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chart.go
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package chart
import (
"fmt"
"io/ioutil"
"log"
"math"
"time"
)
// Chart ist the very simple interface for all charts: They can be plotted to a graphics output.
type Chart interface {
Plot(g Graphics) // Plot the chart to g.
Reset() // Reset any setting made during last plot.
}
// Expansion determines the way an axis range is expanded to align
// nicely with the tics on the axis.
type Expansion int
// Suitable values for Expand in RangeMode.
const (
ExpandNextTic Expansion = iota // Set min/max to next tic really below/above min/max of data.
ExpandToTic // Set to next tic below/above or equal to min/max of data.
ExpandTight // Use data min/max as limit.
ExpandABit // Like ExpandToTic and add/subtract ExpandABitFraction of tic distance.
)
// ExpandABitFraction is the fraction of a major tic spacing added during
// axis range expansion with the ExpandABit mode.
var ExpandABitFraction = 0.5
// RangeMode describes how one end of an axis is set up. There are basically three different main modes:
// * Fixed: Fixed==true.
// Use Value/TValue as fixed value this ignoring the actual data range.
// * Unconstrained autoscaling: Fixed==false && Constrained==false.
// Set range to whatever data requires.
// * Constrained autoscaling: Fixed==false && Constrained==true.
// Scale axis according to data present, but limit scaling to intervall [Lower,Upper]
// For both autoscaling modes Expand defines how much expansion is done below/above
// the lowest/highest data point.
type RangeMode struct {
Fixed bool // If false: autoscaling. If true: use (T)Value/TValue as fixed setting
Constrained bool // If false: full autoscaling. If true: use (T)Lower (T)Upper as limits
Expand Expansion // One of ExpandNextTic, ExpandTight, ExpandABit
Value float64 // Value of end point of axis in Fixed=true mode, ignorder otherwise
TValue time.Time // Same as Value, but used for Date/Time axis
Lower, Upper float64 // Lower and upper limit for constrained autoscaling
TLower, TUpper time.Time // Same s Lower/Upper, but used for Date/Time axis
}
// GridMode describes the way a grid on the major tics is drawn
type GridMode int
const (
GridOff GridMode = iota // No grid lines
GridLines // Grid lines
GridBlocks // Zebra style background
)
// MirrorAxis describes if and how an axis is drawn on the oposite side of
// a chart,
type MirrorAxis int
const (
MirrorAxisAndTics MirrorAxis = 0 // draw a full mirrored axis including tics
MirrorNothing MirrorAxis = -1 // do not draw a mirrored axis
MirrorAxisOnly MirrorAxis = 1 // just draw a mirrord axis, but omit tics
)
// TicSetting describes how (if at all) tics are shown on an axis.
type TicSetting struct {
Hide bool // dont show tics if true
HideLabels bool // don't show tic labels if true
Tics int // 0: across axis, 1: inside, 2: outside, other: off
Minor int // 0: off, 1: auto, >1: number of intervalls (not number of tics!)
Delta float64 // wanted step between major tics. 0 means auto
TDelta TimeDelta // same as Delta, but used for Date/Time axis
Grid GridMode // GridOff, GridLines, GridBlocks
Mirror MirrorAxis // 0: mirror axis and tics, -1: don't mirror anything, 1: mirror axis only (no tics)
// Format is used to print the tic labels. If unset FmtFloat is used.
Format func(float64) string
// TFormat is used to print tic labels for date/time axis.
TFormat func(time.Time, TimeDelta) string
// TLocation allows to fix the timezone in which date/time axis tic labels
// are printed.
TLocation *time.Location
UserDelta bool // true if Delta or TDelta was input
}
// Tic describs a single tic on an axis.
type Tic struct {
Pos float64 // position of the tic on the axis (in data coordinates).
LabelPos float64 // position of the label on the axis (in data coordinates).
Label string // the Label of the tic
Align int // alignment of the label: -1: left/top, 0 center, 1 right/bottom (unused)
}
// Range encapsulates all information about an axis.
type Range struct {
Label string // Label of axis
Log bool // Logarithmic axis?
