mirror of
https://github.com/nasa/openmct.git
synced 2025-02-19 00:51:39 +00:00
90 lines
3.6 KiB
JavaScript
90 lines
3.6 KiB
JavaScript
/*****************************************************************************
|
|
* Open MCT Web, Copyright (c) 2014-2015, United States Government
|
|
* as represented by the Administrator of the National Aeronautics and Space
|
|
* Administration. All rights reserved.
|
|
*
|
|
* Open MCT Web is licensed under the Apache License, Version 2.0 (the
|
|
* "License"); you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
* http://www.apache.org/licenses/LICENSE-2.0.
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
* License for the specific language governing permissions and limitations
|
|
* under the License.
|
|
*
|
|
* Open MCT Web includes source code licensed under additional open source
|
|
* licenses. See the Open Source Licenses file (LICENSES.md) included with
|
|
* this source code distribution or the Licensing information page available
|
|
* at runtime from the About dialog for additional information.
|
|
*****************************************************************************/
|
|
/*global define*/
|
|
|
|
define(
|
|
function () {
|
|
"use strict";
|
|
|
|
/**
|
|
* Defines the `mct-background-image` directive.
|
|
*
|
|
* Used as an attribute, this will set the `background-image`
|
|
* property to the URL given in its value, but only after that
|
|
* image has loaded; this avoids "flashing" as images change.
|
|
*
|
|
* If `src` is falsy, no image will be displayed (immediately.)
|
|
*
|
|
*/
|
|
function MCTBackgroundImage($document) {
|
|
function link(scope, element, attrs) {
|
|
// General strategy here:
|
|
// - Keep count of how many images have been requested; this
|
|
// counter will be used as an internal identifier or sorts
|
|
// for each image that loads.
|
|
// - As the src attribute changes, begin loading those images.
|
|
// - When images do load, update the background-image property
|
|
// of the element, but only if a more recently
|
|
// requested image has not already been loaded.
|
|
// The order in which URLs are passed in and the order
|
|
// in which images are actually loaded may be different, so
|
|
// some strategy like this is necessary to ensure that images
|
|
// do not display out-of-order.
|
|
var div, requested = 0, loaded = 0;
|
|
|
|
function nextImage(url) {
|
|
var myCounter = requested,
|
|
image;
|
|
|
|
function useImage() {
|
|
if (loaded <= myCounter) {
|
|
loaded = myCounter;
|
|
element.css('background-image', "url('" + url + "')");
|
|
}
|
|
}
|
|
|
|
if (!url) {
|
|
loaded = myCounter;
|
|
element.css('background-image', 'none');
|
|
} else {
|
|
image = $document[0].createElement('img');
|
|
image.src = url;
|
|
image.onload = useImage;
|
|
}
|
|
|
|
requested += 1;
|
|
}
|
|
|
|
scope.$watch('mctBackgroundImage', nextImage);
|
|
}
|
|
|
|
return {
|
|
restrict: "A",
|
|
scope: { mctBackgroundImage: "=" },
|
|
link: link
|
|
};
|
|
}
|
|
|
|
return MCTBackgroundImage;
|
|
}
|
|
);
|