just passing the full range.

_examples/scatter/main.go

@@ -16,7 +16,7 @@ func drawChart(res http.ResponseWriter, req *http.Request) {
 				Style: chart.Style{
 					Show:             true,
 					StrokeWidth:      chart.Disabled,
-					DotWidthProvider: func(rx, ry, x, y float64) float64 { return 10 * (y / ry) },
+					DotWidthProvider: func(_, yr chart.Range, x, y float64) float64 { return 10 * (y / yr.GetDelta()) },
 					DotColorProvider: chart.Viridis,
 				},
 				XValues: chart.Sequence.Random(128, 1024),

draw.go

@@ -66,11 +66,11 @@ func (d draw) LineSeries(r Renderer, canvasBox Box, xrange, yrange Range, style
 
 			dotWidth := defaultDotWidth
 			if style.DotWidthProvider != nil {
-				dotWidth = style.DotWidthProvider(xrange.GetDelta(), yrange.GetDelta(), vx, vy)
+				dotWidth = style.DotWidthProvider(xrange, yrange, vx, vy)
 			}
 
 			if style.DotColorProvider != nil {
-				dotColor := style.DotColorProvider(xrange.GetDelta(), yrange.GetDelta(), vx, vy)
+				dotColor := style.DotColorProvider(xrange, yrange, vx, vy)
 
 				r.SetFillColor(dotColor)
 				r.SetStrokeColor(dotColor)

value_provider.go

@@ -37,7 +37,7 @@ type FullBoundedValueProvider interface {
 }
 
 // SizeProvider is a provider for integer size.
-type SizeProvider func(rx, ry, x, y float64) float64
+type SizeProvider func(xrange, yrange Range, x, y float64) float64
 
 // ColorProvider is a provider for dot size.
-type ColorProvider func(rx, ry, x, y float64) drawing.Color
+type ColorProvider func(xrange, yrange Range, x, y float64) drawing.Color

viridis.go

@@ -266,7 +266,10 @@ var viridisColors = [256]drawing.Color{
 }
 
 // Viridis creates a color map provider.
-func Viridis(rx, ry, x, y float64) drawing.Color {
-	index := uint8((y / ry) * 256)
+func Viridis(xr, yr Range, x, y float64) drawing.Color {
+	delta := yr.GetDelta()
+	normalized := y / delta
+	adjusted := normalized + yr.GetMin()
+	index := uint8(adjusted * 256)
 	return viridisColors[index]
 }