From 2772798122db690839980358611619eff670ccb1 Mon Sep 17 00:00:00 2001
From: vicanso <vicansocanbico@gmail.com>
Date: Tue, 28 Dec 2021 23:37:15 +0800
Subject: [PATCH] feat: support font setting for charts

---
 charts.go      | 31 +++++++++++++++++++++++++++++++
 charts_test.go | 13 +++++++++++++
 echarts.go     |  7 +++++--
 3 files changed, 49 insertions(+), 2 deletions(-)

diff --git a/charts.go b/charts.go
index f5fcb1f..3cef373 100644
--- a/charts.go
+++ b/charts.go
@@ -26,7 +26,9 @@ import (
 	"bytes"
 	"errors"
 	"io"
+	"sync"
 
+	"github.com/golang/freetype/truetype"
 	"github.com/wcharczuk/go-chart/v2"
 )
 
@@ -66,9 +68,36 @@ type (
 		Legend       Legend
 		TickPosition chart.TickPosition
 		Log          chart.Logger
+		Font         *truetype.Font
 	}
 )
 
+var fonts = sync.Map{}
+var ErrFontNotExists = errors.New("font is not exists")
+
+// InstallFont installs the font for charts
+func InstallFont(fontFamily string, data []byte) error {
+	font, err := truetype.Parse(data)
+	if err != nil {
+		return err
+	}
+	fonts.Store(fontFamily, font)
+	return nil
+}
+
+// GetFont returns the font of font family
+func GetFont(fontFamily string) (*truetype.Font, error) {
+	value, ok := fonts.Load(fontFamily)
+	if !ok {
+		return nil, ErrFontNotExists
+	}
+	f, ok := value.(*truetype.Font)
+	if !ok {
+		return nil, ErrFontNotExists
+	}
+	return f, nil
+}
+
 type Graph interface {
 	Render(rp chart.RendererProvider, w io.Writer) error
 }
@@ -136,6 +165,7 @@ func newPieChart(opt Options) *chart.PieChart {
 		}
 	}
 	return &chart.PieChart{
+		Font:       opt.Font,
 		Background: opt.getBackground(),
 		Title:      opt.Title.Text,
 		TitleStyle: opt.Title.Style,
@@ -178,6 +208,7 @@ func newChart(opt Options) *chart.Chart {
 	}
 
 	c := &chart.Chart{
+		Font:       opt.Font,
 		Log:        opt.Log,
 		Background: opt.getBackground(),
 		ColorPalette: &ThemeColorPalette{
diff --git a/charts_test.go b/charts_test.go
index 3173868..98a7288 100644
--- a/charts_test.go
+++ b/charts_test.go
@@ -28,8 +28,21 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/wcharczuk/go-chart/v2"
+	"github.com/wcharczuk/go-chart/v2/roboto"
 )
 
+func TestFont(t *testing.T) {
+	assert := assert.New(t)
+
+	fontFamily := "roboto"
+	err := InstallFont(fontFamily, roboto.Roboto)
+	assert.Nil(err)
+
+	font, err := GetFont(fontFamily)
+	assert.Nil(err)
+	assert.NotNil(font)
+}
+
 func TestChartsOptions(t *testing.T) {
 	assert := assert.New(t)
 
diff --git a/echarts.go b/echarts.go
index bd5a950..a55da5a 100644
--- a/echarts.go
+++ b/echarts.go
@@ -184,8 +184,7 @@ type ECharsOptions struct {
 		// 暂不支持(go-chart默认title只能居中)
 		TextAlign string `json:"textAlign"`
 		TextStyle struct {
-			Color string `json:"color"`
-			// TODO 字体支持
+			Color      string  `json:"color"`
 			FontFamily string  `json:"fontFamily"`
 			FontSize   float64 `json:"fontSize"`
 			Height     float64 `json:"height"`
@@ -288,6 +287,10 @@ func (e *ECharsOptions) ToOptions() Options {
 			FontSize:  titleTextStyle.FontSize,
 		},
 	}
+	if e.Title.TextStyle.FontFamily != "" {
+		// 如果获取字体失败忽略
+		o.Font, _ = GetFont(e.Title.TextStyle.FontFamily)
+	}
 
 	if titleTextStyle.FontSize != 0 && titleTextStyle.Height > titleTextStyle.FontSize {
 		padding := int(titleTextStyle.Height-titleTextStyle.FontSize) / 2