src: fix CreateGC attributes encoding

- Every attribute must have 4 byte length.
- Add test.

lib/corereqs.js

@@ -70,7 +70,7 @@ var valueMask = {
     CreateGC: {
        'function'             : { // TODO: alias? _function?
           mask: 0x00000001,
-          format: 'C'
+          format: 'Cxxx'
         },
        planeMask              : {
           mask: 0x00000002,
@@ -86,27 +86,27 @@ var valueMask = {
         },
        lineWidth              : {
           mask: 0x00000010,
-          format: 'S'
+          format: 'Sxx'
         },
        lineStyle              : {
           mask: 0x00000020,
-          format: 'C'
+          format: 'Cxxx'
         },
        capStyle               : {
           mask: 0x00000040,
-          format: 'C'
+          format: 'Cxxx'
         },
        joinStyle              : {
           mask: 0x00000080,
-          format: 'C'
+          format: 'Cxxx'
         },
        fillStyle              : {
           mask: 0x00000100,
-          format: 'C'
+          format: 'Cxxx'
         },
        fillRule               : {
           mask: 0x00000200,
-          format: 'C'
+          format: 'Cxxx'
         },
        tile                   : {
           mask: 0x00000400,
@@ -118,11 +118,11 @@ var valueMask = {
         },
        tileStippleXOrigin     : {
           mask: 0x00001000,
-          format: 's'
+          format: 'sxx'
         },
        tileStippleYOrigin     : {
           mask: 0x00002000,
-          format: 's'
+          format: 'sxx'
         },
        font                   : {
           mask: 0x00004000,
@@ -130,19 +130,19 @@ var valueMask = {
         },
        subwindowMode          : {
           mask: 0x00008000,
-          format: 'C'
+          format: 'Cxxx'
         },
        graphicsExposures      : {
           mask: 0x00010000,
-          format: 'C'
+          format: 'Cxxx'
         },
        clipXOrigin            : {
           mask: 0x00020000,
-          format: 'S'
+          format: 'Sxx'
         },
        clipYOrigin            : {
           mask: 0x00040000,
-          format: 'S'
+          format: 'Sxx'
         },
        clipMask               : {
           mask: 0x00080000,
@@ -150,15 +150,15 @@ var valueMask = {
         },
        dashOffset             : {
           mask: 0x00100000,
-          format: 'S'
+          format: 'Sxx'
         },
        dashes                 : {
           mask: 0x00200000,
-          format: 'C'
+          format: 'Cxxx'
         },
        arcMode                : {
           mask: 0x00400000,
-          format: 'C'
+          format: 'Cxxx'
         }
     },
     ConfigureWindow: {

test/createGC.js

@@ -0,0 +1,46 @@
+var x11 = require('../lib');
+var should = require('should');
+
+describe('CreateGC', function() {
+    before(function(done) {
+        var self = this;
+        this.client = x11.createClient(function(err, dpy) {
+            should.not.exist(err);
+            self.X = dpy.client;
+            self.root = dpy.screen[0].root;
+            self.white = dpy.screen[0].white_pixel;
+            self.black = dpy.screen[0].black_pixel;
+            self.wid = self.X.AllocID();
+            self.X.CreateWindow(self.wid, self.root, 0, 0, 1, 1); // 1x1 pixel window
+            self.X.MapWindow(self.wid);
+            self.X.QueryTree(self.root, function(err, list) {
+                should.not.exist(err);
+                list.children.indexOf(self.wid).should.not.equal(-1);
+                done();
+            });
+        });
+    });
+
+    it('should create a Graphic Context correctly', function() {
+        var self = this;
+        this.client.on('error', function(err) {
+            should.not.exist(err);
+        });
+
+        this.gc = this.X.AllocID();
+        this.X.CreateGC(this.gc,
+                        this.wid,
+                        {
+                            foreground: this.black,
+                            background: this.white,
+                            lineStyle : 0
+                        }
+        );
+    });
+
+    after(function(done) {
+        this.X.DestroyWindow(this.wid);
+        this.X.on('end', done);
+        this.X.terminate();
+    });
+});