func canvasContext(c jquery.JQuery) (x *canvas.Context) {
x = canvas.GetContext(c)
h := float64(c.Width())
w := float64(c.Height())
x.PixelsPerPoint = screenPixelsPerPoint
x.PointsPerPixel = 1 / screenPixelsPerPoint
x.Size = r2.XY(h*x.PointsPerPixel, w*x.PointsPerPixel)
// Always work in points not pixels.
x.Scale(r2.XY1(screenPixelsPerPoint))
return
}
func (m *myElog) Draw(ctx *canvas.Context) {
vw := &m.view
err := rpc.Call("Listener.GetEventView", &struct{}{}, vw)
if err != nil {
panic(err)
}
ctx.Save()
ctx.BeginPath()
ctx.SetFillStyle(canvas.RGBA{A: 1, R: .95, G: .95, B: .95})
ctx.Rect(0, ctx.Size)
ctx.Fill()
ctx.Restore()
vw.GetTimeBounds(&m.tb)
// Switch to Cartesian coordinates where (0,0) is at the lower left and S is the upper right.
m.margin = r2.XY(16., 24.)
m.max = ctx.Size - 2*m.margin
ctx.Translate(r2.XY(m.margin.X(), ctx.Size.Y()-m.margin.Y()))
/* Draw and label time axis. */
{
ctx.Save()
ctx.SetStrokeStyle(canvas.RGBA{A: 1})
ctx.LineWidth = 1
ctx.BeginPath()
ctx.MoveTo(0)
ctx.LineTo(r2.XY(m.max.X(), 0))
ctx.Stroke()
ctx.Font = "10px Ariel"
ctx.TextBaseline = "top"
ctx.TextAlign = "center"
nUnit := int(.5 + m.tb.Dt/(m.tb.Round*m.tb.Unit))
x, dx := r2.XY1(0), r2.XY(m.max.X()/float64(nUnit), 0)
t, dt := m.tb.Min, m.tb.Round*m.tb.Unit
for i := 0; i <= nUnit; i++ {
str := fmt.Sprintf("%.0f", t/m.tb.Unit)
dy := r2.XY(0, 2)
ctx.FillText(str, x+dy)
ctx.BeginPath()
ctx.MoveTo(x + dy)
ctx.LineTo(x - dy)
ctx.Stroke()
x += dx
t += dt
}
ctx.Font = "11px Ariel"
label := fmt.Sprintf("Time in %s from %s", m.tb.UnitName, m.tb.Start.Format("2006-01-02 15:04:05"))
ctx.FillText(label, r2.XY(m.max.X()/2, 14))
ctx.Restore()
}
{
ctx.Save()
dy := 7.
ctx.Font = fmt.Sprintf("%.0fpt monospace", dy)
ctx.TextAlign = "center"
ctx.TextBaseline = "middle"
black := canvas.RGBA{A: 1}
stroke := canvas.RGBA{A: 1, R: 151 / 256., G: 187 / 256., B: 205 / 256.}
fill := stroke
fill.A = .2
labelStyle := canvas.RGBA{A: 1}
ctx.SetStrokeStyle(black)
ctx.SetFillStyle(fill)
lastXmax := 0.
idy := 0
for i := range vw.Events {
e := &vw.Events[i]
t := vw.Time(e).Sub(m.tb.Start).Seconds()
// label := e.Type().Name
label := e.String()
if len(label) > 20 {
label = label[:20]
}
dx := 1.1*ctx.MeasureText(label) + r2.XY(0, 1.5*dy)
x := r2.XY(m.max.X()*(t-m.tb.Min)/m.tb.Dt, -m.max.Y()/2)
if i > 0 && x.X()-.5*dx.X() < lastXmax {
idy++
} else {
idy = 0
}
thisDy := 0.
if idy != 0 {
// Even stacked events go down; odd events up.
if idy%2 == 0 {
thisDy = float64(idy/2) * dy
} else {
thisDy = -float64((1+idy)/2) * dy
}
}
// fmt.Println(idy, thisDy)
x += r2.XY(0, thisDy*2)
lastXmax = x.X() + .5*dx.X()
ctx.CenteredRoundedRect(x, dx, 2)
ctx.SetFillStyle(fill)
ctx.Fill()
ctx.Stroke()
ctx.SetFillStyle(labelStyle)
ctx.FillText(label, x)
}
ctx.Restore()
}
}
