SvgImport: Implement onError() callback

Closes #969

src/core/PaperScript.js

@@ -525,10 +525,13 @@ Base.exports.PaperScript = (function() {
                 // same order the script tags appear.
                 // If the async attribute is specified on the script element,
                 // request the source asynchronously and execute as soon as
-                // it is retreived.
-                Http.request('get', src, function(code) {
-                    execute(code, scope, src);
-                }, async);
+                // it is retrieved.
+                Http.request({
+                    url: src, async: async,
+                    onLoad: function(code) {
+                        execute(code, scope, src);
+                    }
+                });
             } else {
                 // We can simply get the code form the script tag.
                 execute(script.innerHTML, scope, script.baseURI);

src/item/Item.js

@@ -2223,7 +2223,10 @@ new function() { // Injection scope for hit-test functions shared with project
      * @option options.onLoad {Function} the callback function to call once the
      *     SVG content is loaded from the given URL receiving two arguments: the
      *     converted `item` and the original `svg` data as a string. Only
-     *     required when loading from external files.
+     *     required when loading from external resources.
+     * @option options.onError {Function} the callback function to call if an
+     *     error occurs during loading. Only required when loading from external
+     *     resources.
      * @option [options.applyMatrix={@link PaperScope#settings}.applyMatrix]
      *     {Boolean} whether imported items should have their transformation
      *     matrices applied to their contents or not

src/item/Project.js

@@ -775,10 +775,13 @@ var Project = PaperScopeItem.extend(/** @lends Project# */{
      *
      * @option [options.expandShapes=false] {Boolean} whether imported shape
      *     items should be expanded to path items
-     * @option options.onLoad(item, svg) {Function} the callback function to
-     *     call once the SVG content is loaded from the given URL receiving two
-     *     arguments: the converted `item` and the original `svg` data as a
-     *     string. Only required when loading from external files.
+     * @option options.onLoad {Function} the callback function to call once the
+     *     SVG content is loaded from the given URL receiving two arguments: the
+     *     converted `item` and the original `svg` data as a string. Only
+     *     required when loading from external resources.
+     * @option options.onError {Function} the callback function to call if an
+     *     error occurs during loading. Only required when loading from external
+     *     resources.
      * @option [options.applyMatrix={@link PaperScope#settings}.applyMatrix]
      *     {Boolean} whether imported items should have their transformation
      *     matrices applied to their contents or not

src/net/Http.js

@@ -11,23 +11,32 @@
  */
 
 var Http = {
-    request: function(method, url, callback, async) {
+    request: function(options) {
         // Code borrowed from Coffee Script and extended:
-        async = (async === undefined) ? true : async;
         var ctor = window.ActiveXObject || window.XMLHttpRequest,
             xhr = new ctor('Microsoft.XMLHTTP');
-        xhr.open(method.toUpperCase(), url, async);
+        xhr.open((options.method || 'get').toUpperCase(), options.url,
+                Base.pick(options.async, true));
         if ('overrideMimeType' in xhr)
             xhr.overrideMimeType('text/plain');
-        xhr.onreadystatechange = function() {
-            if (xhr.readyState === 4) {
-                var status = xhr.status;
-                if (status === 0 || status === 200) {
-                    callback.call(xhr, xhr.responseText);
-                } else {
-                    throw new Error('Could not load ' + url + ' (Error '
-                            + status + ')');
+        xhr.onload = function() {
+            var status = xhr.status;
+            if (status === 0 || status === 200) {
+                if (options.onLoad) {
+                    options.onLoad.call(xhr, xhr.responseText);
                 }
+            } else {
+                xhr.onerror();
+            }
+        };
+        xhr.onerror = function() {
+            var status = xhr.status,
+                message = 'Could not load "' + options.url + '" (Status: '
+                        + status + ')';
+            if (options.onError) {
+                options.onError(message, status);
+            } else {
+                throw new Error(message);
             }
         };
         return xhr.send(null);

src/svg/SvgImport.js

@@ -635,7 +635,7 @@ new function() {
         return item;
     }
 
-    function importSVG(source, options, isRoot) {
+    function importSVG(source, options) {
         if (!source)
             return null;
         options = typeof options === 'function' ? { onLoad: options }
@@ -644,51 +644,65 @@ new function() {
             // Remember current scope so we can restore it in onLoad.
             scope = paper;
 
