Wt::WImage Class Reference

A widget that displays an image. More...

#include <Wt/WImage>

Inheritance diagram for Wt::WImage:

Public Member Functions
	WImage (WContainerWidget *parent=0)
	Creates an empty image widget.
	WImage (const WLink &imageLink, WContainerWidget *parent=0)
	Creates an image widget with a given image link. More...
	WImage (const WLink &imageLink, const WString &altText, WContainerWidget *parent=0)
	Creates an image widget with a given image link and alternate text. More...
void	setAlternateText (const WString &text)
	Sets an alternate text. More...
const WString &	alternateText () const
	Returns the alternate text. More...
void	setImageLink (const WLink &link)
	Sets the image link. More...
const WLink &	imageLink () const
	Returns the image link. More...
void	setImageRef (const std::string &url)
	Sets the image URL (deprecated). More...
const std::string	imageRef () const
	Returns the image URL (deprecated). More...
void	setResource (WResource *resource)
	Sets the image resource (deprecated). More...
WResource *	resource () const
	Returns the image resource (deprecated. More...
void	addArea (WAbstractArea *area)
	Adds an interactive area. More...
void	insertArea (int index, WAbstractArea *area)
	Inserts an interactive area. More...
void	removeArea (WAbstractArea *area)
	Removes an interactive area. More...
WAbstractArea *	area (int index) const
	Returns the interactive area at the given index. More...
const std::vector< WAbstractArea * >	areas () const
	Returns the interactive areas set for this widget. More...
EventSignal &	imageLoaded ()
	Event emitted when the image was loaded.
Public Member Functions inherited from Wt::WInteractWidget
	WInteractWidget (WContainerWidget *parent=0)
	Create an InteractWidget with optional parent.
EventSignal< WKeyEvent > &	keyWentDown ()
	Event signal emitted when a keyboard key is pushed down. More...
EventSignal< WKeyEvent > &	keyPressed ()
	Event signal emitted when a "character" was entered. More...
EventSignal< WKeyEvent > &	keyWentUp ()
	Event signal emitted when a keyboard key is released. More...
EventSignal &	enterPressed ()
	Event signal emitted when enter was pressed. More...
EventSignal &	escapePressed ()
	Event signal emitted when escape was pressed. More...
EventSignal< WMouseEvent > &	clicked ()
	Event signal emitted when a mouse key was clicked on this widget. More...
EventSignal< WMouseEvent > &	doubleClicked ()
	Event signal emitted when a mouse key was double clicked on this widget. More...
EventSignal< WMouseEvent > &	mouseWentDown ()
	Event signal emitted when a mouse key was pushed down on this widget. More...
EventSignal< WMouseEvent > &	mouseWentUp ()
	Event signal emitted when a mouse key was released on this widget. More...
EventSignal< WMouseEvent > &	mouseWentOut ()
	Event signal emitted when the mouse went out of this widget. More...
EventSignal< WMouseEvent > &	mouseWentOver ()
	Event signal emitted when the mouse entered this widget. More...
EventSignal< WMouseEvent > &	mouseMoved ()
	Event signal emitted when the mouse moved over this widget. More...
EventSignal< WMouseEvent > &	mouseDragged ()
	Event signal emitted when the mouse is dragged over this widget. More...
EventSignal< WMouseEvent > &	mouseWheel ()
	Event signal emitted when the mouse scroll wheel was used. More...
EventSignal< WTouchEvent > &	touchStarted ()
	Event signal emitted when a finger is placed on the screen. More...
EventSignal< WTouchEvent > &	touchEnded ()
	Event signal emitted when a finger is removed from the screen. More...
EventSignal< WTouchEvent > &	touchMoved ()
	Event signal emitted when a finger, which is already placed on the screen, is moved across the screen. More...
EventSignal< WGestureEvent > &	gestureStarted ()
	Event signal emitted when a gesture is started. More...
EventSignal< WGestureEvent > &	gestureChanged ()
	Event signal emitted when a gesture is changed. More...
EventSignal< WGestureEvent > &	gestureEnded ()
	Event signal emitted when a gesture is ended. More...
void	setDraggable (const std::string &mimeType, WWidget *dragWidget=0, bool isDragWidgetOnly=false, WObject *sourceWidget=0)
	Configure dragging for drag and drop. More...
void	unsetDraggable ()
	Disable drag & drop for this widget. More...
void	setMouseOverDelay (int delay)
