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") } }