Merge pull request #125 from MadsMadsDk/master

Add a new boolean option, relativeToWrapper.
dixonandmoe · Sep 15, 2018 · fdd78ad · fdd78ad
2 parents 7d631cd + 4465b85
commit fdd78ad
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diff --git a/package-lock.json b/package-lock.json
diff --git a/rellax.js b/rellax.js
@@ -63,6 +63,7 @@
       speed: -2,
       center: false,
       wrapper: null,
+      relativeToWrapper: false,
       round: true,
       vertical: true,
       horizontal: false,
@@ -154,6 +155,11 @@
       // If the element has the percentage attribute, the posY and posX needs to be
       // the current scroll position's value, so that the elements are still positioned based on HTML layout
       var wrapperPosY = self.options.wrapper ? self.options.wrapper.scrollTop : (window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop);
+      // If the option relativeToWrapper is true, use the wrappers offset to top, subtracted from the current page scroll.
+      if (self.options.relativeToWrapper) {
+        var scrollPosY = (window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop);
+        wrapperPosY = scrollPosY - self.options.wrapper.offsetTop;
+      }
       var posY = self.options.vertical ? ( dataPercentage || self.options.center ? wrapperPosY : 0 ) : 0;
       var posX = self.options.horizontal ? ( dataPercentage || self.options.center ? (window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft) : 0 ) : 0;
 
@@ -218,6 +224,11 @@
 
       posY = self.options.wrapper ? self.options.wrapper.scrollTop : (document.documentElement || document.body.parentNode || document.body).scrollTop || window.pageYOffset;
       posX = self.options.wrapper ? self.options.wrapper.scrollLeft : (document.documentElement || document.body.parentNode || document.body).scrollLeft || window.pageXOffset;
+      // If option relativeToWrapper is true, use relative wrapper value instead.
+      if (self.options.relativeToWrapper) {
+        var scrollPosY = (document.documentElement || document.body.parentNode || document.body).scrollTop || window.pageYOffset;
+        posY = scrollPosY - self.options.wrapper.offsetTop;
+      }
 
 
       if (oldY != posY && self.options.vertical) {