GUAC-1305: Add guacImage service for determining supported image formats.

2025-10-31 09:03:21 +00:00 · 2015-09-20 17:05:55 -07:00
parent e1003b56ba
commit 8e15aa94db
1 changed files with 115 additions and 0 deletions
--- a/guacamole/src/main/webapp/app/client/services/guacImage.js
+++ b/guacamole/src/main/webapp/app/client/services/guacImage.js
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) 2015 Glyptodon LLC
+ *
+ * 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 above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * 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.
+ */
+
+/**
+ * A service for checking browser image support.
+ */
+angular.module('client').factory('guacImage', ['$injector', function guacImage($injector) {
+
+    // Required services
+    var $q = $injector.get('$q');
+
+    var service = {};
+
+    /**
+     * Map of possibly-supported image mimetypes to corresponding test images
+     * encoded with base64. If the image is correctly decoded, it will be a
+     * single pixel (1x1) image.
+     *
+     * @type Object.<String, String>
+     */
+    var testImages = {
+
+        /**
+         * Test JPEG image, encoded as base64.
+         */
+        'image/jpeg' :
+            '/9j/4AAQSkZJRgABAQEASABIAAD/2wBDAAMCAgMCAgMDAwMEAwMEBQgFBQQEBQoH'
+          + 'BwYIDAoMDAsKCwsNDhIQDQ4RDgsLEBYQERMUFRUVDA8XGBYUGBIUFRT/2wBDAQME'
+          + 'BAUEBQkFBQkUDQsNFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQU'
+          + 'FBQUFBQUFBQUFBQUFBT/wAARCAABAAEDAREAAhEBAxEB/8QAFAABAAAAAAAAAAA'
+          + 'AAAAAAAAACf/EABQQAQAAAAAAAAAAAAAAAAAAAAD/xAAUAQEAAAAAAAAAAAAAAA'
+          + 'AAAAAA/8QAFBEBAAAAAAAAAAAAAAAAAAAAAP/aAAwDAQACEQMRAD8AVMH/2Q==',
+
+        /**
+         * Test PNG image, encoded as base64.
+         */
+        'image/png' :
+            'iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEX///+nxBvI'
+          + 'AAAACklEQVQI12NgAAAAAgAB4iG8MwAAAABJRU5ErkJggg=='
+
+    };
+
+    /**
+     * Return a promise which resolves with to an array of image mimetypes
+     * supported by the browser, once those mimetypes are known. The returned
+     * promise is guaranteed to resolve successfully.
+     *
+     * @returns {Promise.<String[]>}
+     *     A promise which resolves with an array of image mimetypes supported
+     *     by the browser.
+     */
+    service.getSupportedMimetypes = function getSupportedMimetypes() {
+
+        var deferred = $q.defer();
+
+        var supported = [];
+        var pendingTests = [];
+
+        // Test each possibly-supported image
+        angular.forEach(testImages, function testImageSupport(data, mimetype) {
+
+            // Add promise for current image test
+            var imageTest = $q.defer();
+            pendingTests.push(imageTest.promise);
+
+            // Attempt to load image
+            var image = new Image();
+            image.src = 'data:' + mimetype + ';base64,' + data;
+
+            // Store as supported depending on whether load was successful
+            image.onload = image.onerror = function imageTestComplete() {
+
+                // Image format is supported if successfully decoded
+                if (image.width === 1 && image.height === 1)
+                    supported.push(mimetype);
+
+                // Test is complete
+                imageTest.resolve();
+
+            };
+
+        });
+
+        // When all image tests are complete, resolve promise with list of
+        // supported formats
+        $q.all(pendingTests).then(function imageTestsCompleted() {
+            deferred.resolve(supported);
+        });
+
+        return deferred.promise;
+
+    };
+
+    return service;
+
+}]);