Time bool // Date/Time axis?
MinMode, MaxMode RangeMode // How to handel min and max of this axis/range
TicSetting TicSetting // How to handle tics.
DataMin, DataMax float64 // Actual min/max values from data. If both zero: not calculated
ShowLimits bool // Display axis Min and Max values on plot
ShowZero bool // Add line to show 0 of this axis
Category []string // If not empty (and neither Log nor Time): Use Category[n] as tic label at pos n+1.
// The following values are set up during plotting
Min, Max float64 // Actual minium and maximum of this axis/range.
TMin, TMax time.Time // Same as Min/Max, but used for Date/Time axis
Tics []Tic // List of tics to display
// The following functions are set up during plotting
Norm func(float64) float64 // Function to map [Min:Max] to [0:1]
InvNorm func(float64) float64 // Inverse of Norm()
Data2Screen func(float64) int // Function to map data value to screen position
Screen2Data func(int) float64 // Inverse of Data2Screen
}
// Fixed is a helper (just reduces typing) functions which turns of autoscaling
// and sets the axis range to [min,max] and the tic distance to delta.
func (r *Range) Fixed(min, max, delta float64) {
r.MinMode.Fixed, r.MaxMode.Fixed = true, true
r.MinMode.Value, r.MaxMode.Value = min, max
r.TicSetting.Delta = delta
}
// TFixed is the date/time version of Fixed.
func (r *Range) TFixed(min, max time.Time, delta TimeDelta) {
r.MinMode.Fixed, r.MaxMode.Fixed = true, true
r.MinMode.TValue, r.MaxMode.TValue = min, max
r.TicSetting.TDelta = delta
}
// Reset the fields in r which have been set up during a plot.
func (r *Range) Reset() {
r.Min, r.Max = 0, 0
r.TMin, r.TMax = time.Time{}, time.Time{}
r.Tics = nil
r.Norm, r.InvNorm = nil, nil
r.Data2Screen, r.Screen2Data = nil, nil
if !r.TicSetting.UserDelta {
r.TicSetting.Delta = 0
r.TicSetting.TDelta = nil
}
}
// Prepare the range r for use, especially set up all values needed for autoscale() to work properly.
func (r *Range) init() { r.Init() }
func (r *Range) Init() {
// All the min stuff
if r.MinMode.Fixed {
// copy TValue to Value if set and time axis
if r.Time && !r.MinMode.TValue.IsZero() {
r.MinMode.Value = float64(r.MinMode.TValue.Unix())
}
r.DataMin = r.MinMode.Value
} else if r.MinMode.Constrained {
// copy TLower/TUpper to Lower/Upper if set and time axis
if r.Time && !r.MinMode.TLower.IsZero() {
r.MinMode.Lower = float64(r.MinMode.TLower.Unix())
}
if r.Time && !r.MinMode.TUpper.IsZero() {
r.MinMode.Upper = float64(r.MinMode.TUpper.Unix())
}
if r.MinMode.Lower == 0 && r.MinMode.Upper == 0 {
// Constrained but un-initialized: Full autoscaling
r.MinMode.Lower = -math.MaxFloat64
r.MinMode.Upper = math.MaxFloat64
}
r.DataMin = r.MinMode.Upper
} else {
r.DataMin = math.MaxFloat64
}
// All the max stuff
if r.MaxMode.Fixed {
// copy TValue to Value if set and time axis
if r.Time && !r.MaxMode.TValue.IsZero() {
r.MaxMode.Value = float64(r.MaxMode.TValue.Unix())
}
r.DataMax = r.MaxMode.Value
} else if r.MaxMode.Constrained {
// copy TLower/TUpper to Lower/Upper if set and time axis
if r.Time && !r.MaxMode.TLower.IsZero() {
r.MaxMode.Lower = float64(r.MaxMode.TLower.Unix())
}
if r.Time && !r.MaxMode.TUpper.IsZero() {
r.MaxMode.Upper = float64(r.MaxMode.TUpper.Unix())
}
if r.MaxMode.Lower == 0 && r.MaxMode.Upper == 0 {
// Constrained but un-initialized: Full autoscaling
r.MaxMode.Lower = -math.MaxFloat64
r.MaxMode.Upper = math.MaxFloat64
}
r.DataMax = r.MaxMode.Upper
} else {
r.DataMax = -math.MaxFloat64
}
// fmt.Printf("At end of init: DataMin / DataMax = %g / %g\n", r.DataMin, r.DataMax)
}
// Update DataMin and DataMax according to the RangeModes.
