Remove pointless multiplication against the scaleFactor in the scale factor conditions, and add a new option called "fit" that allows the object-fit strategy to be configured to either contain within the parent element or cover it (with the default set to the original behavior)

README.md

@@ -23,8 +23,9 @@ window.onload = function() {
         id: "element", // the id of the element to be contained (alternative to 'element')
         width: 100, // (optional) native element width in pixels (unset: detected element width)
         height: 100, // (optional) native element height in pixels (unset: detected element height)
-        valign: "top", // (optional) vertical alignment: top|bottom (unset: center)
+        valign: "top", // (optional) vertical alignment: center|top|bottom (unset: center)
-        halign: "left", // (optional) horizontal alignment: left|right (unset: center)
+        halign: "left", // (optional) horizontal alignment: center|left|right (unset: center)
+        fit: "contain", // (optional) object fit: cover|contain (unset: cover)
         scale: true // (optional) use transform scale instead of width and height (unset: false)
     });
 
@@ -43,10 +44,12 @@ window.onload = function() {
 * `setHeight(height)`: Set the height (run `update()` to apply).
 * `setValign(valign)`: Set the vertical alignment (run `update()` to apply).
 * `setHalign(halign)`: Set the horizontal alignment (run `update()` to apply).
+* `setFit(fit)`: Set the object fit (run `update()` to apply).
 * `getWidth()`: Return the current width.
 * `getHeight()`: Return the current height.
 * `getValign()`: Return the current vertical alignment.
 * `getHalign()`: Return the current horizontal alignment.
+* `getFit()`: Return the current object fit.
 * `getScale()`: Return the current scale factor being applied to the contained element.
 
 ## Credits

contain-element.js

@@ -5,6 +5,7 @@ function ContainElement(options) {
         elementHeight = options.height || element.offsetHeight,
         valign = options.valign || "center",
         halign = options.halign || "center",
+        fit = options.fit || "cover",
         scale = options.scale;
 
     // Apply required attributes to the element
@@ -28,10 +29,20 @@ function ContainElement(options) {
         // Run the scale/position functionality if able to determine the parent element's width and height
         if (parentWidth && parentHeight) {
             // Calculate the scale factor
-            if (parentWidth > parentHeight / (elementHeight * scaleFactor) * (elementWidth * scaleFactor)) {
+            if (fit === "cover") {
-                scaleFactor = parentWidth / elementWidth;
+                if (parentWidth > parentHeight / elementHeight * elementWidth) {
+                    scaleFactor = parentWidth / elementWidth;
+                } else {
+                    scaleFactor = parentHeight / elementHeight;
+                }
+            } else if (fit === "contain") {
+                if (parentHeight > parentWidth / elementWidth * elementHeight) {
+                    scaleFactor = parentWidth / elementWidth;
+                } else {
+                    scaleFactor = parentHeight / elementHeight;
+                }
             } else {
-                scaleFactor = parentHeight / elementHeight;
+                scaleFactor = 1;
             }
 
             // Scale the element using the scale factor
@@ -43,7 +54,7 @@ function ContainElement(options) {
             }
 
             // Anchor the element horizontally to the left/center/right
-            if (parentWidth < elementWidth * scaleFactor) {
+            if (parentWidth !== elementWidth * scaleFactor) {
                 switch (halign) {
                     case "left":
                         // Anchor horizontally to the left of the parent element
@@ -64,7 +75,7 @@ function ContainElement(options) {
             }
 
             // Anchor the element vertically to the top/center/bottom
-            if (elementHeight * scaleFactor > parentHeight) {
+            if (parentHeight !== elementHeight * scaleFactor) {
                 switch (valign) {
                     case "top":
                         // Anchor vertically to the top of the parent element
@@ -107,6 +118,9 @@ function ContainElement(options) {
     // External function to set halign
     this.setHalign = function(newHalign) { halign = newHalign; };
 
