refactor: adjust bar series

bar_series.go

@@ -52,19 +52,39 @@ func (bs BarSeries) Render(r chart.Renderer, canvasBox chart.Box, xrange, yrange
 
 	cb := canvasBox.Bottom
 	cl := canvasBox.Left
+
+	columnWidth := canvasBox.Width() / bs.Len()
+	// 块间隔
+	columnMargin := columnWidth / 10
+	minColumnMargin := 2
+	if columnMargin < minColumnMargin {
+		columnMargin = minColumnMargin
+	}
 	margin := bs.Margin
 	if margin <= 0 {
 		margin = defaultBarMargin
 	}
-	barWidth := bs.BarWidth
-	if barWidth <= 0 {
-		barWidth = canvasBox.Width() / (bs.Len() * bs.Count)
+	// 如果margin大于column margin
+	if margin > columnMargin {
+		margin = columnMargin
+	}
+
+	allBarMarginWidth := (bs.Count - 1) * margin
+	barWidth := ((columnWidth - 2*columnMargin) - allBarMarginWidth) / bs.Count
+	if bs.BarWidth > 0 && bs.BarWidth < barWidth {
+		barWidth = bs.BarWidth
+		// 重新计息columnMargin
+		columnMargin = (columnWidth - allBarMarginWidth - (bs.Count * barWidth)) / 2
 	}
 
 	for i := 0; i < bs.Len(); i++ {
 		vx, vy := bs.GetValues(i)
 
-		x := cl + xrange.Translate(vx) + bs.Index*(margin+barWidth) + bs.Offset
+		x := cl + xrange.Translate(vx)
+		// 由于bar是居中展示，因此需要往前移一个显示块
+		x += (-columnWidth + columnMargin)
+		// 计算是第几个bar，位置右偏
+		x += bs.Index * (margin + barWidth)
 		y := cb - yrange.Translate(vy)
 
 		chart.Draw.Box(r, chart.Box{
@@ -74,5 +94,4 @@ func (bs BarSeries) Render(r chart.Renderer, canvasBox chart.Box, xrange, yrange
 			Bottom: canvasBox.Bottom - 1,
 		}, style)
 	}
-
 }

base_series.go

@@ -79,10 +79,11 @@ func (cs BaseSeries) GetValues(index int) (float64, float64) {
 
 // GetFirstValues gets the first x,y values.
 func (cs BaseSeries) GetFirstValues() (float64, float64) {
+	index := 0
 	if cs.TickPosition == chart.TickPositionBetweenTicks {
-		return cs.XValues[1], cs.YValues[1]
+		index++
 	}
-	return cs.XValues[0], cs.YValues[0]
+	return cs.XValues[index], cs.YValues[index]
 }
 
 // GetLastValues gets the last x,y values.

charts.go

@@ -44,6 +44,21 @@ type (
 		Series       []Series
 		Title        Title
 		Legend       Legend
+		TickPosition chart.TickPosition
+	}
+	ECharOption struct {
+		Title struct {
+			Text      string
+			TextStyle struct {
+				Color      string
+				FontFamily string
+			}
+		}
+		XAxis struct {
+			Type        string
+			BoundaryGap bool
+			Data        []string
+		}
 	}
 )
 
@@ -69,8 +84,7 @@ func ToSVG(c *chart.Chart) ([]byte, error) {
 	return render(c, chart.SVG)
 }
 func New(opt Option) *chart.Chart {
-	tickPosition := chart.TickPositionBetweenTicks
-	// tickPosition = chart.TickPositionUnset
+	tickPosition := opt.TickPosition
 
 	xAxis, xValues := GetXAxisAndValues(opt.XAxis, tickPosition, opt.Theme)
 
@@ -92,6 +106,7 @@ func New(opt Option) *chart.Chart {
 		YAxis:  GetYAxis(opt.Theme),
 		Series: GetSeries(opt.Series, tickPosition, opt.Theme),
 	}
+	// TODO 校验xAxis与yAxis的数量是否一致
 	// 设置secondary的样式
 	c.YAxisSecondary.Style = c.YAxis.Style
 	if legendSize != 0 {

series.go

@@ -62,12 +62,16 @@ func GetSeries(series []Series, tickPosition chart.TickPosition, theme string) [
 		style := chart.Style{
 			StrokeWidth: lineStrokeWidth,
 			StrokeColor: getSeriesColor(theme, index),
+			// TODO 调整为通过dot with color 生成
 			DotColor: getSeriesColor(theme, index),
 			DotWidth: dotWith,
 		}
+		// 如果居中，需要多增加一个点
+		if tickPosition == chart.TickPositionBetweenTicks {
 			item.Data = append([]float64{
 				0.0,
 			}, item.Data...)
+		}
 		baseSeries := BaseSeries{
 			Name:         item.Name,
 			XValues:      item.XValues,