feat: support mark point for line chart

line_chart.go

@@ -23,6 +23,8 @@
 package charts
 
 import (
+	"math"
+
 	"github.com/wcharczuk/go-chart/v2"
 	"github.com/wcharczuk/go-chart/v2/drawing"
 )
@@ -47,7 +49,19 @@ func lineChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error)
 	xRange := result.xRange
 	for i, series := range opt.SeriesList {
 		points := make([]Point, 0)
+		minIndex := -1
+		maxIndex := -1
+		minValue := math.MaxFloat64
+		maxValue := -math.MaxFloat64
 		for j, item := range series.Data {
+			if item.Value < minValue {
+				minIndex = j
+				minValue = item.Value
+			}
+			if item.Value > maxValue {
+				maxIndex = j
+				maxValue = item.Value
+			}
 			y := yRange.getRestHeight(item.Value)
 			x := xRange.getWidth(float64(j))
 			points = append(points, Point{
@@ -86,6 +100,34 @@ func lineChartRender(opt ChartOption, result *basicRenderResult) (*Draw, error)
 			DotWidth:     2,
 			DotFillColor: dotFillColor,
 		})
+		// draw mark point
+		symbolSize := 30
+		if series.MarkPoint.SymbolSize > 0 {
+			symbolSize = series.MarkPoint.SymbolSize
+		}
+		for _, markPointData := range series.MarkPoint.Data {
+			p := points[minIndex]
+			value := minValue
+			switch markPointData.Type {
+			case SeriesMarkPointDataTypeMax:
+				p = points[maxIndex]
+				value = maxValue
+			}
+			chart.Style{
+				FillColor: seriesColor,
+			}.WriteToRenderer(r)
+			d.pin(p.X, p.Y-symbolSize>>1, symbolSize)
+
+			chart.Style{
+				FontColor:   NewTheme(ThemeDark).GetTextColor(),
+				FontSize:    10,
+				StrokeWidth: 1,
+				Font:        opt.Font,
+			}.WriteTextOptionsToRenderer(d.Render)
+			text := commafWithDigits(value)
+			textBox := r.MeasureText(text)
+			d.text(text, p.X-textBox.Width()>>1, p.Y-symbolSize>>1-2)
+		}
 	}
 
 	return result.d, nil