// Plot implements the plot.Plotter interface.
func (b *BarChart) Plot(da plot.DrawArea, plt *plot.Plot) {
trX, trY := plt.Transforms(&da)
for i, ht := range b.Values {
x := b.XMin + float64(i)
xmin := trX(float64(x))
if !da.ContainsX(xmin) {
continue
}
xmin = xmin - b.Width/2 + b.Offset
xmax := xmin + b.Width
bottom := b.stackedOn.BarHeight(i)
ymin := trY(bottom)
ymax := trY(bottom + ht)
pts := []plot.Point{
{xmin, ymin},
{xmin, ymax},
{xmax, ymax},
{xmax, ymin},
}
poly := da.ClipPolygonY(pts)
da.FillPolygon(b.Color, poly)
pts = append(pts, plot.Point{xmin, ymin})
outline := da.ClipLinesY(pts)
da.StrokeLines(b.LineStyle, outline...)
}
}
func (b *BarChart) Thumbnail(da *plot.DrawArea) {
pts := []plot.Point{
{da.Min.X, da.Min.Y},
{da.Min.X, da.Max().Y},
{da.Max().X, da.Max().Y},
{da.Max().X, da.Min.Y},
}
poly := da.ClipPolygonY(pts)
da.FillPolygon(b.Color, poly)
pts = append(pts, plot.Point{da.Min.X, da.Min.Y})
outline := da.ClipLinesY(pts)
da.StrokeLines(b.LineStyle, outline...)
}