func main() {
X, err := xgbutil.NewConn()
if err != nil {
log.Fatal(err)
}
// Read an example gopher image into a regular png image.
img, _, err := image.Decode(bytes.NewBuffer(gopher.GopherPng()))
if err != nil {
log.Fatal(err)
}
// Now convert it into an X image.
ximg := xgraphics.NewConvert(X, img)
// Now show it in a new window.
// We set the window title and tell the program to quit gracefully when
// the window is closed.
// There is also a convenience method, XShow, that requires no parameters.
ximg.XShowExtra("The Go Gopher!", true)
// If we don't block, the program will end and the window will disappear.
// We could use a 'select{}' here, but xevent.Main will emit errors if
// something went wrong, so use that instead.
xevent.Main(X)
}
func main() {
X, err := xgbutil.NewConn()
fatal(err)
// Whenever the mousebind package is used, you must call Initialize.
// Similarly for the keybind package.
keybind.Initialize(X)
mousebind.Initialize(X)
// Easter egg! Use a right click to draw a gopher.
gopherPng, _, err := image.Decode(bytes.NewBuffer(gopher.GopherPng()))
fatal(err)
// Now scale it to a reasonable size.
gopher := xgraphics.Scale(gopherPng, gopherWidth, gopherHeight)
// Create a new xgraphics.Image. It automatically creates an X pixmap for
// you, and handles drawing to windows in the XDraw, XPaint and
// XSurfaceSet functions.
// N.B. An error is possible since X pixmap allocation can fail.
canvas := xgraphics.New(X, image.Rect(0, 0, width, height))
// Color in the background color.
canvas.For(func(x, y int) xgraphics.BGRA {
return bg
})
// Use the convenience function XShowExtra to create and map the
// canvas window.
// XShowExtra will also set the surface window of canvas for us.
// We also use XShowExtra to set the name of the window and to quit the
// main event loop when the window is closed.
win := canvas.XShowExtra("Pointer painting", true)
// Listen for pointer motion events and key press events.
win.Listen(xproto.EventMaskButtonPress | xproto.EventMaskButtonRelease |
xproto.EventMaskKeyPress)
// The mousebind drag function runs three callbacks: one when the drag is
// first started, another at each "step" in the drag, and a final one when
// the drag is done.
// The button sequence (in this case '1') is pressed, the first callback
// is executed. If the first return value is true, the drag continues
// and a pointer grab is initiated with the cursor id specified in the
// second return value (use 0 to keep the cursor unchanged).
// If it's false, the drag stops.
// Note that Drag will automatically compress MotionNotify events.
mousebind.Drag(X, win.Id, win.Id, "1", false,
func(X *xgbutil.XUtil, rx, ry, ex, ey int) (bool, xproto.Cursor) {
drawPencil(canvas, win, ex, ey)
return true, 0
},
func(X *xgbutil.XUtil, rx, ry, ex, ey int) {
drawPencil(canvas, win, ex, ey)
},
func(X *xgbutil.XUtil, rx, ry, ex, ey int) {})
mousebind.Drag(X, win.Id, win.Id, "3", false,
func(X *xgbutil.XUtil, rx, ry, ex, ey int) (bool, xproto.Cursor) {
drawGopher(canvas, gopher, win, ex, ey)
return true, 0
},
func(X *xgbutil.XUtil, rx, ry, ex, ey int) {
drawGopher(canvas, gopher, win, ex, ey)
},
func(X *xgbutil.XUtil, rx, ry, ex, ey int) {})
// Bind to the clear key specified, and just redraw the bg color.
keybind.KeyPressFun(
func(X *xgbutil.XUtil, ev xevent.KeyPressEvent) {
clearCanvas(canvas, win)
}).Connect(X, win.Id, clearKey, false)
// Bind a callback to each key specified in the 'pencils' color map.
// The response is to simply switch the pencil color.
for key, clr := range pencils {
c := clr
keybind.KeyPressFun(
func(X *xgbutil.XUtil, ev xevent.KeyPressEvent) {
log.Printf("Changing pencil color to: %#v", c)
pencil = c
}).Connect(X, win.Id, key, false)
}
// Output some basic directions.
fmt.Println("Use the left or right buttons on your mouse to paint " +
"squares and gophers.")
fmt.Println("Pressing numbers 1, 2, 3, 4, 5 or 6 will switch your pencil " +
"color.")
fmt.Println("Pressing 'c' will clear the canvas.")
xevent.Main(X)
}