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Legend style improvements #200

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Legend style improvements #200

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bbad84f
feat: implement legend type with fixed length line on the left side
d-Rickyy-b Feb 5, 2022
5407f1f
docs: add example for legend with line on the left side
d-Rickyy-b Feb 5, 2022
f0b2833
fix: use padding in legend from passed style
d-Rickyy-b Feb 8, 2022
901d2bb
fix: use fixed length for left stroked legend
d-Rickyy-b Feb 8, 2022
1288c8d
fix: respect user defined legend style paddings
d-Rickyy-b Feb 8, 2022
6eff591
fix: introduce individual spacing constant for legend
d-Rickyy-b Feb 8, 2022
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5 changes: 5 additions & 0 deletions defaults.go
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Original file line number Diff line number Diff line change
Expand Up @@ -58,6 +58,11 @@ const (
// DefaultMinimumTickVerticalSpacing is the minimum distance between vertical ticks.
DefaultMinimumTickVerticalSpacing = 20

// DefaultLegendHorizontalSpacing is the minimum distance between two horizontal elements in the legend.
DefaultLegendHorizontalSpacing = 20
// DefaultLegendVerticalSpacing is the minimum distance between two vertical elements in the legend.
DefaultLegendVerticalSpacing = 10

// DefaultDateFormat is the default date format.
DefaultDateFormat = "2006-01-02"
// DefaultDateHourFormat is the date format for hour timestamp formats.
Expand Down
62 changes: 62 additions & 0 deletions examples/legend_line_left/main.go
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Original file line number Diff line number Diff line change
@@ -0,0 +1,62 @@
package main

import (
"github.com/wcharczuk/go-chart/v2"
"os"
"time"
)

func main() {
xv, yv := xvalues(), yvalues()

priceSeries := chart.TimeSeries{
Name: "Very long name for a time series to test legend",
Style: chart.Style{
StrokeColor: chart.GetDefaultColor(0),
},
XValues: xv,
YValues: yv,
}

linRegSeries := &chart.LinearRegressionSeries{
Name: "Regression",
InnerSeries: priceSeries,
}

graph := chart.Chart{
XAxis: chart.XAxis{
TickPosition: chart.TickPositionBetweenTicks,
},
YAxis: chart.YAxis{
Range: &chart.ContinuousRange{
Max: 220.0,
Min: 180.0,
},
},
Series: []chart.Series{
priceSeries,
linRegSeries,
},
}