func (r *Range) autoscale(x float64) {
if x < r.DataMin && !r.MinMode.Fixed {
if !r.MinMode.Constrained {
// full autoscaling
r.DataMin = x
} else {
r.DataMin = fmin(fmax(x, r.MinMode.Lower), r.DataMin)
}
}
if x > r.DataMax && !r.MaxMode.Fixed {
if !r.MaxMode.Constrained {
// full autoscaling
r.DataMax = x
} else {
r.DataMax = fmax(fmin(x, r.MaxMode.Upper), r.DataMax)
}
}
}
// Units are the SI prefixes for 10^3n
var Units = []string{" y", " z", " a", " f", " p", " n", " µ", "m", " k", " M", " G", " T", " P", " E", " Z", " Y"}
// FmtFloat yields a string representation of f. E.g. 12345.67 --> "12.3 k"; 0.09876 --> "99 m"
func FmtFloat(f float64) string {
af := math.Abs(f)
if f == 0 {
return "0"
} else if 1 <= af && af < 10 {
return fmt.Sprintf("%.1f", f)
} else if 10 <= af && af <= 1000 {
return fmt.Sprintf("%.0f", f)
}
if af < 1 {
var p = 8
for math.Abs(f) < 1 && p >= 0 {
f *= 1000
p--
}
return FmtFloat(f) + Units[p]
}
var p = 7
for math.Abs(f) > 1000 && p < 16 {
f /= 1000
p++
}
return FmtFloat(f) + Units[p]
}
func almostEqual(a, b, d float64) bool {
return math.Abs(a-b) < d
}
// applyRangeMode returns val constrained by mode. val is considered the upper end of an range/axis
// if upper is true. To allow proper rounding to tic (depending on desired RangeMode)
// the ticDelta has to be provided. Logaritmic axis are selected by log = true and ticDelta
// is ignored: Tics are of the form 1*10^n.
func applyRangeMode(mode RangeMode, val, ticDelta float64, upper, log bool) float64 {
if mode.Fixed {
return mode.Value
}
if mode.Constrained {
if val < mode.Lower {
val = mode.Lower
} else if val > mode.Upper {
val = mode.Upper
}
}
switch mode.Expand {
case ExpandToTic, ExpandNextTic:
var v float64
if upper {
if log {
v = math.Pow10(int(math.Ceil(math.Log10(val))))
} else {
v = math.Ceil(val/ticDelta) * ticDelta
}
} else {
if log {
v = math.Pow10(int(math.Floor(math.Log10(val))))
} else {
v = math.Floor(val/ticDelta) * ticDelta
}
}
if mode.Expand == ExpandNextTic {
if upper {
if log {
if val/v < 2 { // TODO(vodo) use ExpandABitFraction
v *= ticDelta
}
} else {
if almostEqual(v, val, ticDelta/15) {
v += ticDelta
}
}
} else {
if log {
if v/val > 7 { // TODO(vodo) use ExpandABitFraction
v /= ticDelta
}
} else {
if almostEqual(v, val, ticDelta/15) {
v -= ticDelta
}
}
}
}
val = v
case ExpandABit:
if upper {
if log {
val *= math.Pow(10, ExpandABitFraction)
} else {
val += ticDelta * ExpandABitFraction
}
} else {
if log {
val /= math.Pow(10, ExpandABitFraction)
} else {
val -= ticDelta * ExpandABitFraction
}
}
}
return val
}
// tApplyRangeMode is the same as applyRangeMode for date/time axis/ranges.
