36 lines
913 B
Go
36 lines
913 B
Go
// Copyright ©2017 The Gonum 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 palette
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import (
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"image/color"
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)
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// Reverse reverses the direction of ColorMap c.
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func Reverse(c ColorMap) ColorMap {
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return reverse{ColorMap: c}
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}
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// reverse is a ColorMap that reverses the direction of the ColorMap it
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// contains.
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type reverse struct {
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ColorMap
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}
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// At implements the ColorMap interface for a Reversed ColorMap.
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func (r reverse) At(v float64) (color.Color, error) {
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return r.ColorMap.At(r.Max() - (v - r.Min()))
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}
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// Palette implements the ColorMap interface for a Reversed ColorMap.
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func (r reverse) Palette(colors int) Palette {
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c := r.ColorMap.Palette(colors).Colors()
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c2 := make([]color.Color, len(c))
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for i, j := 0, len(c)-1; i < j; i, j = i+1, j-1 {
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c2[i], c2[j] = c[j], c[i]
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}
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return palette(c2)
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}
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