some regression tests

chart_test.go

@@ -2,6 +2,7 @@ package chart
 
 import (
 	"bytes"
+	"math"
 	"testing"
 	"time"
 
@@ -265,3 +266,41 @@ func TestChartSingleSeries(t *testing.T) {
 	c.Render(PNG, buffer)
 	assert.NotEmpty(buffer.Bytes())
 }
+
+func TestChartRegressionBadRanges(t *testing.T) {
+	assert := assert.New(t)
+
+	c := Chart{
+		Series: []Series{
+			ContinuousSeries{
+				XValues: []float64{math.Inf(1), math.Inf(1), math.Inf(1), math.Inf(1), math.Inf(1)},
+				YValues: []float64{1.0, 2.0, 3.0, 4.0, 4.5},
+			},
+		},
+	}
+	buffer := bytes.NewBuffer([]byte{})
+	c.Render(PNG, buffer)
+	assert.True(true, "Render needs to finish.")
+}
+
+func TestChartRegressionBadRangesByUser(t *testing.T) {
+	assert := assert.New(t)
+
+	c := Chart{
+		YAxis: YAxis{
+			Range: Range{
+				Min: math.Inf(-1),
+				Max: math.Inf(1), // this could really happen? eh.
+			},
+		},
+		Series: []Series{
+			ContinuousSeries{
+				XValues: Seq(1.0, 10.0),
+				YValues: Seq(1.0, 10.0),
+			},
+		},
+	}
+	buffer := bytes.NewBuffer([]byte{})
+	c.Render(PNG, buffer)
+	assert.True(true, "Render needs to finish.")
+}

defaults.go

@@ -43,8 +43,10 @@ const (
 	//DefaultHorizontalTickWidth is half the margin.
 	DefaultHorizontalTickWidth = DefaultYAxisMargin >> 1
 
-	// DefaultTickCount is the defautl number of ticks to show
+	// DefaultTickCount is the default number of ticks to show
 	DefaultTickCount = 10
+	// DefaultTickCountSanityCheck is a hard limit on number of ticks to prevent infinite loops.
+	DefaultTickCountSanityCheck = 1 << 10 //1024
 
 	// DefaultMinimumTickHorizontalSpacing is the minimum distance between horizontal ticks.
 	DefaultMinimumTickHorizontalSpacing = 20

tick.go

@@ -9,6 +9,11 @@ func GenerateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick {
 			Value: cursor,
 			Label: vf(cursor),
 		})
+
+		// this guard is in place in case step is super, super small.
+		if len(ticks) > DefaultTickCountSanityCheck {
+			return ticks
+		}
 	}
 	return ticks
 }

time_series.go

@@ -30,7 +30,7 @@ func (ts TimeSeries) Len() int {
 
 // GetValue gets a value at a given index.
 func (ts TimeSeries) GetValue(index int) (x float64, y float64) {
-	x = float64(ts.XValues[index].Unix())
+	x = TimeToFloat64(ts.XValues[index])
 	y = ts.YValues[index]
 	return
 }

util.go

@@ -122,3 +122,16 @@ func AbsInt(value int) int {
 	}
 	return value
 }
+
+// Seq produces an array of floats from [start,end] by optional steps.
+func Seq(start, end float64, steps ...float64) []float64 {
+	var values []float64
+	step := 1.0
+	if len(steps) > 0 {
+		step = steps[0]
+	}
+	for x := start; x <= end; x += step {
+		values = append(values, x)
+	}
+	return values
+}