docs: add example of using chinese

examples/basic/chinese.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"log"
+	"os"
+
+	charts "github.com/vicanso/go-charts"
+)
+
+func echartsRender() ([]byte, error) {
+	return charts.RenderEChartsToPNG(`{
+		"title": {
+			"text": "用户访问次数",
+			"textStyle": {
+				"fontFamily": "chinese"
+			}
+		},
+		"xAxis": {
+			"data": ["周一", "周二", "周三", "周四", "周五", "周六", "周日"]
+		},
+		"series": [
+			{
+				"data": [150, 230, 224, 218, 135, 147, 260],
+				"label": {
+					"show": true
+				}
+			}
+		]
+	}`)
+}
+
+func main() {
+	fontData, err := os.ReadFile("/Users/darcy/Downloads/NotoSansCJKsc-VF.ttf")
+	if err != nil {
+		log.Fatalln("Error when reading font file:", err)
+	}
+
+	if err := charts.InstallFont("chinese", fontData); err != nil {
+		log.Fatalln("Error when instaling font:", err)
+	}
+
+	fileData, err := echartsRender()
+
+	if err != nil {
+		log.Fatalln("Error when rendering image:", err)
+	}
+	if err := os.WriteFile("chinese.png", fileData, 0644); err != nil {
+		log.Fatalln("Error when save image to chinese.png:", err)
+	}
+}