feat: support bar margin

horizontal_bar_chart.go

@@ -50,6 +50,8 @@ type HorizontalBarChartOption struct {
 	// The legend option
 	Legend    LegendOption
 	BarHeight int
+	// Margin of bar
+	BarMargin int
 }
 
 // NewHorizontalBarChart returns a horizontal bar chart renderer
@@ -81,6 +83,9 @@ func (h *horizontalBarChart) render(result *defaultRenderResult, seriesList Seri
 		margin = 5
 		barMargin = 3
 	}
+	if opt.BarMargin > 0 {
+		barMargin = opt.BarMargin
+	}
 	seriesCount := len(seriesList)
 	// 总的高度-两个margin-(总数-1)的barMargin
 	barHeight := (height - 2*margin - barMargin*(seriesCount-1)) / seriesCount