From 07c96b1948a3671aacdde8f2de78b258d83db08b Mon Sep 17 00:00:00 2001
From: Will Charczuk <will@clotheshor.se>
Date: Tue, 12 Jul 2016 22:55:46 -0700
Subject: [PATCH] updates

---
 chart.go | 31 +++++++++++++++++++++++++++++++
 yaxis.go | 11 ++++-------
 2 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/chart.go b/chart.go
index 0d06a21..c32696f 100644
--- a/chart.go
+++ b/chart.go
@@ -95,6 +95,11 @@ func (c Chart) Render(rp RendererProvider, w io.Writer) error {
 	xf, yf, yfa := c.getValueFormatters()
 	xr, yr, yra = c.setRangeDomains(canvasBox, xr, yr, yra)
 
+	err = c.checkRanges(xr, yr, yra)
+	if err != nil {
+		return err
+	}
+
 	if c.hasAxes() {
 		xt, yt, yta = c.getAxesTicks(r, xr, yr, yra, xf, yf, yfa)
 		canvasBox = c.getAxisAdjustedCanvasBox(r, canvasBox, xr, yr, yra, xt, yt, yta)
@@ -180,6 +185,23 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 	return
 }
 
+func (c Chart) checkRanges(xr, yr, yra Range) error {
+
+	if math.IsInf(xr.Delta(), 0) || math.IsNaN(xr.Delta()) {
+		return errors.New("Invalid (infinite or NaN) x-range delta")
+	}
+	if math.IsInf(yr.Delta(), 0) || math.IsNaN(yr.Delta()) {
+		return errors.New("Invalid (infinite or NaN) y-range delta")
+	}
+	if c.hasSecondarySeries() {
+		if math.IsInf(yra.Delta(), 0) || math.IsNaN(yra.Delta()) {
+			return errors.New("Invalid (infinite or NaN) y-secondary-range delta")
+		}
+	}
+
+	return nil
+}
+
 func (c Chart) getDefaultCanvasBox() Box {
 	dpt := c.Background.Padding.GetTop(DefaultBackgroundPadding.Top)
 	dpl := c.Background.Padding.GetLeft(DefaultBackgroundPadding.Left)
@@ -275,6 +297,15 @@ func (c Chart) hasAnnotationSeries() bool {
 	return false
 }
 
+func (c Chart) hasSecondarySeries() bool {
+	for _, s := range c.Series {
+		if s.GetYAxis() == YAxisSecondary {
+			return true
+		}
+	}
+	return false
+}
+
 func (c Chart) getAnnotationAdjustedCanvasBox(r Renderer, canvasBox Box, xr, yr, yra Range, xf, yf, yfa ValueFormatter) Box {
 	annotationSeriesBox := canvasBox.Clone()
 	for seriesIndex, s := range c.Series {
diff --git a/yaxis.go b/yaxis.go
index 36c6ccd..833ce08 100644
--- a/yaxis.go
+++ b/yaxis.go
@@ -37,14 +37,10 @@ func (ya YAxis) GetStyle() Style {
 // GetTicks returns the ticks for a series. It coalesces between user provided ticks and
 // generated ticks.
 func (ya YAxis) GetTicks(r Renderer, ra Range, defaults Style, vf ValueFormatter) []Tick {
-	var ticks []Tick
 	if len(ya.Ticks) > 0 {
-		ticks = ya.Ticks
-	} else {
-		ticks = ya.generateTicks(r, ra, defaults, vf)
+		return ya.Ticks
 	}
-
-	return ticks
+	return ya.generateTicks(r, ra, defaults, vf)
 }
 
 func (ya YAxis) generateTicks(r Renderer, ra Range, defaults Style, vf ValueFormatter) []Tick {
@@ -65,7 +61,8 @@ func (ya YAxis) getTickCount(r Renderer, ra Range, defaults Style, vf ValueForma
 	//given the domain, figure out how many ticks we can draw ...
 	label := vf(ra.Min)
 	tb := r.MeasureText(label)
-	return int(math.Ceil(float64(ra.Domain) / float64(tb.Height()+DefaultMinimumTickVerticalSpacing)))
+	count := int(math.Ceil(float64(ra.Domain) / float64(tb.Height()+DefaultMinimumTickVerticalSpacing)))
+	return count
 }
 
 // GetGridLines returns the gridlines for the axis.