diff --git a/README.md b/README.md
index 5fd93a5..96b8c2d 100644
--- a/README.md
+++ b/README.md
@@ -54,7 +54,7 @@ graph := chart.Chart{
             },
             Annotations: []chart.Annotation{
                 chart.Annotation{
-                    X:     float64(xvalues[len(xvalues)-1].Unix()), //todo: helpers for this.
+                    X:     chart.TimeToFloat64(xvalues[len(xvalues)-1]),
                     Y:     yvalues[len(yvalues)-1],
                     Label: chart.FloatValueFormatter(yvalues[len(yvalues)-1]),
                 },
diff --git a/annotation_series.go b/annotation_series.go
index aeed26d..22ed729 100644
--- a/annotation_series.go
+++ b/annotation_series.go
@@ -1,45 +1,6 @@
 package chart
 
-import (
-	"math"
-	"time"
-)
-
-// CreateContinuousSeriesLastValueLabel returns a (1) value annotation series.
-func CreateContinuousSeriesLastValueLabel(name string, xvalues, yvalues []float64, valueFormatter ValueFormatter) AnnotationSeries {
-	return AnnotationSeries{
-		Name: name,
-		Style: Style{
-			Show:        true,
-			StrokeColor: GetDefaultSeriesStrokeColor(0),
-		},
-		Annotations: []Annotation{
-			Annotation{
-				X:     xvalues[len(xvalues)-1],
-				Y:     yvalues[len(yvalues)-1],
-				Label: valueFormatter(yvalues[len(yvalues)-1]),
-			},
-		},
-	}
-}
-
-// CreateTimeSeriesLastValueLabel returns a (1) value annotation series.
-func CreateTimeSeriesLastValueLabel(name string, xvalues []time.Time, yvalues []float64, valueFormatter ValueFormatter) AnnotationSeries {
-	return AnnotationSeries{
-		Name: name,
-		Style: Style{
-			Show:        true,
-			StrokeColor: GetDefaultSeriesStrokeColor(0),
-		},
-		Annotations: []Annotation{
-			Annotation{
-				X:     float64(xvalues[len(xvalues)-1].Unix()),
-				Y:     yvalues[len(yvalues)-1],
-				Label: valueFormatter(yvalues[len(yvalues)-1]),
-			},
-		},
-	}
-}
+import "math"
 
 // Annotation is a label on the chart.
 type Annotation struct {
diff --git a/style.go b/style.go
index 5ffe2f5..0274535 100644
--- a/style.go
+++ b/style.go
@@ -15,17 +15,15 @@ type Style struct {
 
 	StrokeWidth float64
 	StrokeColor drawing.Color
-
-	FillColor drawing.Color
-
-	FontSize  float64
-	FontColor drawing.Color
-	Font      *truetype.Font
+	FillColor   drawing.Color
+	FontSize    float64
+	FontColor   drawing.Color
+	Font        *truetype.Font
 }
 
 // IsZero returns if the object is set or not.
 func (s Style) IsZero() bool {
-	return s.StrokeColor.IsZero() && s.FillColor.IsZero() && s.StrokeWidth == 0 && s.FontSize == 0 && s.Font == nil
+	return s.StrokeColor.IsZero() && s.FillColor.IsZero() && s.StrokeWidth == 0 && s.FontColor.IsZero() && s.FontSize == 0 && s.Font == nil
 }
 
 // GetStrokeColor returns the stroke color.
@@ -107,12 +105,12 @@ func (s Style) GetPadding(defaults ...Box) Box {
 
