Add unloading capability to the image loader

src/components/images/imageFetcher.js

@@ -2,28 +2,36 @@ define(['dom'], function (dom) {
     'use strict';
 
     function loadImage(elem, url) {
-
         if (!elem) {
             return Promise.reject('elem cannot be null');
         }
 
         if (elem.tagName !== "IMG") {
-
             elem.style.backgroundImage = "url('" + url + "')";
             return Promise.resolve();
-
-            //return loadImageIntoImg(document.createElement('img'), url).then(function () {
-            //    elem.style.backgroundImage = "url('" + url + "')";
-            //    return Promise.resolve();
-            //});
-
         }
         return loadImageIntoImg(elem, url);
     }
 
+    function unloadImage(elem) {
+        if (!elem) {
+            return Promise.reject('elem cannot be null');
+        }
+
+        var url;
+        if (elem.tagName !== "IMG") {
+            url = elem.style.backgroundImage.slice(4, -1).replace(/"/g, "");
+            elem.style.backgroundImage = 'none';
+        } else {
+            url = elem.getAttribute("src");
+            elem.setAttribute("src", "");
+        }
+
+        return Promise.resolve(url);
+    }
+
     function loadImageIntoImg(elem, url) {
         return new Promise(function (resolve, reject) {
-
             dom.addEventListener(elem, 'load', resolve, {
                 once: true
             });
@@ -32,7 +40,8 @@ define(['dom'], function (dom) {
     }
 
     return {
-        loadImage: loadImage
+        loadImage: loadImage,
+        unloadImage: unloadImage
     };
 
 });

src/components/images/imageLoader.js

@@ -3,40 +3,36 @@ define(['lazyLoader', 'imageFetcher', 'layoutManager', 'browser', 'appSettings',
 
     var self = {};
 
-    function fillImage(elem, source, enableEffects) {
-
-        if (!elem) {
-            throw new Error('elem cannot be null');
+    function fillImage(entry) {
+        if (!entry) {
+            throw new Error('entry cannot be null');
         }
 
-        if (!source) {
-            source = elem.getAttribute('data-src');
+        var source = entry.target.getAttribute('data-src');
+
+        if (entry.intersectionRatio > 0 && source) {
+            fillImageElement(entry.target, source);
+        } else if (!source) {
+            emptyImageElement(entry.target);
+        }
     }
 
-        if (!source) {
-            return;
-        }
-
-        fillImageElement(elem, source, enableEffects);
-    }
-
-    function fillImageElement(elem, source, enableEffects) {
+    function fillImageElement(elem, source) {
         imageFetcher.loadImage(elem, source).then(function () {
-
-            if (enableEffects !== false) {
-                fadeIn(elem);
+            if (userSettings.enableFastFadein()) {
+                elem.classList.add('lazy-image-fadein-fast');
+            } else {
+                elem.classList.add('lazy-image-fadein');
             }
 
             elem.removeAttribute("data-src");
         });
     }
 
-    function fadeIn(elem) {
-        if (userSettings.enableFastFadein()) {
-            elem.classList.add('lazy-image-fadein-fast');
-        } else {
-            elem.classList.add('lazy-image-fadein');
-        }
+    function emptyImageElement(elem) {
+        imageFetcher.unloadImage(elem).then(function (url) {
+            elem.setAttribute("data-src", url);
+        });
     }
 
     function lazyChildren(elem) {

src/components/lazyloader/lazyloader-intersectionobserver.js

@@ -11,42 +11,15 @@ define(['require', 'browser'], function (require, browser) {
     }
 
     LazyLoader.prototype.createObserver = function () {
+        var callback = this.options.callback;
 
-        var observerOptions = {};
-        var options = this.options;
-        var loadedCount = 0;
-        var callback = options.callback;
-
-        observerOptions.rootMargin = "50%";
-
-        var observerId = 'obs' + new Date().getTime();
-
-        var self = this;
-        var observer = new IntersectionObserver(function (entries) {
-            for (var j = 0, length2 = entries.length; j < length2; j++) {
-                var entry = entries[j];
-
-                if (entry.intersectionRatio > 0) {
-
-                    // Stop watching and load the image
-                    var target = entry.target;
-
-                    observer.unobserve(target);
-
-                    if (!target[observerId]) {
-                        target[observerId] = 1;
-                        callback(target);
-                        loadedCount++;
-
-                        if (loadedCount >= self.elementCount) {
-                            self.destroyObserver();
-                        }
-                    }
-                }
-            }
+        var observer = new IntersectionObserver(
+            (entries, observer) => {
+                entries.forEach(entry => {
+                    callback(entry);
                 },
-        observerOptions
-        );
+                {rootMargin: "50%"});
+            });
 
         this.observer = observer;
     };

