feature; solving issue #121

draw.go

@@ -47,12 +47,26 @@ func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style
  if style.ShouldDrawStroke() {
  style.GetStrokeOptions().WriteDrawingOptionsToRenderer(r)
 
- r.MoveTo(x0, y0)
+ vxprev := 0.0
+ if vs.Len() > 0 {
+ vxprev, _ = vs.GetValues( 0 ) // make sure vxprev starts at the beginning
+ }
+ maxspan := style.GetStrokeMaxSpanGap()
+ r.MoveTo(x0, y0)
  for i := 1; i < vs.Len(); i++ {
  vx, vy = vs.GetValues(i)
  x = cl + xrange.Translate(vx)
- y = cb - yrange.Translate(vy)
- r.LineTo(x, y)
+ y = cb - yrange.Translate(vy)
+ df := vxprev - vx
+ if df < 0 {
+ df *= -1 // make it work, regardless of direction ox X-axis
+ }
+ if df <= maxspan { // span the gap i.e. connect the two points
+ r.LineTo(x, y)
+ } else { // do not span the gap
+ r.MoveTo(x, y)
+ }
+ vxprev = vx
  }
  r.Stroke()
  }

examples/custom_styles/main.go

@@ -25,9 +25,10 @@ func main() {
  Style: chart.Style{
  StrokeColor: drawing.ColorRed, // will supercede defaults
  FillColor: drawing.ColorRed.WithAlpha(64), // will supercede defaults
+ StrokeMaxSpanGap: 2, // do not span gaps more than 2.0 wide
  },
- XValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
- YValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0},
+ XValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0, 8.0, 10.0},
+ YValues: []float64{1.0, 2.0, 3.0, 4.0, 5.0, 8.0, 10.0},
  },
  },
  }

style.go

@@ -51,6 +51,7 @@ type Style struct {
  StrokeWidth float64
  StrokeColor drawing.Color
  StrokeDashArray []float64
+ StrokeMaxSpanGap float64 // in xvalue unit, nano second for timeseries
 
  DotColor drawing.Color
  DotWidth float64
@@ -122,6 +123,12 @@ func (s Style) String() string {
  output = append(output, "\"stroke_color\": null")
  }
 
+ if s.StrokeMaxSpanGap >= 0 {
+ output = append(output, fmt.Sprintf("\"stroke_maxspangap\": %.02f", s.StrokeMaxSpanGap))
+ } else {
+ output = append(output, "\"stroke_maxspangap\": null")
+ }
+
  if len(s.StrokeDashArray) > 0 {
  var elements []string
  for _, v := range s.StrokeDashArray {
@@ -194,6 +201,11 @@ func (s Style) GetStrokeColor(defaults ...drawing.Color) drawing.Color {
  return s.StrokeColor
 }
 
+// GetStrokeMaxSpanGap returns the max span gap, smaller or equal gaps are connected, larger ones are not.
+func (s Style) GetStrokeMaxSpanGap() float64 {
+ return s.StrokeMaxSpanGap
+}
+
 // GetFillColor returns the fill color.
 func (s Style) GetFillColor(defaults ...drawing.Color) drawing.Color {
  if s.FillColor.IsZero() {
@@ -388,6 +400,7 @@ 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)
+ final.StrokeMaxSpanGap = s.GetStrokeMaxSpanGap()
 
  final.DotColor = s.GetDotColor(defaults.DotColor)
  final.DotWidth = s.GetDotWidth(defaults.DotWidth)
@@ -416,6 +429,7 @@ func (s Style) GetStrokeOptions() Style {
  StrokeDashArray: s.StrokeDashArray,
  StrokeColor: s.StrokeColor,
  StrokeWidth: s.StrokeWidth,
+ StrokeMaxSpanGap:s.StrokeMaxSpanGap,
  }
 }
 
@@ -443,7 +457,8 @@ func (s Style) GetFillAndStrokeOptions() Style {
  return Style{
  ClassName: s.ClassName,
  StrokeDashArray: s.StrokeDashArray,
- FillColor: s.FillColor,
+ StrokeMaxSpanGap:s.StrokeMaxSpanGap,
+ FillColor: s.FillColor,
  StrokeColor: s.StrokeColor,
  StrokeWidth: s.StrokeWidth,
  }