MANTIS bidder: support tracking viewability of ad (prebid#2696)

* support tracking viewability of ad

* safeframe support

modules/mantisBidAdapter.js

@@ -7,7 +7,12 @@ function inIframe() {
     return true;
   }
 }
-
+function pixel(url, parent) {
+  var img = document.createElement('img');
+  img.src = url;
+  img.style.cssText = 'display:none !important;';
+  (parent || document.body).appendChild(img);
+}
 function isDesktop(ignoreTouch) {
   var supportsTouch = !ignoreTouch && ('ontouchstart' in window || navigator.msMaxTouchPoints);
   if (inIframe()) {
@@ -16,7 +21,72 @@ function isDesktop(ignoreTouch) {
   var width = window.innerWidth || window.document.documentElement.clientWidth || window.document.body.clientWidth;
   return !supportsTouch && (!width || width >= (window.mantis_breakpoint || 768));
 }
-
+function onVisible(element, doOnVisible, time, pct) {
+  var started = null;
+  var notified = false;
+  var onNotVisible = null;
+  var whenNotVisible = function () {
+    if (notified && onNotVisible) {
+      onNotVisible();
+    }
+    notified = false;
+  };
+  var interval;
+  var listener;
+  var doCheck = function (winWidth, winHeight, rect) {
+    var hidden = typeof document.hidden !== 'undefined' && document.hidden;
+    if (rect.width == 0 || rect.height == 0 || hidden) {
+      return whenNotVisible();
+    }
+    var minHeight = (rect.height * pct);
+    var minWidth = (rect.width * pct);
+    var inView = (
+      (
+        (rect.top < 0 && rect.bottom >= minHeight) ||
+        (rect.top > 0 && (winHeight - rect.top) >= minHeight)
+      ) &&
+      (
+        (rect.left < 0 && rect.right >= minWidth) ||
+        (rect.left > 0 && (winWidth - rect.left) >= minWidth)
+      )
+    );
+    if (!inView) {
+      return whenNotVisible();
+    }
+    if (!started && time) {
+      started = Date.now();
+      return whenNotVisible();
+    }
+    if (time && Date.now() - started < time) {
+      return whenNotVisible();
+    }
+    if (notified) {
+      return;
+    }
+    doOnVisible(function (ack) {
+      if (ack) {
+        notified = true;
+      } else {
+        interval && clearInterval(interval);
+        listener && listener();
+      }
+    }, function (onHidden) {
+      onNotVisible = onHidden;
+    });
+  };
+  if (isAmp()) {
+    listener = window.context.observeIntersection(function (changes) {
+      changes.forEach(function (change) {
+        doCheck(change.rootBounds.width, change.rootBounds.height, change.boundingClientRect);
+      });
+    });
+  }
+  interval = setInterval(function () {
+    var winHeight = (window.innerHeight || document.documentElement.clientHeight);
+    var winWidth = (window.innerWidth || document.documentElement.clientWidth);
+    doCheck(winWidth, winHeight, element.getBoundingClientRect());
+  }, 100);
+}
 function storeUuid(uuid) {
   if (window.mantis_uuid) {
     return false;
@@ -30,6 +100,13 @@ function storeUuid(uuid) {
   }
 }
 
+function onMessage(type, callback) {
+  window.addEventListener('message', function (event) {
+    if (event.data.mantis && event.data.type == type) {
+      callback(event.data.data);
+    }
+  }, false);
+}
 function isSendable(val) {
   if (val === null || val === undefined) {
     return false;
@@ -42,19 +119,15 @@ function isSendable(val) {
   }
   return true;
 }
-
 function isObject(value) {
   return Object.prototype.toString.call(value) === '[object Object]';
 }
-
 function isAmp() {
   return typeof window.context === 'object' && (window.context.tagName === 'AMP-AD' || window.context.tagName === 'AMP-EMBED');
 }
-
 function isSecure() {
   return document.location.protocol === 'https:';
 }
-
 function isArray(value) {
   return Object.prototype.toString.call(value) === '[object Array]';
 }
@@ -94,7 +167,8 @@ function buildMantisUrl(path, data, domain) {
     referrer: document.referrer,
     tz: new Date().getTimezoneOffset(),
     buster: new Date().getTime(),
-    secure: isSecure()
+    secure: isSecure(),
+    version: 8
   };
   if (!inIframe() || isAmp()) {
     params.mobile = !isAmp() && isDesktop(true) ? 'false' : 'true';
@@ -151,6 +225,7 @@ const spec = {
       }
     });
     const query = {
+      measurable: true,
       bids: validBidRequests.map(function (bid) {
         return {
           bidId: bid.bidId,
@@ -160,8 +235,7 @@ const spec = {
           })
         };
       }),
-      property: property,
-      version: 2
+      property: property
     };
     return {
       method: 'GET',
@@ -200,7 +274,30 @@ const spec = {
     }
   }
 };
+onMessage('iframe', function (data) {
+  if (window.$sf) {
+    var viewed = false;
+    $sf.ext.register(data.width, data.height, function () {
+      if ($sf.ext.inViewPercentage() < 50 || viewed) {
+        return;
+      }
+      viewed = true;
+      pixel(data.pixel);
+    });
+  } else {
+    var frames = document.getElementsByTagName('iframe');
+    for (var i = 0; i < frames.length; i++) {
+      var frame = frames[i];
+      if (frame.name == data.frame) {
+        onVisible(frame, function (stop) {
+          pixel(data.pixel);
+          stop();
+        }, 1000, 0.50);
+      }
+    }
+  }
+});
 
-export {spec};
+export { spec };
 
 registerBidder(spec);