termui/chart.go

package termui

import "fmt"

const VDASH = '┊'
const HDASH = '┈'
const ORIGIN = '└'

// only 16 possible combinations, why bother
var braillePatterns = map[[2]int]rune{
	[2]int{0, 0}: '⣀',
	[2]int{0, 1}: '⡠',
	[2]int{0, 2}: '⡐',
	[2]int{0, 3}: '⡈',

	[2]int{1, 0}: '⢄',
	[2]int{1, 1}: '⠤',
	[2]int{1, 2}: '⠔',
	[2]int{1, 3}: '⠌',

	[2]int{2, 0}: '⢂',
	[2]int{2, 1}: '⠢',
	[2]int{2, 2}: '⠒',
	[2]int{2, 3}: '⠊',

	[2]int{3, 0}: '⢁',
	[2]int{3, 1}: '⠡',
	[2]int{3, 2}: '⠑',
	[2]int{3, 3}: '⠉',
}

type LineChart struct {
	Block
	Data          []float64
	DataLabels    []string
	Mode          string // braille | dot
	DotStyle      rune
	LineColor     Attribute
	scale         float64
	AxesColor     Attribute
	drawingX      int
	drawingY      int
	axisYHeight   int
	axisXWidth    int
	axisYLebelGap int
	axisXLebelGap int
	topValue      float64
	bottomValue   float64
	labelX        [][]rune
	labelY        [][]rune
	labelYSpace   int
	maxY          float64
	minY          float64
}

func NewLineChart() *LineChart {
	lc := &LineChart{Block: *NewBlock()}
	lc.AxesColor = theme.LineChartAxes
	lc.LineColor = theme.LineChartLine
	lc.Mode = "braille"
	lc.DotStyle = '•'
	lc.axisXLebelGap = 2
	lc.axisYLebelGap = 1
	return lc
}

// one cell contains two data points
func (lc *LineChart) renderBraille() []Point {
	ps := []Point{}
	getBaseMod := func(d float64) (b, m int) {
		b = int((d - lc.minY) / lc.scale)
		m = int(((d-lc.minY)-float64(b)*lc.scale)/0.25 + 0.5)
		return
	}
	for i := 0; i+1 < len(lc.Data) && i/2 < lc.axisXWidth; i += 2 {
		b0, m0 := getBaseMod(lc.Data[i])
		b1, m1 := getBaseMod(lc.Data[i+1])

		if b0 > b1 {
			m1 = 0
		}
		if b0 < b1 {
			m1 = 3
		}

		p := Point{}
		p.Ch = braillePatterns[[2]int{m0, m1}]
		p.Bg = lc.BgColor
		p.Fg = lc.LineColor
		p.Y = lc.innerY + lc.innerHeight - 3 - b0
		p.X = lc.innerX + lc.labelYSpace + 1 + i/2
		ps = append(ps, p)
	}
	return ps
}

func (lc *LineChart) renderDot() []Point {
	ps := []Point{}
	for i := 0; i < len(lc.Data) && i < lc.axisXWidth; i++ {
		p := Point{}
		p.Ch = lc.DotStyle
		p.Fg = lc.LineColor
		p.Bg = lc.BgColor
		p.X = lc.innerX + lc.labelYSpace + 1 + i
		p.Y = lc.innerY + lc.innerHeight - 3 - int((lc.Data[i]-lc.minY)/lc.scale+0.5)
		ps = append(ps, p)
	}

	return ps
}

func (lc *LineChart) calcLabelX() {
	lc.labelX = [][]rune{}

	for i, l := 0, 0; i < len(lc.DataLabels) && l < lc.axisXWidth; i++ {
		if lc.Mode == "dot" {
			if l >= len(lc.DataLabels) {
				break
			}

			s := str2runes(lc.DataLabels[l])
			if l+len(s) <= lc.axisXWidth {
				lc.labelX = append(lc.labelX, s)
			}
			l += (len(s) + lc.axisXLebelGap) // -1 needed
		} else {
			if 2*l >= len(lc.DataLabels) {
				break
			}

			s := str2runes(lc.DataLabels[2*l])
			if l+len(s) <= lc.axisXWidth {
				lc.labelX = append(lc.labelX, s)
			}
			l += (len(s) + lc.axisXLebelGap) // -1 needed

