Sparklines for macOS, iOS and tvOS

A lightweight sparkline component, supporting Swift, SwiftUI, macCatalyst and Objective-C.

What is a sparkline?

A sparkline is a very small chart, typically drawn without axes or coordinates. It presents the general shape of the variation (typically over time) in some measurement, such as temperature or stock market price, in a simple and highly condensed way. Sparklines are small enough to be embedded in text, or several sparklines may be grouped together as elements of a small multiple. Whereas the typical chart is designed to show as much data as possible, and is set off from the flow of text, sparklines are intended to be succinct, memorable, and located where they are discussed.

Source: Wikipedia

What ISN'T a sparkline?

DSFSparkline IS NOT designed to be a full-featured graphing library. It was built to be lightweight, to create small, memorable charts within an app.

If you need features like labelling, real-time updating, axis-labelling, interactivity, legends or beautiful charts at larger sizes, you might be better served by the Charts library, Core plot or SciChart (paid). You can find a whole lot more here.

Features

• Multiple graph styles support, such as line, bar, tablet etc.
• Support for sparkline customizations, such as zero-line, grid lines, highlighting.
• Prebuilt NSView/UIView/SwiftUI types for quick integration
• Independently scalable for sparklines at any size
• y-range can automatically grow or shrink to encompass the full y-range of data.
• y-range can be fixed and the sparkline will truncate to the specified range
• SwiftUI support for all sparkline types
• NSAttributedString support
• IBDesignable support for prebuilt types so you can see and configure your sparklines in interface builder.
• Optional drawing of a 'zero line' on the bar and line graphs (thanks Tito Ciuro)
• Playground support

TL;DR - Show me something!

Create a retina-scale (144dpi) bitmap with a simple line overlay graph

// A datasource with a simple set of data
let source = DSFSparkline.DataSource(values: [4, 1, 8, 7, 5, 9, 3], range: 0 ... 10)

let bitmap = DSFSparklineSurface.Bitmap()   // Create a bitmap surface
let stack = DSFSparklineOverlay.Line()      // Create a line overlay
stack.dataSource = source                   // Assign the datasource to the overlay
bitmap.addOverlay(stack)                    // And add the overlay to the surface.

// Generate an image with retina scale
let image = bitmap.image(width: 50, height: 25, scale: 2)

// Embed a sparkline in an NSAttributedString
let attributedString = bitmap.attributedString(size: CGSize(width: 40, height: 18), scale: 2)

Create a Swift-UI line graph sparkline with zero-line and highlight range overlays

fileprivate let SwiftUIDemoDataSource: DSFSparkline.DataSource = {
   let d = DSFSparkline.DataSource(windowSize: 20, range: 0 ... 1, zeroLineValue: 0.5)
     d.push(values: [
        0.72, 0.84, 0.15, 0.16, 0.30, 0.58, 0.87, 0.44, 0.02, 0.27,
        0.48, 0.16, 0.15, 0.14, 0.81, 0.53, 0.67, 0.52, 0.07, 0.50
     ])
     return d
  }()

struct SuperCoolLineSpark: View {
   // The overlay representing the zero-line for the data source
   var zeroOverlay: DSFSparklineOverlay = {
      let zeroLine = DSFSparklineOverlay.ZeroLine()
      zeroLine.dataSource = SwiftUIDemoDataSource
      zeroLine.dashStyle = []
      return zeroLine
   }()

   // The overlay to draw a highlight between range 0 ..< 0.2
   var rangeOverlay: DSFSparklineOverlay = {
      let highlight = DSFSparklineOverlay.RangeHighlight()
      highlight.dataSource = SwiftUIDemoDataSource
      highlight.highlightRange = 0.0 ..< 0.2
      highlight.fill = DSFSparkline.Fill.Color(DSFColor.gray.withAlphaComponent(0.4).cgColor)
      return highlight
   }()

