introduces the `Range` interface (instead of a concrete type).

annotation_series.go

@@ -40,7 +40,7 @@ func (as AnnotationSeries) Measure(r Renderer, canvasBox Box, xrange, yrange Ran
 		Bottom: 0,
 	}
 	if as.Style.IsZero() || as.Style.Show {
-		style := as.Style.WithDefaultsFrom(Style{
+		style := as.Style.InheritFrom(Style{
 			Font:        defaults.Font,
 			FillColor:   DefaultAnnotationFillColor,
 			FontSize:    DefaultAnnotationFontSize,
@@ -64,7 +64,7 @@ func (as AnnotationSeries) Measure(r Renderer, canvasBox Box, xrange, yrange Ran
 // Render draws the series.
 func (as AnnotationSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
 	if as.Style.IsZero() || as.Style.Show {
-		style := as.Style.WithDefaultsFrom(Style{
+		style := as.Style.InheritFrom(Style{
 			Font:        defaults.Font,
 			FontColor:   DefaultTextColor,
 			FillColor:   DefaultAnnotationFillColor,

annotation_series_test.go

@@ -29,12 +29,12 @@ func TestAnnotationSeriesMeasure(t *testing.T) {
 	f, err := GetDefaultFont()
 	assert.Nil(err)
 
-	xrange := Range{
+	xrange := &ContinuousRange{
 		Min:    1.0,
 		Max:    4.0,
 		Domain: 100,
 	}
-	yrange := Range{
+	yrange := &ContinuousRange{
 		Min:    1.0,
 		Max:    4.0,
 		Domain: 100,
@@ -82,12 +82,12 @@ func TestAnnotationSeriesRender(t *testing.T) {
 	f, err := GetDefaultFont()
 	assert.Nil(err)
 
-	xrange := Range{
+	xrange := &ContinuousRange{
 		Min:    1.0,
 		Max:    4.0,
 		Domain: 100,
 	}
-	yrange := Range{
+	yrange := &ContinuousRange{
 		Min:    1.0,
 		Max:    4.0,
 		Domain: 100,

axis.go

@@ -14,7 +14,17 @@ const (
 type Axis interface {
 	GetName() string
 	GetStyle() Style
-	GetTicks(r Renderer, ra Range, vf ValueFormatter) []Tick
+
+	GetTicks() []Tick
+	GenerateTicks(r Renderer, ra Range, vf ValueFormatter) []Tick
+
+	// GetGridLines returns the gridlines for the axis.
 	GetGridLines(ticks []Tick) []GridLine
-	Render(c *Chart, r Renderer, canvasBox Box, ra Range, ticks []Tick)
+
+	// Measure should return an absolute box for the axis.
+	// This is used when auto-fitting the canvas to the background.
+	Measure(r Renderer, canvasBox Box, ra Range, style Style, ticks []Tick) Box
+
+	// Render renders the axis.
+	Render(r Renderer, canvasBox Box, ra Range, style Style, ticks []Tick)
 }

bollinger_band_series.go

@@ -108,7 +108,7 @@ func (bbs *BollingerBandsSeries) GetBoundedLastValue() (x, y1, y2 float64) {
 
 // Render renders the series.
 func (bbs *BollingerBandsSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	s := bbs.Style.WithDefaultsFrom(defaults.WithDefaultsFrom(Style{
+	s := bbs.Style.InheritFrom(defaults.InheritFrom(Style{
 		StrokeWidth: 1.0,
 		StrokeColor: DefaultAxisColor.WithAlpha(64),
 		FillColor:   DefaultAxisColor.WithAlpha(32),

chart.go

@@ -137,7 +137,7 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 	var miny, maxy float64 = math.MaxFloat64, 0
 	var minya, maxya float64 = math.MaxFloat64, 0
 
-	hasSecondaryAxis := false
+	seriesMappedToSecondaryAxis := false
 
 	// note: a possible future optimization is to not scan the series values if
 	// all axis are represented by either custom ticks or custom ranges.
@@ -162,7 +162,7 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 						minya = math.Min(minya, vy2)
 						maxya = math.Max(maxya, vy1)
 						maxya = math.Max(maxya, vy2)
-						hasSecondaryAxis = true
+						seriesMappedToSecondaryAxis = true
 					}
 				}
 			} else if vp, isValueProvider := s.(ValueProvider); isValueProvider {
@@ -179,27 +179,40 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 					} else if seriesAxis == YAxisSecondary {
 						minya = math.Min(minya, vy)
 						maxya = math.Max(maxya, vy)
-						hasSecondaryAxis = true
+						seriesMappedToSecondaryAxis = true
 					}
 				}
 			}
 		}
 	}
 
