termui/widgets/barchart.go

// Copyright 2017 Zack Guo <zack.y.guo@gmail.com>. All rights reserved.
// Use of this source code is governed by a MIT license that can
// be found in the LICENSE file.

package widgets

import (
	"fmt"
	"image"

	rw "github.com/mattn/go-runewidth"

	. "github.com/gizak/termui"
)

type BarChart struct {
	Block
	BarColors    []Color
	LabelStyles  []Style
	NumStyles    []Style // only Fg and Modifier are used
	NumFormatter func(float64) string
	Data         []float64
	Labels       []string
	BarWidth     int
	BarGap       int
	MaxVal       float64
}

func NewBarChart() *BarChart {
	return &BarChart{
		Block:        *NewBlock(),
		BarColors:    Theme.BarChart.Bars,
		NumStyles:    Theme.BarChart.Nums,
		LabelStyles:  Theme.BarChart.Labels,
		NumFormatter: func(n float64) string { return fmt.Sprint(n) },
		BarGap:       1,
		BarWidth:     3,
	}
}

func (self *BarChart) Draw(buf *Buffer) {
	self.Block.Draw(buf)

	maxVal := self.MaxVal
	if maxVal == 0 {
		maxVal, _ = GetMaxFloat64FromSlice(self.Data)
	}

	barXCoordinate := self.Inner.Min.X

	for i, data := range self.Data {
		// draw bar
		height := int((data / maxVal) * float64(self.Inner.Dy()-1))
		for x := barXCoordinate; x < MinInt(barXCoordinate+self.BarWidth, self.Inner.Max.X); x++ {
			for y := self.Inner.Max.Y - 2; y > (self.Inner.Max.Y-2)-height; y-- {
				c := NewCell(' ', NewStyle(ColorClear, SelectColor(self.BarColors, i)))
				buf.SetCell(c, image.Pt(x, y))
			}
		}

		// draw label
		if i < len(self.Labels) {
			labelXCoordinate := barXCoordinate +
				int((float64(self.BarWidth) / 2)) -
				int((float64(rw.StringWidth(self.Labels[i])) / 2))
			buf.SetString(
				self.Labels[i],
				SelectStyle(self.LabelStyles, i),
				image.Pt(labelXCoordinate, self.Inner.Max.Y-1),
			)
		}

		// draw number
		numberXCoordinate := barXCoordinate + int((float64(self.BarWidth) / 2))
		if numberXCoordinate <= self.Inner.Max.X {
			buf.SetString(
				self.NumFormatter(data),
				NewStyle(
					SelectStyle(self.NumStyles, i+1).Fg,
					SelectColor(self.BarColors, i),
					SelectStyle(self.NumStyles, i+1).Modifier,
				),
				image.Pt(numberXCoordinate, self.Inner.Max.Y-2),
			)
		}

		barXCoordinate += (self.BarWidth + self.BarGap)
	}
}