package chart import ( "errors" "io" "math" "github.com/golang/freetype/truetype" ) // BarChart is a chart that draws bars on a range. type BarChart struct { Title string TitleStyle Style Width int Height int DPI float64 BarWidth int Background Style Canvas Style XAxis Style YAxis YAxis BarSpacing int Font *truetype.Font defaultFont *truetype.Font Bars []Value Elements []Renderable } // GetDPI returns the dpi for the chart. func (bc BarChart) GetDPI() float64 { if bc.DPI == 0 { return DefaultDPI } return bc.DPI } // GetFont returns the text font. func (bc BarChart) GetFont() *truetype.Font { if bc.Font == nil { return bc.defaultFont } return bc.Font } // GetWidth returns the chart width or the default value. func (bc BarChart) GetWidth() int { if bc.Width == 0 { return DefaultChartWidth } return bc.Width } // GetHeight returns the chart height or the default value. func (bc BarChart) GetHeight() int { if bc.Height == 0 { return DefaultChartHeight } return bc.Height } // GetBarSpacing returns the spacing between bars. func (bc BarChart) GetBarSpacing() int { if bc.BarSpacing == 0 { return DefaultBarSpacing } return bc.BarSpacing } // GetBarWidth returns the default bar width. func (bc BarChart) GetBarWidth() int { if bc.BarWidth == 0 { return DefaultBarWidth } return bc.BarWidth } // Render renders the chart with the given renderer to the given io.Writer. func (bc BarChart) Render(rp RendererProvider, w io.Writer) error { if len(bc.Bars) == 0 { return errors.New("Please provide at least one bar.") } r, err := rp(bc.GetWidth(), bc.GetHeight()) if err != nil { return err } if bc.Font == nil { defaultFont, err := GetDefaultFont() if err != nil { return err } bc.defaultFont = defaultFont } r.SetDPI(bc.GetDPI()) bc.drawBackground(r) var canvasBox Box var yt []Tick var yr Range var yf ValueFormatter canvasBox = bc.getDefaultCanvasBox() yr = bc.getRanges() yr = bc.setRangeDomains(canvasBox, yr) yf = bc.getValueFormatters() if bc.hasAxes() { yt = bc.getAxesTicks(r, yr, yf) canvasBox = bc.getAdjustedCanvasBox(r, canvasBox, yr, yt) yr = bc.setRangeDomains(canvasBox, yr) } bc.drawBars(r, canvasBox, yr) bc.drawXAxis(r, canvasBox) bc.drawYAxis(r, canvasBox, yr, yt) bc.drawTitle(r) for _, a := range bc.Elements { a(r, canvasBox, bc.styleDefaultsElements()) } return r.Save(w) } func (bc BarChart) getRanges() Range { var yrange Range if bc.YAxis.Range != nil && !bc.YAxis.Range.IsZero() { yrange = bc.YAxis.Range } else { yrange = &ContinuousRange{} } if !yrange.IsZero() { return yrange } if len(bc.YAxis.Ticks) > 0 { tickMin, tickMax := math.MaxFloat64, -math.MaxFloat64 for _, t := range bc.YAxis.Ticks { tickMin = math.Min(tickMin, t.Value) tickMax = math.Max(tickMax, t.Value) } yrange.SetMin(tickMin) yrange.SetMax(tickMax) return yrange } min, max := math.MaxFloat64, -math.MaxFloat64 for _, b := range bc.Bars { min = math.Min(b.Value, min) max = math.Max(b.Value, max) } yrange.SetMin(min) yrange.SetMax(max) return yrange } func (bc BarChart) drawBackground(r Renderer) { Draw.Box(r, Box{ Right: bc.GetWidth(), Bottom: bc.GetHeight(), }, bc.getBackgroundStyle()) } func (bc BarChart) drawBars(r Renderer, canvasBox Box, yr Range) { xoffset := canvasBox.Left width, spacing, _ := bc.calculateScaledTotalWidth(canvasBox) bs2 := spacing >> 1 var barBox Box var bxl, bxr, by int for index, bar := range bc.Bars { bxl = xoffset + bs2 bxr = bxl + width by = canvasBox.Bottom - yr.Translate(bar.Value) barBox = Box{ Top: by, Left: bxl, Right: bxr, Bottom: canvasBox.Bottom, } Draw.Box(r, barBox, bar.Style.InheritFrom(bc.styleDefaultsBar(index))) xoffset += width + spacing } } func (bc BarChart) drawXAxis(r Renderer, canvasBox Box) { if bc.XAxis.Show { axisStyle := bc.XAxis.InheritFrom(bc.styleDefaultsAxes()) axisStyle.WriteToRenderer(r) width, spacing, _ := bc.calculateScaledTotalWidth(canvasBox) r.MoveTo(canvasBox.Left, canvasBox.Bottom) r.LineTo(canvasBox.Right, canvasBox.Bottom) r.Stroke() r.MoveTo(canvasBox.Left, canvasBox.Bottom) r.LineTo(canvasBox.Left, canvasBox.Bottom+DefaultVerticalTickHeight) r.Stroke() cursor := canvasBox.Left for index, bar := range bc.Bars { barLabelBox := Box{ Top: canvasBox.Bottom + DefaultXAxisMargin, Left: cursor, Right: cursor + width + spacing, Bottom: bc.GetHeight(), } if len(bar.Label) > 0 { Draw.TextWithin(r, bar.Label, barLabelBox, axisStyle) } axisStyle.WriteToRenderer(r) if index < len(bc.Bars)-1 { r.MoveTo(barLabelBox.Right, canvasBox.Bottom) r.LineTo(barLabelBox.Right, canvasBox.Bottom+DefaultVerticalTickHeight) r.Stroke() } cursor += width + spacing } } } func (bc BarChart) drawYAxis(r Renderer, canvasBox Box, yr Range, ticks []Tick) { if bc.YAxis.Style.Show { axisStyle := bc.YAxis.Style.InheritFrom(bc.styleDefaultsAxes()) axisStyle.WriteToRenderer(r) r.MoveTo(canvasBox.Right, canvasBox.Top) r.LineTo(canvasBox.Right, canvasBox.Bottom) r.Stroke() r.MoveTo(canvasBox.Right, canvasBox.Bottom) r.LineTo(canvasBox.Right+DefaultHorizontalTickWidth, canvasBox.Bottom) r.Stroke() var ty int var tb Box for _, t := range ticks { ty = canvasBox.Bottom - yr.Translate(t.Value) axisStyle.GetStrokeOptions().WriteToRenderer(r) r.MoveTo(canvasBox.Right, ty) r.LineTo(canvasBox.Right+DefaultHorizontalTickWidth, ty) r.Stroke() axisStyle.GetTextOptions().WriteToRenderer(r) tb = r.MeasureText(t.Label) Draw.Text(r, t.Label, canvasBox.Right+DefaultYAxisMargin+5, ty+(tb.Height()>>1), axisStyle) } } } func (bc BarChart) drawTitle(r Renderer) { if len(bc.Title) > 0 && bc.TitleStyle.Show { Draw.TextWithin(r, bc.Title, bc.box(), bc.styleDefaultsTitle()) } } func (bc BarChart) hasAxes() bool { return bc.YAxis.Style.Show } func (bc BarChart) setRangeDomains(canvasBox Box, yr Range) Range { yr.SetDomain(canvasBox.Height()) return yr } func (bc BarChart) getDefaultCanvasBox() Box { return bc.box() } func (bc BarChart) getValueFormatters() ValueFormatter { if bc.YAxis.ValueFormatter != nil { return bc.YAxis.ValueFormatter } return FloatValueFormatter } func (bc BarChart) getAxesTicks(r Renderer, yr Range, yf ValueFormatter) (yticks []Tick) { if bc.YAxis.Style.Show { yticks = bc.YAxis.GetTicks(r, yr, bc.styleDefaultsAxes(), yf) } return } func (bc BarChart) calculateEffectiveBarSpacing(canvasBox Box) int { totalWithBaseSpacing := bc.calculateTotalBarWidth(bc.GetBarWidth(), bc.GetBarSpacing()) if totalWithBaseSpacing > canvasBox.Width() { lessBarWidths := canvasBox.Width() - (len(bc.Bars) * bc.GetBarWidth()) if lessBarWidths > 0 { return int(math.Ceil(float64(lessBarWidths) / float64(len(bc.Bars)))) } return 0 } return bc.GetBarSpacing() } func (bc BarChart) calculateEffectiveBarWidth(canvasBox Box, spacing int) int { totalWithBaseWidth := bc.calculateTotalBarWidth(bc.GetBarWidth(), spacing) if totalWithBaseWidth > canvasBox.Width() { totalLessBarSpacings := canvasBox.Width() - (len(bc.Bars) * spacing) if