Provides a container for painting operations, enabling arbitrary graphical shapes to be constructed and reused. More...

#include <Path2D.hpp>

Inheritance diagram for CDPL::Vis::Path2D:

Public Types
enum	FillRule { EVEN_ODD , WINDING }
	Specifies which method to use for filling closed shapes described by the `Path2D` object. More...

Public Member Functions
	Path2D ()
	Constructs an empty `Path2D` instance. More...

	Path2D (const Path2D &path)
	Constructs a copy of the `Path2D` instance path. More...

virtual	~Path2D ()
	Virtual destructor. More...

bool	isEmpty () const
	Tells whether the `Path2D` instance does not contain any elements. More...

bool	hasDrawingElements () const
	Tells whether the `Path2D` instance contains any elements representing drawing operations (lines and arcs). More...

void	clear ()
	Deletes all path elements added so far and sets the fill rule to its default. More...

void	setFillRule (FillRule rule)
	Sets the fill rule of the path to the specified value. More...

FillRule	getFillRule () const
	Returns the currently set fill rule. More...

void	moveTo (double x, double y)
	Sets the current position to (x, y) and starts a new subpath, implicitly closing the previous path. More...

void	moveTo (const Math::Vector2D &pos)
	Sets the current position to pos and starts a new subpath, implicitly closing the previous path. More...

void	arc (double cx, double cy, double rx, double ry, double start_ang, double sweep)
	Creates an elliptical arc centered at (cx, cy) with ellipse radii rx and ry beginning at the angle start_ang and extending sweep degrees clockwise. More...

void	arc (const Math::Vector2D &ctr, double rx, double ry, double start_ang, double sweep)
	Creates an elliptical arc centered at ctr with ellipse radii rx and ry beginning at the angle start_ang and extending sweep degrees clockwise. More...

void	arcTo (double cx, double cy, double rx, double ry, double start_ang, double sweep)
	Creates an elliptical arc centered at (cx, cy) with ellipse radii rx and ry beginning at the angle start_ang and extending sweep degrees clockwise. More...

void	arcTo (const Math::Vector2D &ctr, double rx, double ry, double start_ang, double sweep)
	Creates an elliptical arc centered at ctr with ellipse radii rx and ry beginning at the angle start_ang and extending sweep degrees clockwise. More...

void	lineTo (double x, double y)
	Adds a straight line from the current position to the point (x, y). More...

void	lineTo (const Math::Vector2D &pos)
	Adds a straight line from the current position to the point (x, y). More...

void	closePath ()
	Closes the current subpath by drawing a line to the beginning of the subpath, automatically starting a new path. More...

void	addEllipse (double x, double y, double width, double height)
	Creates an ellipse positioned at (x, y) with the specified width and height, and adds it to this path as a closed subpath. More...

void	addEllipse (const Math::Vector2D &pos, double width, double height)
	Creates an ellipse positioned at pos with the specified width and height, and adds it to this path as a closed subpath. More...

void	addRectangle (double x, double y, double width, double height)
	Creates a rectangle positioned at (x, y) with the specified width and height, and adds it to this path as a closed subpath. More...

void	addRectangle (const Math::Vector2D &pos, double width, double height)
	Creates a rectangle positioned at pos with the specified width and height, and adds it to this path as a closed subpath. More...

void	getBounds (Rectangle2D &bounds) const
	Calculates the axis-aligned bounding box of the path. More...

void	convert (Path2DConverter &conv) const
	Iterates over the stored path elements and calls the corresponding method of conv for each visited element. More...

bool	operator== (const Path2D &path) const
	Equality comparison operator. More...

bool	operator!= (const Path2D &path) const
	Non-equality comparison operator. More...

Path2D &	operator+= (const Path2D &path)
	Appends the elements stored in the `Path2D` instance path to this path. More...

Path2D &	operator= (const Path2D &path)
	Assignment operator. More...

Detailed Description

Provides a container for painting operations, enabling arbitrary graphical shapes to be constructed and reused.

A path consits of a number of graphical building blocks, such as rectangles, ellipses, lines and arcs. Building blocks can be joined to form closed subpaths, for example a rounded rectangle, or they can exist independently as unclosed subpaths, such as lines and curves. A closed path has coinciding start and end points.

Path2D objects can be used for filling, outlining, and clipping. The main advantage over a sequence of basic drawing operations is that complex shapes need to be created only once and can be stored for repeated later uses.