func tApplyRangeMode(mode RangeMode, val time.Time, step TimeDelta, upper bool) (bound time.Time, tic time.Time) {
if mode.Fixed {
bound = mode.TValue
if upper {
tic = RoundDown(val, step)
} else {
tic = RoundUp(val, step)
}
return
}
if mode.Constrained { // TODO(vodo) use T...
sval := val.Unix()
if sval < int64(mode.Lower) {
sval = int64(mode.Lower)
} else if sval > int64(mode.Upper) {
sval = int64(mode.Upper)
}
val = time.Unix(sval, 0).In(val.Location())
}
switch mode.Expand {
case ExpandToTic:
if upper {
val = RoundUp(val, step)
} else {
val = RoundDown(val, step)
}
return val, val
case ExpandNextTic:
if upper {
tic = RoundUp(val, step)
} else {
tic = RoundDown(val, step)
}
s := tic.Unix()
if math.Abs(float64(s-val.Unix())/float64(step.Seconds())) < 0.15 {
if upper {
val = RoundUp(time.Unix(s+step.Seconds()/2, 0).In(val.Location()), step)
} else {
val = RoundDown(time.Unix(s-step.Seconds()/2, 0).In(val.Location()), step)
}
} else {
val = tic
}
return val, val
case ExpandABit:
if upper {
tic = RoundDown(val, step)
val = time.Unix(tic.Unix()+step.Seconds()/2, 0).In(val.Location())
} else {
tic = RoundUp(val, step)
val = time.Unix(tic.Unix()-step.Seconds()/2, 0).In(val.Location())
}
return
}
return val, val
}
func f2d(x float64) string {
s := int64(x)
t := time.Unix(s, 0)
return t.Format("2006-01-02 15:04:05 (Mon)")
}
func (r *Range) tSetup(desiredNumberOfTics, maxNumberOfTics int, delta, mindelta float64) {
DebugLogger.Printf("Data: [ %s : %s ] --> delta/mindelta = %.3g/%.3g (desired %d/max %d)\n",
f2d(r.DataMin), f2d(r.DataMax), delta, mindelta, desiredNumberOfTics, maxNumberOfTics)
var td TimeDelta
if r.TicSetting.TDelta != nil {
td = r.TicSetting.TDelta
r.TicSetting.UserDelta = true
} else {
td = MatchingTimeDelta(delta, 3)
r.TicSetting.UserDelta = false
}
r.ShowLimits = true
// Set up time tic delta
mint := time.Unix(int64(r.DataMin), 0)
maxt := time.Unix(int64(r.DataMax), 0)
if r.TicSetting.TLocation != nil {
mint = mint.In(r.TicSetting.TLocation)
maxt = maxt.In(r.TicSetting.TLocation)
}
var ftic, ltic time.Time
r.TMin, ftic = tApplyRangeMode(r.MinMode, mint, td, false)
r.TMax, ltic = tApplyRangeMode(r.MaxMode, maxt, td, true)
r.TicSetting.Delta, r.TicSetting.TDelta = float64(td.Seconds()), td
r.Min, r.Max = float64(r.TMin.Unix()), float64(r.TMax.Unix())
ftd := float64(td.Seconds())
actNumTics := int((r.Max - r.Min) / ftd)
if actNumTics > maxNumberOfTics {
// recalculate time tic delta
DebugLogger.Printf("Switching from %s no next larger step %s", td, NextTimeDelta(td))
td = NextTimeDelta(td)
ftd = float64(td.Seconds())
r.TMin, ftic = tApplyRangeMode(r.MinMode, mint, td, false)
r.TMax, ltic = tApplyRangeMode(r.MaxMode, maxt, td, true)
r.TicSetting.Delta, r.TicSetting.TDelta = float64(td.Seconds()), td
r.Min, r.Max = float64(r.TMin.Unix()), float64(r.TMax.Unix())
actNumTics = int((r.Max - r.Min) / ftd)
}
DebugLogger.Printf("DataRange: %s TO %s", f2d(r.DataMin), f2d(r.DataMax))
DebugLogger.Printf("AxisRange: %s TO %s", f2d(r.Min), f2d(r.Max))
DebugLogger.Printf("TicsRange: %s TO %s Step %s",
