain empty. More...

virtual void	setMargin (const WLength &margin, WFlags< Side > sides=AllSides) override
	Sets CSS margins around the widget. More...

virtual WLength	margin (Side side) const override
	Returns a CSS margin set. More...

virtual void	setHiddenKeepsGeometry (bool enabled) override
	Sets whether the widget keeps its geometry when hidden. More...

virtual bool	hiddenKeepsGeometry () const override
	Returns whether the widget keeps its geometry when hidden. More...

virtual void	setHidden (bool hidden, const WAnimation &animation=WAnimation()) override
	Hides or shows the widget. More...

virtual bool	isHidden () const override
	Returns whether the widget is set hidden. More...

virtual bool	isVisible () const override
	Returns whether the widget is visible. More...

virtual void	setDisabled (bool disabled) override
	Sets whether the widget is disabled. More...

virtual bool	isDisabled () const override
	Returns whether the widget is set disabled. More...

virtual bool	isEnabled () const override
	Returns whether the widget is enabled. More...

virtual void	setPopup (bool popup) override
	Lets the widget overlay over other sibling widgets. More...

virtual bool	isPopup () const override
	Returns whether the widget is overlayed. More...

virtual void	setInline (bool isInline) override
	Sets whether the widget is displayed inline or as a block. More...

virtual bool	isInline () const override
	Returns whether the widget is displayed inline or as block. More...

virtual void	setDecorationStyle (const WCssDecorationStyle &style) override
	Sets a CSS decoration style. More...

virtual WCssDecorationStyle &	decorationStyle () override
	Returns the decoration style of this widget. More...

virtual void	setStyleClass (const WString &styleClass) override
	Sets (one or more) CSS style classes. More...

virtual WString	styleClass () const override
	Returns the CSS style class. More...

virtual void	addStyleClass (const WString &styleClass, bool force=false) override
	Adds a CSS style class. More...

virtual void	removeStyleClass (const WString &styleClass, bool force=false) override
	Removes a CSS style class. More...

virtual bool	hasStyleClass (const WString &styleClass) const override
	Returns whether the widget has a style class.

virtual void	setVerticalAlignment (AlignmentFlag alignment, const WLength &length=WLength()) override
	Sets the vertical alignment. More...

virtual AlignmentFlag	verticalAlignment () const override
	Returns the vertical alignment. More...

virtual WLength	verticalAlignmentLength () const override
	Returns the fixed vertical alignment that was set. More...

virtual void	setToolTip (const WString &text, TextFormat textFormat=TextFormat::Plain) override
	Sets a tooltip. More...

virtual void	setDeferredToolTip (bool enable, TextFormat textFormat=TextFormat::Plain) override
	Enable deferred tooltip. More...

virtual WString	toolTip () const override
	Returns the tooltip.

virtual void	setAttributeValue (const std::string &name, const WString &value) override
	Sets an attribute value. More...

virtual WString	attributeValue (const std::string &name) const override
	Returns an attribute value. More...

virtual void	setJavaScriptMember (const std::string &name, const std::string &value) override
	Sets a JavaScript member. More...

virtual std::string	javaScriptMember (const std::string &name) const override
	Returns the value of a JavaScript member. More...

virtual void	callJavaScriptMember (const std::string &name, const std::string &args) override
	Calls a JavaScript member. More...

virtual bool	loaded () const override
	Returns whether this widget has been loaded. More...

virtual void	setId (const std::string &id) override
	Sets the CSS Id. More...

virtual WWidget *	find (const std::string &name) override
	Finds a descendent widget by name. More...

virtual WWidget *	findById (const std::string &id) override
	Finds a descendent widget by id.

virtual void	setSelectable (bool selectable) override
	Sets as selectable. More...

virtual void	doJavaScript (const std::string &javascript) override
	Executes the given JavaScript statements when the widget is rendered or updated. More...

virtual const std::string	id () const override
	Returns the (unique) identifier for this object. More...

void	setLoadLaterWhenInvisible (bool)
	Change the way the widget is loaded when invisible. More...

