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