cairoArc {RGtk2} | R Documentation

## cairoArc

### Description

Adds a circular arc of the given `radius` to the current path. The arc is centered at (`xc`, `yc`), begins at `angle1` and proceeds in the direction of increasing angles to end at `angle2`. If `angle2` is less than `angle1` it will be progressively increased by 2*M_PI until it is greater than `angle1`.

### Usage

    cairoArc(cr, xc, yc, radius, angle1, angle2)

### Arguments

``cr`` | [`Cairo`] a cairo context
``xc`` | [numeric] X position of the center of the arc
``yc`` | [numeric] Y position of the center of the arc
``radius`` | [numeric] the radius of the arc
``angle1`` | [numeric] the start angle, in radians
``angle2`` | [numeric] the end angle, in radians

### Details

If there is a current point, an initial line segment will be added to the path to connect the current point to the beginning of the arc. If this initial line is undesired, it can be avoided by calling `cairoNewSubPath` before calling `cairoArc`.

Angles are measured in radians. An angle of 0.0 is in the direction of the positive X axis (in user space). An angle of `M_PI`/2.0 radians (90 degrees) is in the direction of the positive Y axis (in user space). Angles increase in the direction from the positive X axis toward the positive Y axis. So with the default transformation matrix, angles increase in a clockwise direction.

(To convert from degrees to radians, use `degrees * (M_PI / 180.)`.)

This function gives the arc in the direction of increasing angles; see `cairoArcNegative` to get the arc in the direction of decreasing angles.

The arc is circular in user space. To achieve an elliptical arc, you can scale the current transformation matrix by different amounts in the X and Y directions. For example, to draw an ellipse in the box given by `x`, `y`, `width`, `height`:

    cr$save()
    cr$translate(x + width / 2, y + height / 2)
    cr$scale(width / 2, height / 2)
    cr$arc(0, 0, 1, 0, 2 * pi)
    cr$restore()

### Author(s)

Derived by RGtkGen from GTK+ documentation

[Package RGtk2 version 2.20.36.3 Index]