ftic.Format("2006-01-02 15:04:05 (Mon)"), ltic.Format("2006-01-02 15:04:05 (Mon)"), td)
// Set up tics
r.Tics = make([]Tic, 0)
step := int64(td.Seconds())
align := 0
var formater func(t time.Time, td TimeDelta) string
if r.TicSetting.TFormat != nil {
formater = r.TicSetting.TFormat
} else {
formater = func(t time.Time, td TimeDelta) string { return td.Format(t) }
}
for i := 0; ftic.Unix() < ltic.Unix(); i++ {
x := float64(ftic.Unix())
label := formater(ftic, td)
var labelPos float64
if td.Period() {
labelPos = x + float64(step)/2
} else {
labelPos = x
}
t := Tic{Pos: x, LabelPos: labelPos, Label: label, Align: align}
r.Tics = append(r.Tics, t)
z := time.Unix(ftic.Unix()+step+step/5, 0)
if r.TicSetting.TLocation != nil {
z = z.In(r.TicSetting.TLocation)
}
ftic = RoundDown(z, td)
}
// last tic might not get label if period
if td.Period() {
r.Tics = append(r.Tics, Tic{Pos: float64(ftic.Unix())})
} else {
x := float64(ftic.Unix())
label := formater(ftic, td)
var labelPos float64
labelPos = x
t := Tic{Pos: x, LabelPos: labelPos, Label: label, Align: align}
r.Tics = append(r.Tics, t)
}
}
// Determine appropriate tic delta for normal (non dat/time) axis from desired delta and minimal delta.
func (r *Range) fDelta(delta, mindelta float64) float64 {
if r.Log {
return 10
}
// Set up nice tic delta of the form 1,2,5 * 10^n
// TODO: deltas of 25 and 250 would be suitable too...
de := math.Pow10(int(math.Floor(math.Log10(delta))))
f := delta / de
switch {
case f < 2:
f = 1
case f < 4:
f = 2
case f < 9:
f = 5
default:
f = 1
de *= 10
}
delta = f * de
if delta < mindelta {
DebugLogger.Printf("Redoing delta: %g < %g", delta, mindelta)
// recalculate tic delta
switch f {
case 1, 5:
delta *= 2
case 2:
delta *= 2.5
default:
fmt.Printf("Oooops. Strange f: %g\n", f)
}
}
return delta
}
// Set up normal (=non date/time axis)
func (r *Range) fSetup(desiredNumberOfTics, maxNumberOfTics int, delta, mindelta float64) {
DebugLogger.Printf("Data: [ %.5g : %.5g ] --> delta/mindelta = %.3g/%.3g (desired %d/max %d)\n",
r.DataMin, r.DataMax, delta, mindelta, desiredNumberOfTics, maxNumberOfTics)
if r.TicSetting.Delta != 0 {
delta = r.TicSetting.Delta
r.TicSetting.UserDelta = true
} else {
delta = r.fDelta(delta, mindelta)
r.TicSetting.UserDelta = false
}
r.Min = applyRangeMode(r.MinMode, r.DataMin, delta, false, r.Log)
r.Max = applyRangeMode(r.MaxMode, r.DataMax, delta, true, r.Log)
r.TicSetting.Delta = delta
DebugLogger.Printf("DataRange: %.6g TO %.6g", r.DataMin, r.DataMax)
DebugLogger.Printf("AxisRange: %.6g TO %.6g", r.Min, r.Max)
formater := FmtFloat
if r.TicSetting.Format != nil {
formater = r.TicSetting.Format
}
if r.Log {
x := math.Pow10(int(math.Ceil(math.Log10(r.Min))))
last := math.Pow10(int(math.Floor(math.Log10(r.Max))))
DebugLogger.Printf("TicsRange: %.6g TO %.6g Factor %.6g", x, last, delta)
r.Tics = make([]Tic, 0, maxNumberOfTics)
for ; x <= last; x = x * delta {
t := Tic{Pos: x, LabelPos: x, Label: formater(x)}
r.Tics = append(r.Tics, t)
// fmt.Printf("%v\n", t)
}
} else {
if len(r.Category) > 0 {
