Graphical Elements

Graphical elements are created and added to plots. They are drawn with a filling of a given color and a stroking of a given color and line width.

Graphical Objects

class Object

A graphical element that can be added to a plot. An instance of the Object cannot be directly created but it is the base class of other elements like, for example, a Path. It is a copyable and movable.

class Path : public Object

A graphical path that can contain polygonal paths, open or closed. It is a copyable and movable object.

Path()

Create a new empty path.

void MoveTo(double x, double y)

Move the path to the given location without a connecting line.

void LineTo(double x, double y)

Add a straight line segment up to the given location.

void ClosePolygon()

Close the current polygon.

class CurvePath : public Object

A graphical path similar to the Path but can additionally contain Bézier and elliptical arcs. More details about how exactly the arcs are drawn can be found from the official SVG documentation on Paths.

Please note that the CurvePath class does not inherit from Path even if it implements all the methods of the latter. This is due to the their internal representation.

CurvePath()

Create an empty path that can contain Bézier and elliptic arcs.

void MoveTo(double x, double y)

Move the path to the given location without a connecting line.

void LineTo(double x, double y)

Add a straight line segment up to the given location.

void Curve3(double x_ctrl, double y_ctrl, double x_to, double y_to)

Add a quadratic Bézier curve up to the point (x_to, y_to) with control point (x_ctrl, y_ctrl).

void Curve4(double x_ctrl1, double y_ctrl1, double x_ctrl2, double y_ctrl2, double x_to, double y_to)

Add a cubic Bézier curve up to the point (x_to, y_to) with control points (x_ctrl1, y_ctrl1) and (x_ctrl2, y_ctrl2).

void ArcTo(double rx, double ry, double angle, bool large_arc_flag, bool sweep_flag, double x, double y)

Add an elliptical path up to the point (x, y). The other parameters are:

• (rx, ry), x and y radius of the ellipse.

• angle, rotation angle of the ellipse’s x axis.

• large_arc_flag, if a large angle or small angle arc should be chosen.

• bool sweep_flag, if the arc should be drawn in the sense of increasing angles.

void ClosePolygon()

Close the current polygon.

class Markers : public Path

Like a path but instead of drawing a path it draws a marker at each vertex of the path.

Markers(double size, Object marker_symbol)

Create an empty Markers path that will draw markers of the specified size, in pixels, and using an object marker_symbol as a marker. The marker symbol should be an object that span a rectangular area of unit side and centered on zero.

Object MarkerSymbol(int index)

Returns a marker symbol from a standard list of symbol.

class Text : public Object

An object that draws a text label. It is meant to be drawn with a fill color, without stroking.

Text(const char *text, double size = 10.0, double hjustif = 0.0, double vjustif = 0.0)

Create a text object with the given text. The size corresponds to the text size in pixel. The other parameters represents the horizontal and vertical justification. For the horizontal 0.0 corresponds to left justification and 1.0 to right justification. For the vertical 0.0 corresponds to alignment on the text’s bottom line and 1.0 to the text’s top line.

void SetAngle(double angle)

Set the angle, in radians, for the text orientation.

void SetPosition(double x, double y)

Set the position of the text.

class DashPath : public Path

A path object but it will be drawn as a dashed lines.

DashPath(std::initializer_list<double> lst)

Create a dashed path with the length of the dash and the gap given by the initializer list. The given lengths will be used for dashing in the screen coordinates space. The number of elements of the initializer list should be a multiple of two so that the elements represents consecutively the length of the dash and the following gap.

void AddDash(double a, double b)

Add a dash length and gap after the creation of the object.

Colors

enum Color

Used to express colors in RGBA format. Corresponds to an unsigned 32 bit integer type. The R, G, B and A corresponds respectively to the red, green, blue and alpha channel and each takes 8 bit. The alpha channel controls the transparency and its values corresponds to zero for completely transparent and 255, 0xff in hexadecimal, for completely opaque. The color can be given directly in hexadecimal format like, for example, 0x00ff00ff for green, or using the functions color::RGB() and color::RGBA().

Color RGBA(unsigned int r, unsigned int g, unsigned int b, unsigned int a)

Form a color from the value of its individual channel.

Color RGB(unsigned int r, unsigned int g, unsigned int b)

Form a color from the value of its individual channel setting the alpha channel to its maximum value.

enumerator Red

enumerator Blue

enumerator Green

enumerator Yellow

enumerator Black

enumerator Gray

enumerator White

enumerator None = 0