From 0a80e7056f69f21d1561f4426877ab7fa376dd4f Mon Sep 17 00:00:00 2001
From: vicanso <tree.xie@outlook.com>
Date: Wed, 28 Sep 2022 20:29:22 +0800
Subject: [PATCH] feat: support setting bar width for bar chart, #24

---
 bar_chart.go    | 10 ++++++++--
 chart_option.go |  2 ++
 charts.go       |  7 ++++---
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/bar_chart.go b/bar_chart.go
index 8826ffb..2addd17 100644
--- a/bar_chart.go
+++ b/bar_chart.go
@@ -59,7 +59,8 @@ type BarChartOption struct {
 	// The option of title
 	Title TitleOption
 	// The legend option
-	Legend LegendOption
+	Legend   LegendOption
+	BarWidth int
 }
 
 func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (Box, error) {
@@ -86,7 +87,12 @@ func (b *barChart) render(result *defaultRenderResult, seriesList SeriesList) (B
 	}
 	seriesCount := len(seriesList)
 	// 总的宽度-两个margin-(总数-1)的barMargin
-	barWidth := (width - 2*margin - barMargin*(seriesCount-1)) / len(seriesList)
+	barWidth := (width - 2*margin - barMargin*(seriesCount-1)) / seriesCount
+	if opt.BarWidth > 0 && opt.BarWidth < barWidth {
+		barWidth = opt.BarWidth
+		// 重新计算margin
+		margin = (width - len(seriesList)*barWidth - barMargin*(seriesCount-1)) / 2
+	}
 	barMaxHeight := seriesPainter.Height()
 	theme := opt.Theme
 	seriesNames := seriesList.Names()
diff --git a/chart_option.go b/chart_option.go
index 93b81ba..447ef52 100644
--- a/chart_option.go
+++ b/chart_option.go
@@ -66,6 +66,8 @@ type ChartOption struct {
 	SymbolShow *bool
 	// The stroke width of line chart
 	LineStrokeWidth float64
+	// The bar with of bar chart
+	BarWidth int
 	// Fill the area of line chart
 	FillArea bool
 	// The child charts
diff --git a/charts.go b/charts.go
index f7e52e4..f8c94a3 100644
--- a/charts.go
+++ b/charts.go
@@ -354,9 +354,10 @@ func Render(opt ChartOption, opts ...OptionFunc) (*Painter, error) {
 	if len(barSeriesList) != 0 {
 		handler.Add(func() error {
 			_, err := NewBarChart(p, BarChartOption{
-				Theme: opt.theme,
-				Font:  opt.font,
-				XAxis: opt.XAxis,
+				Theme:    opt.theme,
+				Font:     opt.font,
+				XAxis:    opt.XAxis,
+				BarWidth: opt.BarWidth,
 			}).render(renderResult, barSeriesList)
 			return err
 		})