std::string	htmlTagName () const
	returns the current html tag name More...

void	setHtmlTagName (const std::string &tag)
	set the custom HTML tag name More...

virtual void	setCanReceiveFocus (bool enabled) override
	Sets whether the widget can receive focus. More...

virtual bool	canReceiveFocus () const override
	Returns whether the widget can receive focus. More...

virtual bool	setFirstFocus () override
	Set focus on the widget's first descendant. More...

virtual void	setFocus (bool focus) override
	Sets focus. More...

virtual bool	hasFocus () const override
	Returns whether the widget currently has the focus.

virtual void	setTabIndex (int index) override
	Sets the tab index. More...

virtual int	tabIndex () const override
	Returns the tab index. More...

EventSignal &	blurred ()
	Signal emitted when the widget lost focus. More...

EventSignal &	focussed ()
	Signal emitted when the widget recieved focus. More...

virtual bool	scrollVisibilityEnabled () const final override
	Returns whether scroll visibility detection is enabled for this widget. More...

virtual void	setScrollVisibilityEnabled (bool enabled) final override
	Sets whether scroll visibility detection is enabled for this widget. More...

virtual int	scrollVisibilityMargin () const final override
	Returns the margin around the viewport within which the widget is considered visible. More...

virtual void	setScrollVisibilityMargin (int margin) final override
	Sets the margin around the viewport within which the widget is considered visible. More...

virtual Signal< bool > &	scrollVisibilityChanged () final override
	Signal triggered when the scroll visibility of this widget changes. More...

virtual bool	isScrollVisible () const final override
	Returns whether this widget is currently considered scroll visible. More...

virtual void	setThemeStyleEnabled (bool enabled) final override
	Sets whether theme styling for a widget is enabled or disabled. More...

virtual bool	isThemeStyleEnabled () const final override
	Returns whether this widget is currently styled by the chosen theme. More...

virtual void	setObjectName (const std::string &name) override
	Sets an object name. More...

void	setFocus ()
	Sets focus. More...

virtual void	setFocus (bool focus)=0
	Sets focus. More...

Public Member Functions inherited from Wt::WWidget
virtual	~WWidget ()
	Destructor. More...

WWidget *	parent () const
	Returns the parent widget.

virtual std::unique_ptr< WWidget >	removeWidget (WWidget *widget)
	Removes a child widget.

template<typename Widget >
std::unique_ptr< Widget >	removeWidget (Widget *widget)
	Removes a child widget. More...

std::unique_ptr< WWidget >	removeFromParent ()
	Removes the widget from its parent. More...

void	setWidth (const WLength &width)
	Sets the width. More...

void	setHeight (const WLength &height)
	Sets the height. More...

virtual void	positionAt (const WWidget *widget, Orientation orientation=Orientation::Vertical)
	Positions a widget next to another widget. More...

virtual void	toggleStyleClass (const WString &styleClass, bool add, bool force=false)
	Toggles a CSS style class.

std::string	jsRef () const
	Returns a JavaScript expression to the corresponding DOM node. More...

void	setFocus ()
	Sets focus. More...

virtual void	acceptDrops (const std::string &mimeType, const WString &hoverStyleClass=WString())
	Sets a mime type to be accepted for dropping. More...

virtual void	stopAcceptDrops (const std::string &mimeType)
	Indicates that a mime type is no longer accepted for dropping. More...

virtual void	htmlText (std::ostream &out)
	Streams the (X)HTML representation. More...

bool	isRendered () const
	Returns whether the widget is rendered. More...

void	hide ()
	Hides the widget. More...

void	animateHide (const WAnimation &animation)
	Hides the widget using an animation. More...

void	show ()
	Shows the widget. More...

void	animateShow (const WAnimation &animation)
	Shows the widget using an animation. More...

void	enable ()
	Enables the widget. More...

void	disable ()
	Disable thes widget. More...

bool	layoutSizeAware () const
	Returns whether the widget is layout size aware. More...

