Source code in the go programming language

package main

// Copyright (c) 2013 Alex Kesling
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

import (
    "log"
    "github.com/jezek/xgb"
    "github.com/jezek/xgb/xproto"
)

func main() {
    // Open the connection to the X server
    X, err := xgb.NewConn()
    if err != nil {
        log.Fatal(err)
    }

    // geometric objects
    points := []xproto.Point{
        {10, 10},
        {10, 20},
        {20, 10},
        {20, 20}};

    polyline := []xproto.Point{
        {50, 10},
        { 5, 20},     // rest of points are relative
        {25,-20},
        {10, 10}};

    segments := []xproto.Segment{
        {100, 10, 140, 30},
        {110, 25, 130, 60}};

    rectangles := []xproto.Rectangle{
        { 10, 50, 40, 20},
        { 80, 50, 10, 40}};

    arcs := []xproto.Arc{
        {10, 100, 60, 40, 0, 90 << 6},
        {90, 100, 55, 40, 0, 270 << 6}};

    setup := xproto.Setup(X)
    // Get the first screen
    screen := setup.DefaultScreen(X)

    // Create black (foreground) graphic context
    foreground, _ := xproto.NewGcontextId(X)
    mask := uint32(xproto.GcForeground | xproto.GcGraphicsExposures)
    values := []uint32{screen.BlackPixel, 0}
    xproto.CreateGC(X, foreground, xproto.Drawable(screen.Root), mask, values)

    // Ask for our window's Id
    win, _ := xproto.NewWindowId(X)
    winDrawable := xproto.Drawable(win)

    // Create the window
    mask = uint32(xproto.CwBackPixel | xproto.CwEventMask)
    values = []uint32{screen.WhitePixel, xproto.EventMaskExposure}
    xproto.CreateWindow(X,                  // Connection
            screen.RootDepth,               // Depth
            win,                            // Window Id
            screen.Root,                    // Parent Window
            0, 0,                           // x, y
            150, 150,                       // width, height
            10,                             // border_width
            xproto.WindowClassInputOutput,  // class
            screen.RootVisual,              // visual
            mask, values)                   // masks

    // Map the window on the screen
    xproto.MapWindow(X, win)

    for {
        evt, err := X.WaitForEvent()
        switch evt.(type) {
            case xproto.ExposeEvent:
                /* We draw the points */
                xproto.PolyPoint(X, xproto.CoordModeOrigin, winDrawable, foreground, points)

                /* We draw the polygonal line */
                xproto.PolyLine(X, xproto.CoordModePrevious, winDrawable, foreground, polyline)

                /* We draw the segments */
                xproto.PolySegment(X, winDrawable, foreground, segments)

                /* We draw the rectangles */
                xproto.PolyRectangle(X, winDrawable, foreground, rectangles)

                /* We draw the arcs */
                xproto.PolyArc(X, winDrawable, foreground, arcs)

            default:
                /* Unknown event type, ignore it */
        }

        if err != nil {
            log.Fatal(err)
        }
    }
    return
}