package geom

import "golang.org/x/mobile/geom"

Package geom defines a two-dimensional coordinate system.

The coordinate system is based on an left-handed Cartesian plane. That is, X increases to the right and Y increases down. For (x,y),

(0,0) → (1,0)
  ↓   ↘
(0,1)   (1,1)

The display window places the origin (0, 0) in the upper-left corner of the screen. Positions on the plane are measured in typographic points, 1/72 of an inch, which is represented by the Pt type.

Any interface that draws to the screen using types from the geom package scales the number of pixels to maintain a Pt as 1/72 of an inch.

Index ¶

Package Files ¶

geom.go

type Point ¶

type Point struct {
    X, Y Pt
}

Point is a point in a two-dimensional plane.

func (Point) String ¶

func (p Point) String() string

String returns a string representation of p like "(1.2,3.4)".

type Pt ¶

type Pt float32

Pt is a length.

The unit Pt is a typographical point, 1/72 of an inch (0.3527 mm).

It can be be converted to a length in current device pixels by multiplying with PixelsPerPt after app initialization is complete.

func (Pt) Px ¶

func (p Pt) Px(pixelsPerPt float32) float32

Px converts the length to current device pixels.

func (Pt) String ¶

func (p Pt) String() string

String returns a string representation of p like "3.2pt".

type Rectangle ¶

type Rectangle struct {
    Min, Max Point
}

A Rectangle is region of points. The top-left point is Min, and the bottom-right point is Max.

func (Rectangle) String ¶

func (r Rectangle) String() string

String returns a string representation of r like "(3,4)-(6,5)".