pie charts!

This commit is contained in:
Will Charczuk 2016-07-28 02:34:44 -07:00
parent ec4d92fc5e
commit c17c9a4bb4
10 changed files with 485 additions and 45 deletions

View File

@ -66,42 +66,85 @@ const (
) )
var ( var (
// DefaultBackgroundColor is the default chart background color. // ColorWhite is white.
// It is equivalent to css color:white. ColorWhite = drawing.Color{R: 255, G: 255, B: 255, A: 255}
DefaultBackgroundColor = drawing.Color{R: 255, G: 255, B: 255, A: 255} // ColorBlue is the basic theme blue color.
// DefaultBackgroundStrokeColor is the default chart border color. ColorBlue = drawing.Color{R: 0, G: 116, B: 217, A: 255}
// It is equivalent to color:white. // ColorCyan is the basic theme cyan color.
DefaultBackgroundStrokeColor = drawing.Color{R: 255, G: 255, B: 255, A: 255} ColorCyan = drawing.Color{R: 0, G: 217, B: 210, A: 255}
// DefaultCanvasColor is the default chart canvas color. // ColorGreen is the basic theme green color.
// It is equivalent to css color:white. ColorGreen = drawing.Color{R: 0, G: 217, B: 101, A: 255}
DefaultCanvasColor = drawing.Color{R: 255, G: 255, B: 255, A: 255} // ColorRed is the basic theme red color.
// DefaultCanvasStrokeColor is the default chart canvas stroke color. ColorRed = drawing.Color{R: 217, G: 0, B: 116, A: 255}
// It is equivalent to css color:white. // ColorOrange is the basic theme orange color.
DefaultCanvasStrokeColor = drawing.Color{R: 255, G: 255, B: 255, A: 255} ColorOrange = drawing.Color{R: 217, G: 101, B: 0, A: 255}
// DefaultTextColor is the default chart text color. // ColorYellow is the basic theme yellow color.
// It is equivalent to #333333. ColorYellow = drawing.Color{R: 217, G: 210, B: 0, A: 255}
DefaultTextColor = drawing.Color{R: 51, G: 51, B: 51, A: 255} // ColorBlack is the basic theme black color.
// DefaultAxisColor is the default chart axis line color. ColorBlack = drawing.Color{R: 51, G: 51, B: 51, A: 255}
// It is equivalent to #333333. // ColorLightGray is the basic theme light gray color.
DefaultAxisColor = drawing.Color{R: 51, G: 51, B: 51, A: 255} ColorLightGray = drawing.Color{R: 239, G: 239, B: 239, A: 255}
// DefaultStrokeColor is the default chart border color.
// It is equivalent to #efefef. // ColorAlternateBlue is a alternate theme color.
DefaultStrokeColor = drawing.Color{R: 239, G: 239, B: 239, A: 255} ColorAlternateBlue = drawing.Color{R: 106, G: 195, B: 203, A: 255}
// DefaultFillColor is the default fill color. // ColorAlternateGreen is a alternate theme color.
// It is equivalent to #0074d9. ColorAlternateGreen = drawing.Color{R: 42, G: 190, B: 137, A: 255}
DefaultFillColor = drawing.Color{R: 0, G: 217, B: 116, A: 255} // ColorAlternateGray is a alternate theme color.
// DefaultAnnotationFillColor is the default annotation background color. ColorAlternateGray = drawing.Color{R: 110, G: 128, B: 139, A: 255}
DefaultAnnotationFillColor = drawing.Color{R: 255, G: 255, B: 255, A: 255} // ColorAlternateYellow is a alternate theme color.
// DefaultGridLineColor is the default grid line color. ColorAlternateYellow = drawing.Color{R: 240, G: 174, B: 90, A: 255}
DefaultGridLineColor = drawing.Color{R: 239, G: 239, B: 239, A: 255} // ColorAlternateLightGray is a alternate theme color.
ColorAlternateLightGray = drawing.Color{R: 187, G: 190, B: 191, A: 255}
) )
var ( var (
// DefaultSeriesStrokeColors are a couple default series colors. // DefaultBackgroundColor is the default chart background color.
DefaultSeriesStrokeColors = []drawing.Color{ // It is equivalent to css color:white.
{R: 0, G: 116, B: 217, A: 255}, DefaultBackgroundColor = ColorWhite
{R: 0, G: 217, B: 116, A: 255}, // DefaultBackgroundStrokeColor is the default chart border color.
{R: 217, G: 0, B: 116, A: 255}, // It is equivalent to color:white.
DefaultBackgroundStrokeColor = ColorWhite
// DefaultCanvasColor is the default chart canvas color.
// It is equivalent to css color:white.
DefaultCanvasColor = ColorWhite
// DefaultCanvasStrokeColor is the default chart canvas stroke color.
// It is equivalent to css color:white.
DefaultCanvasStrokeColor = ColorWhite
// DefaultTextColor is the default chart text color.
// It is equivalent to #333333.
DefaultTextColor = ColorBlack
// DefaultAxisColor is the default chart axis line color.
// It is equivalent to #333333.
DefaultAxisColor = ColorBlack
// DefaultStrokeColor is the default chart border color.
// It is equivalent to #efefef.
DefaultStrokeColor = ColorLightGray
// DefaultFillColor is the default fill color.
// It is equivalent to #0074d9.
DefaultFillColor = ColorBlue
// DefaultAnnotationFillColor is the default annotation background color.
DefaultAnnotationFillColor = ColorWhite
// DefaultGridLineColor is the default grid line color.
DefaultGridLineColor = ColorLightGray
)
var (
// DefaultColors are a couple default series colors.
DefaultColors = []drawing.Color{
ColorBlue,
ColorGreen,
ColorRed,
ColorCyan,
ColorOrange,
}
// DefaultAlternateColors are a couple alternate colors.
DefaultAlternateColors = []drawing.Color{
ColorAlternateBlue,
ColorAlternateGreen,
ColorAlternateGray,
ColorAlternateYellow,
ColorAlternateLightGray,
} }
) )
@ -117,10 +160,17 @@ var (
) )
// GetDefaultSeriesStrokeColor returns a color from the default list by index. // GetDefaultSeriesStrokeColor returns a color from the default list by index.
// NOTE: the index will wrap around (using a modulo).g // NOTE: the index will wrap around (using a modulo).
func GetDefaultSeriesStrokeColor(index int) drawing.Color { func GetDefaultSeriesStrokeColor(index int) drawing.Color {
finalIndex := index % len(DefaultSeriesStrokeColors) finalIndex := index % len(DefaultColors)
return DefaultSeriesStrokeColors[finalIndex] return DefaultColors[finalIndex]
}
// GetDefaultPieChartValueColor returns a color from the default list by index.
// NOTE: the index will wrap around (using a modulo).
func GetDefaultPieChartValueColor(index int) drawing.Color {
finalIndex := index % len(DefaultAlternateColors)
return DefaultAlternateColors[finalIndex]
} }
var ( var (