+	if xrange == nil {
+		xrange = &ContinuousRange{}
+	}
+
+	if yrange == nil {
+		yrange = &ContinuousRange{}
+	}
+
+	if yrangeAlt == nil {
+		yrangeAlt = &ContinuousRange{}
+	}
+
 	if len(c.XAxis.Ticks) > 0 {
 		tickMin, tickMax := math.MaxFloat64, 0.0
 		for _, t := range c.XAxis.Ticks {
 			tickMin = math.Min(tickMin, t.Value)
 			tickMax = math.Max(tickMax, t.Value)
 		}
-		xrange.Min = tickMin
+
-		xrange.Max = tickMax
+		xrange.SetMin(tickMin)
-	} else if !c.XAxis.Range.IsZero() {
+		xrange.SetMax(tickMax)
-		xrange.Min = c.XAxis.Range.Min
+	} else if c.XAxis.Range != nil && !c.XAxis.Range.IsZero() {
-		xrange.Max = c.XAxis.Range.Max
+		xrange.SetMin(c.XAxis.Range.GetMin())
+		xrange.SetMax(c.XAxis.Range.GetMax())
 	} else {
-		xrange.Min = minx
+		xrange.SetMin(minx)
-		xrange.Max = maxx
+		xrange.SetMax(maxx)
 	}
 
 	if len(c.YAxis.Ticks) > 0 {
@@ -208,15 +221,20 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 			tickMin = math.Min(tickMin, t.Value)
 			tickMax = math.Max(tickMax, t.Value)
 		}
-		yrange.Min = tickMin
+		yrange.SetMin(tickMin)
-		yrange.Max = tickMax
+		yrange.SetMax(tickMax)
-	} else if !c.YAxis.Range.IsZero() {
+	} else if c.YAxis.Range != nil && !c.YAxis.Range.IsZero() {
-		yrange.Min = c.YAxis.Range.Min
+		yrange.SetMin(c.YAxis.Range.GetMin())
-		yrange.Max = c.YAxis.Range.Max
+		yrange.SetMax(c.YAxis.Range.GetMax())
 	} else {
-		yrange.Min = miny
+		yrange.SetMin(miny)
-		yrange.Max = maxy
+		yrange.SetMax(maxy)
-		yrange.Min, yrange.Max = yrange.GetRoundedRangeBounds()
+
+		delta := yrange.GetDelta()
+		roundTo := GetRoundToForDelta(delta)
+		rmin, rmax := RoundDown(yrange.GetMin(), roundTo), RoundUp(yrange.GetMax(), roundTo)
+		yrange.SetMin(rmin)
+		yrange.SetMax(rmax)
 	}
 
 	if len(c.YAxisSecondary.Ticks) > 0 {
@@ -225,30 +243,34 @@ func (c Chart) getRanges() (xrange, yrange, yrangeAlt Range) {
 			tickMin = math.Min(tickMin, t.Value)
 			tickMax = math.Max(tickMax, t.Value)
 		}
-		yrangeAlt.Min = tickMin
+		yrangeAlt.SetMin(tickMin)
-		yrangeAlt.Max = tickMax
+		yrangeAlt.SetMax(tickMax)
-	} else if !c.YAxisSecondary.Range.IsZero() {
+	} else if c.YAxisSecondary.Range != nil && !c.YAxisSecondary.Range.IsZero() {
-		yrangeAlt.Min = c.YAxisSecondary.Range.Min
+		yrangeAlt.SetMin(c.YAxisSecondary.Range.GetMin())
-		yrangeAlt.Max = c.YAxisSecondary.Range.Max
+		yrangeAlt.SetMax(c.YAxisSecondary.Range.GetMax())
-	} else if hasSecondaryAxis {
+	} else if seriesMappedToSecondaryAxis {
-		yrangeAlt.Min = minya
+		yrangeAlt.SetMin(minya)
-		yrangeAlt.Max = maxya
+		yrangeAlt.SetMax(maxya)
-		yrangeAlt.Min, yrangeAlt.Max = yrangeAlt.GetRoundedRangeBounds()
+
+		delta := yrangeAlt.GetDelta()
+		roundTo := GetRoundToForDelta(delta)
+		rmin, rmax := RoundDown(yrangeAlt.GetMin(), roundTo), RoundUp(yrangeAlt.GetMax(), roundTo)
+		yrangeAlt.SetMin(rmin)
+		yrangeAlt.SetMax(rmax)
 	}
 
 	return
 }
 
 func (c Chart) checkRanges(xr, yr, yra Range) error {
-
+	if math.IsInf(xr.GetDelta(), 0) || math.IsNaN(xr.GetDelta()) || xr.GetDelta() == 0 {
-	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()) {
+	if math.IsInf(yr.GetDelta(), 0) || math.IsNaN(yr.GetDelta()) || yr.GetDelta() == 0 {
 		return errors.New("Invalid (infinite or NaN) y-range delta")
 	}
 	if c.hasSecondarySeries() {
-		if math.IsInf(yra.Delta(), 0) || math.IsNaN(yra.Delta()) {
+		if math.IsInf(yra.GetDelta(), 0) || math.IsNaN(yra.GetDelta()) || yra.GetDelta() == 0 {
 			return errors.New("Invalid (infinite or NaN) y-secondary-range delta")
 		}
 	}
@@ -320,14 +342,11 @@ func (c Chart) getAxisAdjustedCanvasBox(r Renderer, canvasBox Box, xr, yr, yra R
 	return canvasBox.OuterConstrain(c.Box(), axesOuterBox)
 }
 
