Merge "Fix mw.viewport.isElementInViewport with scrolled page"

diff --git a/resources/src/mediawiki/mediawiki.viewport.js b/resources/src/mediawiki/mediawiki.viewport.js
index aa9dd05..6396331 100644 (file)
--- a/resources/src/mediawiki/mediawiki.viewport.js
+++ b/resources/src/mediawiki/mediawiki.viewport.js
@@ -50,14 +50,25 @@
                 * @return {boolean}
                 */
                isElementInViewport: function ( el, rectangle ) {
-                       var elRect = el.getBoundingClientRect(),
+                       var $el = $( el ),
+                               offset = $el.offset(),
+                               rect = {
+                                       height: $el.height(),
+                                       width: $el.width(),
+                                       top: offset.top,
+                                       left: offset.left
+                               },
                                viewport = rectangle || this.makeViewportFromWindow();
 
                        return (
-                               ( viewport.bottom >= elRect.top ) &&
-                               ( viewport.right >= elRect.left ) &&
-                               ( viewport.top <= elRect.top + elRect.height ) &&
-                               ( viewport.left <= elRect.left + elRect.width )
+                               // Top border must be above viewport's bottom
+                               ( viewport.bottom >= rect.top ) &&
+                               // Left border must be before viewport's right border
+                               ( viewport.right >= rect.left ) &&
+                               // Bottom border must be below viewport's top
+                               ( viewport.top <= rect.top + rect.height ) &&
+                               // Right border must be after viewport's left border
+                               ( viewport.left <= rect.left + rect.width )
                        );
                },
 

diff --git a/tests/qunit/suites/resources/mediawiki/mediawiki.viewport.test.js b/tests/qunit/suites/resources/mediawiki/mediawiki.viewport.test.js
index 61391d8..f404294 100644 (file)
--- a/tests/qunit/suites/resources/mediawiki/mediawiki.viewport.test.js
+++ b/tests/qunit/suites/resources/mediawiki/mediawiki.viewport.test.js
@@ -60,6 +60,29 @@
                        'It should default to the window object if no viewport is given' );
        } );
 
+       QUnit.test( 'isElementInViewport with scrolled page', 1, function ( assert ) {
+               var viewport = {
+                               top: 2000,
+                               left: 0,
+                               right: 1000,
+                               bottom: 2500
+                       },
+                       el = $( '<div />' )
+                               .appendTo( '#qunit-fixture' )
+                               .width( 20 )
+                               .height( 20 )
+                               .offset( {
+                                       top: 2300,
+                                       left: 20
+                               } )
+                               .get( 0 );
+               window.scrollTo( viewport.left, viewport.top );
+               assert.ok( mw.viewport.isElementInViewport( el, viewport ),
+                       'It should return true when the element is fully enclosed in the ' +
+                       'viewport even when the page is scrolled down' );
+               window.scrollTo( 0, 0 );
+       } );
+
        QUnit.test( 'isElementCloseToViewport', 3, function ( assert ) {
                var
                        viewport = {