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@ -101,10 +101,10 @@ func (p *Path) CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64) {
} }
// ArcTo adds an arc to the path // ArcTo adds an arc to the path
func (p *Path) ArcTo(cx, cy, rx, ry, startAngle, angle float64) { func (p *Path) ArcTo(cx, cy, rx, ry, startAngle, delta float64) {
endAngle := startAngle + angle endAngle := startAngle + delta
clockWise := true clockWise := true
if angle < 0 { if delta < 0 {
clockWise = false clockWise = false
} }
// normalize // normalize
@ -124,7 +124,7 @@ func (p *Path) ArcTo(cx, cy, rx, ry, startAngle, angle float64) {
} else { } else {
p.MoveTo(startX, startY) p.MoveTo(startX, startY)
} }
p.appendToPath(ArcToComponent, cx, cy, rx, ry, startAngle, angle) p.appendToPath(ArcToComponent, cx, cy, rx, ry, startAngle, delta)
p.x = cx + math.Cos(endAngle)*rx p.x = cx + math.Cos(endAngle)*rx
p.y = cy + math.Sin(endAngle)*ry p.y = cy + math.Sin(endAngle)*ry
} }

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@ -171,8 +171,8 @@ func (gc *StackGraphicContext) CubicCurveTo(cx1, cy1, cx2, cy2, x, y float64) {
} }
// ArcTo draws an arc. // ArcTo draws an arc.
func (gc *StackGraphicContext) ArcTo(cx, cy, rx, ry, startAngle, angle float64) { func (gc *StackGraphicContext) ArcTo(cx, cy, rx, ry, startAngle, delta float64) {
gc.current.Path.ArcTo(cx, cy, rx, ry, startAngle, angle) gc.current.Path.ArcTo(cx, cy, rx, ry, startAngle, delta)
} }
// Close closes a path. // Close closes a path.

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@ -0,0 +1,35 @@
package main
import (
"fmt"
"log"
"net/http"
"github.com/wcharczuk/go-chart"
)
func drawChart(res http.ResponseWriter, req *http.Request) {
pie := chart.PieChart{
Canvas: chart.Style{
FillColor: chart.ColorLightGray,
},
Values: []chart.PieChartValue{
{Value: 0.3, Label: "Blue"},
{Value: 0.2, Label: "Green"},
{Value: 0.2, Label: "Gray"},
{Value: 0.1, Label: "Orange"},
{Value: 0.1, Label: "??"},
},
}
res.Header().Set("Content-Type", "image/png")
err := pie.Render(chart.PNG, res)
if err != nil {
fmt.Printf("Error rendering pie chart: %v\n", err)
}
}
func main() {
http.HandleFunc("/", drawChart)
log.Fatal(http.ListenAndServe(":8080", nil))
}

