Resizable: Fix content shrink on resize

Make resizable elements not shrink on resize when they have scrollbars
and "box-sizing: content-box".

Fixes: gh-2277
Closes gh-2281

3 files changed, 191 insertions, 17 deletions

diff --git a/tests/unit/resizable/core.js b/tests/unit/resizable/core.js
index b3c61514a..b47f0b645 100644
--- a/tests/unit/resizable/core.js
+++ b/tests/unit/resizable/core.js
@@ -244,4 +244,72 @@ QUnit.test( "nested resizable", function( assert ) {
 	outer.remove();
 } );
 
+QUnit.test( "Resizable with scrollbars and box-sizing: border-box", function( assert ) {
+	assert.expect( 4 );
+	testResizableWithBoxSizing( assert, {
+		isBorderBox: true,
+		applyScaleTransform: false
+	} );
+} );
+
+QUnit.test( "Resizable with scrollbars and box-sizing: content-box", function( assert ) {
+	assert.expect( 4 );
+	testResizableWithBoxSizing( assert, {
+		isBorderBox: false,
+		applyScaleTransform: false
+	} );
+} );
+
+QUnit.test( "Resizable with scrollbars, a transform and box-sizing: border-box", function( assert ) {
+	assert.expect( 4 );
+	testResizableWithBoxSizing( assert, {
+		isBorderBox: true,
+		applyScaleTransform: true
+	} );
+} );
+
+QUnit.test( "Resizable with scrollbars, a transform and box-sizing: content-box", function( assert ) {
+	assert.expect( 4 );
+	testResizableWithBoxSizing( assert, {
+		isBorderBox: false,
+		applyScaleTransform: true
+	} );
+} );
+
+function testResizableWithBoxSizing( assert, options ) {
+	var widthBefore, heightBefore,
+		cssBoxSizing = options.isBorderBox ? "border-box" : "content-box",
+		cssTransform = options.applyScaleTransform ? "scale(1.5)" : "",
+		elementContent = $( "<div>" )
+			.css( {
+				width: "200px",
+				height: "200px",
+				padding: "10px",
+				border: "5px",
+				borderStyle: "solid",
+				margin: "20px"
+			} )
+			.appendTo( "#resizable1" ),
+		element = $( "#resizable1" ).css( { overflow: "auto", transform: cssTransform } ).resizable(),
+		handle = ".ui-resizable-se";
+
+	$( "<style> * { box-sizing: " + cssBoxSizing + "; } </style>" ).appendTo( "#qunit-fixture" );
+
+	// In some browsers scrollbar may change element size (when "box-sizing: content-box")
+	widthBefore = element.innerWidth();
+	heightBefore = element.innerHeight();
+
+	// Both scrollbars
+	testHelper.drag( handle, 10, 10 );
+	assert.equal( parseFloat( element.innerWidth() ), widthBefore + 10, "element width (both scrollbars)" );
+	assert.equal( parseFloat( element.innerHeight() ), heightBefore + 10, "element height (both scrollbars)" );
+
+	// Single (vertical) scrollbar.
+	elementContent.css( "width", "50px" );
+
+	testHelper.drag( handle, 10, 10 );
+	assert.equal( parseFloat( element.innerWidth() ), widthBefore + 20, "element width (only vertical scrollbar)" );
+	assert.equal( parseFloat( element.innerHeight() ), heightBefore + 20, "element height (only vertical scrollbar)" );
+}
+
 } );
diff --git a/tests/unit/resizable/options.js b/tests/unit/resizable/options.js
index add8d8034..b80c051d5 100644
--- a/tests/unit/resizable/options.js
+++ b/tests/unit/resizable/options.js
@@ -542,21 +542,22 @@ QUnit.test( "alsoResize + multiple selection", function( assert ) {
 QUnit.test( "alsoResize with box-sizing: border-box", function( assert ) {
 	assert.expect( 4 );
 