+    // External function to set fit
+    this.setFit = function(newFit) { fit = newFit; };
+
     // External function to return the current elementWidth
     this.getWidth = function() { return elementWidth; };
 
@@ -119,6 +133,9 @@ function ContainElement(options) {
     // External function to return the current halign
     this.getHalign = function() { return halign; };
 
+    // External function to return the current fit
+    this.getFit = function() { return fit; };
+
     // External function to return the current scale factor
     this.getScale = function() { return scaleFactor; };
 }

contain-element.min.js

@@ -1 +1 @@
-function ContainElement(t){function e(){var t=n.parentElement.offsetWidth,r=n.parentElement.offsetHeight;if(t&&r){if(i=t>r/(s*i)*(l*i)?t/l:r/s,f?n.style.transform="scale("+i+")":(n.style.width=l*i+"px",n.style.height=s*i+"px"),t<l*i)switch(a){case"left":n.style.left="0px";break;case"right":n.style.left=0-(l*i-t)+"px";break;default:n.style.left=0-(l*i-t)/2+"px"}else n.style.left="0px";if(s*i>r)switch(o){case"top":n.style.top="0px";break;case"bottom":n.style.top=0-(s*i-r)+"px";break;default:n.style.top=0-(s*i-r)/2+"px"}else n.style.top="0px"}else window.setTimeout(e,30)}var i=1,n=t.element||document.getElementById(t.id),l=t.width||n.offsetWidth,s=t.height||n.offsetHeight,o=t.valign||"center",a=t.halign||"center",f=t.scale;n.style.position="absolute",n.parentElement.style.overflow="hidden",f&&(n.style.transformOrigin="left top"),-1===["relative","absolute","fixed"].indexOf(window.getComputedStyle(n.parentElement,null).getPropertyValue("position"))&&(n.parentElement.style.position="relative"),e(),this.update=e,this.setWidth=function(t){l=t},this.setHeight=function(t){s=t},this.setValign=function(t){o=t},this.setHalign=function(t){a=t},this.getWidth=function(){return l},this.getHeight=function(){return s},this.getValign=function(){return o},this.getHalign=function(){return a},this.getScale=function(){return i}}
+function ContainElement(t){function e(){var t=n.parentElement.offsetWidth,h=n.parentElement.offsetHeight;if(t&&h){if(i="cover"===r?t>h/l*s?t/s:h/l:"contain"===r?h>t/s*l?t/s:h/l:1,a?n.style.transform="scale("+i+")":(n.style.width=s*i+"px",n.style.height=l*i+"px"),t!==s*i)switch(f){case"left":n.style.left="0px";break;case"right":n.style.left=0-(s*i-t)+"px";break;default:n.style.left=0-(s*i-t)/2+"px"}else n.style.left="0px";if(h!==l*i)switch(o){case"top":n.style.top="0px";break;case"bottom":n.style.top=0-(l*i-h)+"px";break;default:n.style.top=0-(l*i-h)/2+"px"}else n.style.top="0px"}else window.setTimeout(e,30)}var i=1,n=t.element||document.getElementById(t.id),s=t.width||n.offsetWidth,l=t.height||n.offsetHeight,o=t.valign||"center",f=t.halign||"center",r=t.fit||"cover",a=t.scale;n.style.position="absolute",n.parentElement.style.overflow="hidden",a&&(n.style.transformOrigin="left top"),-1===["relative","absolute","fixed"].indexOf(window.getComputedStyle(n.parentElement,null).getPropertyValue("position"))&&(n.parentElement.style.position="relative"),e(),this.update=e,this.setWidth=function(t){s=t},this.setHeight=function(t){l=t},this.setValign=function(t){o=t},this.setHalign=function(t){f=t},this.setFit=function(t){r=t},this.getWidth=function(){return s},this.getHeight=function(){return l},this.getValign=function(){return o},this.getHalign=function(){return f},this.getFit=function(){return r},this.getScale=function(){return i}}