feat: support pie, radar and funnel chart

examples/funnel_chart/main.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"github.com/vicanso/go-charts"
+)
+
+func writeFile(buf []byte) error {
+	tmpPath := "./tmp"
+	err := os.MkdirAll(tmpPath, 0700)
+	if err != nil {
+		return err
+	}
+
+	file := filepath.Join(tmpPath, "funnel-chart.png")
+	err = ioutil.WriteFile(file, buf, 0600)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func main() {
+	p, err := charts.NewPainter(charts.PainterOptions{
+		Width:  800,
+		Height: 600,
+		Type:   charts.ChartOutputPNG,
+	})
+	if err != nil {
+		panic(err)
+	}
+	_, err = charts.NewFunnelChart(p, charts.FunnelChartOption{
+		Title: charts.TitleOption{
+			Text: "Funnel",
+		},
+		Legend: charts.NewLegendOption([]string{
+			"Show",
+			"Click",
+			"Visit",
+			"Inquiry",
+			"Order",
+		}),
+		SeriesList: []charts.Series{
+
+			{
+				Type: charts.ChartTypeFunnel,
+				Name: "Show",
+				Data: charts.NewSeriesDataFromValues([]float64{
+					100,
+				}),
+			},
+			{
+				Type: charts.ChartTypeFunnel,
+				Name: "Click",
+				Data: charts.NewSeriesDataFromValues([]float64{
+					80,
+				}),
+			},
+			{
+				Type: charts.ChartTypeFunnel,
+				Name: "Visit",
+				Data: charts.NewSeriesDataFromValues([]float64{
+					60,
+				}),
+			},
+			{
+				Type: charts.ChartTypeFunnel,
+				Name: "Inquiry",
+				Data: charts.NewSeriesDataFromValues([]float64{
+					40,
+				}),
+			},
+			{
+				Type: charts.ChartTypeFunnel,
+				Name: "Order",
+				Data: charts.NewSeriesDataFromValues([]float64{
+					20,
+				}),
+			},
+		},
+	}).Render()
+	if err != nil {
+		panic(err)
+	}
+
+	buf, err := p.Bytes()
+	if err != nil {
+		panic(err)
+	}
+	err = writeFile(buf)
+	if err != nil {
+		panic(err)
+	}
+}