Wt::WVirtualImage Class Reference

An abstract widget that shows a viewport to a virtually large image. More...

#include <Wt/WVirtualImage.h>

Inheritance diagram for Wt::WVirtualImage:

Public Member Functions
	WVirtualImage (int viewPortWidth, int viewPortHeight, ::int64_t imageWidth, ::int64_t imageHeight, int gridImageSize=256)
	Creates a viewport for a virtual image.
	~WVirtualImage ()
	Destructor.
void	redrawAll ()
	Regenerates and redraws the image pieces.
void	enableDragging ()
	Enables mouse dragging to scroll around the image.
void	scroll (::int64_t dx, ::int64_t dy)
	Scrolls the viewport of the image over a distance.
void	scrollTo (::int64_t x, ::int64_t y)
	Scrolls the viewport of the image to a specific coordinate.
::int64_t	imageWidth () const
	Returns the virtual image width.
::int64_t	imageHeight () const
	Returns the virtual image height.
void	resizeImage (::int64_t w, ::int64_t h)
	Resizes the virtual image.
int	viewPortWidth () const
	Returns the viewport width.
int	viewPortHeight () const
	Returns the viewport height.
int	gridImageSize () const
	Returns the size of a single piece.
::int64_t	currentTopLeftX () const
	Returns the current top left X coordinate.
::int64_t	currentTopLeftY () const
	Returns the current top left Y coordinate.
::int64_t	currentBottomRightX () const
	Returns the current bottom right X coordinate.
::int64_t	currentBottomRightY () const
	Returns the current bottom right Y coordinate.
Signal< ::int64_t, ::int64_t > &	viewPortChanged ()
	Signal emitted whenever the viewport changes.
Public Member Functions inherited from Wt::WCompositeWidget
	WCompositeWidget ()
	Creates a WCompositeWidget.
	WCompositeWidget (std::unique_ptr< WWidget > implementation)
	Creates a WCompositeWidget with given implementation.
virtual std::vector< WWidget * >	children () const override
	Returns child widgets.
virtual std::unique_ptr< WWidget >	removeWidget (WWidget *widget) override
	Removes a child widget.
virtual void	setObjectName (const std::string &name) override
	Sets an object name.
virtual std::string	objectName () const override
	Returns the object name.
virtual const std::string	id () const override
	Returns the (unique) identifier for this object.
virtual void	setPositionScheme (PositionScheme scheme) override
	Sets the CSS position scheme.
virtual PositionScheme	positionScheme () const override
	Returns the CSS position scheme.
virtual void	setOffsets (const WLength &offset, WFlags< Side > sides=AllSides) override
	Sets CSS offsets for a non-statically positioned widget.
virtual WLength	offset (Side s) const override
	Returns a CSS offset.
virtual void	resize (const WLength &width, const WLength &height) override
	Resizes the widget.
virtual WLength	width () const override
	Returns the width.
virtual WLength	height () const override
	Returns the height.
virtual void	setMinimumSize (const WLength &width, const WLength &height) override
	Sets a minimum size.
virtual WLength	minimumWidth () const override
	Returns the minimum width.
virtual WLength	minimumHeight () const override
	Returns the minimum height.
virtual void	setMaximumSize (const WLength &width, const WLength &height) override
	Sets a maximum size.
virtual WLength	maximumWidth () const override
	Returns the maximum width.
virtual WLength	maximumHeight () const override
	Returns the maximum height.
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.
virtual void	setFloatSide (Side s) override
	Specifies a CSS float side.
virtual Side	floatSide () const override
	Returns the CSS float side.
virtual void	setClearSides (WFlags< Side > sides) override
	Sets the sides that should be cleared of floats.
virtual WFlags< Side >	clearSides () const override
	Returns the sides that should remain empty.
virtual void	setMargin (const WLength &margin, WFlags< Side > sides=AllSides) override
	Sets CSS margins around the widget.
virtual WLength	margin (Side side) const override
	Returns a CSS margin set.
virtual void	setHiddenKeepsGeometry (bool enabled) override
	Sets whether the widget keeps its geometry when hidden.
virtual bool	hiddenKeepsGeometry () const override
	Returns whether the widget keeps its geometry when hidden.
virtual void	setHidden (bool hidden, const WAnimation &animation=WAnimation()) override
	Hides or shows the widget.
virtual bool	isHidden () const override
	Returns whether the widget is set hidden.
virtual bool	isVisible () const override
	Returns whether the widget is visible.
virtual void	setDisabled (bool disabled) override
	Sets whether the widget is disabled.
virtual bool	isDisabled () const override
	Returns whether the widget is set disabled.
virtual bool	isEnabled () const override
	Returns whether the widget is enabled.
virtual void	setPopup (bool popup) override
	Lets the widget overlay over other sibling widgets.
virtual bool	isPopup () const override
	Returns whether the widget is overlayed.
virtual void	setInline (bool isInline) override
	Sets whether the widget is displayed inline or as a block.
virtual bool	isInline () const override
	Returns whether the widget is displayed inline or as block.
virtual void	setDecorationStyle (const WCssDecorationStyle &style) override
	Sets a CSS decoration style.
virtual WCssDecorationStyle &	decorationStyle () override
	Returns the decoration style of this widget.
virtual void	setStyleClass (const WString &styleClass) override
	Sets (one or more) CSS style classes.
virtual WString	styleClass () const override
	Returns the CSS style class.
virtual void	addStyleClass (const WString &styleClass, bool force=false) override
	Adds a CSS style class.
virtual void	removeStyleClass (const WString &styleClass, bool force=false) override
	Removes a CSS style class.
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::Auto) override
	Sets the vertical alignment.
virtual AlignmentFlag	verticalAlignment () const override
	Returns the vertical alignment.
virtual WLength	verticalAlignmentLength () const override
	Returns the fixed vertical alignment that was set.
virtual void	setToolTip (const WString &text, TextFormat textFormat=TextFormat::Plain) override
	Sets a tooltip.
virtual WString	toolTip () const override
	Returns the tooltip.
