feat: support label for line chart, #23

bar_chart.go

@@ -62,13 +62,6 @@ type BarChartOption struct {
 	Legend LegendOption
 }
 
-type barChartLabelRenderOption struct {
-	Text  string
-	Style Style
-	X     int
-	Y     int
-}
-
 func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (Box, error) {
 	p := b.p
 	opt := b.opt
@@ -100,11 +93,12 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 
 	markPointPainter := NewMarkPointPainter(seriesPainter)
 	markLinePainter := NewMarkLinePainter(seriesPainter)
+	labelPainter := NewSeriesLabelPainter(seriesPainter)
 	rendererList := []Renderer{
+		labelPainter,
 		markPointPainter,
 		markLinePainter,
 	}
-	labelRenderOptions := make([]barChartLabelRenderOption, 0)
 	for index := range seriesList {
 		series := seriesList[index]
 		yRange := result.axisRanges[series.AxisIndex]
@@ -168,8 +162,7 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 			}
 
 			textBox := seriesPainter.MeasureText(text)
-
+			labelPainter.Add(LabelValue{
-			labelRenderOptions = append(labelRenderOptions, barChartLabelRenderOption{
 				Text:  text,
 				Style: labelStyle,
 				X:     x + (barWidth-textBox.Width())>>1,
@@ -192,10 +185,6 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 			Range:       yRange,
 		})
 	}
-	for _, labelOpt := range labelRenderOptions {
-		seriesPainter.OverrideTextStyle(labelOpt.Style)
-		seriesPainter.Text(labelOpt.Text, labelOpt.X, labelOpt.Y)
-	}
 	// 最大、最小的mark point
 	err := doRender(rendererList...)
 	if err != nil {

line_chart.go

@@ -97,7 +97,9 @@ func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (
 	}
 	markPointPainter := NewMarkPointPainter(seriesPainter)
 	markLinePainter := NewMarkLinePainter(seriesPainter)
+	labelPainter := NewSeriesLabelPainter(seriesPainter)
 	rendererList := []Renderer{
+		labelPainter,
 		markPointPainter,
 		markLinePainter,
 	}
@@ -105,6 +107,8 @@ func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (
 	if strokeWidth == 0 {
 		strokeWidth = defaultStrokeWidth
 	}
+	seriesNames := seriesList.Names()
+	theme := opt.Theme
 	for index := range seriesList {
 		series := seriesList[index]
 		seriesColor := opt.Theme.GetSeriesColor(series.index)
@@ -125,6 +129,32 @@ func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (
 				Y: h,
 			}
 			points = append(points, p)
+
+			// 如果label不需要展示，则返回
+			if !series.Label.Show {
+				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,
+				Style: labelStyle,
+				X:     p.X - textBox.Width()>>1,
+				Y:     p.Y - distance,
+			})
 		}
 		// 如果需要填充区域
 		if opt.FillArea {

series_label.go

@@ -0,0 +1,56 @@
+// 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 LabelValue struct {
+	Text  string
+	Style Style
+	X     int
+	Y     int
+}
+
+type SeriesLabelPainter struct {
+	p      *Painter
+	values []LabelValue
+}
+
+func NewSeriesLabelPainter(p *Painter) *SeriesLabelPainter {
+	return &SeriesLabelPainter{
+		p:      p,
+		values: make([]LabelValue, 0),
+	}
+}
+
+func (o *SeriesLabelPainter) Add(value LabelValue) {
+	o.values = append(o.values, value)
+}
+
+func (o *SeriesLabelPainter) Render() (Box, error) {
+	for _, item := range o.values {
+		o.p.OverrideTextStyle(item.Style)
+		o.p.Text(item.Text, item.X, item.Y)
+	}
+	return chart.BoxZero, nil
+}