306b829431
This relies on type aliases, a language feature new in Go 1.9.
The package documentation, in draw.go, explicitly gives the intent of
this package:
This package is a superset of and a drop-in replacement for the
image/draw package in the standard library.
Drop-in replacement means that I can replace all of my "image/draw"
imports with "golang.org/x/image/draw", to access additional features in
this package, and no further changes are required. That's mostly true,
but not completely true unless we use type aliases.
Without type aliases, users might need to import both "image/draw" and
"golang.org/x/image/draw" in order to convert from two conceptually
equivalent but different (from the compiler's point of view) types, such
as from one draw.Op type to another draw.Op type, to satisfy some other
interface or function signature.
Change-Id: Ice6d000d49b019c2d8761739a904232e9cd01cae
Reviewed-on: https://go-review.googlesource.com/36730
Run-TryBot: Nigel Tao <nigeltao@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
50 lines
1.3 KiB
Go
50 lines
1.3 KiB
Go
// Copyright 2015 The Go Authors. All rights reserved.
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file.
|
|
|
|
// +build !go1.9
|
|
|
|
package draw
|
|
|
|
import (
|
|
"image"
|
|
"image/color"
|
|
"image/draw"
|
|
)
|
|
|
|
// Drawer contains the Draw method.
|
|
type Drawer interface {
|
|
// Draw aligns r.Min in dst with sp in src and then replaces the
|
|
// rectangle r in dst with the result of drawing src on dst.
|
|
Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point)
|
|
}
|
|
|
|
// Image is an image.Image with a Set method to change a single pixel.
|
|
type Image interface {
|
|
image.Image
|
|
Set(x, y int, c color.Color)
|
|
}
|
|
|
|
// Op is a Porter-Duff compositing operator.
|
|
type Op int
|
|
|
|
const (
|
|
// Over specifies ``(src in mask) over dst''.
|
|
Over Op = Op(draw.Over)
|
|
// Src specifies ``src in mask''.
|
|
Src Op = Op(draw.Src)
|
|
)
|
|
|
|
// Draw implements the Drawer interface by calling the Draw function with
|
|
// this Op.
|
|
func (op Op) Draw(dst Image, r image.Rectangle, src image.Image, sp image.Point) {
|
|
(draw.Op(op)).Draw(dst, r, src, sp)
|
|
}
|
|
|
|
// Quantizer produces a palette for an image.
|
|
type Quantizer interface {
|
|
// Quantize appends up to cap(p) - len(p) colors to p and returns the
|
|
// updated palette suitable for converting m to a paletted image.
|
|
Quantize(p color.Palette, m image.Image) color.Palette
|
|
}
|