	Sets a delay for the mouse over event. More...
int	mouseOverDelay () const
	Returns the mouse over signal delay. More...
virtual void	setPopup (bool popup)
	Lets the widget overlay over other sibling widgets. More...
virtual void	load ()
	Loads content just before the widget is used. More...
virtual bool	isEnabled () const
	Returns whether the widget is enabled. More...
Public Member Functions inherited from Wt::WWebWidget
	WWebWidget (WContainerWidget *parent=0)
	Construct a WebWidget with a given parent. More...
virtual void	setPositionScheme (PositionScheme scheme)
	Sets the CSS position scheme. More...
virtual PositionScheme	positionScheme () const
	Returns the CSS position scheme. More...
virtual void	setOffsets (const WLength &offset, WFlags< Side > sides=All)
	Sets CSS offsets for a non-statically positioned widget. More...
virtual WLength	offset (Side s) const
	Returns a CSS offset. More...
virtual void	resize (const WLength &width, const WLength &height)
	Resizes the widget. More...
virtual WLength	width () const
	Returns the width. More...
virtual WLength	height () const
	Returns the height. More...
virtual void	setMinimumSize (const WLength &width, const WLength &height)
	Sets a minimum size. More...
virtual WLength	minimumWidth () const
	Returns the minimum width. More...
virtual WLength	minimumHeight () const
	Returns the minimum height. More...
virtual void	setMaximumSize (const WLength &width, const WLength &height)
	Sets a maximum size. More...
virtual WLength	maximumWidth () const
	Returns the maximum width. More...
virtual WLength	maximumHeight () const
	Returns the maximum height. More...
virtual void	setLineHeight (const WLength &height)
	Sets the CSS line height for contained text.
virtual WLength	lineHeight () const
	Returns the CSS line height for contained text. More...
virtual void	setFloatSide (Side s)
	Specifies a CSS float side. More...
virtual Side	floatSide () const
	Returns the CSS float side. More...
virtual void	setClearSides (WFlags< Side > sides)
	Sets the sides that should be cleared of floats. More...
virtual WFlags< Side >	clearSides () const
	Returns the sides that should remain empty. More...
virtual void	setMargin (const WLength &margin, WFlags< Side > sides=All)
	Sets CSS margins around the widget. More...
virtual WLength	margin (Side side) const
	Returns a CSS margin set. More...
virtual void	setHiddenKeepsGeometry (bool enabled)
	Sets whether the widget keeps its geometry when hidden. More...
virtual bool	hiddenKeepsGeometry () const
	Returns whether the widget keeps its geometry when hidden. More...
virtual void	setHidden (bool hidden, const WAnimation &animation=WAnimation())
	Hides or shows the widget. More...
virtual bool	isHidden () const
	Returns whether the widget is set hidden. More...
virtual bool	isVisible () const
	Returns whether the widget is visible. More...
virtual void	setDisabled (bool disabled)
	Sets whether the widget is disabled. More...
virtual bool	isDisabled () const
	Returns whether the widget is set disabled. More...
virtual bool	isPopup () const
	Returns whether the widget is overlayed. More...
virtual void	setInline (bool isInline)
	Sets whether the widget is displayed inline or as a block. More...
virtual bool	isInline () const
	Returns whether the widget is displayed inline or as block. More...
virtual void	setDecorationStyle (const WCssDecorationStyle &style)
	Sets a CSS decoration style. More...
virtual WCssDecorationStyle &	decorationStyle ()
	Returns the decoration style of this widget. More...
virtual void	setStyleClass (const WString &styleClass)
	Sets (one or more) CSS style classes. More...
virtual WString	styleClass () const
	Returns the CSS style class. More...
virtual void	addStyleClass (const WString &styleClass, bool force=false)
	Adds a CSS style class. More...
virtual void	removeStyleClass (const WString &styleClass, bool force=false)
	Removes a CSS style class. More...
virtual bool	hasStyleClass (const WString &styleClass) const
	Returns whether the widget has a style class.
virtual void	setVerticalAlignment (AlignmentFlag alignment, const WLength &length=WLength())
	Sets the vertical alignment. More...
virtual AlignmentFlag	verticalAlignment () const
	Returns the vertical alignment. More...
virtual WLength	verticalAlignmentLength () const
