fixed dependencies

vendor/gonum.org/v1/plot/plotter/palettethumbnailer.go

@@ -0,0 +1,43 @@
+// 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)
+}