graph.Elements = []chart.Renderable{chart.LegendLineLeft(&graph, chart.Style{})}

f, _ := os.Create("output.png")
defer f.Close()
graph.Render(chart.PNG, f)
}

func xvalues() []time.Time {
rawx := []string{"2015-07-17", "2015-07-20", "2015-07-21", "2015-07-22", "2015-07-23", "2015-07-24", "2015-07-27", "2015-07-28", "2015-07-29", "2015-07-30", "2015-07-31", "2015-08-03", "2015-08-04", "2015-08-05", "2015-08-06", "2015-08-07", "2015-08-10", "2015-08-11", "2015-08-12", "2015-08-13", "2015-08-14", "2015-08-17", "2015-08-18", "2015-08-19", "2015-08-20", "2015-08-21", "2015-08-24", "2015-08-25", "2015-08-26", "2015-08-27", "2015-08-28", "2015-08-31", "2015-09-01", "2015-09-02", "2015-09-03", "2015-09-04", "2015-09-08", "2015-09-09", "2015-09-10", "2015-09-11", "2015-09-14", "2015-09-15", "2015-09-16", "2015-09-17", "2015-09-18", "2015-09-21", "2015-09-22", "2015-09-23", "2015-09-24", "2015-09-25", "2015-09-28", "2015-09-29", "2015-09-30", "2015-10-01", "2015-10-02", "2015-10-05", "2015-10-06", "2015-10-07", "2015-10-08", "2015-10-09", "2015-10-12", "2015-10-13", "2015-10-14", "2015-10-15", "2015-10-16", "2015-10-19", "2015-10-20", "2015-10-21", "2015-10-22", "2015-10-23", "2015-10-26", "2015-10-27", "2015-10-28", "2015-10-29", "2015-10-30", "2015-11-02", "2015-11-03", "2015-11-04", "2015-11-05", "2015-11-06", "2015-11-09", "2015-11-10", "2015-11-11", "2015-11-12", "2015-11-13", "2015-11-16", "2015-11-17", "2015-11-18", "2015-11-19", "2015-11-20", "2015-11-23", "2015-11-24", "2015-11-25", "2015-11-27", "2015-11-30", "2015-12-01", "2015-12-02", "2015-12-03", "2015-12-04", "2015-12-07", "2015-12-08", "2015-12-09", "2015-12-10", "2015-12-11", "2015-12-14", "2015-12-15", "2015-12-16", "2015-12-17", "2015-12-18", "2015-12-21", "2015-12-22", "2015-12-23", "2015-12-24", "2015-12-28", "2015-12-29", "2015-12-30", "2015-12-31", "2016-01-04", "2016-01-05", "2016-01-06", "2016-01-07", "2016-01-08", "2016-01-11", "2016-01-12", "2016-01-13", "2016-01-14", "2016-01-15", "2016-01-19", "2016-01-20", "2016-01-21", "2016-01-22", "2016-01-25", "2016-01-26", "2016-01-27", "2016-01-28", "2016-01-29", "2016-02-01", "2016-02-02", "2016-02-03", "2016-02-04", "2016-02-05", "2016-02-08", "2016-02-09", "2016-02-10", "2016-02-11", "2016-02-12", "2016-02-16", "2016-02-17", "2016-02-18", "2016-02-19", "2016-02-22", "2016-02-23", "2016-02-24", "2016-02-25", "2016-02-26", "2016-02-29", "2016-03-01", "2016-03-02", "2016-03-03", "2016-03-04", "2016-03-07", "2016-03-08", "2016-03-09", "2016-03-10", "2016-03-11", "2016-03-14", "2016-03-15", "2016-03-16", "2016-03-17", "2016-03-18", "2016-03-21", "2016-03-22", "2016-03-23", "2016-03-24", "2016-03-28", "2016-03-29", "2016-03-30", "2016-03-31", "2016-04-01", "2016-04-04", "2016-04-05", "2016-04-06", "2016-04-07", "2016-04-08", "2016-04-11", "2016-04-12", "2016-04-13", "2016-04-14", "2016-04-15", "2016-04-18", "2016-04-19", "2016-04-20", "2016-04-21", "2016-04-22", "2016-04-25", "2016-04-26", "2016-04-27", "2016-04-28", "2016-04-29", "2016-05-02", "2016-05-03", "2016-05-04", "2016-05-05", "2016-05-06", "2016-05-09", "2016-05-10", "2016-05-11", "2016-05-12", "2016-05-13", "2016-05-16", "2016-05-17", "2016-05-18", "2016-05-19", "2016-05-20", "2016-05-23", "2016-05-24", "2016-05-25", "2016-05-26", "2016-05-27", "2016-05-31", "2016-06-01", "2016-06-02", "2016-06-03", "2016-06-06", "2016-06-07", "2016-06-08", "2016-06-09", "2016-06-10", "2016-06-13", "2016-06-14", "2016-06-15", "2016-06-16", "2016-06-17", "2016-06-20", "2016-06-21", "2016-06-22", "2016-06-23", "2016-06-24", "2016-06-27", "2016-06-28", "2016-06-29", "2016-06-30", "2016-07-01", "2016-07-05", "2016-07-06", "2016-07-07", "2016-07-08", "2016-07-11", "2016-07-12", "2016-07-13", "2016-07-14", "2016-07-15"}

var dates []time.Time
for _, ts := range rawx {
parsed, _ := time.Parse(chart.DefaultDateFormat, ts)
dates = append(dates, parsed)
}
return dates
}