A Path2D object can be constructed as an empty path, or as a copy of another Path2D instance. Once created, lines and curves can be added to the path using the lineTo(), arcTo() and arc() functions. The lines and curves stretch from the current position to the position passed as argument. The current position is always the end point of the last drawing operation. Use the moveTo() method to move the current position without adding a component. The moveTo() method implicitly starts a new subpath, and closes the previous one. Another way of starting a new subpath is to call the closePath() method which closes the current path by adding a line from the current position back to the path's start position. The Path2D class also provides convenience methods for the generation of common shapes: addEllipse() and addRectangle(). The generation of these shapes is implemented by executing a sequence of appropriate moveTo(), lineTo() and arcTo() calls. The axis-aligned bounding box of a path constructed in this way can be calculated by the method getBounds().

Whether or not a Path2D object contains any elements can be queried by the method isEmpty(). Whether the path also features visual elements (lines and arcs) can be queried by the method hasDrawingElements(). The method clear() deletes all elements added so far and sets the default fill rule (see setFillRule() and getFillRule()).

Elements added to a Path2D object cannot inspected directly. For path analysis and rendering the method convert() is available which calls element type specific methods on a provided instance of a class implementing the Vis::Path2DConverter interface.

Since: 1.1

Member Enumeration Documentation

◆ FillRule

enum CDPL::Vis::Path2D::FillRule

Specifies which method to use for filling closed shapes described by the Path2D object.

Enumerator

EVEN_ODD

Specifies that the path has to be filled using the odd even fill rule.

With this rule, the question whether a point is inside the shape can be answered by the following method: Draw a horizontal line from the point to a location outside the shape, and count the number of intersections. If the number of intersections is an odd number, the point is inside the shape.

WINDING

Specifies that the path has to be filled using the non-zero winding rule.

With this rule, the question whether a point is inside the shape can be answered by the following method: Draw a horizontal line from the point to a location outside the shape. Determine whether the direction of the line at each intersection point is up or down. The winding number is determined by summing the direction of each intersection. If the number is non-zero, the point is inside the shape.

Constructor & Destructor Documentation

◆ Path2D() [1/2]

CDPL::Vis::Path2D::Path2D ( )

Constructs an empty Path2D instance.

◆ Path2D() [2/2]

CDPL::Vis::Path2D::Path2D ( const Path2D & path )

Constructs a copy of the Path2D instance path.

Parameters

path	The `Path2D` instance to copy.

◆ ~Path2D()

virtual CDPL::Vis::Path2D::~Path2D ( )

virtual

Virtual destructor.

Member Function Documentation

◆ isEmpty()

bool CDPL::Vis::Path2D::isEmpty ( ) const

Tells whether the Path2D instance does not contain any elements.

Returns: true is no elements have been added to the Path2D instance so far, and false otherwise.

◆ hasDrawingElements()

bool CDPL::Vis::Path2D::hasDrawingElements ( ) const

Tells whether the Path2D instance contains any elements representing drawing operations (lines and arcs).

Returns: true if the Path2D instance contains any visual elements, and false otherwise.

◆ clear()

void CDPL::Vis::Path2D::clear ( )

Deletes all path elements added so far and sets the fill rule to its default.

See also: setFillRule()

◆ setFillRule()

void CDPL::Vis::Path2D::setFillRule ( FillRule rule )

Sets the fill rule of the path to the specified value.

Parameters

rule	The new fill rule.

Note: The default fill rule is Path2D::EVEN_ODD.

◆ getFillRule()

FillRule CDPL::Vis::Path2D::getFillRule ( ) const

Returns the currently set fill rule.

Returns: The currently set fill rule.

◆ moveTo() [1/2]

void CDPL::Vis::Path2D::moveTo	(	double	x,
		double	y
	)

Sets the current position to (x, y) and starts a new subpath, implicitly closing the previous path.

Parameters

x	Specifies the x-coordinate of the new position.
y	Specifies the y-coordinate of the new position.

◆ moveTo() [2/2]

void CDPL::Vis::Path2D::moveTo ( const Math::Vector2D & pos )

Sets the current position to pos and starts a new subpath, implicitly closing the previous path.

Parameters

pos	A 2D vector specifying the new position.