 // WithDefaultsFrom coalesces two styles into a new style.
 func (s Style) WithDefaultsFrom(defaults Style) (final Style) {
+	final.StrokeColor = s.GetStrokeColor(defaults.StrokeColor)
+	final.StrokeWidth = s.GetStrokeWidth(defaults.StrokeWidth)
 	final.FillColor = s.GetFillColor(defaults.FillColor)
 	final.FontColor = s.GetFontColor(defaults.FontColor)
 	final.Font = s.GetFont(defaults.Font)
 	final.Padding = s.GetPadding(defaults.Padding)
-	final.StrokeColor = s.GetStrokeColor(defaults.StrokeColor)
-	final.StrokeWidth = s.GetStrokeWidth(defaults.StrokeWidth)
 	return
 }
 
diff --git a/style_test.go b/style_test.go
new file mode 100644
index 0000000..cb7ffdd
--- /dev/null
+++ b/style_test.go
@@ -0,0 +1,237 @@
+package chart
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/blendlabs/go-assert"
+	"github.com/golang/freetype/truetype"
+	"github.com/wcharczuk/go-chart/drawing"
+)
+
+func TestStyleIsZero(t *testing.T) {
+	assert := assert.New(t)
+	zero := Style{}
+	assert.True(zero.IsZero())
+
+	strokeColor := Style{StrokeColor: drawing.ColorWhite}
+	assert.False(strokeColor.IsZero())
+
+	fillColor := Style{FillColor: drawing.ColorWhite}
+	assert.False(fillColor.IsZero())
+
+	strokeWidth := Style{StrokeWidth: 5.0}
+	assert.False(strokeWidth.IsZero())
+
+	fontSize := Style{FontSize: 12.0}
+	assert.False(fontSize.IsZero())
+
+	fontColor := Style{FontColor: drawing.ColorWhite}
+	assert.False(fontColor.IsZero())
+
+	font := Style{Font: &truetype.Font{}}
+	assert.False(font.IsZero())
+}
+
+func TestStyleGetStrokeColor(t *testing.T) {
+	assert := assert.New(t)
+
+	unset := Style{}
+	assert.Equal(drawing.ColorTransparent, unset.GetStrokeColor())
+	assert.Equal(drawing.ColorWhite, unset.GetStrokeColor(drawing.ColorWhite))
+
+	set := Style{StrokeColor: drawing.ColorWhite}
+	assert.Equal(drawing.ColorWhite, set.GetStrokeColor())
+	assert.Equal(drawing.ColorWhite, set.GetStrokeColor(drawing.ColorBlack))
+}
+
+func TestStyleGetFillColor(t *testing.T) {
+	assert := assert.New(t)
+
+	unset := Style{}
+	assert.Equal(drawing.ColorTransparent, unset.GetFillColor())
+	assert.Equal(drawing.ColorWhite, unset.GetFillColor(drawing.ColorWhite))
+
+	set := Style{FillColor: drawing.ColorWhite}
+	assert.Equal(drawing.ColorWhite, set.GetFillColor())
+	assert.Equal(drawing.ColorWhite, set.GetFillColor(drawing.ColorBlack))
+}
+
+func TestStyleGetStrokeWidth(t *testing.T) {
+	assert := assert.New(t)
+
+	unset := Style{}
+	assert.Equal(DefaultStrokeWidth, unset.GetStrokeWidth())
+	assert.Equal(DefaultStrokeWidth+1, unset.GetStrokeWidth(DefaultStrokeWidth+1))
+
+	set := Style{StrokeWidth: DefaultStrokeWidth + 2}
+	assert.Equal(DefaultStrokeWidth+2, set.GetStrokeWidth())
+	assert.Equal(DefaultStrokeWidth+2, set.GetStrokeWidth(DefaultStrokeWidth+1))
+}
+
+func TestStyleGetFontSize(t *testing.T) {
+	assert := assert.New(t)
+
+	unset := Style{}
+	assert.Equal(DefaultFontSize, unset.GetFontSize())
+	assert.Equal(DefaultFontSize+1, unset.GetFontSize(DefaultFontSize+1))
+
+	set := Style{FontSize: DefaultFontSize + 2}
+	assert.Equal(DefaultFontSize+2, set.GetFontSize())
+	assert.Equal(DefaultFontSize+2, set.GetFontSize(DefaultFontSize+1))
+}
+
+func TestStyleGetFontColor(t *testing.T) {
+	assert := assert.New(t)
+
+	unset := Style{}
+	assert.Equal(drawing.ColorTransparent, unset.GetFontColor())
+	assert.Equal(drawing.ColorWhite, unset.GetFontColor(drawing.ColorWhite))
+
+	set := Style{FontColor: drawing.ColorWhite}
+	assert.Equal(drawing.ColorWhite, set.GetFontColor())
+	assert.Equal(drawing.ColorWhite, set.GetFontColor(drawing.ColorBlack))
+}
+
+func TestStyleGetFont(t *testing.T) {
+	assert := assert.New(t)
+
+	f, err := GetDefaultFont()
+	assert.Nil(err)
+
+	unset := Style{}
+	assert.Nil(unset.GetFont())
+	assert.Equal(f, unset.GetFont(f))
+
+	set := Style{Font: f}