func yvalues() []float64 {
return []float64{212.47, 212.59, 211.76, 211.37, 210.18, 208.00, 206.79, 209.33, 210.77, 210.82, 210.50, 209.79, 209.38, 210.07, 208.35, 207.95, 210.57, 208.66, 208.92, 208.66, 209.42, 210.59, 209.98, 208.32, 203.97, 197.83, 189.50, 187.27, 194.46, 199.27, 199.28, 197.67, 191.77, 195.41, 195.55, 192.59, 197.43, 194.79, 195.85, 196.74, 196.01, 198.45, 200.18, 199.73, 195.45, 196.46, 193.90, 193.60, 192.90, 192.87, 188.01, 188.12, 191.63, 192.13, 195.00, 198.47, 197.79, 199.41, 201.21, 201.33, 201.52, 200.25, 199.29, 202.35, 203.27, 203.37, 203.11, 201.85, 205.26, 207.51, 207.00, 206.60, 208.95, 208.83, 207.93, 210.39, 211.00, 210.36, 210.15, 210.04, 208.08, 208.56, 207.74, 204.84, 202.54, 205.62, 205.47, 208.73, 208.55, 209.31, 209.07, 209.35, 209.32, 209.56, 208.69, 210.68, 208.53, 205.61, 209.62, 208.35, 206.95, 205.34, 205.87, 201.88, 202.90, 205.03, 208.03, 204.86, 200.02, 201.67, 203.50, 206.02, 205.68, 205.21, 207.40, 205.93, 203.87, 201.02, 201.36, 198.82, 194.05, 191.92, 192.11, 193.66, 188.83, 191.93, 187.81, 188.06, 185.65, 186.69, 190.52, 187.64, 190.20, 188.13, 189.11, 193.72, 193.65, 190.16, 191.30, 191.60, 187.95, 185.42, 185.43, 185.27, 182.86, 186.63, 189.78, 192.88, 192.09, 192.00, 194.78, 192.32, 193.20, 195.54, 195.09, 193.56, 198.11, 199.00, 199.78, 200.43, 200.59, 198.40, 199.38, 199.54, 202.76, 202.50, 202.17, 203.34, 204.63, 204.38, 204.67, 204.56, 203.21, 203.12, 203.24, 205.12, 206.02, 205.52, 206.92, 206.25, 204.19, 206.42, 203.95, 204.50, 204.02, 205.92, 208.00, 208.01, 207.78, 209.24, 209.90, 210.10, 208.97, 208.97, 208.61, 208.92, 209.35, 207.45, 206.33, 207.97, 206.16, 205.01, 204.97, 205.72, 205.89, 208.45, 206.50, 206.56, 204.76, 206.78, 204.85, 204.91, 204.20, 205.49, 205.21, 207.87, 209.28, 209.34, 210.24, 209.84, 210.27, 210.91, 210.28, 211.35, 211.68, 212.37, 212.08, 210.07, 208.45, 208.04, 207.75, 208.37, 206.52, 207.85, 208.44, 208.10, 210.81, 203.24, 199.60, 203.20, 206.66, 209.48, 209.92, 208.41, 209.66, 209.53, 212.65, 213.40, 214.95, 214.92, 216.12, 215.83}
}
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183 changes: 151 additions & 32 deletions legend.go
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Expand Up @@ -13,6 +13,12 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
FontSize: 8.0,
StrokeColor: DefaultAxisColor,
StrokeWidth: DefaultAxisLineWidth,
Padding: Box{
Top: 5,
Left: 5,
Right: 5,
Bottom: 5,
},
}

var legendStyle Style
Expand All @@ -23,12 +29,6 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
}

// DEFAULTS
legendPadding := Box{
Top: 5,
Left: 5,
Right: 5,
Bottom: 5,
}
lineTextGap := 5
lineLengthMinimum := 25

Expand All @@ -50,10 +50,10 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
}

legendContent := Box{
Top: legend.Top + legendPadding.Top,
Left: legend.Left + legendPadding.Left,
Right: legend.Left + legendPadding.Left,
Bottom: legend.Top + legendPadding.Top,
Top: legend.Top + legendStyle.Padding.Top,
Left: legend.Left + legendStyle.Padding.Left,
Right: legend.Left + legendStyle.Padding.Left,
Bottom: legend.Top + legendStyle.Padding.Top,
}

legendStyle.GetTextOptions().WriteToRenderer(r)
Expand All @@ -64,7 +64,7 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
if len(labels[x]) > 0 {
tb := r.MeasureText(labels[x])
if labelCount > 0 {
legendContent.Bottom += DefaultMinimumTickVerticalSpacing
legendContent.Bottom += DefaultLegendVerticalSpacing
}
legendContent.Bottom += tb.Height()
right := legendContent.Left + tb.Width() + lineTextGap + lineLengthMinimum
Expand All @@ -74,8 +74,8 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
}

legend = legend.Grow(legendContent)
legend.Right = legendContent.Right + legendPadding.Right
legend.Bottom = legendContent.Bottom + legendPadding.Bottom
legend.Right = legendContent.Right + legendStyle.Padding.Right
legend.Bottom = legendContent.Bottom + legendStyle.Padding.Bottom