	Returns the fixed vertical alignment that was set. More...
virtual void	setToolTip (const WString &text, TextFormat textFormat=PlainText)
	Sets a tooltip. More...
virtual void	setDeferredToolTip (bool enable, TextFormat textFormat=PlainText)
	Enable deferred tooltip. More...
virtual WString	toolTip () const
	Returns the tooltip.
virtual void	refresh ()
	Refresh the widget. More...
virtual void	setAttributeValue (const std::string &name, const WString &value)
	Sets an attribute value. More...
virtual WString	attributeValue (const std::string &name) const
	Returns an attribute value. More...
virtual void	setJavaScriptMember (const std::string &name, const std::string &value)
	Sets a JavaScript member. More...
virtual std::string	javaScriptMember (const std::string &name) const
	Returns the value of a JavaScript member. More...
virtual void	callJavaScriptMember (const std::string &name, const std::string &args)
	Calls a JavaScript member. More...
virtual bool	loaded () const
	Returns whether this widget has been loaded. More...
virtual void	setId (const std::string &id)
	Sets the CSS Id. More...
virtual WWidget *	find (const std::string &name)
	Finds a descendent widget by name. More...
virtual WWidget *	findById (const std::string &id)
	Finds a descendent widget by id.
virtual void	setSelectable (bool selectable)
	Sets as selectable. More...
virtual void	doJavaScript (const std::string &javascript)
	Executes the given JavaScript statements when the widget is rendered or updated. More...
virtual const std::string	id () const
	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...
const std::vector< WWidget * > &	children () const
	Returns contained widgets. More...
Signal &	childrenChanged ()
	Signal emitted when children have been added or removed. More...
virtual void	setCanReceiveFocus (bool enabled)
	Sets whether the widget can receive focus. More...
virtual bool	canReceiveFocus () const
	Returns whether the widget can receive focus. More...
virtual bool	setFirstFocus ()
	Set focus on the widget's first descendant. More...
virtual void	setFocus (bool focus)
	Sets focus. More...
virtual bool	hasFocus () const
	Returns whether the widget currently has the focus.
virtual void	setTabIndex (int index)
	Sets the tab index. More...
virtual int	tabIndex () const
	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 WT_CXX11ONLY(finaloverride)
	Returns whether scroll visibility detection is enabled for this widget. More...
virtual void	setScrollVisibilityEnabled (bool enabled) WT_CXX11ONLY(finaloverride)
	Sets whether scroll visibility detection is enabled for this widget. More...
virtual int	scrollVisibilityMargin () const WT_CXX11ONLY(finaloverride)
	Returns the margin around the viewport within which the widget is considered visible. More...
virtual void	setScrollVisibilityMargin (int margin) WT_CXX11ONLY(finaloverride)
	Sets the margin around the viewport within which the widget is considered visible. More...
virtual Signal< bool > &	scrollVisibilityChanged () WT_CXX11ONLY(finaloverride)
	Signal triggered when the scroll visibility of this widget changes. More...
virtual bool	isScrollVisible () const WT_CXX11ONLY(finaloverride)
	Returns whether this widget is currently considered scroll visible. More...
virtual void	setThemeStyleEnabled (bool enabled)
	Sets whether theme styling for a widget is enabled or disabled. More...
virtual bool	isThemeStyleEnabled () const
	Returns whether this widget is currently styled by the chosen theme. More...
Public Member Functions inherited from Wt::WWidget
virtual	~WWidget ()
	Destructor. More...
WWidget *	parent () const
	Returns the parent widget. More...
virtual void	removeChild (WObject *child)
	Removes a child object. 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=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	setObjectName (const std::string &name)
	Sets an object name. 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
	WObject (WObject *parent=0)
	Create a WObject with a given parent object. More...
virtual	~WObject ()
	Destructor. 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...
void	addChild (WObject *child)
	Adds a child object. More...
const std::vector< WObject * > &	children () const
	Returns the children.
WObject *	parent () const
	Returns the parent object.

