Wt::WPdfImage Class Reference

A paint device for rendering to a PDF. More...

#include <Wt/WPdfImage.h>

Inheritance diagram for Wt::WPdfImage:

Public Member Functions
	WPdfImage (const WLength &width, const WLength &height)
	Create a PDF resource that represents a single-page PDF document. More...
	WPdfImage (HPDF_Doc pdf, HPDF_Page page, HPDF_REAL x, HPDF_REAL y, HPDF_REAL width, HPDF_REAL height)
	Create a PDF paint device to paint inside an existing page. More...
	~WPdfImage ()
	Destructor.
void	addFontCollection (const std::string &directory, bool recursive=true)
	Adds a font collection. More...
virtual WFlags< PaintDeviceFeatureFlag >	features () const override
	Returns device features.
virtual void	setChanged (WFlags< PainterChangeFlag > flags) override
	Indicates changes in painter state. More...
virtual void	drawArc (const WRectF &rect, double startAngle, double spanAngle) override
	Draws an arc. More...
virtual void	drawImage (const WRectF &rect, const std::string &imgUri, int imgWidth, int imgHeight, const WRectF &sourceRect) override
	Draws an image. More...
virtual void	drawLine (double x1, double y1, double x2, double y2) override
	Draws a line. More...
virtual void	drawRect (const WRectF &rect) override
	Draws a rectangle. More...
virtual void	drawPath (const WPainterPath &path) override
	Draws a path. More...
virtual void	drawText (const WRectF &rect, WFlags< AlignmentFlag > alignmentFlags, TextFlag textFlag, const WString &text, const WPointF *clipPoint) override
	Draws text. More...
virtual WTextItem	measureText (const WString &text, double maxWidth=-1, bool wordWrap=false) override
	Measures rendered text size. More...
virtual WFontMetrics	fontMetrics () override
	Returns font metrics. More...
virtual void	init () override
	Initializes the device for painting. More...
virtual void	done () override
	Finishes painting on the device. More...
virtual bool	paintActive () const override
	Returns whether painting is active. More...
virtual WLength	width () const override
	Returns the device width. More...
virtual WLength	height () const override
	Returns the device height. More...
virtual void	handleRequest (const Http::Request &request, Http::Response &response) override
	Handles a request. More...
Public Member Functions inherited from Wt::WResource
	WResource ()
	Creates a new resource.
	~WResource ()
	Destroys the resource. More...
void	suggestFileName (const Wt::WString &name, ContentDisposition disposition=ContentDisposition::Attachment)
	Suggests a filename to the user for the data streamed by this resource. More...
const Wt::WString &	suggestedFileName () const
	Returns the suggested file name. More...
void	setDispositionType (ContentDisposition cd)
	Configures the Content-Disposition header. More...
ContentDisposition	dispositionType () const
	Returns the currently configured content disposition. More...
void	setChanged ()
	Generates a new URL for this resource and emits the changed signal. More...
void	setInvalidAfterChanged (bool enabled)
	Return "page not found" for prior resource URLs after change. More...
bool	invalidAfterChanged () const
	Should "page not found" be returned for outdated resource URLs. More...
void	setInternalPath (const std::string &path)
	Sets an internal path for this resource. More...
std::string	internalPath () const
	Returns the internal path. More...
const std::string &	generateUrl ()
	Generates an URL for this resource. More...
const std::string &	url () const
	Returns the current URL for this resource. More...
Signal &	dataChanged ()
	Signal emitted when the data presented in this resource has changed. More...
void	setUploadProgress (bool enabled)
	Indicate interest in upload progress. More...
Signal< ::uint64_t, ::uint64_t > &	dataReceived ()
	Signal emitted when data has been received for this resource. More...
void	write (std::ostream &out, const Http::ParameterMap &parameters=Http::ParameterMap(), const Http::UploadedFileMap &files=Http::UploadedFileMap())
	Stream the resource to a stream. More...
virtual void	handleAbort (const Http::Request &request)
	Handles a continued request being aborted. More...
void	haveMoreData ()
	Indicate that more data is available. More...
void	setTakesUpdateLock (bool enabled)
	Set whether this resource takes the WApplication's update lock. More...
bool	takesUpdateLock () const
	Returns whether this resources takes the WApplication's update lock. 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 const std::string	id () const
	Returns the (unique) identifier for this object. 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...
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...
Public Member Functions inherited from Wt::WPaintDevice
virtual	~WPaintDevice ()
	Destructor. More...