Draw.Box(r, legend, legendStyle)

Expand All @@ -89,7 +89,7 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
label = labels[x]
if len(label) > 0 {
if legendCount > 0 {
ycursor += DefaultMinimumTickVerticalSpacing
ycursor += DefaultLegendVerticalSpacing
}

tb := r.MeasureText(label)
Expand All @@ -101,7 +101,7 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {

lx := tx + tb.Width() + lineTextGap
ly := ty - th2
lx2 := legendContent.Right - legendPadding.Right
lx2 := legendContent.Right - legendStyle.Padding.Right

r.SetStrokeColor(lines[x].GetStrokeColor())
r.SetStrokeWidth(lines[x].GetStrokeWidth())
Expand All @@ -118,6 +118,125 @@ func Legend(c *Chart, userDefaults ...Style) Renderable {
}
}

// LegendLineLeft is a legend with the line drawn left to the legend text.
func LegendLineLeft(c *Chart, userDefaults ...Style) Renderable {
return func(r Renderer, cb Box, chartDefaults Style) {
legendDefaults := Style{
FillColor: drawing.ColorWhite,
FontColor: DefaultTextColor,
FontSize: 8.0,
StrokeColor: DefaultAxisColor,
StrokeWidth: DefaultAxisLineWidth,
Padding: Box{
Top: 5,
Left: 5,
Right: 5,
Bottom: 5,
},
}

var legendStyle Style
if len(userDefaults) > 0 {
legendStyle = userDefaults[0].InheritFrom(chartDefaults.InheritFrom(legendDefaults))
} else {
legendStyle = chartDefaults.InheritFrom(legendDefaults)
}

// DEFAULTS
lineTextGap := 5
lineLengthMinimum := 25
strokeLength := 17

var labels []string
var lines []Style
for index, s := range c.Series {
if !s.GetStyle().Hidden {
if _, isAnnotationSeries := s.(AnnotationSeries); !isAnnotationSeries {
labels = append(labels, s.GetName())
lines = append(lines, s.GetStyle().InheritFrom(c.styleDefaultsSeries(index)))
}
}
}

legend := Box{
Top: cb.Top,
Left: cb.Left,
// bottom and right will be sized by the legend content + relevant padding.
}

legendContent := Box{
Top: legend.Top + legendStyle.Padding.Top,
Left: legend.Left + legendStyle.Padding.Left,
Right: legend.Left + legendStyle.Padding.Left,
Bottom: legend.Top + legendStyle.Padding.Top,
}

legendStyle.GetTextOptions().WriteToRenderer(r)

// measure
labelCount := 0
for x := 0; x < len(labels); x++ {
if len(labels[x]) > 0 {
tb := r.MeasureText(labels[x])
if labelCount > 0 {
legendContent.Bottom += DefaultLegendVerticalSpacing
}
legendContent.Bottom += tb.Height()
right := legendContent.Left + tb.Width() + lineTextGap + lineLengthMinimum
legendContent.Right = MaxInt(legendContent.Right, right)
labelCount++
}
}

legend = legend.Grow(legendContent)
legend.Right = legendContent.Right + legendStyle.Padding.Right
legend.Bottom = legendContent.Bottom + legendStyle.Padding.Bottom

Draw.Box(r, legend, legendStyle)

legendStyle.GetTextOptions().WriteToRenderer(r)

ycursor := legendContent.Top
lx := legendContent.Left
legendCount := 0
var label string
for x := 0; x < len(labels); x++ {
label = labels[x]
if len(label) > 0 {
if legendCount > 0 {
ycursor += DefaultLegendVerticalSpacing
}

// Calculate text dimensions
tb := r.MeasureText(label)
ty := ycursor + tb.Height()
th2 := tb.Height() >> 1

// Calculate line x and y coordinates
ly := ty - th2

// Calculate line ending x coordinate
lx2 := lx + strokeLength

r.SetStrokeColor(lines[x].GetStrokeColor())
r.SetStrokeWidth(lines[x].GetStrokeWidth())
r.SetStrokeDashArray(lines[x].GetStrokeDashArray())

r.MoveTo(lx, ly)
r.LineTo(lx2, ly)
r.Stroke()