virtual void	setDeferredToolTip (bool enable, TextFormat textFormat=TextFormat::Plain) override
	Enable deferred tooltip.
virtual void	refresh () override
	Refresh the widget.
virtual void	setAttributeValue (const std::string &name, const WString &value) override
	Sets an attribute value.
virtual WString	attributeValue (const std::string &name) const override
	Returns an attribute value.
virtual void	setJavaScriptMember (const std::string &name, const std::string &value) override
	Sets a JavaScript member.
virtual std::string	javaScriptMember (const std::string &name) const override
	Returns the value of a JavaScript member.
virtual void	callJavaScriptMember (const std::string &name, const std::string &args) override
	Calls a JavaScript member.
virtual void	load () override
	Loads content just before the widget is used.
virtual bool	loaded () const override
	Returns whether this widget has been loaded.
virtual void	setCanReceiveFocus (bool enabled) override
	Sets whether the widget can receive focus.
virtual bool	canReceiveFocus () const override
	Returns whether the widget can receive focus.
virtual void	setFocus (bool focus) override
	Sets focus.
virtual bool	setFirstFocus () override
	Set focus on the widget's first descendant.
virtual bool	hasFocus () const override
	Returns whether the widget currently has the focus.
virtual void	setTabIndex (int index) override
	Sets the tab index.
virtual int	tabIndex () const override
	Returns the tab index.
virtual void	setId (const std::string &id) override
	Sets the CSS Id.
virtual WWidget *	find (const std::string &name) override
	Finds a descendent widget by name.
virtual WWidget *	findById (const std::string &name) override
	Finds a descendent widget by id.
virtual void	setSelectable (bool selectable) override
	Sets as selectable.
virtual void	doJavaScript (const std::string &js) override
	Executes the given JavaScript statements when the widget is rendered or updated.
virtual void	propagateSetEnabled (bool enabled) override
	Propagates that a widget was enabled or disabled through children.
virtual bool	scrollVisibilityEnabled () const final override
	Returns whether scroll visibility detection is enabled for this widget.
virtual void	setScrollVisibilityEnabled (bool enabled) final override
	Sets whether scroll visibility detection is enabled for this widget.
virtual int	scrollVisibilityMargin () const final override
	Returns the margin around the viewport within which the widget is considered visible.
virtual void	setScrollVisibilityMargin (int margin) final override
	Sets the margin around the viewport within which the widget is considered visible.
virtual Signal< bool > &	scrollVisibilityChanged () final override
	Signal triggered when the scroll visibility of this widget changes.
virtual bool	isScrollVisible () const final override
	Returns whether this widget is currently considered scroll visible.
virtual void	setThemeStyleEnabled (bool enabled) final override
	Sets whether theme styling for a widget is enabled or disabled.
virtual bool	isThemeStyleEnabled () const final override
	Returns whether this widget is currently styled by the chosen theme.
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.
void	setFocus ()
	Sets focus.
virtual void	setFocus (bool focus)=0
	Sets focus.
Public Member Functions inherited from Wt::WWidget
virtual	~WWidget ()
	Destructor.
WWidget *	parent () const
	Returns the parent widget.
template<typename Widget >
std::unique_ptr< Widget >	removeWidget (Widget *widget)
	Removes a child widget.
std::unique_ptr< WWidget >	removeFromParent ()
	Removes the widget from its parent.
void	setWidth (const WLength &width)
	Sets the width.
void	setHeight (const WLength &height)
	Sets the height.
virtual void	positionAt (const WWidget *widget, Orientation orientation=Orientation::Vertical)
	Positions a widget next to another widget.
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.
void	setFocus ()
	Sets focus.
virtual void	acceptDrops (const std::string &mimeType, const WString &hoverStyleClass=WString())
	Sets a mime type to be accepted for dropping.
virtual void	stopAcceptDrops (const std::string &mimeType)
	Indicates that a mime type is no longer accepted for dropping.
virtual void	htmlText (std::ostream &out)
	Streams the (X)HTML representation.
bool	isRendered () const
	Returns whether the widget is rendered.
void	hide ()
	Hides the widget.
void	animateHide (const WAnimation &animation)
	Hides the widget using an animation.
void	show ()
	Shows the widget.
void	animateShow (const WAnimation &animation)
	Shows the widget using an animation.
void	enable ()
	Enables the widget.
void	disable ()
	Disable thes widget.
bool	layoutSizeAware () const
	Returns whether the widget is layout size aware.
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.
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.
void	resetLearnedSlots ()
	Resets learned stateless slot implementations.
template<class T >
void	resetLearnedSlot (void(T::*method)())
	Resets a learned stateless slot implementation.
template<class T >
WStatelessSlot *	implementStateless (void(T::*method)())
	Declares a slot to be stateless and learn client-side behaviour on first invocation.
template<class T >
WStatelessSlot *	implementStateless (void(T::*method)(), void(T::*undoMethod)())
	Declares a slot to be stateless and learn client-side behaviour in advance.
void	isNotStateless ()
	Marks the current function as not stateless.
template<class T >
WStatelessSlot *	implementJavaScript (void(T::*method)(), const std::string &jsCode)
	Provides a JavaScript implementation for a method.
Public Member Functions inherited from Wt::Core::observable
	observable () noexcept
	Default constructor.
virtual	~observable ()
	Destructor.
template<typename... Args, typename C >
auto	bindSafe (void(C::*method)(Args...)) noexcept
	Protects a method call against object destruction.
template<typename... Args, typename C >
auto	bindSafe (void(C::*method)(Args...) const) const noexcept
	Protects a const method call against object destruction.
template<typename Function >
auto	bindSafe (const Function &function) noexcept
	Protects a function against object destruction.

