feat: support legend render function

chart.go

@@ -41,7 +41,6 @@ type Point struct {
 
 type Series struct {
 	Type       string
-	Name       string
 	Data       []SeriesData
 	YAxisIndex int
 	Style      chart.Style
@@ -50,6 +49,7 @@ type Series struct {
 type ChartOption struct {
 	Theme           string
 	Title           TitleOption
+	Legend          LegendOption
 	XAxis           XAxisOption
 	Width           int
 	Height          int
@@ -60,6 +60,7 @@ type ChartOption struct {
 }
 
 func (o *ChartOption) FillDefault(t *Theme) {
+	f, _ := chart.GetDefaultFont()
 	if o.BackgroundColor.IsZero() {
 		o.BackgroundColor = t.GetBackgroundColor()
 	}
@@ -70,7 +71,7 @@ func (o *ChartOption) FillDefault(t *Theme) {
 		o.Title.Style.FontSize = 14
 	}
 	if o.Title.Style.Font == nil {
-		o.Title.Style.Font, _ = chart.GetDefaultFont()
+		o.Title.Style.Font = f
 	}
 	if o.Title.Style.Padding.IsZero() {
 		o.Title.Style.Padding = chart.Box{
@@ -80,6 +81,15 @@ func (o *ChartOption) FillDefault(t *Theme) {
 			Bottom: 5,
 		}
 	}
+	if o.Legend.Style.FontSize == 0 {
+		o.Legend.Style.FontSize = 8
+	}
+	if o.Legend.Style.Font == nil {
+		o.Legend.Style.Font = f
+	}
+	if o.Legend.Style.FontColor.IsZero() {
+		o.Legend.Style.FontColor = t.GetTitleColor()
+	}
 }
 
 func (o *ChartOption) getWidth() int {

legend.go

@@ -0,0 +1,95 @@
+// MIT License
+
+// Copyright (c) 2022 Tree Xie
+
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+package charts
+
+import (
+	"github.com/wcharczuk/go-chart/v2"
+)
+
+type LegendOption struct {
+	Style chart.Style
+	Data  []string
+	Left  string
+	Right string
+	Align string
+}
+
+func drawLegend(p *Draw, opt *LegendOption, theme *Theme) (chart.Box, error) {
+	if len(opt.Data) == 0 {
+		return chart.BoxZero, nil
+	}
+	padding := opt.Style.Padding
+	legendDraw, err := NewDraw(DrawOption{
+		Parent: p,
+	}, PaddingOption(padding))
+	if err != nil {
+		return chart.BoxZero, err
+	}
+	r := legendDraw.Render
+	opt.Style.GetTextOptions().WriteToRenderer(r)
+
+	x := 0
+	y := 0
+	legendWidth := 30
+	legendDotHeight := 5
+	textPadding := 5
+	legendMargin := 10
+	for index, text := range opt.Data {
+		if index != 0 {
+			x += legendMargin
+		}
+		style := chart.Style{
+			StrokeColor: theme.GetSeriesColor(index),
+			FillColor:   theme.GetSeriesColor(index),
+			StrokeWidth: 2,
+		}
+		textBox := r.MeasureText(text)
+		renderText := func() {
+			x += textPadding
+			legendDraw.text(text, x, y+legendDotHeight-1)
+			x += textBox.Width()
+			x += textPadding
+		}
+
+		if opt.Align == PositionRight {
+			renderText()
+		}
+
+		style.GetFillAndStrokeOptions().WriteDrawingOptionsToRenderer(r)
+		legendDraw.moveTo(x, y)
+		legendDraw.lineTo(x+legendWidth, y)
+		r.Stroke()
+		legendDraw.circle(float64(legendDotHeight), x+legendWidth>>1, y)
+		r.FillStroke()
+		x += legendWidth
+
+		if opt.Align != PositionRight {
+			renderText()
+		}
+	}
+	legendBox := padding.Clone()
+	legendBox.Right = legendBox.Left + x
+	legendBox.Bottom = legendBox.Top + 2*legendDotHeight
+
+	return legendBox, nil
+}

line_chart.go

@@ -53,7 +53,13 @@ func NewLineChart(opt LineChartOption) (*Draw, error) {
 	}
 
 	// 标题
-	_, titleHeight, err := drawTitle(d, &opt.Title)
+	titleBox, err := drawTitle(d, &opt.Title)
+	if err != nil {
+		return nil, err
+	}
+
+	opt.Legend.Style.Padding.Left += titleBox.Right
+	_, err = drawLegend(d, &opt.Legend, &theme)
 	if err != nil {
 		return nil, err
 	}
@@ -66,7 +72,7 @@ func NewLineChart(opt LineChartOption) (*Draw, error) {
 
 	// 暂时仅支持单一yaxis
 	yRange, err := drawYAxis(d, &opt.ChartOption, &theme, xAxisHeight, chart.Box{
-		Top: titleHeight,
+		Top: titleBox.Height(),
 	})
 	if err != nil {
 		return nil, err
@@ -75,7 +81,7 @@ func NewLineChart(opt LineChartOption) (*Draw, error) {
 	sd, err := NewDraw(DrawOption{
 		Parent: d,
 	}, PaddingOption(chart.Box{
-		Top:  titleHeight,
+		Top:  titleBox.Height(),
 		Left: YAxisWidth,
 	}))
 	if err != nil {

title.go

@@ -41,9 +41,9 @@ type titleMeasureOption struct {
 	text   string
 }
 
-func drawTitle(d *Draw, opt *TitleOption) (int, int, error) {
+func drawTitle(d *Draw, opt *TitleOption) (chart.Box, error) {
 	if len(opt.Text) == 0 {
-		return 0, 0, nil
+		return chart.BoxZero, nil
 	}
 
 	padding := opt.Style.Padding
@@ -51,7 +51,7 @@ func drawTitle(d *Draw, opt *TitleOption) (int, int, error) {
 		Parent: d,
 	}, PaddingOption(padding))
 	if err != nil {
-		return 0, 0, err
+		return chart.BoxZero, err
 	}
 
 	r := titleDraw.Render
@@ -107,6 +107,9 @@ func drawTitle(d *Draw, opt *TitleOption) (int, int, error) {
 		titleY += textMaxHeight
 	}
 	height := titleY + padding.Top + padding.Bottom
+	box := padding.Clone()
+	box.Right = box.Left + width
+	box.Bottom = box.Top + height
 
-	return width, height, nil
+	return box, nil
 }

util.go

@@ -22,7 +22,12 @@
 
 package charts
 
-import "github.com/wcharczuk/go-chart/v2"
+import (
+	"strconv"
+	"strings"
+
+	"github.com/wcharczuk/go-chart/v2"
+)
 
 func TrueFlag() *bool {
 	t := true
@@ -90,3 +95,14 @@ func reverseIntSlice(intList []int) {
 		intList[i], intList[j] = intList[j], intList[i]
 	}
 }
+
+func convertPercent(value string) float64 {
+	if !strings.HasSuffix(value, "%") {
+		return -1
+	}
+	v, err := strconv.Atoi(strings.ReplaceAll(value, "%", ""))
+	if err != nil {
+		return -1
+	}
+	return float64(v) / 100
+}