284
pie_chart.go Normal file
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@ -0,0 +1,284 @@
package chart
import (
"errors"
"io"
"math"
"github.com/golang/freetype/truetype"
)
// PieChartValue is a slice of a pie-chart.
type PieChartValue struct {
Style Style
Label string
Value float64
}
// PieChart is a chart that draws sections of a circle based on percentages.
type PieChart struct {
Title string
TitleStyle Style
Width int
Height int
DPI float64
Background Style
Canvas Style
Font *truetype.Font
defaultFont *truetype.Font
Values []PieChartValue
Elements []Renderable
}
// GetDPI returns the dpi for the chart.
func (pc PieChart) GetDPI(defaults ...float64) float64 {
if pc.DPI == 0 {
if len(defaults) > 0 {
return defaults[0]
}
return DefaultDPI
}
return pc.DPI
}
// GetFont returns the text font.
func (pc PieChart) GetFont() *truetype.Font {
if pc.Font == nil {
return pc.defaultFont
}
return pc.Font
}
// GetWidth returns the chart width or the default value.
func (pc PieChart) GetWidth() int {
if pc.Width == 0 {
return DefaultChartWidth
}
return pc.Width
}
// GetHeight returns the chart height or the default value.
func (pc PieChart) GetHeight() int {
if pc.Height == 0 {
return DefaultChartWidth
}
return pc.Height
}
// Render renders the chart with the given renderer to the given io.Writer.
func (pc PieChart) Render(rp RendererProvider, w io.Writer) error {
if len(pc.Values) == 0 {
return errors.New("Please provide at least one value.")
}
r, err := rp(pc.GetWidth(), pc.GetHeight())
if err != nil {
return err
}
if pc.Font == nil {
defaultFont, err := GetDefaultFont()
if err != nil {
return err
}
pc.defaultFont = defaultFont
}
r.SetDPI(pc.GetDPI(DefaultDPI))
canvasBox := pc.getDefaultCanvasBox()
canvasBox = pc.getCircleAdjustedCanvasBox(canvasBox)
pc.drawBackground(r)
pc.drawCanvas(r, canvasBox)
valuesWithPlaceholder, err := pc.finalizeValues(pc.Values)
if err != nil {
return err
}
pc.drawSlices(r, canvasBox, valuesWithPlaceholder)
pc.drawTitle(r)
for _, a := range pc.Elements {
a(r, canvasBox, pc.styleDefaultsElements())
}
return r.Save(w)
}
func (pc PieChart) drawBackground(r Renderer) {
DrawBox(r, Box{
Right: pc.GetWidth(),
Bottom: pc.GetHeight(),
}, pc.getBackgroundStyle())
}
func (pc PieChart) drawCanvas(r Renderer, canvasBox Box) {
DrawBox(r, canvasBox, pc.getCanvasStyle())
}
func (pc PieChart) drawTitle(r Renderer) {
if len(pc.Title) > 0 && pc.TitleStyle.Show {
r.SetFont(pc.TitleStyle.GetFont(pc.GetFont()))
r.SetFontColor(pc.TitleStyle.GetFontColor(DefaultTextColor))
titleFontSize := pc.TitleStyle.GetFontSize(DefaultTitleFontSize)
r.SetFontSize(titleFontSize)
textBox := r.MeasureText(pc.Title)
textWidth := textBox.Width()
textHeight := textBox.Height()
titleX := (pc.GetWidth() >> 1) - (textWidth >> 1)
titleY := pc.TitleStyle.Padding.GetTop(DefaultTitleTop) + textHeight
r.Text(pc.Title, titleX, titleY)
}
}
func (pc PieChart) drawSlices(r Renderer, canvasBox Box, values []PieChartValue) {
cx, cy := canvasBox.Center()
diameter := MinInt(canvasBox.Width(), canvasBox.Height())
radius := float64(diameter >> 1)
radius2 := (radius * 2.0) / 3.0
var rads, delta, delta2, total float64