-func (c Chart) setRangeDomains(canvasBox Box, xr, yr, yra Range) (xr2, yr2, yra2 Range) {
+func (c Chart) setRangeDomains(canvasBox Box, xr, yr, yra Range) (Range, Range, Range) {
-	xr2.Min, xr2.Max = xr.Min, xr.Max
+	xr.SetDomain(canvasBox.Width())
-	xr2.Domain = canvasBox.Width()
+	yr.SetDomain(canvasBox.Height())
-	yr2.Min, yr2.Max = yr.Min, yr.Max
+	yra.SetDomain(canvasBox.Height())
-	yr2.Domain = canvasBox.Height()
+	return xr, yr, yra
-	yra2.Min, yra2.Max = yra.Min, yra.Max
-	yra2.Domain = canvasBox.Height()
-	return
 }
 
 func (c Chart) hasAnnotationSeries() bool {
@@ -372,7 +391,7 @@ func (c Chart) getAnnotationAdjustedCanvasBox(r Renderer, canvasBox Box, xr, yr,
 }
 
 func (c Chart) getBackgroundStyle() Style {
-	return c.Background.WithDefaultsFrom(c.styleDefaultsBackground())
+	return c.Background.InheritFrom(c.styleDefaultsBackground())
 }
 
 func (c Chart) drawBackground(r Renderer) {
@@ -383,7 +402,7 @@ func (c Chart) drawBackground(r Renderer) {
 }
 
 func (c Chart) getCanvasStyle() Style {
-	return c.Canvas.WithDefaultsFrom(c.styleDefaultsCanvas())
+	return c.Canvas.InheritFrom(c.styleDefaultsCanvas())
 }
 
 func (c Chart) drawCanvas(r Renderer, canvasBox Box) {

chart_test.go

@@ -77,24 +77,24 @@ func TestChartGetRanges(t *testing.T) {
 	}
 
 	xrange, yrange, yrangeAlt := c.getRanges()
-	assert.Equal(-2.0, xrange.Min)
+	assert.Equal(-2.0, xrange.GetMin())
-	assert.Equal(5.0, xrange.Max)
+	assert.Equal(5.0, xrange.GetMax())
 
-	assert.Equal(-2.1, yrange.Min)
+	assert.Equal(-2.1, yrange.GetMin())
-	assert.Equal(4.5, yrange.Max)
+	assert.Equal(4.5, yrange.GetMax())
 
-	assert.Equal(10.0, yrangeAlt.Min)
+	assert.Equal(10.0, yrangeAlt.GetMin())
-	assert.Equal(14.0, yrangeAlt.Max)
+	assert.Equal(14.0, yrangeAlt.GetMax())
 
 	cSet := Chart{
 		XAxis: XAxis{
-			Range: Range{Min: 9.8, Max: 19.8},
+			Range: &ContinuousRange{Min: 9.8, Max: 19.8},
 		},
 		YAxis: YAxis{
-			Range: Range{Min: 9.9, Max: 19.9},
+			Range: &ContinuousRange{Min: 9.9, Max: 19.9},
 		},
 		YAxisSecondary: YAxis{
-			Range: Range{Min: 9.7, Max: 19.7},
+			Range: &ContinuousRange{Min: 9.7, Max: 19.7},
 		},
 		Series: []Series{
 			ContinuousSeries{
@@ -114,14 +114,14 @@ func TestChartGetRanges(t *testing.T) {
 	}
 
 	xr2, yr2, yra2 := cSet.getRanges()
-	assert.Equal(9.8, xr2.Min)
+	assert.Equal(9.8, xr2.GetMin())
-	assert.Equal(19.8, xr2.Max)
+	assert.Equal(19.8, xr2.GetMax())
 
-	assert.Equal(9.9, yr2.Min)
+	assert.Equal(9.9, yr2.GetMin())
-	assert.Equal(19.9, yr2.Max)
+	assert.Equal(19.9, yr2.GetMax())
 
-	assert.Equal(9.7, yra2.Min)
+	assert.Equal(9.7, yra2.GetMin())
-	assert.Equal(19.7, yra2.Max)
+	assert.Equal(19.7, yra2.GetMax())
 }
 
 func TestChartGetRangesUseTicks(t *testing.T) {
@@ -139,7 +139,7 @@ func TestChartGetRangesUseTicks(t *testing.T) {
 				{4.0, "4.0"},
 				{5.0, "Five"},
 			},
-			Range: Range{
+			Range: &ContinuousRange{
 				Min: -5.0,
 				Max: 5.0,
 			},
@@ -153,10 +153,10 @@ func TestChartGetRangesUseTicks(t *testing.T) {
 	}
 
 	xr, yr, yar := c.getRanges()
-	assert.Equal(-2.0, xr.Min)
+	assert.Equal(-2.0, xr.GetMin())
-	assert.Equal(2.0, xr.Max)
+	assert.Equal(2.0, xr.GetMax())
-	assert.Equal(0.0, yr.Min)
+	assert.Equal(0.0, yr.GetMin())
-	assert.Equal(5.0, yr.Max)
+	assert.Equal(5.0, yr.GetMax())
 	assert.True(yar.IsZero(), yar.String())
 }
 
@@ -165,7 +165,7 @@ func TestChartGetRangesUseUserRanges(t *testing.T) {
 
 	c := Chart{
 		YAxis: YAxis{
-			Range: Range{
+			Range: &ContinuousRange{
 				Min: -5.0,
 				Max: 5.0,
 			},
@@ -179,10 +179,10 @@ func TestChartGetRangesUseUserRanges(t *testing.T) {
 	}
 
 	xr, yr, yar := c.getRanges()
-	assert.Equal(-2.0, xr.Min)
+	assert.Equal(-2.0, xr.GetMin())
-	assert.Equal(2.0, xr.Max)
+	assert.Equal(2.0, xr.GetMax())
-	assert.Equal(-5.0, yr.Min)
+	assert.Equal(-5.0, yr.GetMin())
-	assert.Equal(5.0, yr.Max)
+	assert.Equal(5.0, yr.GetMax())
 	assert.True(yar.IsZero(), yar.String())
 }
 
