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. 12 package 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 17 import ( 18 "image" 19 "image/draw" 20 ) 21 22 // Draw calls DrawMask with a nil mask. 23 func 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. 30 func 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. 35 type Drawer = draw.Drawer 36 37 // FloydSteinberg is a Drawer that is the Src Op with Floyd-Steinberg error 38 // diffusion. 39 var FloydSteinberg Drawer = floydSteinberg{} 40 41 type floydSteinberg struct{} 42 43 func (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. 48 type Image = draw.Image 49 50 // RGBA64Image extends both the Image and image.RGBA64Image interfaces with a 51 // SetRGBA64 method to change a single pixel. SetRGBA64 is equivalent to 52 // calling Set, but it can avoid allocations from converting concrete color 53 // types to the color.Color interface type. 54 type RGBA64Image = draw.RGBA64Image 55 56 // Op is a Porter-Duff compositing operator. 57 type Op = draw.Op 58 59 const ( 60 // Over specifies ``(src in mask) over dst''. 61 Over Op = draw.Over 62 // Src specifies ``src in mask''. 63 Src Op = draw.Src 64 ) 65 66 // Quantizer produces a palette for an image. 67 type Quantizer = draw.Quantizer 68