-        function onLoadCallback(svg) {
+        function onLoad(svg) {
             paper = scope;
-            var item = importSVG(svg, options, isRoot),
+            var item = importSVG(svg, options, true),
                 onLoad = options.onLoad;
             if (onLoad)
                 onLoad.call(this, item, svg);
         }
 
-        if (isRoot) {
-            // Have the group not pass on all transformations to its children,
-            // as this is how SVG works too.
-            // See if it's a string but handle markup separately
-            if (typeof source === 'string' && !/^.*</.test(source)) {
-                // First see if we're meant to import an element with the given
-                // id.
-                node = document.getElementById(source);
-                // Check if the string does not represent SVG data, in which
-                // case it must be the URL of a SVG to be loaded.
-                if (node) {
-                    source = null;
-                } else {
-                    return Http.request('get', source, onLoadCallback);
-                }
-            } else if (typeof File !== 'undefined' && source instanceof File) {
-                // Load local file through FileReader
-                var reader = new FileReader();
-                reader.onload = function() {
-                    onLoadCallback(reader.result);
-                };
-                return reader.readAsText(source);
+        function onError(message, status) {
+            var onError = options.onError;
+            if (onError) {
+                onError.call(this, message, status);
+            } else {
+                throw new Error(message);
             }
         }
+
+        // Have the group not pass on all transformations to its children,
+        // as this is how SVG works too.
+        // See if it's a string but handle markup separately
+        if (typeof source === 'string' && !/^.*</.test(source)) {
+            // First see if we're meant to import an element with the given
+            // id.
+            node = document.getElementById(source);
+            // Check if the string does not represent SVG data, in which
+            // case it must be the URL of a SVG to be loaded.
+            if (node) {
+                source = null;
+            } else {
+                Http.request({
+                    url: source, async: true,
+                    onLoad: onLoad, onError: onError
+                });
+            }
+        } else if (typeof File !== 'undefined' && source instanceof File) {
+            // Load local file through FileReader
+            var reader = new FileReader();
+            reader.onload = function() {
+                onLoad(reader.result);
+            };
+            reader.onerror = function() {
+                onError(reader.error);
+            };
+            return reader.readAsText(source);
+        }
+
         if (typeof source === 'string') {
             node = new window.DOMParser().parseFromString(source,
                     'image/svg+xml');
         }
         if (!node.nodeName)
             throw new Error('Unsupported SVG source: ' + source);
-        return importNode(node, options, isRoot);
+        return importNode(node, options, true);
     }
 
     // NOTE: Documentation is in Item#importSVG()
     Item.inject({
         importSVG: function(node, options) {
-            return this.addChild(importSVG(node, options, true));
+            return this.addChild(importSVG(node, options));
         }
     });
 
@@ -696,7 +710,7 @@ new function() {
     Project.inject({
         importSVG: function(node, options) {
             this.activate();
-            return importSVG(node, options, true);
+            return importSVG(node, options);
         }
     });
 };

test/tests/SvgImport.js

@@ -122,31 +122,18 @@ test('Import complex CompoundPath and clone', function() {
 
 function importSVG(assert, url, message, options) {
     var done = assert.async();
-    if (!message)
-        message = 'The imported SVG "' + url + '" should visually be the same '
-            + 'as the rasterized original SVG data.';
     project.importSVG(url, {
         onLoad: function(item, svg) {
-            function getValue(name) {
-                return parseFloat(svg.getAttribute(name));
+            if (!message) {
+                message = 'The imported SVG "' + url + '" should visually be '
+                    + 'the same as the rasterized original SVG data.';
             }
-            /*
-            var size = new Size(getValue('width'), getValue('height'));
-            var group = new Group({
-                children: [
-                    new Shape.Rectangle({
-                        clipMask: true,
-                        size: size
-                    }),
-                    item
-                ]
-            });
-            */
             compareSVG(done, item, svg, message, options);
         },
         onError: function(error) {
-            // TODO: Implement in SvgImport first!
-            pushFailure('Loading SVG from a valid URL should not give an error.');
+            var ok = !!(options && options.expectError);
+            QUnit.push(ok, false, !ok, ok && message
+                || 'Loading SVG from a valid URL should not give an error.');
             done();
         }
     });
@@ -164,4 +151,10 @@ if (!isNode) {
             importSVG(assert, 'assets/' + name);
         });
     });
+
+    test('Import inexistent file', function(assert) {
+        importSVG(assert, 'assets/inexistent.svg',
+            'Load an inexistent SVG file should trigger an error',
+            { expectError: true });
+    });
 }