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Wt::WImage Class Reference

A widget that displays an image. More...

#include <Wt/WImage>

Inheritance diagram for Wt::WImage:
Inheritance graph
[legend]

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 WStringalternateText () const
 Returns the alternate text. More...
 
void setImageLink (const WLink &link)
 Sets the image link. More...
 
const WLinkimageLink () 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...
 
WResourceresource () 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...
 
WAbstractAreaarea (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...
 
EventSignalimageLoaded ()
 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...
 
EventSignalenterPressed ()
 Event signal emitted when enter was pressed. More...
 
EventSignalescapePressed ()
 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 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< SideclearSides () 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 WCssDecorationStyledecorationStyle ()
 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 setTabIndex (int index)
 Sets the tab index. More...
 
virtual int tabIndex () const
 Returns the tab index. More...
 
virtual void setId (const std::string &id)
 Sets the CSS Id. More...
 
virtual WWidgetfind (const std::string &name)
 Finds a descendent widget by name. More...
 
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...
 
const std::vector< WWidget * > & children () const
 Returns contained widgets. More...
 
SignalchildrenChanged ()
 Signal emitted when children have been added or removed. More...
 
virtual bool setFirstFocus ()
 Set focus on the widget's first descendant. More...
 
- Public Member Functions inherited from Wt::WWidget
virtual ~WWidget ()
 Destructor. More...
 
WWidgetparent () 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...
 
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
 WObject (WObject *parent=0)
 Create a WObject with a given parent object. More...
 
virtual ~WObject ()
 Destructor. More...
 
virtual void setObjectName (const std::string &name)
 Sets an object name. 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...
 
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.
 
WObjectparent () const
 Returns the parent object.
 

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...
 
- Protected Member Functions inherited from Wt::WInteractWidget
virtual void propagateSetEnabled (bool enabled)
 Propagates that a widget was enabled or disabled through children. More...
 
- Static Protected Member Functions inherited from Wt::WObject
static WObjectsender ()
 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 *)
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.

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