1// Copyright 2015 The Go Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style 3// license that can be found in the LICENSE file. 4 5// Package draw provides image composition functions. 6// 7// See "The Go image/draw package" for an introduction to this package: 8// http://golang.org/doc/articles/image_draw.html 9// 10// This package is a superset of and a drop-in replacement for the image/draw 11// package in the standard library. 12package draw 13 14// This file just contains the API exported by the image/draw package in the 15// standard library. Other files in this package provide additional features. 16 17import ( 18 "image" 19 "image/draw" 20) 21 22// Draw calls DrawMask with a nil mask. 23func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op) { 24 draw.Draw(dst, r, src, sp, draw.Op(op)) 25} 26 27// DrawMask aligns r.Min in dst with sp in src and mp in mask and then 28// replaces the rectangle r in dst with the result of a Porter-Duff 29// composition. A nil mask is treated as opaque. 30func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) { 31 draw.DrawMask(dst, r, src, sp, mask, mp, draw.Op(op)) 32} 33 34// Drawer contains the Draw method. 35type Drawer = draw.Drawer 36 37// FloydSteinberg is a Drawer that is the Src Op with Floyd-Steinberg error 38// diffusion. 39var FloydSteinberg Drawer = floydSteinberg{} 40 41type floydSteinberg struct{} 42 43func (floydSteinberg) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) { 44 draw.FloydSteinberg.Draw(dst, r, src, sp) 45} 46 47// Image is an image.Image with a Set method to change a single pixel. 48type Image = draw.Image 49 50// Op is a Porter-Duff compositing operator. 51type Op = draw.Op 52 53const ( 54 // Over specifies ``(src in mask) over dst''. 55 Over Op = draw.Over 56 // Src specifies ``src in mask''. 57 Src Op = draw.Src 58) 59 60// Quantizer produces a palette for an image. 61type Quantizer = draw.Quantizer 62