feat: support bar height for horizontal bar chart

bar_chart.go

@@ -91,7 +91,7 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 	if opt.BarWidth > 0 && opt.BarWidth < barWidth {
 		barWidth = opt.BarWidth
 		// 重新计算margin
-		margin = (width - len(seriesList)*barWidth - barMargin*(seriesCount-1)) / 2
+		margin = (width - seriesCount*barWidth - barMargin*(seriesCount-1)) / 2
 	}
 	barMaxHeight := seriesPainter.Height()
 	theme := opt.Theme

chart_option.go

@@ -68,6 +68,8 @@ type ChartOption struct {
 	LineStrokeWidth float64
 	// The bar with of bar chart
 	BarWidth int
+	// The bar height of horizontal bar chart
+	BarHeight int
 	// Fill the area of line chart
 	FillArea bool
 	// The child charts

charts.go

@@ -369,6 +369,7 @@ func Render(opt ChartOption, opts ...OptionFunc) (*Painter, error) {
 			_, err := NewHorizontalBarChart(p, HorizontalBarChartOption{
 				Theme:        opt.theme,
 				Font:         opt.font,
+				BarHeight:    opt.BarHeight,
 				YAxisOptions: opt.YAxisOptions,
 			}).render(renderResult, horizontalBarSeriesList)
 			return err

horizontal_bar_chart.go

@@ -48,7 +48,8 @@ type HorizontalBarChartOption struct {
 	// The option of title
 	Title TitleOption
 	// The legend option
-	Legend LegendOption
+	Legend    LegendOption
+	BarHeight int
 }
 
 // NewHorizontalBarChart returns a horizontal bar chart renderer
@@ -82,7 +83,11 @@ func (h *horizontalBarChart) render(result *defaultRenderResult, seriesList Seri
 	}
 	seriesCount := len(seriesList)
 	// 总的高度-两个margin-(总数-1)的barMargin
-	barHeight := (height - 2*margin - barMargin*(seriesCount-1)) / len(seriesList)
+	barHeight := (height - 2*margin - barMargin*(seriesCount-1)) / seriesCount
+	if opt.BarHeight > 0 && opt.BarHeight < barHeight {
+		barHeight = opt.BarHeight
+		margin = (height - seriesCount*barHeight - barMargin*(seriesCount-1)) / 2
+	}
 
 	theme := opt.Theme