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// Copyright ©2018 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 plot_test
import (
"image/color"
"os"
"gonum.org/v1/plot"
"gonum.org/v1/plot/vg"
"gonum.org/v1/plot/vg/draw"
"gonum.org/v1/plot/vg/vgimg"
)
type exampleThumbnailer struct {
color.Color
}
// Thumbnail fulfills the plot.Thumbnailer interface.
func (et exampleThumbnailer) 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(et.Color, poly)
pts = append(pts, vg.Point{X: c.Min.X, Y: c.Min.Y})
outline := c.ClipLinesY(pts)
c.StrokeLines(draw.LineStyle{
Color: color.Black,
Width: vg.Points(1),
}, outline...)
}
// This example creates a some standalone legends with borders around them.
func ExampleLegend_standalone() {
c := vgimg.New(vg.Points(120), vg.Points(100))
dc := draw.New(c)
// These example thumbnailers could be replaced with any of Plotters
// in the plotter subpackage.
red := exampleThumbnailer{Color: color.NRGBA{R: 255, A: 255}}
green := exampleThumbnailer{Color: color.NRGBA{G: 255, A: 255}}
blue := exampleThumbnailer{Color: color.NRGBA{B: 255, A: 255}}
l, err := plot.NewLegend()
if err != nil {
panic(err)
}
l.Add("red", red)
l.Add("green", green)
l.Add("blue", blue)
l.Padding = vg.Millimeter
// purpleRectangle draws a purple rectangle around the given Legend.
purpleRectangle := func(l plot.Legend) {
r := l.Rectangle(dc)
dc.StrokeLines(draw.LineStyle{
Color: color.NRGBA{R: 255, B: 255, A: 255},
Width: vg.Points(1),
}, []vg.Point{
{X: r.Min.X, Y: r.Min.Y}, {X: r.Min.X, Y: r.Max.Y}, {X: r.Max.X, Y: r.Max.Y},
{X: r.Max.X, Y: r.Min.Y}, {X: r.Min.X, Y: r.Min.Y},
})
}
l.Draw(dc)
purpleRectangle(l)
l.Left = true
l.Draw(dc)
purpleRectangle(l)
l.Top = true
l.Draw(dc)
purpleRectangle(l)
l.Left = false
l.Draw(dc)
purpleRectangle(l)
w, err := os.Create("testdata/legend_standalone.png")
if err != nil {
panic(err)
}
defer w.Close()
png := vgimg.PngCanvas{Canvas: c}
if _, err := png.WriteTo(w); err != nil {
panic(err)
}
}
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