Public Member Functions inherited from Wt::WObject
void	addChild (std::unique_ptr< WObject > child)
	Add a child WObject whose lifetime is determined by this WObject.

template<typename Child >
Child *	addChild (std::unique_ptr< Child > child)
	Add a child WObject, returning a raw pointer. More...

std::unique_ptr< WObject >	removeChild (WObject *child)
	Remove a child WObject, so its lifetime is no longer determined by this WObject.

template<typename Child >
std::unique_ptr< Child >	removeChild (Child *child)
	Remove a child WObject, so its lifetime is no longer determined by this WObject. More...

virtual std::string	objectName () const
	Returns the object name. More...

void	resetLearnedSlots ()
	Resets learned stateless slot implementations. More...

template<class T >
void	resetLearnedSlot (void(T::*method)())
	Resets a learned stateless slot implementation. More...

template<class T >
WStatelessSlot *	implementStateless (void(T::*method)())
	Declares a slot to be stateless and learn client-side behaviour on first invocation. More...

template<class T >
WStatelessSlot *	implementStateless (void(T::method)(), void(T::undoMethod)())
	Declares a slot to be stateless and learn client-side behaviour in advance. More...

void	isNotStateless ()
	Marks the current function as not stateless. More...

template<class T >
WStatelessSlot *	implementJavaScript (void(T::*method)(), const std::string &jsCode)
	Provides a JavaScript implementation for a method. More...

Public Member Functions inherited from Wt::Core::observable
	observable () noexcept
	Default constructor.

virtual	~observable ()
	Destructor. More...

template<typename... Args, typename C >
auto	bindSafe (void(C::*method)(Args...)) noexcept
	Protects a method call against object destruction. More...

template<typename... Args, typename C >
auto	bindSafe (void(C::*method)(Args...) const) const noexcept
	Protects a const method call against object destruction. More...

template<typename Function >
auto	bindSafe (const Function &function) noexcept
	Protects a function against object destruction. More...

Protected Member Functions
virtual std::unique_ptr< WWidget >	renderView ()=0
	Creates a widget that renders the View. More...

Protected Member Functions inherited from Wt::WWebWidget
virtual void	propagateSetEnabled (bool enabled) override
	Propagates that a widget was enabled or disabled through children. More...

virtual void	enableAjax () override
	Progresses to an Ajax-enabled widget. More...

virtual WStatelessSlot *	getStateless (Method method) override
	On-demand stateless slot implementation. More...

Protected Member Functions inherited from Wt::WWidget
void	setLayoutSizeAware (bool sizeAware)
	Sets the widget to be aware of its size set by a layout manager. More...

virtual void	layoutSizeChanged (int width, int height)
	Virtual method that indicates a size change. More...

	WWidget ()
	Creates a widget.

virtual void	dropEvent (WDropEvent dropEvent)
	Handles a drop event. More...

virtual int	boxPadding (Orientation orientation) const
	Returns the widget's built-in padding. More...

virtual int	boxBorder (Orientation orientation) const
	Returns the widget's built-in border width. More...

void	scheduleRender (WFlags< RepaintFlag > flags=None)
	Schedules rerendering of the widget. More...

Additional Inherited Members
Public Types inherited from Wt::WObject
typedef void(WObject::*	Method) ()
	Typedef for a WObject method without arguments.

Static Public Member Functions inherited from Wt::WWebWidget
static std::string	jsStringLiteral (const std::string &v, char delimiter='\'')
	Turn a CharEncoding::UTF8 encoded string into a JavaScript string literal. More...

Static Public Member Functions inherited from Wt::WWidget
static WString	tr (const char *key)
	Short hand for WString::tr() More...

Detailed Description

An abstract base class for an MVC view that is rendered using a widget.

In principle, Wt widgets are self-contained and manage both their content, behavior and layout. From the point of view of a Model-View-Controller (MVC) design pattern, they implement each of these, except for the view widgets that work in conjunction with WAbstractItemModel. As a developer you can chose to keep Model, View and Controller together or separate them as you wish.

