refactor: support custom value formatter

bar_chart.go

@@ -69,6 +69,7 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 	seriesPainter := result.seriesPainter
 
 	xRange := NewRange(AxisRangeOption{
+		Painter:     b.p,
 		DivideCount: len(opt.XAxis.Data),
 		Size:        seriesPainter.Width(),
 	})

chart_option.go

@@ -74,6 +74,8 @@ type ChartOption struct {
 	FillArea bool
 	// The child charts
 	Children []ChartOption
+	// The value formatter
+	ValueFormatter ValueFormatter
 }
 
 // OptionFunc option function

charts.go

@@ -188,6 +188,7 @@ func defaultRender(p *Painter, opt defaultRenderOption) (*defaultRenderResult, e
 		}
 		max, min := opt.SeriesList.GetMaxMin(index)
 		r := NewRange(AxisRangeOption{
+			Painter: p,
 			Min:     min,
 			Max:     max,
 			// 高度需要减去x轴的高度
@@ -287,6 +288,9 @@ func Render(opt ChartOption, opts ...OptionFunc) (*Painter, error) {
 		opt.Parent = p
 	}
 	p := opt.Parent
+	if opt.ValueFormatter != nil {
+		p.valueFormatter = opt.ValueFormatter
+	}
 	if !opt.Box.IsZero() {
 		p = p.Child(PainterBoxOption(opt.Box))
 	}

examples/line_chart/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -98,6 +99,9 @@ func main() {
 			}
 			opt.SymbolShow = charts.FalseFlag()
 			opt.LineStrokeWidth = 1
+			opt.ValueFormatter = func(f float64) string {
+				return fmt.Sprintf("%.0f", f)
+			}
 		},
 	)
 

horizontal_bar_chart.go

@@ -93,6 +93,7 @@ func (h *horizontalBarChart) render(result *defaultRenderResult, seriesList Seri
 
 	max, min := seriesList.GetMaxMin(0)
 	xRange := NewRange(AxisRangeOption{
+		Painter:     p,
 		Min:         min,
 		Max:         max,
 		DivideCount: defaultAxisDivideCount,

mark_line_test.go

@@ -55,6 +55,7 @@ func TestMarkLine(t *testing.T) {
 					StrokeColor: drawing.ColorBlack,
 					Series:      series,
 					Range: NewRange(AxisRangeOption{
+						Painter:     p,
 						Min:         0,
 						Max:         5,
 						Size:        p.Height(),

painter.go

@@ -31,6 +31,8 @@ import (
 	"github.com/wcharczuk/go-chart/v2"
 )
 
+type ValueFormatter func(float64) string
+
 type Painter struct {
 	render chart.Renderer
 	box    Box
@@ -40,6 +42,7 @@ type Painter struct {
 	theme  ColorPalette
 	// 类型
 	outputType     string
+	valueFormatter ValueFormatter
 }
 
 type PainterOptions struct {
@@ -188,6 +191,9 @@ func (p *Painter) setOptions(opts ...PainterOption) {
 
 func (p *Painter) Child(opt ...PainterOption) *Painter {
 	child := &Painter{
+		// 格式化
+		valueFormatter: p.valueFormatter,
+		// render
 		render: p.render,
 		box:    p.box.Clone(),
 		font:   p.font,

range.go

@@ -29,6 +29,7 @@ import (
 const defaultAxisDivideCount = 6
 
 type axisRange struct {
+	p           *Painter
 	divideCount int
 	min         float64
 	max         float64
@@ -37,6 +38,7 @@ type axisRange struct {
 }
 
 type AxisRangeOption struct {
+	Painter *Painter
 	// The min value of axis
 	Min float64
 	// The max value of axis
@@ -93,6 +95,7 @@ func NewRange(opt AxisRangeOption) axisRange {
 		max = float64(ceilFloatToInt(expectMax))
 	}
 	return axisRange{
+		p:           opt.Painter,
 		divideCount: divideCount,
 		min:         min,
 		max:         max,
@@ -105,9 +108,13 @@ func NewRange(opt AxisRangeOption) axisRange {
 func (r axisRange) Values() []string {
 	offset := (r.max - r.min) / float64(r.divideCount)
 	values := make([]string, 0)
+	formatter := commafWithDigits
+	if r.p != nil && r.p.valueFormatter != nil {
+		formatter = r.p.valueFormatter
+	}
 	for i := 0; i <= r.divideCount; i++ {
 		v := r.min + float64(i)*offset
-		value := commafWithDigits(v)
+		value := formatter(v)
 		values = append(values, value)
 	}
 	return values