point.md
In rswipl: Embed 'SWI'-'Prolog'

class point {#class-point}

A point describes a discrete position in an infinite two-dimensional plain. Points are used to describe positions when communicating with graphical objects.

Note that the coordinate system used by PCE deals both with negative and positive coordinates.

@see class size @see class area

point<->x: int Coordinate of the point object. Most graphical objects interpret the value in pixel units.
point<->y: int Inherits description from: point-x

point->copy: from=point Copy x- and y values from the argument. See also <-copy, <-clone and ->set.
point->equal: to=point Succeeds if <-x and <-y of both points are equal. See also object ->equal and object ->same_reference.
point->initialise: x=[int], y=[int] Create a point object from its <-x and <-y value. When a value is omitted, 0 is used.
point->offset: dx=int, dy=int Add dx to <-x and dy to <-y. See also ->plus.

point<-convert: event|char_array -> point Convert event to its position relative to its receiver using event <-position or a text of the form , . The latter is discouraged (backward compatibility).

@see event<-position
point<-copy: -> point New point with same <-x and <-y. The copy is created using the equivalent of the expression below.
```
?(P?class, instance, ?(P, slot, x), ?(P, slot, y))
```
See also ->copy.
point<-difference: to=point -> point New point with <-x and <-y obtained by subtracting the receiver's coordinates from the argument (vector subtraction). See also <-distance and ->minus.
point<-distance: to=point -> int Rounded integer reflecting the (pixel) distance between both points.
point<-print_name: -> string Printed representation as ,