A first stab at porting the XCB X11 protocol bindings to go.

The python script needs a checkout of xcb/proto to generate
an xproto.go file, which together with xgb.go provide functions
to access all of the core X11 protocol requests. I have included the
generated file.

Extensions and authentication methods are not implemented.

R=r, rsc, nigeltao_golang
https://golang.org/cl/162053

src/pkg/Makefile

@@ -99,6 +99,7 @@ DIRS=\
 	unicode\
 	utf8\
 	websocket\
+	xgb\
 	xml\
 
 NOTEST=\
@@ -113,6 +114,7 @@ NOTEST=\
 	runtime\
 	syscall\
 	testing/iotest\
+	xgb\
 
 TEST=\
 	$(filter-out $(NOTEST),$(DIRS))

src/pkg/xgb/Makefile

+# Copyright 2009 The Go Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+include ../../Make.$(GOARCH)
+
+TARG=xgb
+GOFILES=\
+	xgb.go\
+	xproto.go\
+
+include ../../Make.pkg
+
+xproto: proto/src/xproto.xml
+	python go_client.py -p proto/ proto/src/xproto.xml
+	gofmt -w xproto.go
+
+proto/src/xproto.xml:
+	git clone git://anongit.freedesktop.org/git/xcb/proto
+

src/pkg/xgb/example.go

+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"fmt";
+	"os";
+	"xgb";
+)
+
+func main() {
+	c, err := xgb.Dial(os.Getenv("DISPLAY"));
+	if err != nil {
+		fmt.Printf("cannot connect: %v\n", err);
+		os.Exit(1);
+	}
+
+	fmt.Printf("vendor = '%s'\n", string(c.Setup.Vendor));
+
+	win := c.NewId();
+	gc := c.NewId();
+
+	c.CreateWindow(0, win, c.DefaultScreen().Root, 150, 150, 200, 200, 0, 0, 0, 0, nil);
+	c.ChangeWindowAttributes(win, xgb.CWEventMask,
+		[]uint32{xgb.EventMaskExposure | xgb.EventMaskKeyRelease});
+	c.CreateGC(gc, win, 0, nil);
+	c.MapWindow(win);
+
+	atom, _ := c.InternAtom(0, "HELLO");
+	fmt.Printf("atom = %d\n", atom.Atom);
+
+	points := make([]xgb.Point, 2);
+	points[1] = xgb.Point{5, 5};
+	points[1] = xgb.Point{100, 120};
+
+	hosts, _ := c.ListHosts();
+	fmt.Printf("hosts = %+v\n", hosts);
+
+	ecookie := c.ListExtensionsRequest();
+	exts, _ := c.ListExtensionsReply(ecookie);
+	for _, name := range exts.Names {
+		fmt.Printf("exts = '%s'\n", name.Name)
+	}
+
+	for {
+		reply, err := c.WaitForEvent();
+		if err != nil {
+			fmt.Printf("error: %v\n", err);
+			os.Exit(1);
+		}
+		fmt.Printf("event %T\n", reply);
+		switch event := reply.(type) {
+		case xgb.ExposeEvent:
+			c.PolyLine(xgb.CoordModeOrigin, win, gc, points)
+		case xgb.KeyReleaseEvent:
+			fmt.Printf("key release!\n");
+			points[0].X = event.EventX;
+			points[0].Y = event.EventY;
+			c.PolyLine(xgb.CoordModeOrigin, win, gc, points);
+			c.Bell(75);
+		}
+	}
+
+	c.Close();
+}