Protected Member Functions
virtual void	render (WFlags< RenderFlag > flags)
	Renders the widget. More...
Protected Member Functions inherited from Wt::WInteractWidget
virtual void	propagateSetEnabled (bool enabled)
	Propagates that a widget was enabled or disabled through children. More...
Protected Member Functions inherited from Wt::WWebWidget
virtual void	enableAjax ()
	Progresses to an Ajax-enabled widget. More...
virtual WStatelessSlot *	getStateless (Method method)
	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 (WContainerWidget *parent=0)
	Creates a widget. More...
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=0)
	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 WString	escapeText (const WString &text, bool newlinesToo=false)
	Escape HTML control characters in the text, to display literally (deprecated). More...
static std::string &	escapeText (std::string &text, bool newlinestoo=false)
	Escape HTML control characters in the text, to display literally (deprecated). More...
static bool	removeScript (WString &text)
	Remove tags/attributes from text that are not passive (deprecated). More...
static std::string	jsStringLiteral (const std::string &v, char delimiter= '\'')
	Turn a 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...
Static Protected Member Functions inherited from Wt::WObject
static WObject *	sender ()
	Returns the sender of the current slot call. More...

Detailed Description

A widget that displays an image.

The image may be specified either as a URL, or may be dynamically generated by a WResource.

You may listen to events by attaching event listeners to signals such as clicked(). Since mouse events pass the coordinates through a WMouseEvent object, it is possible to react to clicks in specific parts of the image. An alternative is to define interactive areas on the image using addArea(), which in addition allows to have customized tool tips for certain image areas (using WAbstractArea::setToolTip()).

Usage example:

Wt::WImage *img = new Wt::WImage("images/johnny_cash.png", this);
img->setAlternateText("Johnny Cash sings a song");

WImage is an inline widget.

CSS

The widget corresponds to the HTML <img> tag and does not provide styling. It can be styled using inline or external CSS as appropriate.

See also

WResource, WPaintedWidget

Constructor & Destructor Documentation

Wt::WImage::WImage	(	const WLink &	imageLink,
		WContainerWidget *	parent = 0
	)

Creates an image widget with a given image link.

The imageLink may link to a URL or resource.

Wt::WImage::WImage	(	const WLink &	imageLink,
		const WString &	altText,
		WContainerWidget *	parent = 0
	)

Creates an image widget with a given image link and alternate text.

The imageLink may link to a URL or resource.

Member Function Documentation

void Wt::WImage::addArea

(

WAbstractArea *

area

)

Adds an interactive area.

Adds the area which listens to events in a specific region of the image. Areas are organized in an indexed list, to which the given area is appended. When areas overlap, the area with the lowest index receives the event.

Ownership of the area is transferred to the image.

See also

insertArea(int, WAbstractArea *)

Note

Currently it is not possible to add a first area after the image has been rendered. If you want to use interactive areas you need to add one immediately.

const WString& Wt::WImage::alternateText

(

)

const

Returns the alternate text.

See also

setAlternateText()

WAbstractArea * Wt::WImage::area

(

int

index

)

const

Returns the interactive area at the given index.

Returns 0 if index was invalid.

See also

insertArea(int, WAbstractArea *)

const std::vector< WAbstractArea * > Wt::WImage::areas

(

)

const

Returns the interactive areas set for this widget.

See also

addArea()

const WLink& Wt::WImage::imageLink

(

)

const

Returns the image link.

See also

setLink()

const std::string Wt::WImage::imageRef

(

)

const

Returns the image URL (deprecated).

When the image is specified as a resource, this returns the current resource URL.

Deprecated:

Use imageLink() instead.

void Wt::WImage::insertArea	(	int	index,
		WAbstractArea *	area
	)

Inserts an interactive area.

Inserts the area which listens to events in the coresponding area of the image. Areas are organized in a list, and the area is inserted at index index. When areas overlap, the area with the lowest index receives the event.

Ownership of the area is transferred to the image.

See also

addArea(WAbstractArea *)

Note

Currently it is not possible to add a first area after the image has been rendered. If you want to use interactive areas you need to add one immediately.

void Wt::WImage::removeArea

(

WAbstractArea *

area

)

Removes an interactive area.

Removes the area from this widget, and also returns the ownership.

See also

addArea(WAbstractArea *)

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

protectedvirtual

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.

WResource * Wt::WImage::resource

(

)

const

Returns the image resource (deprecated.

Returns 0 if no image resource was set.

Deprecated:

Use setImageLink() instead.

void Wt::WImage::setAlternateText

(

const WString &

text

)

Sets an alternate text.

The alternate text should provide a fallback for browsers that do not display an image. If no sensible fallback text can be provided, an empty text is preferred over nonsense.

This should not be confused with toolTip() text, which provides additional information that is displayed when the mouse hovers over the image.

The default alternate text is an empty text ("").

See also

alternateText()

void Wt::WImage::setImageLink

(

const WLink &

link

)

Sets the image link.

The image may be specified as a URL or as a resource. A resource specifies application-dependent content, which may be used to generate an image on demand.

void Wt::WImage::setImageRef

(

const std::string &

url

)

Sets the image URL (deprecated).

Deprecated:

Use setImageLink() instead.

void Wt::WImage::setResource

(

WResource *

resource

)

Sets the image resource (deprecated).

Deprecated:

Use setImageLink() instead.