◆ arc() [1/2]

void CDPL::Vis::Path2D::arc	(	double	cx,
		double	cy,
		double	rx,
		double	ry,
		double	start_ang,
		double	sweep
	)

Creates an elliptical arc centered at (cx, cy) with ellipse radii rx and ry beginning at the angle start_ang and extending sweep degrees clockwise.

Angles are specified in degrees. Counter-clockwise arcs can be specified using negative angles. After the arc has been added, the current position is the end point of the arc. To draw a line back to the first point, use the closePath() method.

Parameters

cx	The x-coordinate of the ellipse center.
cy	The y-coordinate of the ellipse center.
rx	The x-radius of the ellipse.
ry	The y-radius of the ellipse.
start_ang	The start angle of the arg in degrees.
sweep	The length of the arg in degrees.

Note: The method first performs a moveTo() call with the starting point of the arc as argument and thus avoids an implicit line being drawn from the current position to the arc's starting position (see arcTo()).

◆ arc() [2/2]

void CDPL::Vis::Path2D::arc	(	const Math::Vector2D &	ctr,
		double	rx,
		double	ry,
		double	start_ang,
		double	sweep
	)

Creates an elliptical arc centered at ctr with ellipse radii rx and ry beginning at the angle start_ang and extending sweep degrees clockwise.

Angles are specified in degrees. Counter-clockwise arcs can be specified using negative angles. After the arc has been added, the current position is the end point of the arc. To draw a line back to the first point, use the closePath() method.

Parameters

ctr	A 2D vector specifying the ellipse center.
rx	The x-radius of the ellipse.
ry	The y-radius of the ellipse.
start_ang	The start angle of the arg in degrees.
sweep	The length of the arg in degrees.

Note: The method first performs a moveTo() call with the starting point of the arc as argument and thus avoids an implicit line being drawn from the current position to the arc's starting position (see arcTo()).

◆ arcTo() [1/2]

void CDPL::Vis::Path2D::arcTo	(	double	cx,
		double	cy,
		double	rx,
		double	ry,
		double	start_ang,
		double	sweep
	)

Creates an elliptical arc centered at (cx, cy) with ellipse radii rx and ry beginning at the angle start_ang and extending sweep degrees clockwise.

Angles are specified in degrees. Counter-clockwise arcs can be specified using negative angles. After the arc has been added, the current position is the end point of the arc. To draw a line back to the first point, use the closePath() method.

Parameters

cx	The x-coordinate of the ellipse center.
cy	The y-coordinate of the ellipse center.
rx	The x-radius of the ellipse.
ry	The y-radius of the ellipse.
start_ang	The start angle of the arg in degrees.
sweep	The length of the arg in degrees.

Note: The method implicitly connects the starting point of the arc to the current position if they are not already connected. The rendering result is undefined if no subpath starting point has been specified (see moveTo())!

◆ arcTo() [2/2]

void CDPL::Vis::Path2D::arcTo	(	const Math::Vector2D &	ctr,
		double	rx,
		double	ry,
		double	start_ang,
		double	sweep
	)

Creates an elliptical arc centered at ctr with ellipse radii rx and ry beginning at the angle start_ang and extending sweep degrees clockwise.

Angles are specified in degrees. Counter-clockwise arcs can be specified using negative angles. After the arc has been added, the current position is the end point of the arc. To draw a line back to the first point, use the closePath() method.

Parameters

ctr	A 2D vector specifying the ellipse center.
rx	The x-radius of the ellipse.
ry	The y-radius of the ellipse.
start_ang	The start angle of the arg in degrees.
sweep	The length of the arg in degrees.

Note: The method implicitly connects the starting point of the arc to the current position if they are not already connected. The rendering result is undefined if no subpath starting point has been specified (see moveTo())!

◆ lineTo() [1/2]

void CDPL::Vis::Path2D::lineTo	(	double	x,
		double	y
	)

Adds a straight line from the current position to the point (x, y).

After the line is drawn, the current position is updated to be at the end point of the line.

Parameters

x	Specifies the x-coordinate of the line's end point.
y	Specifies the y-coordinate of the line's end point.

Note: The rendering result is undefined if no subpath starting point has been specified (see moveTo())!

◆ lineTo() [2/2]

void CDPL::Vis::Path2D::lineTo ( const Math::Vector2D & pos )

Adds a straight line from the current position to the point (x, y).

After the line is drawn, the current position is updated to be at the end point of the line.

Parameters

pos	A 2D vector specifying the line end point.

Note: The rendering result is undefined if no subpath starting point has been specified (see moveTo())!