   // The actual line graph
   var lineOverlay: DSFSparklineOverlay = {
      let lineOverlay = DSFSparklineOverlay.Line()
      lineOverlay.dataSource = SwiftUIDemoDataSource

      lineOverlay.primaryStrokeColor = DSFColor.systemBlue.cgColor
      lineOverlay.primaryFill = DSFSparkline.Fill.Color(DSFColor.systemBlue.withAlphaComponent(0.3).cgColor)

      lineOverlay.secondaryStrokeColor = DSFColor.systemYellow.cgColor
      lineOverlay.secondaryFill = DSFSparkline.Fill.Color(DSFColor.systemYellow.withAlphaComponent(0.3).cgColor)

      lineOverlay.strokeWidth = 1
      lineOverlay.markerSize = 4
      lineOverlay.centeredAtZeroLine = true

      return lineOverlay
   }()

   var body: some View {
      DSFSparklineSurface.SwiftUI([
         rangeOverlay,    // range highlight overlay
         zeroOverlay,     // zero-line overlay
         lineOverlay,     // line graph overlay
      ])
      .frame(width: 150, height: 40)
   }
}

Available graph types

Line

A simple line sparkline. The line can be centered around a zero line to indicate positive and negative values. You can also add (optional) markers to the data points.

You can custom-draw the markers by supplying a drawing callback block (markerDrawingBlock) where you can customize which markers are drawn (for example, just the min and max values) and how they are drawn.

Standard	Centered

Interpolated	Interpolated Centered

Standard Markers	Interpolated Markers

Custom Markers (min/max only)	Custom Markers (Last 5 values)

//
// A custom marker drawing function that draws the maximum value in green, the minimum value in red
//
self.myLineView.markerDrawingBlock = { context, markerFrames in
   // Get the frames containing the minimum and maximum values
   if let minMarker = markerFrames.min(by: { (a, b) -> Bool in a.value < b.value }),
      let maxMarker = markerFrames.min(by: { (a, b) -> Bool in a.value > b.value }) {

      // Draw minimum marker

      context.setFillColor(DSFColor.systemRed.cgColor)
      context.fill(minMarker.rect)
      context.setLineWidth(0.5)
      context.setStrokeColor(DSFColor.white.cgColor)
      context.stroke(minMarker.rect)

      // Draw maximum marker

      context.setFillColor(DSFColor.systemGreen.cgColor)
      context.fill(maxMarker.rect)

      context.setLineWidth(0.5)
      context.setStrokeColor(DSFColor.white.cgColor)
      context.stroke(maxMarker.rect)
   }
}

Bar

A simple barchart sparkline. The bar can be centered around a zero line to indicate positive and negative values.

Standard	Centered

Stackline

A stackline sparkline is similar to a bar chart except that it doesn't separate out individual columns. The stackline can be centered around a zero line to indicate positive and negative values.

Standard	Centered

Stripes

A stripes graph. A good example of a stripes graph is the 'warming stripes' climate graph.

Values from the datasource are mapped to a supplied gradient

Standard	Integral (pixel boundaries)

Dot

A dot sparkline reminiscent of Activity Viewer's CPU history graphs

Standard	Inverted

Win/Loss/Tie

A win-loss graph, where positive values in the datasource are represented as a 'win', negative values represented as a 'loss', and zero values are a 'tie'.

Win/Loss	Win/Loss/Tie

Tablet

A tablet graph, where positive values in the datasource are represented as a filled circle, negative values represented as an unfilled circle. The behaviour is identical to the win/loss graph.

Standard

Pie

A basic pie sparkline

Standard

DataBar

A databar sparkline. Supports percentage and totals types.

Percent	Total

PercentBar

A percentbar sparkline takes a single value (0 ... 1) and draws a horizontal bar chart containing the value with an optional text label.

WiperGauge

A simple gauge with a single value (0 ... 1). The color displayed in the gauge can be one of

• a single flat color
• a color mapped from a gradient to the value
• a color mapped from a color bucket to the value

Standard

Demos

You can find a lot of examples of sparklines in projects in the Demos/Samples subfolder, providing examples for macOS (swift and objc), iO, tvOS, macCatalyst and SwiftUI.

There's also a simple Xcode Playground available in the Demos/Playground subfolder where you can play with the different sparkline types

Building your sparkline

Using prebuilt views

A prebuilt view is useful to quickly add a sparkline using SwiftUI or via Interface Builder (while providing previews using @IBDesignable). These views a slightly more limited set of styling and customizations but are much quicker to implement than using overlays directly.

