package widgets import ( "image" "math" . "github.com/gizak/termui" ) const ( piechartOffsetUp = -.5 * math.Pi // the northward angle resolutionFactor = .0001 // circle resolution: precision vs. performance fullCircle = 2.0 * math.Pi // the full circle angle xStretch = 2.0 // horizontal adjustment ) // PieChartLabel callback type PieChartLabel func(dataIndex int, currentValue float64) string type PieChart struct { Block Data []float64 // list of data items Colors []Color // colors to by cycled through Label PieChartLabel // callback function for labels Offset float64 // which angle to start drawing at? (see piechartOffsetUp) } // NewPieChart Creates a new pie chart with reasonable defaults and no labels. func NewPieChart() *PieChart { return &PieChart{ Block: *NewBlock(), Colors: Theme.PieChart.Slices, Offset: piechartOffsetUp, } } func (self *PieChart) Draw(buf *Buffer) { self.Block.Draw(buf) center := self.Inner.Min.Add(self.Inner.Size().Div(2)) radius := MinFloat64(float64(self.Inner.Dx()/2/xStretch), float64(self.Inner.Dy()/2)) // compute slice sizes sum := SumFloat64Slice(self.Data) sliceSizes := make([]float64, len(self.Data)) for i, v := range self.Data { sliceSizes[i] = v / sum * fullCircle } borderCircle := &circle{center, radius} middleCircle := circle{Point: center, radius: radius / 2.0} // draw sectors phi := self.Offset for i, size := range sliceSizes { for j := 0.0; j < size; j += resolutionFactor { borderPoint := borderCircle.at(phi + j) line := line{P1: center, P2: borderPoint} line.draw(NewCell(SHADED_BLOCK, NewStyle(SelectColor(self.Colors, i))), buf) } phi += size } // draw labels if self.Label != nil { phi = self.Offset for i, size := range sliceSizes { labelPoint := middleCircle.at(phi + size/2.0) if len(self.Data) == 1 { labelPoint = center } buf.SetString( self.Label(i, self.Data[i]), NewStyle(SelectColor(self.Colors, i)), image.Pt(labelPoint.X, labelPoint.Y), ) phi += size } } } type circle struct { image.Point radius float64 } // computes the point at a given angle phi func (self circle) at(phi float64) image.Point { x := self.X + int(RoundFloat64(xStretch*self.radius*math.Cos(phi))) y := self.Y + int(RoundFloat64(self.radius*math.Sin(phi))) return image.Point{X: x, Y: y} } // computes the perimeter of a circle func (self circle) perimeter() float64 { return 2.0 * math.Pi * self.radius } // a line between two points type line struct { P1, P2 image.Point } // draws the line func (self line) draw(cell Cell, buf *Buffer) { isLeftOf := func(p1, p2 image.Point) bool { return p1.X <= p2.X } isTopOf := func(p1, p2 image.Point) bool { return p1.Y <= p2.Y } p1, p2 := self.P1, self.P2 buf.SetCell(NewCell('*', cell.Style), self.P2) width, height := self.size() if width > height { // paint left to right if !isLeftOf(p1, p2) { p1, p2 = p2, p1 } flip := 1.0 if !isTopOf(p1, p2) { flip = -1.0 } for x := p1.X; x <= p2.X; x++ { ratio := float64(height) / float64(width) factor := float64(x - p1.X) y := ratio * factor * flip buf.SetCell(cell, image.Pt(x, int(RoundFloat64(y))+p1.Y)) } } else { // paint top to bottom if !isTopOf(p1, p2) { p1, p2 = p2, p1 } flip := 1.0 if !isLeftOf(p1, p2) { flip = -1.0 } for y := p1.Y; y <= p2.Y; y++ { ratio := float64(width) / float64(height) factor := float64(y - p1.Y) x := ratio * factor * flip buf.SetCell(cell, image.Pt(int(RoundFloat64(x))+p1.X, y)) } } } // width and height of a line func (self line) size() (w, h int) { return AbsInt(self.P2.X - self.P1.X), AbsInt(self.P2.Y - self.P1.Y) }