@@ -310,15 +310,15 @@ func TestChartGetAxesTicks(t *testing.T) {
 	c := Chart{
 		XAxis: XAxis{
 			Style: Style{Show: true},
-			Range: Range{Min: 9.8, Max: 19.8},
+			Range: &ContinuousRange{Min: 9.8, Max: 19.8},
 		},
 		YAxis: YAxis{
 			Style: Style{Show: true},
-			Range: Range{Min: 9.9, Max: 19.9},
+			Range: &ContinuousRange{Min: 9.9, Max: 19.9},
 		},
 		YAxisSecondary: YAxis{
 			Style: Style{Show: true},
-			Range: Range{Min: 9.7, Max: 19.7},
+			Range: &ContinuousRange{Min: 9.7, Max: 19.7},
 		},
 	}
 	xr, yr, yar := c.getRanges()
@@ -337,7 +337,7 @@ func TestChartSingleSeries(t *testing.T) {
 		Width:  1024,
 		Height: 400,
 		YAxis: YAxis{
-			Range: Range{
+			Range: &ContinuousRange{
 				Min: 0.0,
 				Max: 4.0,
 			},
@@ -377,7 +377,7 @@ func TestChartRegressionBadRangesByUser(t *testing.T) {
 
 	c := Chart{
 		YAxis: YAxis{
-			Range: Range{
+			Range: &ContinuousRange{
 				Min: math.Inf(-1),
 				Max: math.Inf(1), // this could really happen? eh.
 			},

concat_series.go

@@ -0,0 +1,32 @@
+package chart
+
+// ConcatSeries is a special type of series that concatenates its `InnerSeries`.
+type ConcatSeries []Series
+
+// Len returns the length of the concatenated set of series.
+func (cs ConcatSeries) Len() int {
+	total := 0
+	for _, s := range cs {
+		if typed, isValueProvider := s.(ValueProvider); isValueProvider {
+			total += typed.Len()
+		}
+	}
+
+	return total
+}
+
+// GetValue returns the value at the (meta) index (i.e 0 => totalLen-1)
+func (cs ConcatSeries) GetValue(index int) (x, y float64) {
+	cursor := 0
+	for _, s := range cs {
+		if typed, isValueProvider := s.(ValueProvider); isValueProvider {
+			len := typed.Len()
+			if index < cursor+len {
+				x, y = typed.GetValue(index - cursor) //FENCEPOSTS.
+				return
+			}
+			cursor += typed.Len()
+		}
+	}
+	return
+}

concat_series_test.go

@@ -0,0 +1,41 @@
+package chart
+
+import (
+	"testing"
+
+	assert "github.com/blendlabs/go-assert"
+)
+
+func TestConcatSeries(t *testing.T) {
+	assert := assert.New(t)
+
+	s1 := ContinuousSeries{
+		XValues: Seq(1.0, 10.0),
+		YValues: Seq(1.0, 10.0),
+	}
+
+	s2 := ContinuousSeries{
+		XValues: Seq(11, 20.0),
+		YValues: Seq(10.0, 1.0),
+	}
+
+	s3 := ContinuousSeries{
+		XValues: Seq(21, 30.0),
+		YValues: Seq(1.0, 10.0),
+	}
+
+	cs := ConcatSeries([]Series{s1, s2, s3})
+	assert.Equal(30, cs.Len())
+
+	x0, y0 := cs.GetValue(0)
+	assert.Equal(1.0, x0)
+	assert.Equal(1.0, y0)
+
+	xm, ym := cs.GetValue(19)
+	assert.Equal(20.0, xm)
+	assert.Equal(1.0, ym)
+
+	xn, yn := cs.GetValue(29)
+	assert.Equal(30.0, xn)
+	assert.Equal(10.0, yn)
+}

continuous_range.go

@@ -0,0 +1,67 @@
+package chart
+
+import (
+	"fmt"
+	"math"
+)
+
+// ContinuousRange represents a boundary for a set of numbers.
+type ContinuousRange struct {
+	Min    float64
+	Max    float64
+	Domain int
+}
+
+// IsZero returns if the ContinuousRange has been set or not.
+func (r ContinuousRange) IsZero() bool {
+	return (r.Min == 0 || math.IsNaN(r.Min)) &&
+		(r.Max == 0 || math.IsNaN(r.Max)) &&
+		r.Domain == 0
+}
+
+// GetMin gets the min value for the continuous range.
+func (r ContinuousRange) GetMin() float64 {
+	return r.Min
+}
+
+// SetMin sets the min value for the continuous range.
+func (r *ContinuousRange) SetMin(min float64) {
+	r.Min = min
+}
+
+// GetMax returns the max value for the continuous range.
+func (r ContinuousRange) GetMax() float64 {
+	return r.Max
+}
+
+// SetMax sets the max value for the continuous range.
+func (r *ContinuousRange) SetMax(max float64) {
+	r.Max = max
+}
+
+// GetDelta returns the difference between the min and max value.
+func (r ContinuousRange) GetDelta() float64 {
+	return r.Max - r.Min
+}
+
+// GetDomain returns the range domain.
+func (r ContinuousRange) GetDomain() int {
+	return r.Domain
+}
+
+// SetDomain sets the range domain.
+func (r *ContinuousRange) SetDomain(domain int) {
+	r.Domain = domain
+}
+
+// String returns a simple string for the ContinuousRange.
+func (r ContinuousRange) String() string {
+	return fmt.Sprintf("ContinuousRange [%.2f,%.2f] => %d", r.Min, r.Max, r.Domain)
+}
+
+// Translate maps a given value into the ContinuousRange space.
+func (r ContinuousRange) Translate(value float64) int {
+	normalized := value - r.Min
+	ratio := normalized / r.GetDelta()
+	return int(math.Ceil(ratio * float64(r.Domain)))
+}

