zntg/ui/spinner.go

package ui

import (
	"math"
	"time"

	"github.com/llgcode/draw2d/draw2dimg"

	"opslag.de/schobers/zntg/allg5"
)

var _ Control = &Spinner{}

type Spinner struct {
	ControlBase
	Text  string
	spin  float32
	circs *allg5.Bitmap
}

func (s *Spinner) Created(ctx Context, p Container) error {
	s.ControlBase.Created(ctx, p)
	const row = 6
	const numCircs = row * row
	const width = 48
	const center = width * .5
	const full = 2 * math.Pi
	s.circs = drawBitmap(row*width, row*width, func(gc *draw2dimg.GraphicContext) {
		var start, a float64 = 0, .2 * math.Pi
		var inc = true
		gc.SetLineWidth(4)
		gc.SetStrokeColor(ctx.Palette().Primary())
		for i := 0; i < numCircs; i++ {
			var left = float64(i%row) * width
			var top = float64(i/row) * width
			gc.ArcTo(left+center, top+center, center-8, center-8, start, a)
			gc.Stroke()
			if inc {
				start += full / numCircs
				a += 1.90 * full / numCircs
				if a >= full {
					inc = false
				}
			} else {
				start += 2.90 * full / numCircs
				a -= 1.90 * full / numCircs
				// if a <= .1*math.Pi {
				// 	inc = true
				// }
			}
		}
	})
	for i := 0; i < numCircs; i++ {
		var left = (i % row) * width
		var top = (i / row) * width
		s.circs.Sub(left, top, width, width)
	}
	return nil
}

func (s *Spinner) Destroyed(ctx Context) {
	s.circs.Destroy()
}

func (s *Spinner) Update(ctx Context, dt time.Duration) {
	var spin = float64(s.spin)
	spin += dt.Seconds() * .5
	for spin > 1. {
		spin -= 1.
	}
	s.spin = float32(spin)
}

func (s *Spinner) Render(ctx Context) {
	var disp = ctx.Display()
	var fonts = ctx.Fonts()

	var width = float32(disp.Width())
	var height = float32(disp.Height())

	var fnt = fonts.Get("default")
	var textW = fnt.TextWidth(s.Text)

	allg5.DrawFilledRectangle(0, 0, width, height, ctx.Palette().Disabled())

	const marginH, marginV float32 = 64, 16
	const textH float32 = 12
	var rectW, rectH float32 = textW + 2*marginH, 3*marginV + textH + 32
	var rectX, rectY = (width - rectW) * .5, (height - rectH) * .5
	allg5.DrawFilledRectangle(rectX, rectY, rectX+rectW, rectY+rectH, ctx.Palette().Lightest())
	DropShadow(rectX, rectY, rectX+rectW, rectY+rectH)
	fnt.Draw(rectX+marginH, rectY+marginV, ctx.Palette().Darkest(), allg5.AlignLeft, s.Text)

	const numCircs = 36
	var i = int(math.Floor(float64(s.spin) * numCircs))
	s.circs.Subs()[i].DrawOptions(width*.5, rectY+2*marginV+2*textH, allg5.DrawOptions{Center: true})

	s.ControlBase.Render(ctx)
}