For the most part, the prebuilt types will be all you need.

If you've used DSFSparklines prior to v4, these are the original view types that you used to display your sparklines.

• A datasource - the set of values to draw
• A prebuilt view type - the NSView/UIView/SwiftUI view to draw your sparkline

Using overlays

There are three fundamental building blocks for an overlay sparkline. Overlay sparklines are more flexible and configurable than the pre-built views, but are more complex to set up and provides no support for @IBDesignable.

• A surface - where it will draw
• A datasource - the set of values to draw
• One or more overlays - the 'layers' which render different components of the sparkline

Surface

A surface represents a destination for a sparkline. This library provides a number of built-in surfaces

• DSFSparklineSurfaceView - An NSView/UIView surface for displaying a sparkline
• DSFSparklineSurface.SwiftUI - A SwiftUI View surface.
• DSFSparklineSurface.Bitmap - A NSImage/UIImage/CGImage/NSAttributedString surface for creating a bitmap from a sparkline.

DataSource

A data source provides data for a sparkline. A datasource can be shared between multiple overlays or prebuilt types (see below) to provide different 'views' of the data contained within the source. And if a DataSource is updated, all sparkline ovelays observing that source will be automatically re-rendered.

There are currently two types of datasource available

DSFSparkline.DataSource

A DataSource that contains values that can be updated by pushing new values into the source.

/// Swift
dataSource.windowSize = 30
assert(dataSource.windowSize == 30)

/// Objective-C
[dataSource setWindowSize:30];
assert([dataSource windowSize] == 30);

/// Swift
dataSource.range = -1.0 ... 1.0

/// Objective-C
[dataSource setRangeWithLowerBound:-1.0 upperBound:1.0];

/// Swift
dataSource.zeroLineValue = 0.2

/// Objective-C
[dataSource setZeroLineValue:0.2];

/// Swift
dataSource.push(value: 4.5)
dataSource.push(values: [6, 7, 8])

/// Objective-C
[dataSource pushWithValue:@(4.5)];

/// Swift
datasource.set(values: [
   0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0,
   0.0, -0.1, -0.2, -0.3, -0.4, -0.5, -0.6, -0.7, -0.8, -0.9, -1.0
])

/// Objective-C
[datasource setWithValues:
   @[@(0.0), @(0.1), @(0.2), @(0.3), @(0.4), @(0.5), @(0.6), @(0.7), @(0.8), @(0.9), @(1),
     @(0.0), @(-0.1), @(-0.2), @(-0.3), @(-0.4), @(-0.5), @(-0.6), @(-0.7), @(-0.8), @(-0.9), @(-1)]];

DSFSparkline.StaticDataSource

A datasource that contains a static set of values. Some types of sparkline use a single 'set' of data, providing no historical context.

/// Swift
let dataSource = DSFSparkline.StaticDataSource([1, 2, 3])

/// Objective-C
DSFSparklineStaticDataSource* dataSource = [[DSFSparklineStaticDataSource alloc] init: @[@(1), @(2), @(3)]];

Overlays

Overlays represent the individual visual components of a sparkline. You can add as many or as few to your surface in any order. For example, you could overlay two different graph types onto the same surface using the same. And as overlays can share their datasource, all overlays using the same source will automatically update if the data changes (for example, in reponse to a push)

For example, there is an overlay that highlights a y-range of data. Or, if you want some grid lines, you can add them using the gridlines overlay.

You can add different instances of an overlay to the same sparkline. For example, if you want to add multiple range highlights you add multiple 'highlight' overlays to the sparkline surface.

The order in which the overlays are added determine where in the z-order that they appear in the sparkline. For example, you can choose to draw the grid on top of the graph if you want by adding the graph overlay BEFORE you add the grid overlay

The overlay allows your sparkline to be as complex or as simple as you want.

Graph types

Dynamic

A dynamic graph automatically updates its overlays as values are 'pushed' onto its datasource. As data is added the assigned overlay is automatically updated to reflect the new data. If more data is added via a push or set the data is added to the datasource, the associated view will automatically update to reflect the new data. Older data that no longer falls within the datasource window is discarded.

This provides the ability to show a historical data set over the breadth of the graph.