DebugLogger.Printf("TicsRange: %d categorical tics.", len(r.Category))
r.Tics = make([]Tic, len(r.Category))
for i, c := range r.Category {
x := float64(i)
if x < r.Min {
continue
}
if x > r.Max {
break
}
r.Tics[i].Pos = math.NaN() // no tic
r.Tics[i].LabelPos = x
r.Tics[i].Label = c
}
} else {
// normal numeric axis
first := delta * math.Ceil(r.Min/delta)
num := int(-first/delta + math.Floor(r.Max/delta) + 1.5)
DebugLogger.Printf("TicsRange: %.6g TO %.6g Step %.6g", first, first+float64(num)*delta, delta)
// Set up tics
r.Tics = make([]Tic, num)
for i, x := 0, first; i < num; i, x = i+1, x+delta {
r.Tics[i].Pos, r.Tics[i].LabelPos = x, x
r.Tics[i].Label = formater(x)
}
}
// TODO(vodo) r.ShowLimits = true
}
}
// Setup several fields of the Range r according to RangeModes and TicSettings.
// DataMin and DataMax of r must be present and should indicate lowest and highest
// value present in the data set. The following fields of r are filled:
// (T)Min and (T)Max lower and upper limit of axis, (T)-version for date/time axis
// Tics slice of tics to draw
// TicSetting.(T)Delta actual tic delta
// Norm and InvNorm mapping of [lower,upper]_data --> [0:1] and inverse
// Data2Screen mapping of data to screen coordinates
// Screen2Data inverse of Data2Screen
// The parameters desiredNumberOfTics and maxNumberOfTics are what the say.
// sWidth and sOffset are screen-width and -offset and are used to set up the
// Data-Screen conversion functions. If revert is true, than screen coordinates
// are assumed to be the other way around than mathematical coordinates.
//
// TODO(vodo) seperate screen stuff into own method.
func (r *Range) Setup(desiredNumberOfTics, maxNumberOfTics, sWidth, sOffset int, revert bool) {
// Sanitize input
if desiredNumberOfTics <= 1 {
desiredNumberOfTics = 2
}
if maxNumberOfTics < desiredNumberOfTics {
maxNumberOfTics = desiredNumberOfTics
}
if r.DataMax == r.DataMin {
r.DataMax = r.DataMin + 1
}
delta := (r.DataMax - r.DataMin) / float64(desiredNumberOfTics-1)
mindelta := (r.DataMax - r.DataMin) / float64(maxNumberOfTics-1)
if r.Time {
r.tSetup(desiredNumberOfTics, maxNumberOfTics, delta, mindelta)
} else { // simple, not a date range
r.fSetup(desiredNumberOfTics, maxNumberOfTics, delta, mindelta)
}
if r.Log {
r.Norm = func(x float64) float64 { return math.Log10(x/r.Min) / math.Log10(r.Max/r.Min) }
r.InvNorm = func(f float64) float64 { return (r.Max-r.Min)*f + r.Min }
} else {
r.Norm = func(x float64) float64 { return (x - r.Min) / (r.Max - r.Min) }
r.InvNorm = func(f float64) float64 { return (r.Max-r.Min)*f + r.Min }
}
if !revert {
r.Data2Screen = func(x float64) int {
return int(float64(sWidth)*r.Norm(x)) + sOffset
}
r.Screen2Data = func(x int) float64 {
return r.InvNorm(float64(x-sOffset) / float64(sWidth))
}
} else {
r.Data2Screen = func(x float64) int {
return sWidth - int(float64(sWidth)*r.Norm(x)) + sOffset
}
r.Screen2Data = func(x int) float64 {
return r.InvNorm(float64(-x+sOffset+sWidth) / float64(sWidth))
}
}
}
// LayoutData encapsulates the layout of the graph area in the whole drawing area.