continuous_range_test.go

@@ -9,7 +9,7 @@ import (
 func TestRangeTranslate(t *testing.T) {
 	assert := assert.New(t)
 	values := []float64{1.0, 2.0, 2.5, 2.7, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0}
-	r := Range{Domain: 1000}
+	r := ContinuousRange{Domain: 1000}
 	r.Min, r.Max = MinAndMax(values...)
 
 	// delta = ~7.0

continuous_series.go

@@ -50,6 +50,6 @@ func (cs ContinuousSeries) GetYAxis() YAxisType {
 
 // Render renders the series.
 func (cs ContinuousSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	style := cs.Style.WithDefaultsFrom(defaults)
+	style := cs.Style.InheritFrom(defaults)
 	DrawLineSeries(r, canvasBox, xrange, yrange, style, cs)
 }

drawing_helpers.go

@@ -114,7 +114,7 @@ func DrawHistogramSeries(r Renderer, canvasBox Box, xrange, yrange Range, s Styl
 
 	//calculate bar width?
 	seriesLength := vs.Len()
-	barWidth := int(math.Floor(float64(xrange.Domain) / float64(seriesLength)))
+	barWidth := int(math.Floor(float64(xrange.GetDomain()) / float64(seriesLength)))
 	if len(barWidths) > 0 {
 		barWidth = barWidths[0]
 	}
@@ -271,9 +271,9 @@ func CreateLegend(c *Chart, userDefaults ...Style) Renderable {
 
 		var legendStyle Style
 		if len(userDefaults) > 0 {
-			legendStyle = userDefaults[0].WithDefaultsFrom(chartDefaults.WithDefaultsFrom(legendDefaults))
+			legendStyle = userDefaults[0].InheritFrom(chartDefaults.InheritFrom(legendDefaults))
 		} else {
-			legendStyle = chartDefaults.WithDefaultsFrom(legendDefaults)
+			legendStyle = chartDefaults.InheritFrom(legendDefaults)
 		}
 
 		// DEFAULTS
@@ -292,7 +292,7 @@ func CreateLegend(c *Chart, userDefaults ...Style) Renderable {
 			if s.GetStyle().IsZero() || s.GetStyle().Show {
 				if _, isAnnotationSeries := s.(AnnotationSeries); !isAnnotationSeries {
 					labels = append(labels, s.GetName())
-					lines = append(lines, s.GetStyle().WithDefaultsFrom(c.styleDefaultsSeries(index)))
+					lines = append(lines, s.GetStyle().InheritFrom(c.styleDefaultsSeries(index)))
 				}
 			}
 		}

ema_series.go

@@ -96,6 +96,6 @@ func (ema *EMASeries) ensureCachedValues() {
 
 // Render renders the series.
 func (ema *EMASeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	style := ema.Style.WithDefaultsFrom(defaults)
+	style := ema.Style.InheritFrom(defaults)
 	DrawLineSeries(r, canvasBox, xrange, yrange, style, ema)
 }

examples/custom_ranges/main.go

@@ -17,7 +17,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 			Style: chart.Style{
 				Show: true,
 			},
-			Range: chart.Range{
+			Range: chart.ContinuousRange{
 				Min: 0.0,
 				Max: 10.0,
 			},

histogram_series.go

@@ -52,6 +52,6 @@ func (hs HistogramSeries) GetBoundedValue(index int) (x, y1, y2 float64) {
 
 // Render implements Series.Render.
 func (hs HistogramSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	style := hs.Style.WithDefaultsFrom(defaults)
+	style := hs.Style.InheritFrom(defaults)
 	DrawHistogramSeries(r, canvasBox, xrange, yrange, style, hs)
 }

macd_series.go

@@ -192,7 +192,7 @@ func (macds *MACDSignalSeries) ensureSignal() {
 
 // Render renders the series.
 func (macds *MACDSignalSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	style := macds.Style.WithDefaultsFrom(defaults)
+	style := macds.Style.InheritFrom(defaults)
 	DrawLineSeries(r, canvasBox, xrange, yrange, style, macds)
 }
 
@@ -284,6 +284,6 @@ func (macdl *MACDLineSeries) ensureEMASeries() {
 
 // Render renders the series.
 func (macdl *MACDLineSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	style := macdl.Style.WithDefaultsFrom(defaults)
+	style := macdl.Style.InheritFrom(defaults)
 	DrawLineSeries(r, canvasBox, xrange, yrange, style, macdl)
 }

range.go

@@ -1,44 +1,41 @@
 package chart
 
-import (
+// NameProvider is a type that returns a name.
-	"fmt"
+type NameProvider interface {
-	"math"
+	GetName() string
-)
-
-// Range represents a boundary for a set of numbers.
-type Range struct {
-	Min    float64
-	Max    float64
-	Domain int
 }
 