+	assert.NotNil(set.GetFont())
+}
+
+func TestStyleGetPadding(t *testing.T) {
+	assert := assert.New(t)
+
+	unset := Style{}
+	assert.True(unset.GetPadding().IsZero())
+	assert.False(unset.GetPadding(DefaultBackgroundPadding).IsZero())
+	assert.Equal(DefaultBackgroundPadding, unset.GetPadding(DefaultBackgroundPadding))
+
+	set := Style{Padding: DefaultBackgroundPadding}
+	assert.False(set.GetPadding().IsZero())
+	assert.Equal(DefaultBackgroundPadding, set.GetPadding())
+	assert.Equal(DefaultBackgroundPadding, set.GetPadding(Box{
+		Top:    DefaultBackgroundPadding.Top + 1,
+		Left:   DefaultBackgroundPadding.Left + 1,
+		Right:  DefaultBackgroundPadding.Right + 1,
+		Bottom: DefaultBackgroundPadding.Bottom + 1,
+	}))
+}
+
+func TestStyleWithDefaultsFrom(t *testing.T) {
+	assert := assert.New(t)
+
+	f, err := GetDefaultFont()
+	assert.Nil(err)
+
+	unset := Style{}
+	set := Style{
+		StrokeColor: drawing.ColorWhite,
+		StrokeWidth: 5.0,
+		FillColor:   drawing.ColorWhite,
+		FontColor:   drawing.ColorWhite,
+		Font:        f,
+		Padding:     DefaultBackgroundPadding,
+	}
+
+	coalesced := unset.WithDefaultsFrom(set)
+	assert.Equal(set, coalesced)
+}
+
+func TestStyleSVG(t *testing.T) {
+	assert := assert.New(t)
+
+	f, err := GetDefaultFont()
+	assert.Nil(err)
+
+	set := Style{
+		StrokeColor: drawing.ColorWhite,
+		StrokeWidth: 5.0,
+		FillColor:   drawing.ColorWhite,
+		FontColor:   drawing.ColorWhite,
+		Font:        f,
+		Padding:     DefaultBackgroundPadding,
+	}
+
+	svgString := set.SVG(DefaultDPI)
+	assert.NotEmpty(svgString)
+	assert.True(strings.Contains(svgString, "stroke:rgba(255,255,255,1.0)"))
+	assert.True(strings.Contains(svgString, "stroke-width:5"))
+	assert.True(strings.Contains(svgString, "fill:rgba(255,255,255,1.0)"))
+}
+
+func TestStyleSVGStroke(t *testing.T) {
+	assert := assert.New(t)
+
+	set := Style{
+		StrokeColor: drawing.ColorWhite,
+		StrokeWidth: 5.0,
+		FillColor:   drawing.ColorWhite,
+		FontColor:   drawing.ColorWhite,
+		Padding:     DefaultBackgroundPadding,
+	}
+	svgStroke := set.SVGStroke()
+	assert.False(svgStroke.StrokeColor.IsZero())
+	assert.NotZero(svgStroke.StrokeWidth)
+	assert.True(svgStroke.FillColor.IsZero())
+	assert.True(svgStroke.FontColor.IsZero())
+}
+
+func TestStyleSVGFill(t *testing.T) {
+	assert := assert.New(t)
+
+	set := Style{
+		StrokeColor: drawing.ColorWhite,
+		StrokeWidth: 5.0,
+		FillColor:   drawing.ColorWhite,
+		FontColor:   drawing.ColorWhite,
+		Padding:     DefaultBackgroundPadding,
+	}
+	svgFill := set.SVGFill()
+	assert.False(svgFill.FillColor.IsZero())
+	assert.Zero(svgFill.StrokeWidth)
+	assert.True(svgFill.StrokeColor.IsZero())
+	assert.True(svgFill.FontColor.IsZero())
+}
+
+func TestStyleSVGFillAndStroke(t *testing.T) {
+	assert := assert.New(t)
+
+	set := Style{
+		StrokeColor: drawing.ColorWhite,
+		StrokeWidth: 5.0,
+		FillColor:   drawing.ColorWhite,
+		FontColor:   drawing.ColorWhite,
+		Padding:     DefaultBackgroundPadding,
+	}
+	svgFillAndStroke := set.SVGFillAndStroke()
+	assert.False(svgFillAndStroke.FillColor.IsZero())
+	assert.NotZero(svgFillAndStroke.StrokeWidth)
+	assert.False(svgFillAndStroke.StrokeColor.IsZero())
+	assert.True(svgFillAndStroke.FontColor.IsZero())
+}
+
+func TestStyleSVGText(t *testing.T) {
+	assert := assert.New(t)
+
+	set := Style{
+		StrokeColor: drawing.ColorWhite,
+		StrokeWidth: 5.0,
+		FillColor:   drawing.ColorWhite,
+		FontColor:   drawing.ColorWhite,
+		Padding:     DefaultBackgroundPadding,
+	}
+	svgStroke := set.SVGText()
+	assert.True(svgStroke.StrokeColor.IsZero())
+	assert.Zero(svgStroke.StrokeWidth)
+	assert.True(svgStroke.FillColor.IsZero())
+	assert.False(svgStroke.FontColor.IsZero())
+}
diff --git a/tick.go b/tick.go
index 374a621..b9f7a78 100644
--- a/tick.go
+++ b/tick.go
@@ -1,5 +1,17 @@
 package chart
 
