go-chart/chart.go

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package chart
import (
"image/color"
"io"
"github.com/golang/freetype/truetype"
)
// Chart is what we're drawing.
/*
The chart box model is as follows:
0,0 width,0
cl,ct cr,ct
cl,cb cr,cb
0, height width,height
*/
type Chart struct {
Title string
TitleFontSize float64
Width int
Height int
Padding int
BackgroundColor color.RGBA
CanvasBackgroundColor color.RGBA
AxisShow bool
AxisStyle Style
AxisFontSize float64
CanvasBorderShow bool
CanvasBorderStyle Style
FinalValueLabelShow bool
FinalValueStyle Style
FontColor color.RGBA
Font *truetype.Font
Series []Series
}
// GetTitleFontSize calculates or returns the title font size.
func (c Chart) GetTitleFontSize() float64 {
if c.TitleFontSize != 0 {
if c.TitleFontSize > DefaultMinimumFontSize {
return c.TitleFontSize
}
}
fontSize := float64(c.Height >> 3)
if fontSize > DefaultMinimumFontSize {
return fontSize
}
return DefaultMinimumFontSize
}
// GetCanvasTop gets the top corner pixel.
func (c Chart) GetCanvasTop() int {
return c.Padding
}
// GetCanvasLeft gets the left corner pixel.
func (c Chart) GetCanvasLeft() int {
return c.Padding
}
// GetCanvasBottom gets the bottom corner pixel.
func (c Chart) GetCanvasBottom() int {
return c.Height - c.Padding
}
// GetCanvasRight gets the right corner pixel.
func (c Chart) GetCanvasRight() int {
return c.Width - c.Padding
}
// GetCanvasWidth returns the width of the canvas.
func (c Chart) GetCanvasWidth() int {
if c.Padding > 0 {
return c.Width - (c.Padding << 1)
}
return c.Width
}
// GetCanvasHeight returns the height of the canvas.
func (c Chart) GetCanvasHeight() int {
if c.Padding > 0 {
return c.Height - (c.Padding << 1)
}
return c.Height
}
// GetBackgroundColor returns the chart background color.
func (c Chart) GetBackgroundColor() color.RGBA {
if ColorIsZero(c.BackgroundColor) {
c.BackgroundColor = DefaultBackgroundColor
}
return c.BackgroundColor
}
// GetCanvasBackgroundColor returns the canvas background color.
func (c Chart) GetCanvasBackgroundColor() color.RGBA {
if ColorIsZero(c.CanvasBackgroundColor) {
c.CanvasBackgroundColor = DefaultCanvasColor
}
return c.CanvasBackgroundColor
}
// GetTextFont returns the text font.
func (c Chart) GetTextFont() (*truetype.Font, error) {
if c.Font != nil {
return c.Font, nil
}
return GetDefaultFont()
}
// GetTextFontColor returns the text font color.
func (c Chart) GetTextFontColor() color.RGBA {
if ColorIsZero(c.FontColor) {
c.FontColor = DefaultTextColor
}
return c.FontColor
}
// Render renders the chart with the given renderer to the given io.Writer.
func (c Chart) Render(provider RendererProvider, w io.Writer) error {
r := provider(c.Width, c.Height)
c.drawBackground(r)
c.drawCanvas(r)
c.drawAxes(r)
for _, series := range c.Series {
c.drawSeries(r, series)
}
err := c.drawTitle(r)
if err != nil {
return err
}
return r.Save(w)
}
func (c Chart) drawBackground(r Renderer) {
r.SetStrokeColor(c.GetBackgroundColor())
r.SetFillColor(c.GetBackgroundColor())
r.SetLineWidth(0)
r.MoveTo(0, 0)
r.LineTo(c.Width, 0)
r.LineTo(c.Width, c.Height)
r.LineTo(0, c.Height)
r.LineTo(0, 0)
r.FillStroke()
r.Close()
}
func (c Chart) drawCanvas(r Renderer) {
if !c.CanvasBorderStyle.IsZero() {
r.SetStrokeColor(c.CanvasBorderStyle.GetStrokeColor())
r.SetLineWidth(c.CanvasBorderStyle.GetStrokeWidth())
} else {
r.SetStrokeColor(c.GetCanvasBackgroundColor())
r.SetLineWidth(0)
}
r.SetFillColor(c.GetCanvasBackgroundColor())
r.MoveTo(c.GetCanvasLeft(), c.GetCanvasTop())
r.LineTo(c.GetCanvasRight(), c.GetCanvasTop())
r.LineTo(c.GetCanvasRight(), c.GetCanvasBottom())
r.LineTo(c.GetCanvasLeft(), c.GetCanvasBottom())
r.LineTo(c.GetCanvasLeft(), c.GetCanvasTop())
r.FillStroke()
r.Close()
}
func (c Chart) drawAxes(r Renderer) {
if c.AxisShow {
if !c.AxisStyle.IsZero() {
r.SetStrokeColor(c.AxisStyle.GetStrokeColor())
r.SetLineWidth(c.AxisStyle.GetStrokeWidth())
} else {
r.SetStrokeColor(DefaultAxisColor)
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r.SetLineWidth(DefaultAxisLineWidth)
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}
r.MoveTo(c.GetCanvasLeft(), c.GetCanvasBottom())
r.LineTo(c.GetCanvasRight(), c.GetCanvasBottom())
r.LineTo(c.GetCanvasRight(), c.GetCanvasTop())
r.Stroke()
}
}
func (c Chart) drawSeries(r Renderer, s Series) {
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r.SetLineWidth(s.GetStyle().GetStrokeWidth())
r.SetStrokeColor(s.GetStyle().GetStrokeColor())
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xrange := s.GetXRange(c.GetCanvasWidth())
yrange := s.GetYRange(c.GetCanvasHeight())
if s.Len() == 0 {
return
}
v0 := s.GetValue(0)
x0 := xrange.Translate(v0.X)
y0 := yrange.Translate(v0.Y)
r.MoveTo(x0, y0)
var v Point
var x, y int
for index := 0; index < s.Len(); index++ {
v = s.GetValue(0)
x = xrange.Translate(v.X)
y = yrange.Translate(v.Y)
r.LineTo(x, y)
}
r.FillStroke()
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}
func (c Chart) drawTitle(r Renderer) error {
if len(c.Title) > 0 {
font, err := c.GetTextFont()
if err != nil {
return err
}
r.SetFontColor(c.GetTextFontColor())
r.SetFont(font)
r.SetFontSize(c.GetTitleFontSize())
textWidth := r.MeasureText(c.Title)
titleX := (c.Width >> 1) - (textWidth >> 1)
titleY := c.GetCanvasTop() + int(c.GetTitleFontSize()/2.0)
r.Text(c.Title, titleX, titleY)
}
return nil
}