closes #150 - added Casper.captureBase64()

@@ -17,6 +17,7 @@ XXXX-XX-XX, v1.0
 - added [`Casper.userAgent()`](http://casperjs.org/api.html#casper.userAgent) to ease a more dynamic setting of user-agent string
 - added [`Tester.assertTitleMatch()`](http://casperjs.org/api.html#tester.assertTitleMatch) method
 - added [`utils.getPropertyPath()`](http://casperjs.org/api.html#utils.getPropertyPath)
+- added [`Casper.captureBase64()`](http://casperjs.org/api.html#casper.captureBase64) for rendering screen captures as base64 strings - closes [#150](https://github.com/n1k0/casperjs/issues/150)
 - added [`Casper.reload()`](http://casperjs.org/api.html#casper.reload)
 - added experimental support of custom headers sending in outgoing request (refs [#137](https://github.com/n1k0/casperjs/issues/137) - PhantomJS 1.6 required)
 - switched to more standard `.textContent` property to get a node text; this allows a better compatibility of the clientutils bookmarklet with non-webkit browsers

@@ -246,7 +246,47 @@ Casper.prototype.capture = function capture(targetFile, clipRect) {
 };
 
 /**
- * Captures the page area containing the provided selector.
+ * Returns a Base64 representation of a binary image capture of the current
+ * page, or an area within the page, in a given format.
+ *
+ * Supported image formats are `bmp`, `jpg`, `jpeg`, `png`, `ppm`, `tiff`,
+ * `xbm` and `xpm`.
+ *
+ * @param  String                   format    The image format
+ * @param  String|Object|undefined  selector  CSS3 selector or clipRect object (optional)
+ * @return Casper
+ */
+Casper.prototype.captureBase64 = function captureBase64(format, area) {
+    "use strict";
+    var base64;
+    var previousClipRect;
+    var formats = ['bmp', 'jpg', 'jpeg', 'png', 'ppm', 'tiff', 'xbm', 'xpm'];
+    if (formats.indexOf(format.toLowerCase()) === -1) {
+        throw new CasperError(f('Unsupported format "%s"', format));
+    }
+    if (utils.isClipRect(area)) {
+        // if area is a clipRect object
+        this.log(f("Capturing base64 %s representation of %s", format, utils.serialize(area)), "debug");
+        previousClipRect = this.page.clipRect;
+        this.page.clipRect = area;
+        base64 = this.page.renderBase64(format);
+    } else if (utils.isValidSelector(area)) {
+        // if area is a selector string or object
+        this.log(f("Capturing base64 %s representation of %s", format, area), "debug");
+        base64 = this.captureBase64(format, this.getElementBounds(area));
+    } else {
+        // whole page capture
+        this.log(f("Capturing base64 %s representation of page", format), "debug");
+        base64 = this.page.renderBase64(format);
+    }
+    if (previousClipRect) {
+        this.page.clipRect = previousClipRect;
+    }
+    return base64;
+};
+
+/**
+ * Captures the page area matching the provided selector.
  *
  * @param  String  targetFile  Target destination file path.
  * @param  String  selector    CSS3 selector

@@ -57,7 +57,7 @@
      * @param  Mixed  value
      */
     function dump(value) {
-        console.log(serialize(value));
+        console.log(serialize(value, 4));
     }
     exports.dump = dump;
 
@@ -304,6 +304,39 @@
     exports.isUndefined = isUndefined;
 
     /**
+     * Checks if value is a valid selector Object.
+     *
+     * @param  mixed  value
+     * @return Boolean
+     */
+    function isValidSelector(value) {
+        if (isString(value)) {
+            try {
+                // phantomjs env has a working document object, let's use it
+                document.querySelector(value);
+            } catch(e) {
+                if ('name' in e && e.name === 'SYNTAX_ERR') {
+                    return false;
+                }
+            }
+            return true;
+        } else if (isObject(value)) {
+            if (!value.hasOwnProperty('type')) {
+                return false;
+            }
+            if (!value.hasOwnProperty('path')) {
+                return false;
+            }
+            if (['css', 'xpath'].indexOf(value.type) === -1) {
+                return false;
+            }
+            return true;
+        }
+        return false;
+    }
+    exports.isValidSelector = isValidSelector;
+
+    /**
      * Checks if the provided var is a WebPage instance
      *
      * @param  mixed  what
@@ -362,13 +395,13 @@
      * @param  Mixed  value
      * @return String
      */
-    function serialize(value) {
+    function serialize(value, indent) {
         if (isArray(value)) {
             value = value.map(function _map(prop) {
                 return isFunction(prop) ? prop.toString().replace(/\s{2,}/, '') : prop;
             });
         }
-        return JSON.stringify(value, null, 4);
+        return JSON.stringify(value, null, indent);
     }
     exports.serialize = serialize;
 

@@ -4,17 +4,26 @@ if (fs.exists(testFile) && fs.isFile(testFile)) {
     fs.remove(testFile);
 }
 
-casper.start('tests/site/index.html', function(self) {
-    self.viewport(300, 200);
+casper.start('tests/site/index.html', function() {
+    this.viewport(300, 200);
     this.test.comment('Casper.capture()');
-    self.capture(testFile);
+    this.capture(testFile);
     this.test.assert(fs.isFile(testFile), 'Casper.capture() captured a screenshot');
 });
 
-try {
-    fs.remove(testFile);
-} catch(e) {}
+casper.thenOpen('tests/site/index.html', function() {
+    this.test.comment('Casper.captureBase64()');
+    this.test.assert(this.captureBase64('png').length > 0,
+                     'Casper.captureBase64() rendered a page capture as base64');
+    this.test.assert(this.captureBase64('png', 'ul').length > 0,
+                     'Casper.captureBase64() rendered a capture from a selector as base64');
+    this.test.assert(this.captureBase64('png', {top: 0, left: 0, width: 30, height: 30}).length > 0,
+                     'Casper.captureBase64() rendered a capture from a clipRect as base64');
+});
 
-casper.run(function(self) {
+casper.run(function() {
+    try {
+        fs.remove(testFile);
+    } catch(e) {}
     this.test.done();
 });

-var utils = require('utils'), t = casper.test;
+var utils = require('utils'), t = casper.test, x = require('casper').selectXPath;
 
 t.comment('fileExt()');
 (function() {
@@ -100,6 +100,33 @@ t.comment('isObject()');
     t.assertEquals(utils.isObject(null), false, 'isObject() checks for an Object');
 })();
 
+t.comment('isValidSelector()');
+(function() {
+    t.assertEquals(utils.isValidSelector({}), false, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector(""), false, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector("a"), true, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector('div#plop form[name="form"] input[type="submit"]'), true, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector(x('//a')), true, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector({
+        type: "css",
+        path: 'div#plop form[name="form"] input[type="submit"]'
+    }), true, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector({
+        type: "xpath",
+        path: '//a'
+    }), true, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector({
+        type: "css"
+    }), false, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector({
+        type: "xpath"
+    }), false, 'isValidSelector() checks for a valid selector');
+    t.assertEquals(utils.isValidSelector({
+        type: "css3",
+        path: "a"
+    }), false, 'isValidSelector() checks for a valid selector');
+})();
+
 t.comment('isWebPage()');
 (function() {
     var pageModule = require('webpage');