+// GenerateTicksWithStep generates a set of ticks.
+func GenerateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick {
+	var ticks []Tick
+	for cursor := ra.Min; cursor < ra.Max; cursor += step {
+		ticks = append(ticks, Tick{
+			Value: cursor,
+			Label: vf(cursor),
+		})
+	}
+	return ticks
+}
+
 // Tick represents a label on an axis.
 type Tick struct {
 	Value float64
diff --git a/tick_test.go b/tick_test.go
new file mode 100644
index 0000000..58a733f
--- /dev/null
+++ b/tick_test.go
@@ -0,0 +1 @@
+package chart
diff --git a/util.go b/util.go
index 406bc3f..1f8fc7c 100644
--- a/util.go
+++ b/util.go
@@ -5,6 +5,11 @@ import (
 	"time"
 )
 
+// TimeToFloat64 returns a float64 representation of a time.
+func TimeToFloat64(t time.Time) float64 {
+	return float64(t.Unix())
+}
+
 // MinAndMax returns both the min and max in one pass.
 func MinAndMax(values ...float64) (min float64, max float64) {
 	if len(values) == 0 {
diff --git a/value_formatter_test.go b/value_formatter_test.go
new file mode 100644
index 0000000..83b347e
--- /dev/null
+++ b/value_formatter_test.go
@@ -0,0 +1,38 @@
+package chart
+
+import (
+	"testing"
+	"time"
+
+	"github.com/blendlabs/go-assert"
+)
+
+func TestTimeValueFormatterWithFormat(t *testing.T) {
+	assert := assert.New(t)
+
+	d := time.Now()
+	di := d.Unix()
+	df := float64(di)
+
+	s := TimeValueFormatterWithFormat(d, DefaultDateFormat)
+	si := TimeValueFormatterWithFormat(di, DefaultDateFormat)
+	sf := TimeValueFormatterWithFormat(df, DefaultDateFormat)
+	assert.Equal(s, si)
+	assert.Equal(s, sf)
+
+	sd := TimeValueFormatter(d)
+	sdi := TimeValueFormatter(di)
+	sdf := TimeValueFormatter(df)
+	assert.Equal(s, sd)
+	assert.Equal(s, sdi)
+	assert.Equal(s, sdf)
+}
+
+func TestFloatValueFormatterWithFormat(t *testing.T) {
+	assert := assert.New(t)
+
+	v := 123.456
+	sv := FloatValueFormatterWithFormat(v, "%.3f")
+	assert.Equal("123.456", sv)
+	assert.Equal("", FloatValueFormatterWithFormat(123, "%.3f"))
+}
diff --git a/xaxis.go b/xaxis.go
index 0f02be9..46277db 100644
--- a/xaxis.go
+++ b/xaxis.go
@@ -37,7 +37,13 @@ func (xa XAxis) GetTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
 
