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// Copyright ©2017 The Gonum 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 plotter
import (
"image/color"
"gonum.org/v1/plot"
"gonum.org/v1/plot/palette"
"gonum.org/v1/plot/vg"
"gonum.org/v1/plot/vg/draw"
)
// PaletteThumbnailers creates a slice of plot.Thumbnailers that can be used to
// add legend entries for the colors in a color palette.
func PaletteThumbnailers(p palette.Palette) []plot.Thumbnailer {
colors := p.Colors()
thumbnailers := make([]plot.Thumbnailer, len(colors))
for i, c := range colors {
thumbnailers[i] = paletteThumbnailer{color: c}
}
return thumbnailers
}
// paletteThumbnailer implements the Thumbnailer interface
// for color palettes.
type paletteThumbnailer struct {
color color.Color
}
// Thumbnail satisfies the plot.Thumbnailer interface.
func (t paletteThumbnailer) Thumbnail(c *draw.Canvas) {
pts := []vg.Point{
{X: c.Min.X, Y: c.Min.Y},
{X: c.Min.X, Y: c.Max.Y},
{X: c.Max.X, Y: c.Max.Y},
{X: c.Max.X, Y: c.Min.Y},
}
poly := c.ClipPolygonY(pts)
c.FillPolygon(t.color, poly)
}
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