line_chart: fix BounaryGap bug from last commit

Last commit disabled the boundary gap when it was small, but it did it at a later point that resulted in just the right side being corrected.
We need to decide if we are disabling the boundary gap for the line before we do the autoDivide action.

line_chart.go

@@ -52,20 +52,19 @@ type LineChartOption struct {
 func (l *lineChart) render(result *defaultRenderResult, seriesList SeriesList) (Box, error) {
 	p := l.p
 	opt := l.opt
-	boundaryGap := !isFalse(opt.XAxis.BoundaryGap)
-
 	seriesPainter := result.seriesPainter
 
+	boundaryGap := !isFalse(opt.XAxis.BoundaryGap)
 	xDivideCount := len(opt.XAxis.Data)
-	if !boundaryGap {
-		xDivideCount--
-	}
-	xDivideValues := autoDivide(seriesPainter.Width(), xDivideCount)
-	if boundaryGap && xDivideCount > 1 && xDivideValues[1]-xDivideValues[0] <= 10 {
+	if boundaryGap && xDivideCount > 1 && seriesPainter.Width()/xDivideCount <= 10 {
 		// boundary gap would be so small it's visually better to disable the line spacing adjustment and just keep
 		// the label changes only
 		boundaryGap = false
 	}
+	if !boundaryGap {
+		xDivideCount--
+	}
+	xDivideValues := autoDivide(seriesPainter.Width(), xDivideCount)
 	xValues := make([]int, len(xDivideValues)-1)
 	if boundaryGap {
 		for i := 0; i < len(xDivideValues)-1; i++ {