var lx, ly int
for index, v := range values {
v.Style.InheritFrom(pc.stylePieChartValue(index)).PersistToRenderer(r)
r.MoveTo(cx, cy)
rads = PercentToRadians(total)
delta = PercentToRadians(v.Value)
r.ArcTo(cx, cy, radius, radius, rads, delta)
r.LineTo(cx, cy)
r.Close()
r.FillStroke()
total = total + v.Value
}
total = 0
for index, v := range values {
v.Style.InheritFrom(pc.stylePieChartValue(index)).PersistToRenderer(r)
if len(v.Label) > 0 {
delta2 = RadianAdd(PercentToRadians(total+(v.Value/2.0)), _pi2)
lx = cx + int(radius2*math.Sin(delta2))
ly = cy - int(radius2*math.Cos(delta2))
tb := r.MeasureText(v.Label)
lx = lx - (tb.Width() >> 1)
r.Text(v.Label, lx, ly)
}
total = total + v.Value
}
}
func (pc PieChart) finalizeValues(values []PieChartValue) ([]PieChartValue, error) {
var total float64
for _, v := range values {
total += v.Value
if total > 1.0 {
return nil, errors.New("Values total exceeded 1.0; please normalize pie chart values to [0,1.0)")
}
}
remainder := 1.0 - total
if RoundDown(remainder, 0.0001) > 0 {
return append(values, PieChartValue{
Style: pc.styleDefaultsPieChartValue(),
Value: remainder,
}), nil
}
return values, nil
}
func (pc PieChart) getDefaultCanvasBox() Box {
return pc.Box()
}
func (pc PieChart) getCircleAdjustedCanvasBox(canvasBox Box) Box {
circleDiameter := MinInt(canvasBox.Width(), canvasBox.Height())
square := Box{
Right: circleDiameter,
Bottom: circleDiameter,
}
return canvasBox.Fit(square)
}
func (pc PieChart) getBackgroundStyle() Style {
return pc.Background.InheritFrom(pc.styleDefaultsBackground())
}
func (pc PieChart) getCanvasStyle() Style {
return pc.Canvas.InheritFrom(pc.styleDefaultsCanvas())
}
func (pc PieChart) styleDefaultsCanvas() Style {
return Style{
FillColor: DefaultCanvasColor,
StrokeColor: DefaultCanvasStrokeColor,
StrokeWidth: DefaultStrokeWidth,
}
}
func (pc PieChart) styleDefaultsPieChartValue() Style {
return Style{
StrokeColor: ColorWhite,
StrokeWidth: 5.0,
FillColor: ColorWhite,
}
}
func (pc PieChart) stylePieChartValue(index int) Style {
return Style{
StrokeColor: ColorWhite,
StrokeWidth: 5.0,
FillColor: GetDefaultPieChartValueColor(index),
FontSize: 24.0,
FontColor: ColorWhite,
Font: pc.GetFont(),
}
}
func (pc PieChart) styleDefaultsBackground() Style {
return Style{
FillColor: DefaultBackgroundColor,
StrokeColor: DefaultBackgroundStrokeColor,
StrokeWidth: DefaultStrokeWidth,
}
}
func (pc PieChart) styleDefaultsSeries(seriesIndex int) Style {
strokeColor := GetDefaultSeriesStrokeColor(seriesIndex)
return Style{
StrokeColor: strokeColor,
StrokeWidth: DefaultStrokeWidth,
Font: pc.GetFont(),
FontSize: DefaultFontSize,
}
}
func (pc PieChart) styleDefaultsElements() Style {
return Style{
Font: pc.GetFont(),
}
}
// Box returns the chart bounds as a box.
func (pc PieChart) Box() Box {
dpr := pc.Background.Padding.GetRight(DefaultBackgroundPadding.Right)
dpb := pc.Background.Padding.GetBottom(DefaultBackgroundPadding.Bottom)
return Box{
Top: pc.Background.Padding.GetTop(DefaultBackgroundPadding.Top),
Left: pc.Background.Padding.GetLeft(DefaultBackgroundPadding.Left),
Right: pc.GetWidth() - dpr,
Bottom: pc.GetHeight() - dpb,
}
}