`DSFSparklineOverlay.Line`

let bitmap = DSFSparklineSurface.Bitmap()   // Create a bitmap surface
let line = DSFSparklineOverlay.Line()      // Create a line overlay
line.strokeWidth = 1
line.primaryFill = primaryFill
line.dataSource = source                   // Assign the datasource to the overlay
bitmap.addOverlay(line)                    // And add the overlay to the surface.

// Generate an image with retina scale
let image = bitmap.image(width: 50, height: 25, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.StackLine`

let bitmap = DSFSparklineSurface.Bitmap()    // Create a bitmap surface
let stack = DSFSparklineOverlay.Stackline()  // Create a stackline overlay
stack.dataSource = source                    // Assign the datasource to the overlay
stack.strokeWidth = 1
stack.primaryFill = primaryFill
bitmap.addOverlay(stack)                     // And add the overlay to the surface.

// Generate an image with retina scale
let image = bitmap.image(width: 50, height: 25, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.Bar`

let bitmap = DSFSparklineSurface.Bitmap()   // Create a bitmap surface
let bar = DSFSparklineOverlay.Bar()         // Create a bar overlay
bar.dataSource = source                     // Assign the datasource to the overlay
bar.primaryFill = primaryFill
bitmap.addOverlay(bar)                      // And add the overlay to the surface.

// Generate an image with retina scale
let image = bitmap.image(width: 50, height: 25, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.Dot`

let bitmap = DSFSparklineSurface.Bitmap()  // Create a bitmap surface
let dot = DSFSparklineOverlay.Dot()        // Create a dot graph overlay
dot = biggersource                         // Assign the datasource to the overlay
bitmap.addOverlay(dot)                     // And add the overlay to the surface.

// Generate an image with retina scale
let image = bitmap.image(width: 50, height: 32, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.WinLossTie`

let bitmap = DSFSparklineSurface.Bitmap()          // Create a bitmap surface
let winLossTie = DSFSparklineOverlay.WinLossTie()  // Create a win-loss-tie overlay
winLossTie.dataSource = winloss                    // Assign the datasource
bitmap.addOverlay(winLossTie)                      // And add the overlay to the surface.

// Generate an image with retina scale
let image = bitmap.image(width: 75, height: 12, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.Tablet`

let bitmap = DSFSparklineSurface.Bitmap()    // Create a bitmap surface
let stack = DSFSparklineOverlay.Tablet()     // Create a tablet overlay
stack.dataSource = winloss                   // Assign a datasource to the overlay
bitmap.addOverlay(stack)                     // And add the overlay to the surface.

// Generate an image with retina scale
let image = bitmap.image(width: 90, height: 16, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.Stripes`

let bitmap = DSFSparklineSurface.Bitmap()    // Create a bitmap surface
let stack = DSFSparklineOverlay.Stripes()    // Create a stripes overlay
stack.dataSource = .init(values: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10])
bitmap.addOverlay(stack)                     // And add the overlay to the surface.

// Generate an image with retina scale
let image = bitmap.image(width: 90, height: 16, scale: 2)

// Do something with 'image'

Static

A static graph has a fixed set of values (for example, a pie chart). The overlays update when a new static data source is assigned to it.

`DSFSparklineOverlay.Pie`

let bitmap = DSFSparklineSurface.Bitmap()
let pie = DSFSparklineOverlay.Pie()
pie.dataSource = DSFSparkline.StaticDataSource([10, 55, 20])
pie.lineWidth = 0.5
pie.strokeColor = CGColor.black

bitmap.addOverlay(pie)

// Generate an image with retina scale
let image = bitmap.image(width: 18, height: 18, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.DataBar`

let bitmap = DSFSparklineSurface.Bitmap()
let stack = DSFSparklineOverlay.DataBar()
stack.dataSource = DSFSparkline.StaticDataSource([10, 20, 30])
stack.lineWidth = 0.5
stack.strokeColor = CGColor.black

bitmap.addOverlay(stack)

// Generate an image with retina scale
let image = bitmap.image(width: 50, height: 18, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.PercentBar`

let bitmap = DSFSparklineSurface.Bitmap()
let percentBar = DSFSparklineOverlay.PercentBar(value: 0.3)

bitmap.addOverlay(percentBar)

// Generate an image with retina scale
let image = bitmap.image(width: 50, height: 18, scale: 2)!