◆ closePath()

void CDPL::Vis::Path2D::closePath ( )

Closes the current subpath by drawing a line to the beginning of the subpath, automatically starting a new path.

A call to this methods has no effect if the current subpath does not contain any elements.

Note: After closing the subpath the current point is undefined!

◆ addEllipse() [1/2]

void CDPL::Vis::Path2D::addEllipse	(	double	x,
		double	y,
		double	width,
		double	height
	)

Creates an ellipse positioned at (x, y) with the specified width and height, and adds it to this path as a closed subpath.

Parameters

x	The x-coordinate of the ellipse center.
y	The y-coordinate of the ellipse center.
width	The width of the ellipse.
height	The height of the ellipse.

◆ addEllipse() [2/2]

void CDPL::Vis::Path2D::addEllipse	(	const Math::Vector2D &	pos,
		double	width,
		double	height
	)

Creates an ellipse positioned at pos with the specified width and height, and adds it to this path as a closed subpath.

Parameters

pos	A 2D vector specifying the ellipse center.
width	The width of the ellipse.
height	The height of the ellipse.

◆ addRectangle() [1/2]

void CDPL::Vis::Path2D::addRectangle	(	double	x,
		double	y,
		double	width,
		double	height
	)

Creates a rectangle positioned at (x, y) with the specified width and height, and adds it to this path as a closed subpath.

Parameters

x	The x-coordinate of the top-left corner.
y	The y-coordinate of the top-left corner.
width	The width of the rectangle.
height	The height of the rectangle.

◆ addRectangle() [2/2]

void CDPL::Vis::Path2D::addRectangle	(	const Math::Vector2D &	pos,
		double	width,
		double	height
	)

Creates a rectangle positioned at pos with the specified width and height, and adds it to this path as a closed subpath.

Parameters

pos	A 2D vector specifying the top-left corner.
width	The width of the rectangle.
height	The height of the rectangle.

◆ getBounds()

void CDPL::Vis::Path2D::getBounds ( Rectangle2D & bounds ) const

Calculates the axis-aligned bounding box of the path.

Parameters

bounds The Vis::Rectangle2D instance storing the calculated bounding box.

◆ convert()

void CDPL::Vis::Path2D::convert ( Path2DConverter & conv ) const

Iterates over the stored path elements and calls the corresponding method of conv for each visited element.

Parameters

conv	An instance of a class implementing the Vis::Path2DConverter interface.

◆ operator==()

bool CDPL::Vis::Path2D::operator== ( const Path2D & path ) const

Equality comparison operator.

Parameters

path	The `Path2D` instance to compare with.

Returns: true if this path is equal to path, and false otherwise.

◆ operator!=()

bool CDPL::Vis::Path2D::operator!= ( const Path2D & path ) const

Non-equality comparison operator.

Parameters

path	The `Path2D` instance to compare with.

Returns: true if this path is not equal to path, and false otherwise.

◆ operator+=()

Path2D& CDPL::Vis::Path2D::operator+= ( const Path2D & path )

Appends the elements stored in the Path2D instance path to this path.

Parameters

path	The `Path2D` instance providing the elements to append.

Returns: A reference to itself.

◆ operator=()

Path2D& CDPL::Vis::Path2D::operator= ( const Path2D & path )

Assignment operator.

Parameters

path	The `Path2D` instance to copy.

Returns: A reference to itself.

The documentation for this class was generated from the following file:

Path2D.hpp

Public Types

Public Member Functions

Detailed Description

Member Enumeration Documentation

◆ FillRule

Constructor & Destructor Documentation

◆ Path2D() [1/2]

◆ Path2D() [2/2]

◆ ~Path2D()

Member Function Documentation

◆ isEmpty()

◆ hasDrawingElements()

◆ clear()

◆ setFillRule()

◆ getFillRule()

◆ moveTo() [1/2]

◆ moveTo() [2/2]

◆ arc() [1/2]

◆ arc() [2/2]

◆ arcTo() [1/2]

◆ arcTo() [2/2]

◆ lineTo() [1/2]

◆ lineTo() [2/2]

◆ closePath()

◆ addEllipse() [1/2]

◆ addEllipse() [2/2]

◆ addRectangle() [1/2]

◆ addRectangle() [2/2]

◆ getBounds()

◆ convert()

◆ operator==()

◆ operator!=()

◆ operator+=()

◆ operator=()