gfxtest

main.go

package main

import (
 "fmt"
 "image"
 "image/color"
 "image/draw"

 "github.com/fogleman/gg"
 "golang.org/x/exp/shiny/driver"
 "golang.org/x/exp/shiny/screen"
 "golang.org/x/mobile/event/key"
 "golang.org/x/mobile/event/lifecycle"
 "golang.org/x/mobile/event/mouse"
 "golang.org/x/mobile/event/paint"
 "golang.org/x/mobile/event/size"
)

var theSize = image.Point{
 X: 640,
 Y: 480,
}

func main() {
 driver.Main(func(s screen.Screen) {
  isDrawing := false
  drawPt := image.Point{}
  w, err := s.NewWindow(&screen.NewWindowOptions{
   Width:  theSize.X,
   Height: theSize.Y,
   Title:  "Test",
  })
  if err != nil {
   panic(err)
   return
  }
  defer w.Release()
  //w.Fill(image.Rect(0, 0, 639, 479), color.Black, draw.Src)
  buf, err := s.NewBuffer(theSize)
  if err != nil {
   panic(err)
  }
  defer buf.Release()
  dc := gg.NewContextForRGBA(buf.RGBA())
  dc.SetRGB(0, 0.5, 0)
  dc.Clear()
  dc.DrawCircle(float64(theSize.X/2), float64(theSize.Y/2), float64(theSize.Y/3))
  dc.SetRGB(0.75, 0.75, 0)
  dc.Fill()
  dc.SetRGB(0, 0, 0)
  fmt.Println(buf.RGBA().Bounds())
  for {
   switch e := w.NextEvent().(type) {
   case size.Event:
    theSize = e.Size()
    w.Fill(image.Rect(0, 0, theSize.X-1, theSize.Y-1), color.Black, draw.Src)
    w.Send(paint.Event{})
   case paint.Event:
    w.Upload(image.Point{X: 0, Y: 0}, buf, buf.Bounds())
    w.Publish()
   case key.Event:
    fmt.Println(e)
    switch e.Code {
    case key.CodeEscape:
     return
    case key.CodeLeftShift:
     if e.Direction == key.DirPress {
      dc.SetRGB(1, 1, 1)
     } else {
      dc.SetRGB(0, 0, 0)
     }
    }
   case mouse.Event:
    switch e.Button {
    case mouse.ButtonLeft:
     isDrawing = !isDrawing
     if isDrawing {
      dc.SetLineWidth(1)
      drawPt.X = int(e.X)
      drawPt.Y = int(e.Y)
     }
    case mouse.ButtonRight:
     dc.SetColor(buf.RGBA().At(int(e.X), int(e.Y)))
    }
    if isDrawing {
     dc.DrawLine(float64(drawPt.X), float64(drawPt.Y), float64(e.X), float64(e.Y))
     drawPt.X = int(e.X)
     drawPt.Y = int(e.Y)
     dc.Stroke()
     w.Send(paint.Event{})
    }
   case lifecycle.Event:
    if e.To == lifecycle.StageDead {
     return
    }
    // etc
   default:
    fmt.Printf("%T\n", e)
   }
  }
 })
}