type LayoutData struct {
Width, Height int // width and height of graph area
Left, Top int // left and top margin
KeyX, KeyY int // x and y coordiante of key
NumXtics, NumYtics int // suggested numer of tics for both axis
}
// Layout graph data area on screen and place key.
func layout(g Graphics, title, xlabel, ylabel string, hidextics, hideytics bool, key *Key) (ld LayoutData) {
fw, fh, _ := g.FontMetrics(Font{})
w, h := g.Dimensions()
if key.Pos == "" {
key.Pos = "itr"
}
width, leftm, height, topm := w-int(6*fw), int(2*fw), h-2*fh, fh
xlabsep, ylabsep := fh, int(3*fw)
if title != "" {
topm += (5 * fh) / 2
height -= (5 * fh) / 2
}
if xlabel != "" {
height -= (3 * fh) / 2
}
if !hidextics {
height -= (3 * fh) / 2
xlabsep += (3 * fh) / 2
}
if ylabel != "" {
leftm += 2 * fh
width -= 2 * fh
}
if !hideytics {
leftm += int(6 * fw)
width -= int(6 * fw)
ylabsep += int(6 * fw)
}
if key != nil && !key.Hide && len(key.Place()) > 0 {
m := key.Place()
kw, kh, _, _ := key.Layout(g, m, Font{}) // TODO: use real font
sepx, sepy := int(fw)+fh, int(fw)+fh
switch key.Pos[:2] {
case "ol":
width, leftm = width-kw-sepx, leftm+kw
ld.KeyX = sepx / 2
case "or":
width = width - kw - sepx
ld.KeyX = w - kw - sepx/2
case "ot":
height, topm = height-kh-sepy, topm+kh
ld.KeyY = sepy / 2
if title != "" {
ld.KeyY += 2 * fh
}
case "ob":
height = height - kh - sepy
ld.KeyY = h - kh - sepy/2
case "it":
ld.KeyY = topm + sepy
case "ic":
ld.KeyY = topm + (height-kh)/2
case "ib":
ld.KeyY = topm + height - kh - sepy
}
switch key.Pos[:2] {
case "ol", "or":
switch key.Pos[2] {
case 't':
ld.KeyY = topm
case 'c':
ld.KeyY = topm + (height-kh)/2
case 'b':
ld.KeyY = topm + height - kh
}
case "ot", "ob":
switch key.Pos[2] {
case 'l':
ld.KeyX = leftm
case 'c':
ld.KeyX = leftm + (width-kw)/2
case 'r':
ld.KeyX = w - kw - sepx
}
}
if key.Pos[0] == 'i' {
switch key.Pos[2] {
case 'l':
ld.KeyX = leftm + sepx
case 'c':
ld.KeyX = leftm + (width-kw)/2
case 'r':
ld.KeyX = leftm + width - kw - sepx
}
}
}
// fmt.Printf("width=%d, height=%d, leftm=%d, topm=%d (fw=%d)\n", width, height, leftm, topm, int(fw))
// Number of tics
if width/int(fw) <= 20 {
ld.NumXtics = 2
} else {
ld.NumXtics = width / int(10*fw)
if ld.NumXtics > 25 {
ld.NumXtics = 25
}
}
ld.NumYtics = height / (4 * fh)
if ld.NumYtics > 20 {
ld.NumYtics = 20
}
ld.Width, ld.Height = width, height
ld.Left, ld.Top = leftm, topm
return
}
// DebugLogger is used to log some information about the chart generation.
var DebugLogger *log.Logger = log.New(ioutil.Discard, "", 0)