src/components/lazyloader/lazyloader-scroll.js

@@ -1,185 +0,0 @@
-define(['visibleinviewport', 'dom', 'browser'], function (visibleinviewport, dom, browser) {
-    'use strict';
-
-    var thresholdX;
-    var thresholdY;
-
-    function resetThresholds() {
-
-        var threshold = 0.3;
-
-        thresholdX = screen.availWidth * threshold;
-        thresholdY = screen.availHeight * threshold;
-    }
-
-    function resetThresholdsOnTimer() {
-
-        setTimeout(resetThresholds, 500);
-    }
-
-    if (browser.iOS) {
-        dom.addEventListener(window, "orientationchange", resetThresholdsOnTimer, { passive: true });
-        dom.addEventListener(window, 'resize', resetThresholdsOnTimer, { passive: true });
-    } else {
-        dom.addEventListener(window, "orientationchange", resetThresholds, { passive: true });
-        dom.addEventListener(window, 'resize', resetThresholds, { passive: true });
-    }
-    resetThresholds();
-
-    function isVisible(elem) {
-        return visibleinviewport(elem, true, thresholdX, thresholdY);
-    }
-
-    var wheelEvent = (document.implementation.hasFeature('Event.wheel', '3.0') ? 'wheel' : 'mousewheel');
-    var self = {};
-
-    function cancelAll(tokens) {
-        for (var i = 0, length = tokens.length; i < length; i++) {
-
-            tokens[i] = true;
-        }
-    }
-
-    function unveilElementsInternal(instance, callback) {
-
-        var unveiledElements = [];
-        var cancellationTokens = [];
-        var loadedCount = 0;
-
-        function unveilInternal(tokenIndex) {
-
-            var anyFound = false;
-            var out = false;
-
-            var elements = instance.elements;
-            // TODO: This out construct assumes left to right, top to bottom
-
-            for (var i = 0, length = elements.length; i < length; i++) {
-
-                if (cancellationTokens[tokenIndex]) {
-                    return;
-                }
-                if (unveiledElements[i]) {
-                    continue;
-                }
-                var elem = elements[i];
-                if (!out && isVisible(elem)) {
-                    anyFound = true;
-                    unveiledElements[i] = true;
-                    callback(elem);
-                    loadedCount++;
-                } else {
-
-                    if (anyFound) {
-                        out = true;
-                    }
-                }
-            }
-
-            if (loadedCount >= elements.length) {
-                dom.removeEventListener(document, 'focus', unveil, {
-                    capture: true,
-                    passive: true
-                });
-                dom.removeEventListener(document, 'scroll', unveil, {
-                    capture: true,
-                    passive: true
-                });
-                dom.removeEventListener(document, wheelEvent, unveil, {
-                    capture: true,
-                    passive: true
-                });
-                dom.removeEventListener(window, 'resize', unveil, {
-                    capture: true,
-                    passive: true
-                });
-            }
-        }
-
-        function unveil() {
-
-            cancelAll(cancellationTokens);
-
-            var index = cancellationTokens.length;
-            cancellationTokens.length++;
-
-            setTimeout(function () {
-                unveilInternal(index);
-            }, 1);
-        }
-
-        dom.addEventListener(document, 'focus', unveil, {
-            capture: true,
-            passive: true
-        });
-        dom.addEventListener(document, 'scroll', unveil, {
-            capture: true,
-            passive: true
-        });
-        dom.addEventListener(document, wheelEvent, unveil, {
-            capture: true,
-            passive: true
-        });
-        dom.addEventListener(window, 'resize', unveil, {
-            capture: true,
-            passive: true
-        });
-
-        unveil();
-    }
-
-    function LazyLoader(options) {
-
-        this.options = options;
-    }
-
-    LazyLoader.prototype.createObserver = function () {
-
-        unveilElementsInternal(this, this.options.callback);
-        this.observer = 1;
-    };
-
-    LazyLoader.prototype.addElements = function (elements) {
-
-        this.elements = this.elements || [];
-
-        for (var i = 0, length = elements.length; i < length; i++) {
-            this.elements.push(elements[i]);
-        }
-
-        var observer = this.observer;
-
-        if (!observer) {
-            this.createObserver();
-        }
-
-    };
-
-    LazyLoader.prototype.destroyObserver = function (elements) {
-
-    };
-
-    LazyLoader.prototype.destroy = function (elements) {
-
-        this.destroyObserver();
-        this.options = null;
-    };
-
-    function unveilElements(elements, root, callback) {
-
-        if (!elements.length) {
-            return;
-        }
-        var lazyLoader = new LazyLoader({
-            callback: callback
-        });
-        lazyLoader.addElements(elements);
-    }
-
-    LazyLoader.lazyChildren = function (elem, callback) {
-
-        unveilElements(elem.getElementsByClassName('lazy'), elem, callback);
-    };
-
-    return LazyLoader;
-});

src/controllers/movies/moviegenres.js

@@ -50,7 +50,8 @@ define(["layoutManager", "loading", "libraryBrowser", "cardBuilder", "lazyLoader
             return enableScrollX() ? "overflowPortrait" : "portrait";
         }
 
-        function fillItemsContainer(elem) {
+        function fillItemsContainer(entry) {
+            var elem = entry.target;
             var id = elem.getAttribute("data-id");
             var viewStyle = self.getCurrentViewStyle();
             var limit = "Thumb" == viewStyle || "ThumbCard" == viewStyle ? 5 : 9;

src/controllers/shows/tvgenres.js

@@ -50,7 +50,8 @@ define(["layoutManager", "loading", "libraryBrowser", "cardBuilder", "lazyLoader
             return enableScrollX() ? "overflowPortrait" : "portrait";
         }
 
-        function fillItemsContainer(elem) {
+        function fillItemsContainer(entry) {
+            var elem = entry.target;
             var id = elem.getAttribute("data-id");
             var viewStyle = self.getCurrentViewStyle();
             var limit = "Thumb" == viewStyle || "ThumbCard" == viewStyle ? 5 : 9;

src/scripts/site.js

@@ -379,12 +379,7 @@ var AppInfo = {};
 
         define("filesystem", [componentsPath + "/filesystem"], returnFirstDependency);
 
-        if (window.IntersectionObserver && !browser.edge) {
         define("lazyLoader", [componentsPath + "/lazyloader/lazyloader-intersectionobserver"], returnFirstDependency);
-        } else {
-            define("lazyLoader", [componentsPath + "/lazyloader/lazyloader-scroll"], returnFirstDependency);
-        }
-
         define("shell", [componentsPath + "/shell"], returnFirstDependency);
 
         define("apiclient", [bowerPath + "/apiclient/apiclient"], returnFirstDependency);