		}
	}
}

func shortenFloatVal(x float64) string {
	s := fmt.Sprintf("%.2f", x)
	if len(s)-3 > 3 {
		s = fmt.Sprintf("%.2e", x)
	}

	if x < 0 {
		s = fmt.Sprintf("%.2f", x)
	}
	return s
}

func (lc *LineChart) calcLabelY() {
	span := lc.topValue - lc.bottomValue
	lc.scale = span / float64(lc.axisYHeight)

	n := (1 + lc.axisYHeight) / (lc.axisYLebelGap + 1)
	lc.labelY = make([][]rune, n)
	maxLen := 0
	for i := 0; i < n; i++ {
		s := str2runes(shortenFloatVal(lc.bottomValue + float64(i)*span/float64(n)))
		if len(s) > maxLen {
			maxLen = len(s)
		}
		lc.labelY[i] = s
	}

	lc.labelYSpace = maxLen
}

func (lc *LineChart) calcLayout() {
	if lc.DataLabels == nil || len(lc.DataLabels) == 0 {
		lc.DataLabels = make([]string, len(lc.Data))
		for i := range lc.Data {
			lc.DataLabels[i] = fmt.Sprint(i)
		}
	}

	lc.minY = lc.Data[0]
	lc.maxY = lc.Data[0]
	for _, v := range lc.Data {
		if v > lc.maxY {
			lc.maxY = v
		}
		if v < lc.minY {
			lc.minY = v
		}
	}

	lc.topValue = lc.maxY * 1.2
	lc.bottomValue = lc.minY * 0.8 //- 0.05*(lc.maxY-lc.minY)
	if lc.minY < 0 {
		lc.bottomValue = lc.minY * 1.2
	}

	lc.axisYHeight = lc.innerHeight - 2
	lc.calcLabelY()

	lc.axisXWidth = lc.innerWidth - 1 - lc.labelYSpace
	lc.calcLabelX()

	lc.drawingX = lc.innerX + 1 + lc.labelYSpace
	lc.drawingY = lc.innerY
}

func (lc *LineChart) plotAxes() []Point {
	origY := lc.innerY + lc.innerHeight - 2
	origX := lc.innerX + lc.labelYSpace

	ps := []Point{newPointWithAttrs(ORIGIN, origX, origY, lc.AxesColor, lc.BgColor)}

	for x := origX + 1; x < origX+lc.axisXWidth; x++ {
		p := Point{}
		p.X = x
		p.Y = origY
		p.Bg = lc.BgColor
		p.Fg = lc.AxesColor
		p.Ch = HDASH
		ps = append(ps, p)
	}

	for dy := 1; dy <= lc.axisYHeight; dy++ {
		p := Point{}
		p.X = origX
		p.Y = origY - dy
		p.Bg = lc.BgColor
		p.Fg = lc.AxesColor
		p.Ch = VDASH
		ps = append(ps, p)
	}

	// x label
	oft := 0
	for _, rs := range lc.labelX {
		if oft+len(rs) > lc.axisXWidth {
			break
		}
		for j, r := range rs {
			p := Point{}
			p.Ch = r
			p.Fg = lc.AxesColor
			p.Bg = lc.BgColor
			p.X = origX + oft + j
			p.Y = lc.innerY + lc.innerHeight - 1
			ps = append(ps, p)
		}
		oft += len(rs) + lc.axisXLebelGap
	}

	// y labels
	for i, rs := range lc.labelY {
		for j, r := range rs {
			p := Point{}
			p.Ch = r
			p.Fg = lc.AxesColor
			p.Bg = lc.BgColor
			p.X = lc.innerX + j
			p.Y = origY - i*(lc.axisYLebelGap+1)
			ps = append(ps, p)
		}
	}

	return ps
}

func (lc *LineChart) Buffer() []Point {
	ps := lc.Block.Buffer()
	if lc.Data == nil || len(lc.Data) == 0 {
		return ps
	}
	lc.calcLayout()
	ps = append(ps, lc.plotAxes()...)

	if lc.Mode == "dot" {
		ps = append(ps, lc.renderDot()...)
	} else {
		ps = append(ps, lc.renderBraille()...)
	}

	return ps
}