Protected Member Functions
virtual WPainter *	painter () const override
	Returns the painter that is currently painting on the device. More...
virtual void	setPainter (WPainter *painter) override
	Sets the painter.
Protected Member Functions inherited from Wt::WResource
void	beingDeleted ()
	Prepares the resource for deletion. More...
Protected Member Functions inherited from Wt::WObject
virtual WStatelessSlot *	getStateless (Method method)
	On-demand stateless slot implementation. More...

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

Detailed Description

A paint device for rendering to a PDF.

A WPdfImage paint device should be used in conjunction with a WPainter, and can be used to make a PDF version of a WPaintedWidget's contents.

The PDF is generated using The Haru Free PDF Library, and this class is included in the library only if libharu was found during the build of the library.

You can use the image as a resource and specialize handleRequest() to paint the contents on the fly. Alternatively can also use write() to serialize to a PDF file (std::ostream). The latter usage is illustrated by the code below:

 Wt::Chart::WCartesianChart
*chart = ...
 
Wt::WPdfImage pdfImage("4cm", "3cm");
{
  Wt::WPainter p(&pdfImage);
  chart->paint(p);
}
std::ofstream f("chart.pdf", std::ios::out | std::ios::binary);
pdfImage.write(f);

A constructor is provided which allows the generated PDF image to be embedded directly into a page of a larger libharu document, and this approach is used for example by the WPdfRenderer to render XHTML to multi-page PDF files.

Font information is embedded in the PDF. Fonts supported are native PostScript fonts (Base-14) (only ASCII-7), or true type fonts (Unicode). See addFontCollection() for more information on how fonts are located and matched to WFont descriptions.

This paint device has the following limitations:

• images (WPainter::drawImage()) can only be included from local files, and only JPG and PNG images are supported.
• drop shadows are not supported.

Constructor & Destructor Documentation

WPdfImage() [1/2]

Wt::WPdfImage::WPdfImage	(	const WLength &	width,
		const WLength &	height
	)

Create a PDF resource that represents a single-page PDF document.

The single page will have a size width x height. The PDF will be using the same DPI (72dpi) as is conventionally used for the desktop.

The passed width and height (such as 4 cm by 3 cm) can be specified in physical units (e.g. 4cm x 3cm), but this will be converted to pixels using the default DPI used in CSS (96dpi) !

See also

write()

WPdfImage() [2/2]

Wt::WPdfImage::WPdfImage	(	HPDF_Doc	pdf,
		HPDF_Page	page,
		HPDF_REAL	x,
		HPDF_REAL	y,
		HPDF_REAL	width,
		HPDF_REAL	height
	)

Create a PDF paint device to paint inside an existing page.

The image will be drawn in the existing page, as an image with lower-left point (x, y) and size (width x height).

Member Function Documentation

addFontCollection()

void Wt::WPdfImage::addFontCollection	(	const std::string &	directory,
		bool	recursive = true
	)

Adds a font collection.

If Wt has been configured to use libpango, then font matching and character selection is done by libpango, which is seeded with information on installed fonts by fontconfig. In that case, invocations for this method is ignored. Only TrueType fonts are supported.

As of Wt 3.3.7, only TrueType fonts will be selected by default. Prior to Wt 3.3.7, you needed to configure fontconfig (which is used by pango) to only return TrueType fonts. This can be done using a fonts.conf configuration file:

<?xml version='1.0'?>
<!DOCTYPE fontconfig SYSTEM 'fonts.dtd'>
<fontconfig>
  <selectfont>
    <rejectfont>
      <glob>*.pfb</glob>
    </rejectfont>
  </selectfont>
</fontconfig>

You may need to add more glob patterns to exclude other fonts than TrueType, and also to exclude TrueType fonts which do not work properly with libharu.

If Wt has not been configured to use libpango, then this method may be used to indicate the location of TrueType fonts. The main drawback compared to libpango is that font selection is not steered by the need for particular characters, i.e. font selection is independent from the text's need for specific characters. Most TrueType fonts provide only partial unicode support. The provided directory will be searched for fonts (currently only TrueType ".ttf" or ".ttc" fonts). TrueType fonts are preferable over Base-14 fonts (which are PDF's default fonts) since they provide partial (or complete) unicode support.

When using Base-14 fonts, WString::narrow() will be called on text which may result in loss of information.

done()

void Wt::WPdfImage::done ( )

overridevirtual

Finishes painting on the device.

This method is called when a WPainter stopped painting.

See also

WPainter::end()

Implements Wt::WPaintDevice.

drawArc()

void Wt::WPdfImage::drawArc ( const WRectF &  rect, double  startAngle, double  spanAngle  )

overridevirtual

Draws an arc.