-// IsZero returns if the range has been set or not.
+// StyleProvider is a type that returns a style.
-func (r Range) IsZero() bool {
+type StyleProvider interface {
-	return (r.Min == 0 || math.IsNaN(r.Min)) &&
+	GetStyle() Style
-		(r.Max == 0 || math.IsNaN(r.Max)) &&
-		r.Domain == 0
 }
 
-// Delta returns the difference between the min and max value.
+// IsZeroable is a type that returns if it's been set or not.
-func (r Range) Delta() float64 {
+type IsZeroable interface {
-	return r.Max - r.Min
+	IsZero() bool
 }
 
-// String returns a simple string for the range.
+// Stringable is a type that has a string representation.
-func (r Range) String() string {
+type Stringable interface {
-	return fmt.Sprintf("Range [%.2f,%.2f] => %d", r.Min, r.Max, r.Domain)
+	String() string
 }
 
-// Translate maps a given value into the range space.
+// Range is a
-func (r Range) Translate(value float64) int {
+type Range interface {
-	normalized := value - r.Min
+	Stringable
-	ratio := normalized / r.Delta()
+	IsZeroable
-	return int(math.Ceil(ratio * float64(r.Domain)))
-}
 
-// GetRoundedRangeBounds returns some `prettified` range bounds.
+	GetMin() float64
-func (r Range) GetRoundedRangeBounds() (min, max float64) {
+	SetMin(min float64)
-	delta := r.Max - r.Min
+
-	roundTo := GetRoundToForDelta(delta)
+	GetMax() float64
-	return RoundDown(r.Min, roundTo), RoundUp(r.Max, roundTo)
+	SetMax(max float64)
+
+	GetDelta() float64
+
+	GetDomain() int
+	SetDomain(domain int)
+
+	// Translate the range to the domain.
+	Translate(value float64) int
 }

sma_series.go

@@ -85,6 +85,6 @@ func (sma SMASeries) getAverage(index int) float64 {
 
 // Render renders the series.
 func (sma SMASeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	style := sma.Style.WithDefaultsFrom(defaults)
+	style := sma.Style.InheritFrom(defaults)
 	DrawLineSeries(r, canvasBox, xrange, yrange, style, sma)
 }

style.go

@@ -28,6 +28,7 @@ func (s Style) IsZero() bool {
 	return s.StrokeColor.IsZero() && s.FillColor.IsZero() && s.StrokeWidth == 0 && s.FontColor.IsZero() && s.FontSize == 0 && s.Font == nil
 }
 
+// String returns a text representation of the style.
 func (s Style) String() string {
 	if s.IsZero() {
 		return "{}"
@@ -184,8 +185,18 @@ func (s Style) GetPadding(defaults ...Box) Box {
 	return s.Padding
 }
 
-// WithDefaultsFrom coalesces two styles into a new style.
+// PersistToRenderer passes the style onto a renderer.
-func (s Style) WithDefaultsFrom(defaults Style) (final Style) {
+func (s Style) PersistToRenderer(r Renderer) {
+	r.SetStrokeColor(s.GetStrokeColor())
+	r.SetStrokeWidth(s.GetStrokeWidth())
+	r.SetStrokeDashArray(s.GetStrokeDashArray())
+	r.SetFont(s.GetFont())
+	r.SetFontColor(s.GetFontColor())
+	r.SetFontSize(s.GetFontSize())
+}
+
+// InheritFrom coalesces two styles into a new style.
+func (s Style) InheritFrom(defaults Style) (final Style) {
 	final.StrokeColor = s.GetStrokeColor(defaults.StrokeColor)
 	final.StrokeWidth = s.GetStrokeWidth(defaults.StrokeWidth)
 	final.StrokeDashArray = s.GetStrokeDashArray(defaults.StrokeDashArray)

style_test.go

@@ -142,7 +142,7 @@ func TestStyleWithDefaultsFrom(t *testing.T) {
 		Padding:     DefaultBackgroundPadding,
 	}
 
-	coalesced := unset.WithDefaultsFrom(set)
+	coalesced := unset.InheritFrom(set)
 	assert.Equal(set, coalesced)
 }
 

tick.go

@@ -3,7 +3,7 @@ package chart
 // GenerateTicksWithStep generates a set of ticks.
 func GenerateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick {
 	var ticks []Tick
-	min, max := ra.Min, ra.Max
+	min, max := ra.GetMin(), ra.GetMax()
 	for cursor := min; cursor <= max; cursor += step {
 		ticks = append(ticks, Tick{
 			Value: cursor,

tick_test.go

@@ -9,6 +9,6 @@ import (
 func TestGenerateTicksWithStep(t *testing.T) {
 	assert := assert.New(t)
 
-	ticks := GenerateTicksWithStep(Range{Min: 1.0, Max: 10.0, Domain: 100}, 1.0, FloatValueFormatter)
+	ticks := GenerateTicksWithStep(&ContinuousRange{Min: 1.0, Max: 10.0, Domain: 100}, 1.0, FloatValueFormatter)
 	assert.Len(ticks, 10)
 }

time_series.go

@@ -56,6 +56,6 @@ func (ts TimeSeries) GetYAxis() YAxisType {
 
 // Render renders the series.
 func (ts TimeSeries) Render(r Renderer, canvasBox Box, xrange, yrange Range, defaults Style) {
-	style := ts.Style.WithDefaultsFrom(defaults)
+	style := ts.Style.InheritFrom(defaults)
 	DrawLineSeries(r, canvasBox, xrange, yrange, style, ts)
 }

xaxis.go

@@ -44,7 +44,7 @@ func (xa XAxis) generateTicks(r Renderer, ra Range, defaults Style, vf ValueForm
 
 func (xa XAxis) getTickStep(r Renderer, ra Range, defaults Style, vf ValueFormatter) float64 {
 	tickCount := xa.getTickCount(r, ra, defaults, vf)
-	step := ra.Delta() / float64(tickCount)
+	step := ra.GetDelta() / float64(tickCount)
 	return step
 }
 
