plot: Can't add data labels to the barchart #475

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1. ffhelicopter commented on Jun 6, 2019

   

   ffhelicopter

   on Jun 6, 2019

   Last edited by kortschak

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   modify plotter/barchart.go

   // Plot implements the plot.Plotter interface.
   func (b *BarChart) Plot(c draw.Canvas, plt *plot.Plot) {
   	trCat, trVal := plt.Transforms(&c)
   	if b.Horizontal {
   		trCat, trVal = trVal, trCat
   	}
   
   	for i, ht := range b.Values {
   		catVal := b.XMin + float64(i)
   		catMin := trCat(float64(catVal))
   		if !b.Horizontal {
   			if !c.ContainsX(catMin) {
   				continue
   			}
   		} else {
   			if !c.ContainsY(catMin) {
   				continue
   			}
   		}
   		catMin = catMin - b.Width/2 + b.Offset
   		catMax := catMin + b.Width
   		bottom := b.stackedOn.BarHeight(i)
   		valMin := trVal(bottom)
   		valMax := trVal(bottom + ht)
   
   		// value point
   		topx := catMin
   		topy := valMax
   
   		var pts []vg.Point
   		var poly []vg.Point
   		if !b.Horizontal {
   			pts = []vg.Point{
   				{catMin, valMin},
   				{catMin, valMax},
   				{catMax, valMax},
   				{catMax, valMin},
   			}
   			poly = c.ClipPolygonY(pts)
   		} else {
   			pts = []vg.Point{
   				{valMin, catMin},
   				{valMin, catMax},
   				{valMax, catMax},
   				{valMax, catMin},
   			}
   			poly = c.ClipPolygonX(pts)
   
   			topx = valMax
   			topy = catMin
   		}
   		c.FillPolygon(b.Color, poly)
   
   		var outline [][]vg.Point
   		if !b.Horizontal {
   			pts = append(pts, vg.Point{X: catMin, Y: valMin})
   			outline = c.ClipLinesY(pts)
   		} else {
   			pts = append(pts, vg.Point{X: valMin, Y: catMin})
   			outline = c.ClipLinesX(pts)
   		}
   		c.StrokeLines(b.LineStyle, outline...)
   		// show the value of each bar on top of it
   		strvalue := fmt.Sprintln(ht)
   		ft, _ := vg.MakeFont(plot.DefaultFont, 10)
   		c.FillText(draw.TextStyle{Color: color.Black, Font: ft}, vg.Point{X: topx, Y: topy}, strvalue)
   
   	}
   }
   
2. kortschak commented on Jun 6, 2019

   

   kortschak

   on Jun 6, 2019

   Member

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   @ffhelicopter Would you like to send a PR?