File size: 4,081 Bytes
f0de4e8
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<style>
* {box-sizing: border-box;}

.img-comp-container {
  position: relative;
  height: 200px; /*should be the same height as the images*/
}

.img-comp-img {
  position: absolute;
  width: auto;
  height: auto;
  overflow:hidden;
}

.img-comp-img img {
  display:block;
  vertical-align:middle;
}

.img-comp-slider {
  position: absolute;
  z-index:9;
  cursor: ew-resize;
  /*set the appearance of the slider:*/
  width: 40px;
  height: 40px;
  background-color: #2196F3;
  opacity: 0.7;
  border-radius: 50%;
}
</style>
<script>
function initComparisons() {
  var x, i;
  /*find all elements with an "overlay" class:*/
  x = document.getElementsByClassName("img-comp-overlay");
  for (i = 0; i < x.length; i++) {
    /*once for each "overlay" element:
    pass the "overlay" element as a parameter when executing the compareImages function:*/
    compareImages(x[i]);
  }
  function compareImages(img) {
    var slider, img, clicked = 0, w, h;
    /*get the width and height of the img element*/
    w = img.offsetWidth;
    h = img.offsetHeight;
    /*set the width of the img element to 50%:*/
    img.style.width = (w / 2) + "px";
    /*create slider:*/
    slider = document.createElement("DIV");
    slider.setAttribute("class", "img-comp-slider");
    /*insert slider*/
    img.parentElement.insertBefore(slider, img);
    /*position the slider in the middle:*/
    slider.style.top = (h / 2) - (slider.offsetHeight / 2) + "px";
    slider.style.left = (w / 2) - (slider.offsetWidth / 2) + "px";
    /*execute a function when the mouse button is pressed:*/
    slider.addEventListener("mousedown", slideReady);
    /*and another function when the mouse button is released:*/
    window.addEventListener("mouseup", slideFinish);
    /*or touched (for touch screens:*/
    slider.addEventListener("touchstart", slideReady);
    /*and released (for touch screens:*/
    window.addEventListener("touchend", slideFinish);
    function slideReady(e) {
      /*prevent any other actions that may occur when moving over the image:*/
      e.preventDefault();
      /*the slider is now clicked and ready to move:*/
      clicked = 1;
      /*execute a function when the slider is moved:*/
      window.addEventListener("mousemove", slideMove);
      window.addEventListener("touchmove", slideMove);
    }
    function slideFinish() {
      /*the slider is no longer clicked:*/
      clicked = 0;
    }
    function slideMove(e) {
      var pos;
      /*if the slider is no longer clicked, exit this function:*/
      if (clicked == 0) return false;
      /*get the cursor's x position:*/
      pos = getCursorPos(e)
      /*prevent the slider from being positioned outside the image:*/
      if (pos < 0) pos = 0;
      if (pos > w) pos = w;
      /*execute a function that will resize the overlay image according to the cursor:*/
      slide(pos);
    }
    function getCursorPos(e) {
      var a, x = 0;
      e = (e.changedTouches) ? e.changedTouches[0] : e;
      /*get the x positions of the image:*/
      a = img.getBoundingClientRect();
      /*calculate the cursor's x coordinate, relative to the image:*/
      x = e.pageX - a.left;
      /*consider any page scrolling:*/
      x = x - window.pageXOffset;
      return x;
    }
    function slide(x) {
      /*resize the image:*/
      img.style.width = x + "px";
      /*position the slider:*/
      slider.style.left = img.offsetWidth - (slider.offsetWidth / 2) + "px";
    }
  }
}
</script>
</head>
<body>

<h1>Compare Two Images</h1>

<p>Click and slide the blue slider to compare two images:</p>

<div class="img-comp-container">
  <div class="img-comp-img">
    <img src="img_snow.jpg" width="300" height="200">
  </div>
  <div class="img-comp-img img-comp-overlay">
    <img src="img_forest.jpg" width="300" height="200">
  </div>
</div>

<script>
/*Execute a function that will execute an image compare function for each element with the img-comp-overlay class:*/
initComparisons();
</script>

</body>
</html>