draw2d/cmd/testX11draw.go

package main

import (
	"fmt"
	"exp/draw"
	"exp/draw/x11"
	"image"
	"math"
	"draw2d.googlecode.com/hg/draw2d"
)

func main() {
	window, err := x11.NewWindow()
	if err != nil {
		fmt.Printf("Cannot open an x11 window\n")
		return
	}
	screen := window.Screen()
	if rgba, ok := screen.(*image.RGBA); ok {
		gc := draw2d.NewGraphicContext(rgba)
		gc.SetStrokeColor(image.Black)
		gc.SetFillColor(image.White)
		gc.Clear()
		for i := 0.0; i < 360; i = i + 10 { // Go from 0 to 360 degrees in 10 degree steps
			gc.BeginPath() // Start a new path
			gc.Save()      // Keep rotations temporary
			gc.MoveTo(144, 144)
			gc.Rotate(i * (math.Pi / 180.0)) // Rotate by degrees on stack from 'for'
			gc.RLineTo(72, 0)
			gc.Stroke()
			gc.Restore() // Get back the unrotated state
		}
		fmt.Printf("This is an rgba image\n")

		window.FlushImage()

		gc.SetLineWidth(3)
		nbclick := 0
		for {

			switch evt := (<-window.EventChan()).(type) {
			case draw.KeyEvent:
				if evt.Key == 'q' {
					window.Close()
				}
			case draw.MouseEvent:
				if evt.Buttons&1 != 0 {
					if nbclick%2 == 0 {
						gc.MoveTo(float64(evt.Loc.X), float64(evt.Loc.Y))
					} else {
						gc.LineTo(float64(evt.Loc.X), float64(evt.Loc.Y))
						gc.Stroke()
						window.FlushImage()
					}
					nbclick = nbclick + 1
				}
			}
		}
	} else {
		fmt.Printf("Not an RGBA image!\n")
	}
}