80 lines
2.5 KiB
Go
80 lines
2.5 KiB
Go
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package draw provides image composition functions.
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//
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// See "The Go image/draw package" for an introduction to this package:
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// http://golang.org/doc/articles/image_draw.html
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//
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// This package is a superset of and a drop-in replacement for the image/draw
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// package in the standard library.
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package draw
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// This file just contains the API exported by the image/draw package in the
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// standard library. Other files in this package provide additional features.
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import (
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"image"
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"image/color"
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"image/draw"
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)
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// Draw calls DrawMask with a nil mask.
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func Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op) {
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draw.Draw(dst, r, src, sp, draw.Op(op))
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}
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// DrawMask aligns r.Min in dst with sp in src and mp in mask and then
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// replaces the rectangle r in dst with the result of a Porter-Duff
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// composition. A nil mask is treated as opaque.
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func DrawMask(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op) {
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draw.DrawMask(dst, r, src, sp, mask, mp, draw.Op(op))
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}
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// Drawer contains the Draw method.
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type Drawer interface {
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// Draw aligns r.Min in dst with sp in src and then replaces the
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// rectangle r in dst with the result of drawing src on dst.
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Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
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}
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// FloydSteinberg is a Drawer that is the Src Op with Floyd-Steinberg error
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// diffusion.
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var FloydSteinberg Drawer = floydSteinberg{}
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type floydSteinberg struct{}
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func (floydSteinberg) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
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draw.FloydSteinberg.Draw(dst, r, src, sp)
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}
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// Image is an image.Image with a Set method to change a single pixel.
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type Image interface {
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image.Image
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Set(x, y int, c color.Color)
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}
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// Op is a Porter-Duff compositing operator.
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type Op int
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const (
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// Over specifies ``(src in mask) over dst''.
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Over Op = Op(draw.Over)
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// Src specifies ``src in mask''.
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Src Op = Op(draw.Src)
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)
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// Draw implements the Drawer interface by calling the Draw function with
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// this Op.
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func (op Op) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
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(draw.Op(op)).Draw(dst, r, src, sp)
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}
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// Quantizer produces a palette for an image.
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type Quantizer interface {
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// Quantize appends up to cap(p) - len(p) colors to p and returns the
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// updated palette suitable for converting m to a paletted image.
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Quantize(p color.Palette, m image.Image) color.Palette
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}
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