This widget facilitates separation of the View from the Model and Controller in a particular way. The View is rendered as a Wt widget. The use of this widget provides two benefits. The classic MVC benefit is a decoupling between view and model, which may allow easier maintainance of code. In addition, this widget enforces the View to be stateless, as it is only created transiently on the server. Therefore the View does not require session resources. This may increase scalability for Internet-deployments.

The rendered View widget returned by renderView() should reflect the current model state. Whenever the model changes, rerendering can be triggered by calling update().

Currently, the View cannot enclose WFormWidgets which would allow direct manipulation of the model (but we are working to remove this limitation in the future, and let the Model/Controller handle editing changes) and the View may only be updated by a complete rerendering of the entire view.

The View widget may contain event handling code, but only in one of the following ways:

event handling implemented directly in JavaScript code
event handling implemented in pre-learned stateless slot implementations

Thus, currently, event handling code related to the View cannot be implemented at server-side (but we are thinking about a solution for this as well...).

Implementation example:

// Shows the contents for a specific role of a model index in a WText widget
class SourceView : public Wt::WViewWidget
{
public:
  // role is the ItemDataRole
  SourceView(int role)
    : role_(role)
  { }
 
  // set an index
  void setIndex(const Wt::WModelIndex& index) {
    if (index != index_
        && (!index.isValid() || !index.data(role_).empty())) {
      index_ = index;
      update(); // trigger rerendering of the view
    }
  }
 
private:
  Wt::WModelIndex index_;
  int             role_;
 
protected:
  virtual std::unique_ptr<Wt::WWidget> renderView() {
    auto result = std::make_unique<Wt::WText>();
    result->setInline(false);
 
    if (!index_.isValid())
      return result;
 
    cpp17::any d = index_.data(role_);
    const std::string& t = cpp17::any_cast<const std::string&>(d);
 
    result->setTextFormat(Wt::TextFormat::Plain);
    result->setText(t);
 
    return result;
  }
};

CSS

This widget does not provide styling, and can be styled using inline or external CSS as appropriate.

Member Function Documentation

◆ load()

void Wt::WViewWidget::load ( )

overridevirtual

Loads content just before the widget is used.

This function is called when a widget is inserted in the widget hierarchy. Widgets that get inserted in the widget hierarchy will be rendered. Visible widgets are rendered immediately, and invisible widgets in the back-ground (or not for a plain HTML session). This method is called when the widget is directly or indirectly inserted into the widget tree.

The default implementation simply propagates the load signal to its children. You may want to override this method to delay loading of resource-intensive contents.

During the life-time of a widget, this method may be called multiple times, so you should make sure that you do a deferred initialization only once.

Reimplemented from Wt::WWebWidget.

◆ refresh()

void Wt::WViewWidget::refresh ( )

overridevirtual

Refresh the widget.

The refresh method is invoked when the locale is changed using WApplication::setLocale() or when the user hit the refresh button.

The widget must actualize its contents in response.

Note: This does not rerender the widget! Calling refresh() usually does not have any effect (unless you've reimplemented refresh() to attach to it an effect).

Reimplemented from Wt::WWebWidget.

◆ render()

void Wt::WViewWidget::render ( WFlags< RenderFlag > flags )

overridevirtual

Renders the widget.

This function renders the widget (or an update for the widget), after this has been scheduled using scheduleRender().

The default implementation will render the widget by serializing changes to JavaScript and HTML. You may want to reimplement this widget if you have been postponing some of the layout / rendering implementation until the latest moment possible. In that case you should make sure you call the base implementation however.

Reimplemented from Wt::WWebWidget.

◆ renderView()

virtual std::unique_ptr<WWidget> Wt::WViewWidget::renderView ( )

protectedpure virtual

Creates a widget that renders the View.

This method must be reimplemented to return a widget that renders the view. The returned widget will be deleted by WViewWidget.

Implemented in Wt::WStaticModelView< Renderer >.

◆ update()

void Wt::WViewWidget::update ( )

Updates the view.

Typically, the model will want to update the view when the model has changed.

This will trigger a call to renderView() to ask for a new rendering of the view.

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

CSS

Member Function Documentation

◆ load()

◆ refresh()

◆ render()

◆ renderView()

◆ update()