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@ -71,6 +71,16 @@ func (rr *rasterRenderer) LineTo(x, y int) {
rr.gc.LineTo(float64(x), float64(y)) rr.gc.LineTo(float64(x), float64(y))
} }
// QuadCurveTo implements the interface method.
func (rr *rasterRenderer) QuadCurveTo(cx, cy, x, y int) {
rr.gc.QuadCurveTo(float64(cx), float64(cy), float64(x), float64(y))
}
// ArcTo implements the interface method.
func (rr *rasterRenderer) ArcTo(cx, cy int, rx, ry, startAngle, delta float64) {
rr.gc.ArcTo(float64(cx), float64(cy), rx, ry, startAngle, delta)
}
// Close implements the interface method. // Close implements the interface method.
func (rr *rasterRenderer) Close() { func (rr *rasterRenderer) Close() {
rr.gc.Close() rr.gc.Close()

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@ -34,6 +34,14 @@ type Renderer interface {
// from the previous point. // from the previous point.
LineTo(x, y int) LineTo(x, y int)
// QuadCurveTo draws a quad curve.
// cx and cy represent the bezier "control points".
QuadCurveTo(cx, cy, x, y int)
// ArcTo draws an arc with a given center (cx,cy)
// a given set of radii (rx,ry), a startAngle and delta (in radians).
ArcTo(cx, cy int, rx, ry, startAngle, delta float64)
// Close finalizes a shape as drawn by LineTo. // Close finalizes a shape as drawn by LineTo.
Close() Close()

