https://yazdfarda.com/static/js/jquery.lazyload.js

1/*
2 * Lazy Load - jQuery plugin for lazy loading images
3 *
4 * Copyright (c) 2007-2012 Mika Tuupola
5 *
6 * Licensed under the MIT license:
7 *   http://www.opensource.org/licenses/mit-license.php
8 *
9 * Project home:
10 *   http://www.appelsiini.net/projects/lazyload
11 *
12 * Version:  1.7.2
13 *
14 */
15(function($, window) {
16
17    $window = $(window);
18
19    $.fn.lazyload = function(options) {
20        var elements = this;
21        var settings = {
22            threshold       : 0,
23            failure_limit   : 0,
24            event           : "scroll",
25            effect          : "show",
26            container       : window,
27            data_attribute  : "original",
28            skip_invisible  : true,
29            appear          : null,
30            load            : null
31        };
32
33        function update() {
34            var counter = 0;
35      
36            elements.each(function() {
37                var $this = $(this);
38                if (settings.skip_invisible && !$this.is(":visible")) {
39                    return;
40                }
41                if ($.abovethetop(this, settings) ||
42                    $.leftofbegin(this, settings)) {
43                        /* Nothing. */
44                } else if (!$.belowthefold(this, settings) &&
45                    !$.rightoffold(this, settings)) {
46                        $this.trigger("appear");
47                } else {
48                    if (++counter > settings.failure_limit) {
49                        return false;
50                    }
51                }
52            });
53
54        }
55
56        if(options) {
57            /* Maintain BC for a couple of versions. */
58            if (undefined !== options.failurelimit) {
59                options.failure_limit = options.failurelimit; 
60                delete options.failurelimit;
61            }
62            if (undefined !== options.effectspeed) {
63                options.effect_speed = options.effectspeed; 
64                delete options.effectspeed;
65            }
66
67            $.extend(settings, options);
68        }
69
70        /* Cache container as jQuery as object. */
71        $container = (settings.container === undefined ||
72                      settings.container === window) ? $window : $(settings.container);
73
74        /* Fire one scroll event per scroll. Not one scroll event per image. */
75        if (0 === settings.event.indexOf("scroll")) {
76            $container.bind(settings.event, function(event) {
77                return update();
78            });
79        }
80
81        this.each(function() {
82            var self = this;
83            var $self = $(self);
84
85            self.loaded = false;
86
87            /* When appear is triggered load original image. */
88            $self.one("appear", function() {
89                if (!this.loaded) {
90                    if (settings.appear) {
91                        var elements_left = elements.length;
92                        settings.appear.call(self, elements_left, settings);
93                    }
94                    $("<img />")
95                        .bind("load", function() {
96                            $self
97                                .hide()
98                                .attr("src", $self.data(settings.data_attribute))
99                                [settings.effect](settings.effect_speed);
100                            self.loaded = true;
101
102                            /* Remove image from array so it is not looped next time. */
103                            var temp = $.grep(elements, function(element) {
104                                return !element.loaded;
105                            });
106                            elements = $(temp);
107
108                            if (settings.load) {
109                                var elements_left = elements.length;
110                                settings.load.call(self, elements_left, settings);
111                            }
112                        })
113                        .attr("src", $self.data(settings.data_attribute));
114                }
115            });
116
117            /* When wanted event is triggered load original image */
118            /* by triggering appear.                              */
119            if (0 !== settings.event.indexOf("scroll")) {
120                $self.bind(settings.event, function(event) {
121                    if (!self.loaded) {
122                        $self.trigger("appear");
123                    }
124                });
125            }
126        });
127
128        /* Check if something appears when window is resized. */
129        $window.bind("resize", function(event) {
130            update();
131        });
132
133        /* Force initial check if images should appear. */
134        update();
135        
136        return this;
137    };
138
139    /* Convenience methods in jQuery namespace.           */
140    /* Use as  $.belowthefold(element, {threshold : 100, container : window}

140) */
141
142    $.belowthefold = function(element, settings) {
143        var fold;
144        
145        if (settings.container === undefined || settings.container === window) {
146            fold = $window.height() + $window.scrollTop();
147        } else {
148            fold = $container.offset().top + $container.height();
149        }
150
151        return fold <= $(element).offset().top - settings.threshold;
152    };
153    
154    $.rightoffold = function(element, settings) {
155        var fold;
156
157        if (settings.container === undefined || settings.container === window) {
158            fold = $window.width() + $window.scrollLeft();
159        } else {
160            fold = $container.offset().left + $container.width();
161        }
162
163        return fold <= $(element).offset().left - settings.threshold;
164    };
165        
166    $.abovethetop = function(element, settings) {
167        var fold;
168        
169        if (settings.container === undefined || settings.container === window) {
170            fold = $window.scrollTop();
171        } else {
172            fold = $container.offset().top;
173        }
174
175        return fold >= $(element).offset().top + settings.threshold  + $(element).height();
176    };
177    
178    $.leftofbegin = function(element, settings) {
179        var fold;
180        
181        if (settings.container === undefined || settings.container === window) {
182            fold = $window.scrollLeft();
183        } else {
184            fold = $container.offset().left;
185        }
186
187        return fold >= $(element).offset().left + settings.threshold + $(element).width();
188    };
189
190    $.inviewport = function(element, settings) {
191         return !$.rightofscreen(element, settings) && !$.leftofscreen(element, settings) && 
192                !$.belowthefold(element, settings) && !$.abovethetop(element, settings);
193     };
194
195    /* Custom selectors for your convenience.   */
196    /* Use as $("img:below-the-fold").something() */
197
198    $.extend($.expr[':'], {
199        "below-the-fold" : function(a) { return $.belowthefold(a, {threshold : 0, container: window}); },
200        "above-the-top"  : function(a) { return !$.belowthefold(a, {threshold : 0, container: window}); },
201        "right-of-screen": function(a) { return $.rightoffold(a, {threshold : 0, container: window}); },
202        "left-of-screen" : function(a) { return !$.rightoffold(a, {threshold : 0, container: window}); },
203        "in-viewport"    : function(a) { return !$.inviewport(a, {threshold : 0, container: window}); },
204        /* Maintain BC for couple of versions. */
205        "above-the-fold" : function(a) { return !$.belowthefold(a, {threshold : 0, container: window}); },
206        "right-of-fold"  : function(a) { return $.rightoffold(a, {threshold : 0, container: window}); },
207        "left-of-fold"   : function(a) { return !$.rightoffold(a, {threshold : 0, container: window}); }
208    });
209
210})(jQuery, window);