totalLessBarSpacings > 0 { return int(math.Ceil(float64(totalLessBarSpacings) / float64(len(bc.Bars)))) } return 0 } return bc.GetBarWidth() } func (bc BarChart) calculateTotalBarWidth(barWidth, spacing int) int { return len(bc.Bars) * (barWidth + spacing) } func (bc BarChart) calculateScaledTotalWidth(canvasBox Box) (width, spacing, total int) { spacing = bc.calculateEffectiveBarSpacing(canvasBox) width = bc.calculateEffectiveBarWidth(canvasBox, spacing) total = bc.calculateTotalBarWidth(width, spacing) return } func (bc BarChart) getAdjustedCanvasBox(r Renderer, canvasBox Box, yrange Range, yticks []Tick) Box { axesOuterBox := canvasBox.Clone() _, _, totalWidth := bc.calculateScaledTotalWidth(canvasBox) if bc.XAxis.Show { xaxisHeight := DefaultVerticalTickHeight axisStyle := bc.XAxis.InheritFrom(bc.styleDefaultsAxes()) axisStyle.WriteToRenderer(r) cursor := canvasBox.Left for _, bar := range bc.Bars { if len(bar.Label) > 0 { barLabelBox := Box{ Top: canvasBox.Bottom + DefaultXAxisMargin, Left: cursor, Right: cursor + bc.GetBarWidth() + bc.GetBarSpacing(), Bottom: bc.GetHeight(), } lines := Text.WrapFit(r, bar.Label, barLabelBox.Width(), axisStyle) linesBox := Text.MeasureLines(r, lines, axisStyle) xaxisHeight = Math.MinInt(linesBox.Height()+(2*DefaultXAxisMargin), xaxisHeight) } } xbox := Box{ Top: canvasBox.Top, Left: canvasBox.Left, Right: canvasBox.Left + totalWidth, Bottom: bc.GetHeight() - xaxisHeight, } axesOuterBox = axesOuterBox.Grow(xbox) } if bc.YAxis.Style.Show { axesBounds := bc.YAxis.Measure(r, canvasBox, yrange, bc.styleDefaultsAxes(), yticks) axesOuterBox = axesOuterBox.Grow(axesBounds) } return canvasBox.OuterConstrain(bc.box(), axesOuterBox) } // box returns the chart bounds as a box. func (bc BarChart) box() Box { dpr := bc.Background.Padding.GetRight(10) dpb := bc.Background.Padding.GetBottom(50) return Box{ Top: 20, Left: 20, Right: bc.GetWidth() - dpr, Bottom: bc.GetHeight() - dpb, } } func (bc BarChart) getBackgroundStyle() Style { return bc.Background.InheritFrom(bc.styleDefaultsBackground()) } func (bc BarChart) styleDefaultsBackground() Style { return Style{ FillColor: DefaultBackgroundColor, StrokeColor: DefaultBackgroundStrokeColor, StrokeWidth: DefaultStrokeWidth, } } func (bc BarChart) styleDefaultsBar(index int) Style { return Style{ StrokeColor: GetAlternateColor(index), StrokeWidth: 3.0, FillColor: GetAlternateColor(index), } } func (bc BarChart) styleDefaultsTitle() Style { return bc.TitleStyle.InheritFrom(Style{ FontColor: DefaultTextColor, Font: bc.GetFont(), FontSize: bc.getTitleFontSize(), TextHorizontalAlign: TextHorizontalAlignCenter, TextVerticalAlign: TextVerticalAlignTop, TextWrap: TextWrapWord, }) } func (bc BarChart) getTitleFontSize() float64 { effectiveDimension := Math.MinInt(bc.GetWidth(), bc.GetHeight()) if effectiveDimension >= 2048 { return 48 } else if effectiveDimension >= 1024 { return 24 } else if effectiveDimension >= 512 { return 18 } else if effectiveDimension >= 256 { return 12 } return 10 } func (bc BarChart) styleDefaultsAxes() Style { return Style{ StrokeColor: DefaultAxisColor, Font: bc.GetFont(), FontSize: DefaultAxisFontSize, FontColor: DefaultAxisColor, TextHorizontalAlign: TextHorizontalAlignCenter, TextVerticalAlign: TextVerticalAlignTop, TextWrap: TextWrapWord, } } func (bc BarChart) styleDefaultsElements() Style { return Style{ Font: bc.GetFont(), } }