@@ -53,8 +53,8 @@ func (xa XAxis) getTickCount(r Renderer, ra Range, defaults Style, vf ValueForma
 	r.SetFontSize(xa.Style.GetFontSize(defaults.GetFontSize(DefaultFontSize)))
 
 	// take a cut at determining the 'widest' value.
-	l0 := vf(ra.Min)
+	l0 := vf(ra.GetMin())
-	ln := vf(ra.Max)
+	ln := vf(ra.GetMax())
 	ll := l0
 	if len(ln) > len(l0) {
 		ll = ln
@@ -62,7 +62,7 @@ func (xa XAxis) getTickCount(r Renderer, ra Range, defaults Style, vf ValueForma
 	llb := r.MeasureText(ll)
 	textWidth := llb.Width()
 	width := textWidth + DefaultMinimumTickHorizontalSpacing
-	count := int(math.Ceil(float64(ra.Domain) / float64(width)))
+	count := int(math.Ceil(float64(ra.GetDomain()) / float64(width)))
 	return count
 }
 
@@ -76,13 +76,7 @@ func (xa XAxis) GetGridLines(ticks []Tick) []GridLine {
 
 // Measure returns the bounds of the axis.
 func (xa XAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick) Box {
-	r.SetStrokeColor(xa.Style.GetStrokeColor(defaults.StrokeColor))
+	xa.Style.InheritFrom(defaults).PersistToRenderer(r)
-	r.SetStrokeWidth(xa.Style.GetStrokeWidth(defaults.StrokeWidth))
-	r.SetStrokeDashArray(xa.Style.GetStrokeDashArray())
-	r.SetFont(xa.Style.GetFont(defaults.GetFont()))
-	r.SetFontColor(xa.Style.GetFontColor(DefaultAxisColor))
-	r.SetFontSize(xa.Style.GetFontSize(defaults.GetFontSize()))
-
 	sort.Sort(Ticks(ticks))
 
 	var left, right, top, bottom = math.MaxInt32, 0, math.MaxInt32, 0
@@ -110,12 +104,7 @@ func (xa XAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, tic
 
 // Render renders the axis
 func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick) {
-	r.SetStrokeColor(xa.Style.GetStrokeColor(defaults.StrokeColor))
+	xa.Style.InheritFrom(defaults).PersistToRenderer(r)
-	r.SetStrokeWidth(xa.Style.GetStrokeWidth(defaults.StrokeWidth))
-	r.SetStrokeDashArray(xa.Style.GetStrokeDashArray())
-	r.SetFont(xa.Style.GetFont(defaults.GetFont()))
-	r.SetFontColor(xa.Style.GetFontColor(DefaultAxisColor))
-	r.SetFontSize(xa.Style.GetFontSize(defaults.GetFontSize()))
 
 	r.MoveTo(canvasBox.Left, canvasBox.Bottom)
 	r.LineTo(canvasBox.Right, canvasBox.Bottom)

xaxis_test.go

@@ -16,7 +16,7 @@ func TestXAxisGetTickCount(t *testing.T) {
 	assert.Nil(err)
 
 	xa := XAxis{}
-	xr := Range{Min: 10, Max: 100, Domain: 1024}
+	xr := &ContinuousRange{Min: 10, Max: 100, Domain: 1024}
 	styleDefaults := Style{
 		Font:     f,
 		FontSize: 10.0,
@@ -36,14 +36,14 @@ func TestXAxisGetTickStep(t *testing.T) {
 	assert.Nil(err)
 
 	xa := XAxis{}
-	xr := Range{Min: 10, Max: 100, Domain: 1024}
+	xr := &ContinuousRange{Min: 10, Max: 100, Domain: 1024}
 	styleDefaults := Style{
 		Font:     f,
 		FontSize: 10.0,
 	}
 	vf := FloatValueFormatter
 	step := xa.getTickStep(r, xr, styleDefaults, vf)
-	assert.Equal(xr.Delta()/16.0, step)
+	assert.Equal(xr.GetDelta()/16.0, step)
 }
 
 func TestXAxisGetTicks(t *testing.T) {
@@ -56,7 +56,7 @@ func TestXAxisGetTicks(t *testing.T) {
 	assert.Nil(err)
 
 	xa := XAxis{}
-	xr := Range{Min: 10, Max: 100, Domain: 1024}
+	xr := &ContinuousRange{Min: 10, Max: 100, Domain: 1024}
 	styleDefaults := Style{
 		Font:     f,
 		FontSize: 10.0,
@@ -78,7 +78,7 @@ func TestXAxisGetTicksWithUserDefaults(t *testing.T) {
 	xa := XAxis{
 		Ticks: []Tick{{Value: 1.0, Label: "1.0"}},
 	}
-	xr := Range{Min: 10, Max: 100, Domain: 1024}
+	xr := &ContinuousRange{Min: 10, Max: 100, Domain: 1024}
 	styleDefaults := Style{
 		Font:     f,
 		FontSize: 10.0,

