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// 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
}
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