// Do something with 'image'

`DSFSparklineOverlay.WiperGauge`

let bitmap = DSFSparklineSurface.Bitmap()
let wiperGauge = DSFSparklineOverlay.WiperGauge()
wiperGauge.value = 0.75

bitmap.addOverlay(wiperGauge)

// Generate an image of the wiper gauge with retina scale
let image = bitmap.image(width: 50, height: 25, scale: 2)

// Do something with 'image'

Component types

A component represents an overlay that isn't a graph in itself. Examples are grid lines, zero-lines, highlights etc. A component uses the same datasource so that it aligns with the graph it is associated with.

Using prebuilt views

DSFSparkline has a number of 'prebuilt' sparkline views available with a more limited scope, designed to be quicker to add to your project, especially relating to Interface Builder (the pre-built types provide an @IBDesignable interface) so you can design the look of your graph from directly within Interface Builder.

Every prebuilt sparkline view has a SwiftUI companion view.

Available prebuilt types

• DSFSparklineLineGraphView / DSFSparklineLineGraphView.SwiftUI
• DSFSparklineStackLineGraphView / DSFSparklineLineGraphView.SwiftUI
• DSFSparklineBarGraphView / DSFSparklineBarGraphView.SwiftUI
• DSFSparklineStripesGraphView / DSFSparklineStripesGraphView.SwiftUI
• DSFSparklineDotGraphView / DSFSparklineDotGraphView.SwiftUI
• DSFSparklineWinLossGraphView / DSFSparklineWinLossGraphView.SwiftUI
• DSFSparklineTabletGraphView / DSFSparklineTabletGraphView.SwiftUI
• DSFSparklinePieGraphView / DSFSparklinePieGraphView.SwiftUI
• DSFSparklineDataBarGraphView / DSFSparklineDataBarGraphView.SwiftUI
• DSFSparklinePercentBarGraphView / DSFSparklinePercentBarGraphView.SwiftUI
• DSFSparklineWiperGaugeGraphView / DSFSparklineWiperGaugeGraphView.SwiftUI

// Create the view
let sparklineView = DSFSparklineLineGraphView(…)
sparklineView.graphColor = UIColor.blue
sparklineView.showZeroLine = true

// Create the datasource and assign to the view
let sparklineDataSource = DSFSparklineDataSource(windowSize: 30, range: -1.0 ... 1.0)
sparklineView.dataSource = sparklineDataSource

…

// Add a single new data element to the sparkline
sparklineDataSource.push(value: 0.7)                          // view automatically updates with new data

// Add a set of data to the sparkline
sparklineDataSource.push(values: [0.3, -0.2, 1.0])            // view automatically updates with new data

// Completely replace the sparkline data with a new set of data
sparklineDataSource.set(values: [0.2, -0.2, 0.0, 0.9, 0.8])   // view automatically resets to new data

struct SparklineView: View {

   let leftDataSource: DSFSparkline.DataSource
   let rightDataSource: DSFSparkline.DataSource
   
   let BigCyanZeroLine = DSFSparkline.ZeroLineDefinition(
      color: .cyan,
      lineWidth: 3,
      lineDashStyle: [4,1,2,1]
   )
   
   var body: some View {
      HStack {
         DSFSparklineLineGraphView.SwiftUI(
            dataSource: leftDataSource,
            graphColor: DSFColor.red,
            interpolated: true)
         DSFSparklineBarGraphView.SwiftUI(
            dataSource: rightDataSource,
            graphColor: DSFColor.blue,
            lineWidth: 2,
            showZeroLine: true,
            zeroLineDefinition: BigCyanZeroLine)
      }
   }
}

Integration

There are demos available in the Demos subfolder for each of the supported platforms. The demos use CocoaPods so you'll need to pod install in the Demos folder.

Import the library into your source files

Cocoapods

pod 'DSFSparkline', :git => 'https://github.com/dagronf/DSFSparkline/'

Swift package manager

Add https://github.com/dagronf/DSFSparkline to your project.

