refactor: adjust series label render

bar_chart.go

@@ -93,9 +93,7 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 
 	markPointPainter := NewMarkPointPainter(seriesPainter)
 	markLinePainter := NewMarkLinePainter(seriesPainter)
-	labelPainter := NewSeriesLabelPainter(seriesPainter)
 	rendererList := []Renderer{
-		labelPainter,
 		markPointPainter,
 		markLinePainter,
 	}
@@ -106,6 +104,18 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 
 		divideValues := xRange.AutoDivide()
 		points := make([]Point, len(series.Data))
+		var labelPainter *SeriesLabelPainter
+		if series.Label.Show {
+			labelPainter = NewSeriesLabelPainter(SeriesLabelPainterParams{
+				P:           seriesPainter,
+				SeriesNames: seriesNames,
+				Label:       series.Label,
+				Theme:       opt.Theme,
+				Font:        opt.Font,
+			})
+			rendererList = append(rendererList, labelPainter)
+		}
+
 		for j, item := range series.Data {
 			if j >= xRange.divideCount {
 				continue
@@ -144,29 +154,14 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 				Y: top,
 			}
 			// 如果label不需要展示，则返回
-			if !series.Label.Show {
+			if labelPainter == nil {
 				continue
 			}
-			distance := series.Label.Distance
-			if distance == 0 {
-				distance = 5
-			}
-			text := NewValueLabelFormatter(seriesNames, series.Label.Formatter)(index, item.Value, -1)
-			labelStyle := Style{
-				FontColor: theme.GetTextColor(),
-				FontSize:  labelFontSize,
-				Font:      opt.Font,
-			}
-			if !series.Label.Color.IsZero() {
-				labelStyle.FontColor = series.Label.Color
-			}
-
-			textBox := seriesPainter.MeasureText(text)
 			labelPainter.Add(LabelValue{
-				Text:  text,
+				Index: index,
-				Style: labelStyle,
+				Value: item.Value,
-				X:     x + (barWidth-textBox.Width())>>1,
+				X:     x + barWidth>>1,
-				Y:     barMaxHeight - h - distance,
+				Y:     barMaxHeight - h,
 			})
 		}
 

line_chart.go

@@ -97,9 +97,7 @@ func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (
 	}
 	markPointPainter := NewMarkPointPainter(seriesPainter)
 	markLinePainter := NewMarkLinePainter(seriesPainter)
-	labelPainter := NewSeriesLabelPainter(seriesPainter)
 	rendererList := []Renderer{
-		labelPainter,
 		markPointPainter,
 		markLinePainter,
 	}
@@ -108,7 +106,6 @@ func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (
 		strokeWidth = defaultStrokeWidth
 	}
 	seriesNames := seriesList.Names()
-	theme := opt.Theme
 	for index := range seriesList {
 		series := seriesList[index]
 		seriesColor := opt.Theme.GetSeriesColor(series.index)
@@ -119,6 +116,17 @@ func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (
 
 		yRange := result.axisRanges[series.AxisIndex]
 		points := make([]Point, 0)
+		var labelPainter *SeriesLabelPainter
+		if series.Label.Show {
+			labelPainter = NewSeriesLabelPainter(SeriesLabelPainterParams{
+				P:           seriesPainter,
+				SeriesNames: seriesNames,
+				Label:       series.Label,
+				Theme:       opt.Theme,
+				Font:        opt.Font,
+			})
+			rendererList = append(rendererList, labelPainter)
+		}
 		for i, item := range series.Data {
 			h := yRange.getRestHeight(item.Value)
 			if item.Value == nullValue {
@@ -131,29 +139,14 @@ func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (
 			points = append(points, p)
 
 			// 如果label不需要展示，则返回
-			if !series.Label.Show {
+			if labelPainter == nil {
 				continue
 			}
-			distance := series.Label.Distance
-			if distance == 0 {
-				distance = 5
-			}
-			text := NewValueLabelFormatter(seriesNames, series.Label.Formatter)(index, item.Value, -1)
-			labelStyle := Style{
-				FontColor: theme.GetTextColor(),
-				FontSize:  labelFontSize,
-				Font:      opt.Font,
-			}
-			if !series.Label.Color.IsZero() {
-				labelStyle.FontColor = series.Label.Color
-			}
-
-			textBox := seriesPainter.MeasureText(text)
 			labelPainter.Add(LabelValue{
-				Text:  text,
+				Index: index,
-				Style: labelStyle,
+				Value: item.Value,
-				X:     p.X - textBox.Width()>>1,
+				X:     p.X,
-				Y:     p.Y - distance,
+				Y:     p.Y,
 			})
 		}
 		// 如果需要填充区域

series_label.go

@@ -22,29 +22,80 @@
 
 package charts
 
-import "github.com/wcharczuk/go-chart/v2"
+import (
+	"github.com/golang/freetype/truetype"
+	"github.com/wcharczuk/go-chart/v2"
+)
 
-type LabelValue struct {
+type labelRenderValue struct {
 	Text  string
 	Style Style
 	X     int
 	Y     int
 }
 
-type SeriesLabelPainter struct {
+type LabelValue struct {
-	p      *Painter
+	Index int
-	values []LabelValue
+	Value float64
+	X     int
+	Y     int
 }
 
-func NewSeriesLabelPainter(p *Painter) *SeriesLabelPainter {
+type SeriesLabelPainter struct {
+	p           *Painter
+	seriesNames []string
+	label       *SeriesLabel
+	theme       ColorPalette
+	font        *truetype.Font
+	values      []labelRenderValue
+}
+
+type SeriesLabelPainterParams struct {
+	P           *Painter
+	SeriesNames []string
+	Label       SeriesLabel
+	Theme       ColorPalette
+	Font        *truetype.Font
+}
+
+func NewSeriesLabelPainter(params SeriesLabelPainterParams) *SeriesLabelPainter {
 	return &SeriesLabelPainter{
-		p:      p,
+		p:           params.P,
-		values: make([]LabelValue, 0),
+		seriesNames: params.SeriesNames,
+		label:       &params.Label,
+		theme:       params.Theme,
+		font:        params.Font,
+		values:      make([]labelRenderValue, 0),
 	}
 }
 
 func (o *SeriesLabelPainter) Add(value LabelValue) {
-	o.values = append(o.values, value)
+	label := o.label
+	distance := label.Distance
+	if distance == 0 {
+		distance = 5
+	}
+	text := NewValueLabelFormatter(o.seriesNames, label.Formatter)(value.Index, value.Value, -1)
+	labelStyle := Style{
+		FontColor: o.theme.GetTextColor(),
+		FontSize:  labelFontSize,
+		Font:      o.font,
+	}
+	if !label.Color.IsZero() {
+		labelStyle.FontColor = label.Color
+	}
+	o.p.OverrideDrawingStyle(labelStyle)
+	textBox := o.p.MeasureText(text)
+	renderValue := labelRenderValue{
+		Text:  text,
+		Style: labelStyle,
+		X:     value.X - textBox.Width()>>1,
+		Y:     value.Y - distance,
+	}
+	if textBox.Width()%2 != 0 {
+		renderValue.X++
+	}
+	o.values = append(o.values, renderValue)
 }
 
 func (o *SeriesLabelPainter) Render() (Box, error) {