42 lines
989 B
Go
42 lines
989 B
Go
// Copyright 2011 The Graphics-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.
|
|
|
|
package graphics
|
|
|
|
import (
|
|
"image"
|
|
"image/draw"
|
|
)
|
|
|
|
// Thumbnail scales and crops src so it fits in dst.
|
|
func Thumbnail(dst draw.Image, src image.Image) error {
|
|
// Scale down src in the dimension that is closer to dst.
|
|
sb := src.Bounds()
|
|
db := dst.Bounds()
|
|
rx := float64(sb.Dx()) / float64(db.Dx())
|
|
ry := float64(sb.Dy()) / float64(db.Dy())
|
|
var b image.Rectangle
|
|
if rx < ry {
|
|
b = image.Rect(0, 0, db.Dx(), int(float64(sb.Dy())/rx))
|
|
} else {
|
|
b = image.Rect(0, 0, int(float64(sb.Dx())/ry), db.Dy())
|
|
}
|
|
|
|
buf := image.NewRGBA(b)
|
|
if err := Scale(buf, src); err != nil {
|
|
return err
|
|
}
|
|
|
|
// Crop.
|
|
// TODO(crawshaw): improve on center-alignment.
|
|
var pt image.Point
|
|
if rx < ry {
|
|
pt.Y = (b.Dy() - db.Dy()) / 2
|
|
} else {
|
|
pt.X = (b.Dx() - db.Dx()) / 2
|
|
}
|
|
draw.Draw(dst, db, buf, pt, draw.Src)
|
|
return nil
|
|
}
|