 func (xa XAxis) generateTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
 	step := xa.getTickStep(r, ra, vf)
-	return xa.generateTicksWithStep(ra, step, vf)
+	return GenerateTicksWithStep(ra, step, vf)
+}
+
+func (xa XAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
+	tickCount := xa.getTickCount(r, ra, vf)
+	step := ra.Delta() / float64(tickCount)
+	return step
 }
 
 func (xa XAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
@@ -58,27 +64,6 @@ func (xa XAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
 	return count
 }
 
-func (xa XAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
-	tickCount := xa.getTickCount(r, ra, vf)
-	step := ra.Delta() / float64(tickCount)
-	return step
-}
-
-func (xa XAxis) generateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick {
-	var ticks []Tick
-	for cursor := ra.Min; cursor < ra.Max; cursor += step {
-		ticks = append(ticks, Tick{
-			Value: cursor,
-			Label: vf(cursor),
-		})
-
-		if len(ticks) == 20 {
-			return ticks
-		}
-	}
-	return ticks
-}
-
 // Render renders the axis
 func (xa XAxis) Render(r Renderer, canvasBox Box, ra Range, ticks []Tick) {
 	tickFontSize := xa.Style.GetFontSize(DefaultFontSize)
diff --git a/yaxis.go b/yaxis.go
index f4ed1f4..5ad2619 100644
--- a/yaxis.go
+++ b/yaxis.go
@@ -36,14 +36,7 @@ func (ya YAxis) GetTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
 
 func (ya YAxis) generateTicks(r Renderer, ra Range, vf ValueFormatter) []Tick {
 	step := ya.getTickStep(r, ra, vf)
-	return ya.generateTicksWithStep(ra, step, vf)
-}
-
-func (ya YAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
-	textHeight := int(ya.Style.GetFontSize(DefaultFontSize))
-	height := textHeight + DefaultMinimumTickVerticalSpacing
-	count := int(math.Ceil(float64(ra.Domain) / float64(height)))
-	return count
+	return GenerateTicksWithStep(ra, step, vf)
 }
 
 func (ya YAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
@@ -51,18 +44,11 @@ func (ya YAxis) getTickStep(r Renderer, ra Range, vf ValueFormatter) float64 {
 	return ra.Delta() / float64(tickCount)
 }
 
-func (ya YAxis) generateTicksWithStep(ra Range, step float64, vf ValueFormatter) []Tick {
-	var ticks []Tick
-	for cursor := ra.Min; cursor < ra.Max; cursor += step {
-		ticks = append(ticks, Tick{
-			Value: cursor,
-			Label: vf(cursor),
-		})
-		if len(ticks) == 20 {
-			return ticks
-		}
-	}
-	return ticks
+func (ya YAxis) getTickCount(r Renderer, ra Range, vf ValueFormatter) int {
+	textHeight := int(ya.Style.GetFontSize(DefaultFontSize))
+	height := textHeight + DefaultMinimumTickVerticalSpacing
+	count := int(math.Ceil(float64(ra.Domain) / float64(height)))
+	return count
 }
 
 // Render renders the axis.