// Calculate Text starting coordinates
textX := lx2 + lineTextGap
r.Text(label, textX, ty)

ycursor += tb.Height()
legendCount++
}
}
}
}

// LegendThin is a legend that doesn't obscure the chart area.
func LegendThin(c *Chart, userDefaults ...Style) Renderable {
return func(r Renderer, cb Box, chartDefaults Style) {
Expand Down Expand Up @@ -179,7 +298,7 @@ func LegendThin(c *Chart, userDefaults ...Style) Renderable {
Bottom: legendYMargin + legendBoxHeight,
}

Draw.Box(r, legendBox, legendDefaults)
Draw.Box(r, legendBox, legendStyle)

r.SetFont(legendStyle.GetFont())
r.SetFontColor(legendStyle.GetFontColor())
Expand Down Expand Up @@ -210,7 +329,7 @@ func LegendThin(c *Chart, userDefaults ...Style) Renderable {
r.LineTo(lx+lineLengthMinimum, ly)
r.Stroke()

tx += textBox.Width() + DefaultMinimumTickHorizontalSpacing + lineTextGap + lineLengthMinimum
tx += textBox.Width() + DefaultLegendHorizontalSpacing + lineTextGap + lineLengthMinimum
}
}
}
Expand All @@ -225,6 +344,12 @@ func LegendLeft(c *Chart, userDefaults ...Style) Renderable {
FontSize: 8.0,
StrokeColor: DefaultAxisColor,
StrokeWidth: DefaultAxisLineWidth,
Padding: Box{
Top: 5,
Left: 5,
Right: 5,
Bottom: 5,
},
}

var legendStyle Style
Expand All @@ -235,12 +360,6 @@ func LegendLeft(c *Chart, userDefaults ...Style) Renderable {
}

// DEFAULTS
legendPadding := Box{
Top: 5,
Left: 5,
Right: 5,
Bottom: 5,
}
lineTextGap := 5
lineLengthMinimum := 25

Expand All @@ -262,10 +381,10 @@ func LegendLeft(c *Chart, userDefaults ...Style) Renderable {
}

legendContent := Box{
Top: legend.Top + legendPadding.Top,
Left: legend.Left + legendPadding.Left,
Right: legend.Left + legendPadding.Left,
Bottom: legend.Top + legendPadding.Top,
Top: legend.Top + legendStyle.Padding.Top,
Left: legend.Left + legendStyle.Padding.Left,
Right: legend.Left + legendStyle.Padding.Left,
Bottom: legend.Top + legendStyle.Padding.Top,
}

legendStyle.GetTextOptions().WriteToRenderer(r)
Expand All @@ -276,7 +395,7 @@ func LegendLeft(c *Chart, userDefaults ...Style) Renderable {
if len(labels[x]) > 0 {
tb := r.MeasureText(labels[x])
if labelCount > 0 {
legendContent.Bottom += DefaultMinimumTickVerticalSpacing
legendContent.Bottom += DefaultLegendVerticalSpacing
}
legendContent.Bottom += tb.Height()
right := legendContent.Left + tb.Width() + lineTextGap + lineLengthMinimum
Expand All @@ -286,8 +405,8 @@ func LegendLeft(c *Chart, userDefaults ...Style) Renderable {
}

legend = legend.Grow(legendContent)
legend.Right = legendContent.Right + legendPadding.Right
legend.Bottom = legendContent.Bottom + legendPadding.Bottom
legend.Right = legendContent.Right + legendStyle.Padding.Right
legend.Bottom = legendContent.Bottom + legendStyle.Padding.Bottom

Draw.Box(r, legend, legendStyle)

Expand All @@ -301,7 +420,7 @@ func LegendLeft(c *Chart, userDefaults ...Style) Renderable {
label = labels[x]
if len(label) > 0 {
if legendCount > 0 {
ycursor += DefaultMinimumTickVerticalSpacing
ycursor += DefaultLegendVerticalSpacing
}

tb := r.MeasureText(label)
Expand All @@ -313,7 +432,7 @@ func LegendLeft(c *Chart, userDefaults ...Style) Renderable {

lx := tx + tb.Width() + lineTextGap
ly := ty - th2
lx2 := legendContent.Right - legendPadding.Right
lx2 := legendContent.Right - legendStyle.Padding.Right

r.SetStrokeColor(lines[x].GetStrokeColor())
r.SetStrokeWidth(lines[x].GetStrokeWidth())
Expand Down