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@ -79,11 +79,11 @@ func (s Style) String() string {
if s.FontSize != 0 { if s.FontSize != 0 {
output = append(output, fmt.Sprintf("\"font_size\": \"%0.2fpt\"", s.FontSize)) output = append(output, fmt.Sprintf("\"font_size\": \"%0.2fpt\"", s.FontSize))
} else { } else {
output = append(output, "\"fill_color\": null") output = append(output, "\"font_size\": null")
} }
if !s.FillColor.IsZero() { if !s.FontColor.IsZero() {
output = append(output, fmt.Sprintf("\"font_color\": %s", s.FillColor.String())) output = append(output, fmt.Sprintf("\"font_color\": %s", s.FontColor.String()))
} else { } else {
output = append(output, "\"font_color\": null") output = append(output, "\"font_color\": null")
} }
@ -190,6 +190,7 @@ func (s Style) PersistToRenderer(r Renderer) {
r.SetStrokeColor(s.GetStrokeColor()) r.SetStrokeColor(s.GetStrokeColor())
r.SetStrokeWidth(s.GetStrokeWidth()) r.SetStrokeWidth(s.GetStrokeWidth())
r.SetStrokeDashArray(s.GetStrokeDashArray()) r.SetStrokeDashArray(s.GetStrokeDashArray())
r.SetFillColor(s.GetFillColor())
r.SetFont(s.GetFont()) r.SetFont(s.GetFont())
r.SetFontColor(s.GetFontColor()) r.SetFontColor(s.GetFontColor())
r.SetFontSize(s.GetFontSize()) r.SetFontSize(s.GetFontSize())

43
util.go
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@ -99,6 +99,21 @@ func RoundDown(value, roundTo float64) float64 {
return d1 * roundTo return d1 * roundTo
} }
// Normalize returns a set of numbers on the interval [0,1] for a given set of inputs.
// An example: 4,3,2,1 => 0.4, 0.3, 0.2, 0.1
// Caveat; the total may be < 1.0; there are going to be issues with irrational numbers etc.
func Normalize(values ...float64) []float64 {
var total float64
for _, v := range values {
total += v
}
output := make([]float64, len(values))
for x, v := range values {
output[x] = RoundDown(v/total, 0.001)
}
return output
}
// MinInt returns the minimum of a set of integers. // MinInt returns the minimum of a set of integers.
func MinInt(values ...int) int { func MinInt(values ...int) int {
min := math.MaxInt32 min := math.MaxInt32
@ -175,3 +190,31 @@ func SeqDays(days int) []time.Time {
func PercentDifference(v1, v2 float64) float64 { func PercentDifference(v1, v2 float64) float64 {
return (v2 - v1) / v1 return (v2 - v1) / v1
} }
// DegreesToRadians returns degrees as radians.
func DegreesToRadians(degrees float64) float64 {
return degrees * (math.Pi / 180.0)
}
const (
_2pi = 2 * math.Pi
_3pi4 = (3 * math.Pi) / 4.0
_pi2 = math.Pi / 2.0
_pi4 = math.Pi / 4.0
)
// PercentToRadians converts a normalized value (0,1) to radians.
func PercentToRadians(pct float64) float64 {
return DegreesToRadians(360.0 * pct)
}
// RadianAdd adds a delta to a base in radians.
func RadianAdd(base, delta float64) float64 {
value := base + delta
if value > _2pi {
return math.Mod(value, _2pi)
} else if value < 0 {
return _2pi + value
}
return value
}

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@ -76,6 +76,15 @@ func (vr *vectorRenderer) LineTo(x, y int) {
vr.p = append(vr.p, fmt.Sprintf("L %d %d", x, y)) vr.p = append(vr.p, fmt.Sprintf("L %d %d", x, y))
} }
// QuadCurveTo draws a quad curve.
func (vr *vectorRenderer) QuadCurveTo(cx, cy, x, y int) {
vr.p = append(vr.p, fmt.Sprintf("Q%d,%d %d,%d", cx, cy, x, y))
}
func (vr *vectorRenderer) ArcTo(cx, cy int, rx, ry, startAngle, delta float64) {
vr.p = append(vr.p, fmt.Sprintf("A %d %d %0.2f 1 1 %d %d", int(rx), int(ry), delta, cx, cy))
}
// Close closes a shape. // Close closes a shape.
func (vr *vectorRenderer) Close() { func (vr *vectorRenderer) Close() {
vr.p = append(vr.p, fmt.Sprintf("Z")) vr.p = append(vr.p, fmt.Sprintf("Z"))