The arc describes the segment of an ellipse enclosed by the rect. The segment starts at startAngle, and spans an angle given by spanAngle. These angles have as unit degree, and are measured counter-clockwise starting from the 3 o'clock position.

The arc must be stroked, filled, and transformed using the current painter settings.

Implements Wt::WPaintDevice.

drawImage()

void Wt::WPdfImage::drawImage ( const WRectF &  rect, const std::string &  imageUri, int  imgWidth, int  imgHeight, const WRectF &  sourceRect  )

overridevirtual

Draws an image.

Draws sourceRect from the image with URL imageUri and original dimensions imgWidth and imgHeight to the location, into the rectangle defined by rect.

The image is transformed using the current painter settings.

Implements Wt::WPaintDevice.

drawLine()

void Wt::WPdfImage::drawLine ( double  x1, double  y1, double  x2, double  y2  )

overridevirtual

Draws a line.

The line must be stroked and transformed using the current painter settings.

Implements Wt::WPaintDevice.

drawPath()

void Wt::WPdfImage::drawPath ( const WPainterPath &  path )

overridevirtual

Draws a path.

The path must be stroked, filled, and transformed using the current painter settings.

Implements Wt::WPaintDevice.

drawRect()

void Wt::WPdfImage::drawRect ( const WRectF &  rectangle )

overridevirtual

Draws a rectangle.

The rect must be stroked, filled, and transformed using the current painter settings.

Implements Wt::WPaintDevice.

drawText()

void Wt::WPdfImage::drawText ( const WRectF &  rect, WFlags< AlignmentFlag >  alignmentFlags, TextFlag  textFlag, const WString &  text, const WPointF *  clipPoint  )

overridevirtual

Draws text.

The text must be rendered, stroked and transformed using the current painter settings.

If clipPoint is not null, a check is performed whether the point is inside of the current clip area. If not, the text is not drawn.

Implements Wt::WPaintDevice.

fontMetrics()

WFontMetrics Wt::WPdfImage::fontMetrics ( )

overridevirtual

Returns font metrics.

This returns font metrics for the current font.

Throws a std::logic_error if the underlying device does not provide font metrics.

Implements Wt::WPaintDevice.

handleRequest()

void Wt::WPdfImage::handleRequest ( const Http::Request &  request, Http::Response &  response  )

overridevirtual

Handles a request.

Reimplement this method so that a proper response is generated for the given request. From the request object you can access request parameters and whether the request is a continuation request. In the response object, you should set the mime type and stream the output data.

A request may also concern a continuation, indicated in Http::Request::continuation(), in which case the next part for a previously created continuation should be served.

While handling a request, which may happen at any time together with event handling, the library makes sure that the resource is not being concurrently deleted, but multiple requests may happend simultaneously for a single resource.

Implements Wt::WResource.

height()

virtual WLength Wt::WPdfImage::height ( ) const

overridevirtual

Returns the device height.

The device height, in pixels, establishes the height of the device coordinate system.

Implements Wt::WPaintDevice.

init()

void Wt::WPdfImage::init ( )

overridevirtual

Initializes the device for painting.

This method is called when a WPainter starts painting.

See also

WPainter::begin(WPaintDevice *), painter()

Implements Wt::WPaintDevice.

measureText()

WTextItem Wt::WPdfImage::measureText ( const WString &  text, double  maxWidth = -1, bool  wordWrap = false  )

overridevirtual

Measures rendered text size.

Returns the bounding rect of the given text when rendered using the current font.

If maxWidth != -1, then the text is truncated to fit in the width.

If wordWrap = true then text is truncated only at word boundaries. Note that in this case the whitespace at the truncated position is included in the text but not accounted for by the returned width (since usually you will not render the whitespace at the end of a line).

Throws a std::logic_error if the underlying device does not provide font metrics.

Implements Wt::WPaintDevice.

paintActive()

virtual bool Wt::WPdfImage::paintActive ( ) const

overridevirtual

Returns whether painting is active.

See also

init(), painter()

Implements Wt::WPaintDevice.

painter()

virtual WPainter* Wt::WPdfImage::painter ( ) const

overrideprotectedvirtual

Returns the painter that is currently painting on the device.

See also

init()

Implements Wt::WPaintDevice.

setChanged()

void Wt::WPdfImage::setChanged ( WFlags< PainterChangeFlag >  flags )

overridevirtual

Indicates changes in painter state.

The flags argument is the logical OR of one or more change flags.

See also

ChangeFlag

Implements Wt::WPaintDevice.

width()

virtual WLength Wt::WPdfImage::width ( ) const

overridevirtual

Returns the device width.

The device width, in pixels, establishes the width of the device coordinate system.

Implements Wt::WPaintDevice.