Static Public Attributes
static const ::int64_t	Infinite = std::numeric_limits< ::int64_t >::max()
	Special value for imageWidth or imageHeight.

Protected Member Functions
virtual std::unique_ptr< WImage >	createImage (::int64_t x, ::int64_t y, int width, int height)
	Creates a grid image for the given rectangle.
virtual std::unique_ptr< WResource >	render (::int64_t x, ::int64_t y, int width, int height)
	Render a grid image for the given rectangle.
virtual void	render (WFlags< RenderFlag > flags) override
	Renders the widget.
Protected Member Functions inherited from Wt::WCompositeWidget
virtual void	enableAjax () override
	Progresses to an Ajax-enabled widget.
void	setImplementation (std::unique_ptr< WWidget > widget)
	Set the implementation widget.
template<typename Widget >
Widget *	setImplementation (std::unique_ptr< Widget > widget)
	Sets the implementation widget, returning a raw pointer.
template<typename W , typename... Args>
W *	setNewImplementation (Args &&... args)
	Creates the implementation widget and sets it, returning a raw pointer.
WWidget *	implementation ()
	Get the implementation widget.
virtual int	boxPadding (Orientation orientation) const override
	Returns the widget's built-in padding.
virtual int	boxBorder (Orientation orientation) const override
	Returns the widget's built-in border width.
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.
virtual void	layoutSizeChanged (int width, int height)
	Virtual method that indicates a size change.
	WWidget ()
	Creates a widget.
virtual void	dropEvent (WDropEvent dropEvent)
	Handles a drop event.
void	scheduleRender (WFlags< RepaintFlag > flags=None)
	Schedules rerendering of the widget.
virtual WStatelessSlot *	getStateless (Method method) override
	On-demand stateless slot implementation.

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::WWidget
static WString	tr (const char *key)
	Short hand for WString::tr()

Detailed Description

An abstract widget that shows a viewport to a virtually large image.

WVirtualImage is an abstract class which renders a large image in small pieces. The large image is broken down, and rendered as a grid of smaller square images parts.

The WVirtualImage may provide interactive navigation using the mouse, by reacting to dragging of the mouse on the image.

The WVirtualImage renders pieces in and bordering the current viewport. In this way, provided the individual pieces load sufficiently fast, the user has effectively the impression of scrolling through a single large image, without glitches. Whenever the image is navigated, if necessary, new images are rendered to maintain the border. Images that are too far from the current viewport are pruned away, so that browser memory remains bounded.

To use this class, you must reimplement one of two virtual methods to specify the contents of each grid piece. Either you provide a suitable WImage for every grid piece, or you provide a WResource which renders the contents for a WImage for every grid piece.