Screenshots

In app

macOS dark	macOS light	iOS

Interface Builder

macOS	tvOS

SwiftUI

NSAttributedString support

Animated

Changes

4.6.0

• Added WiperGauge sparkline type

4.3.0

• Added the ability to custom-draw markers for the 'line' sparkline type (raised issue)
• Fixed a minor issue where insetting certain graph types to remove clipping (line with markers, bar) would mean that zeroline, highlight overlays and grids would be appear to be very slightly off.

4.2.0

• Added 'percent bar' sparkline type.

4.1.2

• Fixed compile issue Cannot find type 'NSTextAttachment' in scope" crashes when using SwiftPackage

4.1.1

• Fixed gradient bucket count issue.
• Added AttributedString SwiftUI demo to the ReportView demo. Demo uses The SwiftUI Lab Attributed String with AppKit bug fix for width calculation.

4.1.0

• Embed sparklines in NSAttributedString.

4.0.0

Substantial re-architect of the drawing code (that used to be directly in the views) into overlays and surfaces that are far more flexible (for example, being able to draw a sparkline bitmap without having to create a view)

The previous view/swiftui types are still available - they have been rebuilt on using the new overlay scheme and are referred to in documentation as 'prebuilt' types. This allowed backwards compatibility with previous versions of the library. Note however that given that the prebuilt views have been re-written there is a possibility of slight visual differences.

3.7.0

• Added stripe graph

3.6.1

• Fixed animations on iOS/tvOS

3.6.0

• Added pie chart, databar chart.
• Added ability to show data markers for line graphs

3.5.2

• Fixed Objective-C Demo app
• Added snapshot method to the base sparkline view class to produce an NSImage/UIImage version of the sparkline for embedded sparklines in text etc.

3.5.1

• Fixed version in podspec

3.5.0

• Added stackline sparkline type
• Added win/loss/tie sparkline type
• Added tablet sparkline type

3.4.0

• Added support for centering line and bar graphs around their zero-line value.

3.3.0

• Fixed issue where iOS background wasn't being drawn correctly in some cases.
• Fixed rare crash where a line graph with < 2 points would crash.

3.2.0

• Changed the zero-line definition class to DSFSparklineZeroLineDefinition for clarity.
• More documentation, especially around SwiftUI. Attempted to make the documentation clearer around drawing parameters.

3.1.0

• Add the ability to customize the zero-line display (Tito Ciuro)
• Changed showZero to showZeroLine for consistency with the new zero-line display values

3.0.0

• Add the ability to set the 'zero' line value. Defaults to zero for backwards compatibility.

You can set where the 'zero' line draws via the zeroLineValue on the datasource.

2.0.0

• The primary views have been renamed with a View postfix. So

  DSFSparklineLineGraph -> DSFSparklineLineGraphView

  DSFSparklineBarGraph -> DSFSparklineBarGraphView

  DSFSparklineDotGraph -> DSFSparklineDotGraphView

• Renamed SLColor and SLView to DSFColor and DSFView for module naming consistency.

• I removed windowSize from the core DSFSparklineDataSourceView. windowSize is related to data, and should never have been part of the UI definition. I've provided a replacement purely for IBDesignable support called graphWindowSize which should only be called from Interface Builder. If you want to set the windowSize from your xib file, set the graphWindowSize inspectable.

  If you see warnings in the log like 2020-12-07 18:22:51.619867+1100 iOS Sparkline Demo[75174:1459637] Failed to set (windowSize) user defined inspected property on (DSFSparkline.DSFSparklineBarGraphView): [<DSFSparkline.DSFSparklineBarGraphView 0x7fe2eb10f2b0> setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key windowSize. it means that you have a windowSize value set in your .xib file. Remove it and set the graphWindowSize value instead.

• For the Bar type, lineWidth and barSpacing now represent the pixel spacing between bars and the pixel width for the line. You may find that your line spacing and bar spacing are now incorrect if you have set fractional values for these in the past (for example, if you set lineWidth = 0.5). The reason for this change is to aid drawing lines on pixel boundaries and avoid antialiasing.

• Fix for zero line being upside-down

License

MIT. Use it for anything you want, just attribute my work. Let me know if you do use it somewhere, I'd love to hear about it!

MIT License

Copyright (c) 2021 Darren Ford

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.