yaxis.go

@@ -17,9 +17,10 @@ type YAxis struct {
 
 	ValueFormatter ValueFormatter
 	Range          Range
-	Ticks          []Tick
 
-	GridLines      []GridLine
+	Ticks     []Tick
+	GridLines []GridLine
+
 	GridMajorStyle Style
 	GridMinorStyle Style
 }
@@ -51,7 +52,7 @@ func (ya YAxis) generateTicks(r Renderer, ra Range, defaults Style, vf ValueForm
 
 func (ya YAxis) getTickStep(r Renderer, ra Range, defaults Style, vf ValueFormatter) float64 {
 	tickCount := ya.getTickCount(r, ra, defaults, vf)
-	step := ra.Delta() / float64(tickCount)
+	step := ra.GetDelta() / float64(tickCount)
 	return step
 }
 
@@ -59,9 +60,9 @@ func (ya YAxis) getTickCount(r Renderer, ra Range, defaults Style, vf ValueForma
 	r.SetFont(ya.Style.GetFont(defaults.GetFont()))
 	r.SetFontSize(ya.Style.GetFontSize(defaults.GetFontSize(DefaultFontSize)))
 	//given the domain, figure out how many ticks we can draw ...
-	label := vf(ra.Min)
+	label := vf(ra.GetMin())
 	tb := r.MeasureText(label)
-	count := int(math.Ceil(float64(ra.Domain) / float64(tb.Height()+DefaultMinimumTickVerticalSpacing)))
+	count := int(math.Ceil(float64(ra.GetDomain()) / float64(tb.Height()+DefaultMinimumTickVerticalSpacing)))
 	return count
 }
 
@@ -75,11 +76,7 @@ func (ya YAxis) GetGridLines(ticks []Tick) []GridLine {
 
 // Measure returns the bounds of the axis.
 func (ya YAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick) Box {
-	r.SetStrokeColor(ya.Style.GetStrokeColor(defaults.StrokeColor))
+	ya.Style.InheritFrom(defaults).PersistToRenderer(r)
-	r.SetStrokeWidth(ya.Style.GetStrokeWidth(defaults.StrokeWidth))
-	r.SetFont(ya.Style.GetFont(defaults.GetFont()))
-	r.SetFontColor(ya.Style.GetFontColor(DefaultAxisColor))
-	r.SetFontSize(ya.Style.GetFontSize(defaults.GetFontSize()))
 
 	sort.Sort(Ticks(ticks))
 
@@ -122,11 +119,7 @@ func (ya YAxis) Measure(r Renderer, canvasBox Box, ra Range, defaults Style, tic
 
 // Render renders the axis.
 func (ya YAxis) Render(r Renderer, canvasBox Box, ra Range, defaults Style, ticks []Tick) {
-	r.SetStrokeColor(ya.Style.GetStrokeColor(defaults.StrokeColor))
+	ya.Style.InheritFrom(defaults).PersistToRenderer(r)
-	r.SetStrokeWidth(ya.Style.GetStrokeWidth(defaults.StrokeWidth))
-	r.SetFont(ya.Style.GetFont(defaults.GetFont()))
-	r.SetFontColor(ya.Style.GetFontColor(DefaultAxisColor))
-	r.SetFontSize(ya.Style.GetFontSize(defaults.GetFontSize(DefaultFontSize)))
 
 	sort.Sort(Ticks(ticks))
 

yaxis_test.go

@@ -16,7 +16,7 @@ func TestYAxisGetTickCount(t *testing.T) {
 	assert.Nil(err)
 
 	ya := YAxis{}
-	yr := Range{Min: 10, Max: 100, Domain: 1024}
+	yr := &ContinuousRange{Min: 10, Max: 100, Domain: 1024}
 	styleDefaults := Style{
 		Font:     f,
 		FontSize: 10.0,
@@ -36,14 +36,14 @@ func TestYAxisGetTickStep(t *testing.T) {
 	assert.Nil(err)
 
 	ya := YAxis{}
-	yr := Range{Min: 10, Max: 100, Domain: 1024}
+	yr := &ContinuousRange{Min: 10, Max: 100, Domain: 1024}
 	styleDefaults := Style{
 		Font:     f,
 		FontSize: 10.0,
 	}
 	vf := FloatValueFormatter
 	step := ya.getTickStep(r, yr, styleDefaults, vf)
-	assert.Equal(yr.Delta()/34.0, step)
+	assert.Equal(yr.GetDelta()/34.0, step)
 }
 
 func TestYAxisGetTicks(t *testing.T) {
@@ -56,7 +56,7 @@ func TestYAxisGetTicks(t *testing.T) {
 	assert.Nil(err)
 
 	ya := YAxis{}
-	yr := Range{Min: 10, Max: 100, Domain: 1024}
+	yr := &ContinuousRange{Min: 10, Max: 100, Domain: 1024}
 	styleDefaults := Style{
 		Font:     f,
 		FontSize: 10.0,
@@ -78,7 +78,7 @@ func TestYAxisGetTicksWithUserDefaults(t *testing.T) {
 	ya := YAxis{
 		Ticks: []Tick{{Value: 1.0, Label: "1.0"}},
 	}
-	yr := Range{Min: 10, Max: 100, Domain: 1024}
+	yr := &ContinuousRange{Min: 10, Max: 100, Domain: 1024}
 	styleDefaults := Style{
 		Font:     f,
 		FontSize: 10.0,