The total image dimensions are (0, 0) to (imageWidth, imageHeight) for a finite image, and become unbounded (including negative numbers) for each dimension which is Infinite.

CSS

Styling through CSS is not applicable.

Constructor & Destructor Documentation

WVirtualImage()

Wt::WVirtualImage::WVirtualImage	(	int	viewPortWidth,
		int	viewPortHeight,
		::int64_t	imageWidth,
		::int64_t	imageHeight,
		int	gridImageSize = 256
	)

Creates a viewport for a virtual image.

You must specify the size of the viewport, and the size of the virtual image. The latter dimensions may be the special value Infinite, indicating that in one or more dimensions, the image size is infinite (in practice limited by the maximum integer value).

In addition, you must specify the size of each square grid item. The default is 256 by 256.

Member Function Documentation

createImage()

std::unique_ptr< WImage > Wt::WVirtualImage::createImage ( ::int64_t  x, ::int64_t  y, int  width, int  height  )

protectedvirtual

Creates a grid image for the given rectangle.

Create the image which spans image coordinates with left upper corner (x, y) and given width and height.

Width and height will not necesarilly equal gridImageSize(), if the the image is not infinite sized.

The default implementation calls render() and creates an image for the resource returned.

You should override this method if you wish to serve for example static image content.

See also

render()

currentBottomRightX()

::int64_t Wt::WVirtualImage::currentBottomRightX

(

)

const

Returns the current bottom right X coordinate.

See also

currentBottomRightY()

currentBottomRightY()

::int64_t Wt::WVirtualImage::currentBottomRightY

(

)

const

Returns the current bottom right Y coordinate.

See also

currentBottomRightX()

currentTopLeftX()

::int64_t Wt::WVirtualImage::currentTopLeftX

(

)

const

Returns the current top left X coordinate.

See also

currentTopLeftY()

currentTopLeftY()

::int64_t Wt::WVirtualImage::currentTopLeftY

(

)

const

Returns the current top left Y coordinate.

See also

currentTopLeftX()

enableDragging()

void Wt::WVirtualImage::enableDragging

(

)

Enables mouse dragging to scroll around the image.

The cursor is changed to a 'move' symbol to indicate the interactivity.

gridImageSize()

int Wt::WVirtualImage::gridImageSize

(

)

const

Returns the size of a single piece.

This is the size of a side of the square pieces that is used to render the visible part of the image.

imageHeight()

::int64_t Wt::WVirtualImage::imageHeight

(

)

const

Returns the virtual image height.

See also

imageWidth(), resizeImage()

imageWidth()

::int64_t Wt::WVirtualImage::imageWidth

(

)

const

Returns the virtual image width.

See also

imageHeight(), resizeImage()

redrawAll()

void Wt::WVirtualImage::redrawAll

(

)

Regenerates and redraws the image pieces.

This method invalidates all current grid images, and recreates them.

render() [1/2]

std::unique_ptr< WResource > Wt::WVirtualImage::render ( ::int64_t  x, ::int64_t  y, int  width, int  height  )

protectedvirtual

Render a grid image for the given rectangle.

Returns a resource that streams an image which renders the rectangle which spans image coordinates with left upper corner (x, y) and given width and height.

Width and height will not necesarilly equal to gridImageSize(), if the the image is not infinite sized.

The default implementation throws an Exception. You must reimplement this method unless you reimplement createImage().

See also

createImage()

render() [2/2]

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

overrideprotectedvirtual

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::WCompositeWidget.

resizeImage()

void Wt::WVirtualImage::resizeImage	(	::int64_t	w,
		::int64_t	h
	)

Resizes the virtual image.

This sets a new virtual size for the image. The viewport size sets the visible portion of the image.

See also

imageWidth(), imageHeight()

scroll()

void Wt::WVirtualImage::scroll	(	::int64_t	dx,
		::int64_t	dy
	)

Scrolls the viewport of the image over a distance.

See also

scrollTo()

scrollTo()

void Wt::WVirtualImage::scrollTo	(	::int64_t	x,
		::int64_t	y
	)

Scrolls the viewport of the image to a specific coordinate.

Scroll the viewport so that its top left coordinate becomes (x, y).

See also

scroll()

viewPortChanged()

Signal< ::int64_t, ::int64_t > & Wt::WVirtualImage::viewPortChanged

(

)

Signal emitted whenever the viewport changes.

The viewport can be changed by the user dragging the image or through the API methods scrollTo() and scroll().

viewPortHeight()

int Wt::WVirtualImage::viewPortHeight

(

)

const

Returns the viewport height.

See also

viewPortWidth()

viewPortWidth()

int Wt::WVirtualImage::viewPortWidth

(

)

const

Returns the viewport width.

See also

viewPortHeight()