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Wt::WPaintDevice Class Referenceabstract

The abstract base class for a paint device. More...

#include <Wt/WPaintDevice>

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

Public Types

enum  ChangeFlag {
  Pen = 0x1, Brush = 0x2, Font = 0x4, Hints = 0x8,
  Transform = 0x10, Clipping = 0x20, Shadow = 0x40
}
 Enumeration to communicate painter state changes. More...
 
enum  FeatureFlag { CanWordWrap = 0x1, HasFontMetrics = 0x2 }
 Enumeration to indicate paint device features. More...
 

Public Member Functions

virtual ~WPaintDevice ()
 Destructor. More...
 
virtual WFlags< FeatureFlagfeatures () const =0
 Returns device features.
 
virtual WLength width () const =0
 Returns the device width. More...
 
virtual WLength height () const =0
 Returns the device height. More...
 
virtual void setChanged (WFlags< ChangeFlag > flags)=0
 Indicates changes in painter state. More...
 
virtual void drawArc (const WRectF &rect, double startAngle, double spanAngle)=0
 Draws an arc. More...
 
virtual void drawImage (const WRectF &rect, const std::string &imageUri, int imgWidth, int imgHeight, const WRectF &sourceRect)=0
 Draws an image. More...
 
virtual void drawLine (double x1, double y1, double x2, double y2)=0
 Draws a line. More...
 
virtual void drawPath (const WPainterPath &path)=0
 Draws a path. More...
 
virtual void drawText (const WRectF &rect, WFlags< AlignmentFlag > alignmentFlags, TextFlag textFlag, const WString &text)=0
 Draws text. More...
 
virtual WTextItem measureText (const WString &text, double maxWidth=-1, bool wordWrap=false)=0
 Measures rendered text size. More...
 
virtual WFontMetrics fontMetrics ()=0
 Returns font metrics. More...
 
virtual void init ()=0
 Initializes the device for painting. More...
 
virtual void done ()=0
 Finishes painting on the device. More...
 
virtual bool paintActive () const =0
 Returns whether painting is active. More...
 

Protected Member Functions

virtual WPainterpainter () const =0
 Returns the painter that is currently painting on the device. More...
 
virtual void setPainter (WPainter *painter)=0
 Sets the painter.
 

Detailed Description

The abstract base class for a paint device.

A WPaintDevice is a device on which may be painted using a WPainter. You should never paint directly on a paint device.

The device defines the size of the drawing area, using width() and height(). These dimensions must be defined in pixel units. In the future, additional information will be included to convert these pixel units to lengths (using DPI information).

You should reimplement this class if you wish to extend the Wt paint system to paint on other devices than the ones provided by the library.

Note: this interface is subject to changes to increase optimization possibilities for the painting using different devices.

See Also
WPainter

Member Enumeration Documentation

Enumeration to communicate painter state changes.

See Also
setChanged(WFlags<ChangeFlag>)
Enumerator
Pen 

Properties of the pen have changed.

Brush 

Properties of the brush have changed.

Font 

Properties of the font have changed.

Hints 

Some render hints have changed.

Transform 

The transformation has changed.

Clipping 

The clipping has changed.

Shadow 

Properties of the shadow have changed.

Enumeration to indicate paint device features.

See Also
features()
Enumerator
CanWordWrap 

Implements drawText() with Wt::TextWordWrap.

HasFontMetrics 

Implements fontMetrics() and measureText()

Constructor & Destructor Documentation

Wt::WPaintDevice::~WPaintDevice ( )
virtual

Destructor.

Frees all resources associated with this device.

Member Function Documentation

virtual void Wt::WPaintDevice::done ( )
pure virtual

Finishes painting on the device.

This method is called when a WPainter stopped painting.

See Also
WPainter::end()

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual void Wt::WPaintDevice::drawArc ( const WRectF rect,
double  startAngle,
double  spanAngle 
)
pure virtual

Draws an arc.

The arc is defined as in WPainter::drawArc(const WRectF& rectangle, int startAngle, int spanAngle)

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

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

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

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.

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual void Wt::WPaintDevice::drawLine ( double  x1,
double  y1,
double  x2,
double  y2 
)
pure virtual

Draws a line.

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

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual void Wt::WPaintDevice::drawPath ( const WPainterPath path)
pure virtual

Draws a path.

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

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual void Wt::WPaintDevice::drawText ( const WRectF rect,
WFlags< AlignmentFlag alignmentFlags,
TextFlag  textFlag,
const WString text 
)
pure virtual

Draws text.

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

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual WFontMetrics Wt::WPaintDevice::fontMetrics ( )
pure virtual

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.

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual WLength Wt::WPaintDevice::height ( ) const
pure virtual

Returns the device height.

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

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual void Wt::WPaintDevice::init ( )
pure virtual

Initializes the device for painting.

This method is called when a WPainter starts painting.

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

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual WTextItem Wt::WPaintDevice::measureText ( const WString text,
double  maxWidth = -1,
bool  wordWrap = false 
)
pure virtual

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.

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual bool Wt::WPaintDevice::paintActive ( ) const
pure virtual

Returns whether painting is active.

See Also
init(), painter()

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual WPainter* Wt::WPaintDevice::painter ( ) const
protectedpure virtual

Returns the painter that is currently painting on the device.

See Also
init()

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.

virtual void Wt::WPaintDevice::setChanged ( WFlags< ChangeFlag flags)
pure virtual

Indicates changes in painter state.

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

See Also
ChangeFlag

Implemented in Wt::WPdfImage, Wt::WRasterImage, and Wt::WVmlImage.

virtual WLength Wt::WPaintDevice::width ( ) const
pure virtual

Returns the device width.

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

Implemented in Wt::WPdfImage, Wt::WRasterImage, Wt::WSvgImage, Wt::WCanvasPaintDevice, and Wt::WVmlImage.


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