draw

Documentation

Overview

Package draw provides image composition functions in the style of the Plan 9 graphics library (see http://plan9.bell-labs.com/magic/man2html/2/draw) and the X Render extension.

Index

• func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
• func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, ...)
• type Image
• type Op

Functions

func Draw

func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)

Draw calls DrawMask with a nil mask and an Over op.

func DrawMask

func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op)

DrawMask aligns r.Min in dst with sp in src and mp in mask and then replaces the rectangle r in dst with the result of a Porter-Duff composition. A nil mask is treated as opaque.

Types

type Image

type Image interface {
	image.Image
	Set(x, y int, c image.Color)
}

A draw.Image is an image.Image with a Set method to change a single pixel.

type Op

type Op int

Op is a Porter-Duff compositing operator.

const (
	// Over specifies “(src in mask) over dst”.
	Over Op = iota
	// Src specifies “src in mask”.
	Src
)