+	$( "<style> * { box-sizing: border-box; } </style>" ).appendTo( "#qunit-fixture" );
+
 	var other = $( "<div>" )
 			.css( {
-				width: 50,
-				height: 50,
-				padding: 10,
-				border: 5
+				width: "50px",
+				height: "50px",
+				padding: "10px",
+				border: "5px",
+				borderStyle: "solid"
 			} )
-			.appendTo( "body" ),
+			.appendTo( "#qunit-fixture" ),
 		element = $( "#resizable1" ).resizable( {
 			alsoResize: other
 		} ),
 		handle = ".ui-resizable-se";
 
-	$( "*" ).css( "box-sizing", "border-box" );
-
 	testHelper.drag( handle, 80, 80 );
 
 	assert.equal( element.width(), 180, "resizable width" );
@@ -565,4 +566,51 @@ QUnit.test( "alsoResize with box-sizing: border-box", function( assert ) {
 	assert.equal( parseFloat( other.css( "height" ) ), 130, "alsoResize height" );
 } );
 
+QUnit.test( "alsoResize with scrollbars and box-sizing: border-box", function( assert ) {
+	assert.expect( 4 );
+	testAlsoResizeWithBoxSizing( assert, {
+		isBorderBox: true
+	} );
+} );
+
+QUnit.test( "alsoResize with scrollbars and box-sizing: content-box", function( assert ) {
+	assert.expect( 4 );
+	testAlsoResizeWithBoxSizing( assert, {
+		isBorderBox: false
+	} );
+} );
+
+function testAlsoResizeWithBoxSizing( assert, options ) {
+	var widthBefore, heightBefore,
+		cssBoxSizing = options.isBorderBox ? "border-box" : "content-box",
+		other = $( "<div>" )
+			.css( {
+				width: "150px",
+				height: "150px",
+				padding: "10px",
+				border: "5px",
+				borderStyle: "solid",
+				margin: "20px",
+				overflow: "scroll"
+			} )
+			.appendTo( "#qunit-fixture" ),
+		element = $( "#resizable1" ).resizable( {
+			alsoResize: other
+		} ),
+		handle = ".ui-resizable-se";
+
+	$( "<style> * { box-sizing: " + cssBoxSizing + "; } </style>" ).appendTo( "#qunit-fixture" );
+
+	// In some browsers scrollbar may change element computed size.
+	widthBefore = other.innerWidth();
+	heightBefore = other.innerHeight();
+
+	testHelper.drag( handle, 80, 80 );
+
+	assert.equal( element.width(), 180, "resizable width" );
+	assert.equal( parseFloat( other.innerWidth() ), widthBefore + 80, "alsoResize width" );
+	assert.equal( element.height(), 180, "resizable height" );
+	assert.equal( parseFloat( other.innerHeight() ), heightBefore + 80, "alsoResize height" );
+}
+
 } );
diff --git a/ui/widgets/resizable.js b/ui/widgets/resizable.js
index 1698d55e8..6f1e0ebde 100644
--- a/ui/widgets/resizable.js
+++ b/ui/widgets/resizable.js
@@ -80,12 +80,18 @@ $.widget( "ui.resizable", $.ui.mouse, {
 
 	_hasScroll: function( el, a ) {
 
-		if ( $( el ).css( "overflow" ) === "hidden" ) {
+		var scroll,
+			has = false,
+			overflow = $( el ).css( "overflow" );
+
+		if ( overflow === "hidden" ) {
 			return false;
 		}
+		if ( overflow === "scroll" ) {
+			return true;
+		}
 
-		var scroll = ( a && a === "left" ) ? "scrollLeft" : "scrollTop",
-			has = false;
+		scroll = ( a && a === "left" ) ? "scrollLeft" : "scrollTop";
 
 		if ( el[ scroll ] > 0 ) {
 			return true;
@@ -362,7 +368,7 @@ $.widget( "ui.resizable", $.ui.mouse, {
 
 	_mouseStart: function( event ) {
 
-		var curleft, curtop, cursor,
+		var curleft, curtop, cursor, calculatedSize,
 			o = this.options,
 			el = this.element;
 
@@ -381,20 +387,24 @@ $.widget( "ui.resizable", $.ui.mouse, {
 		this.offset = this.helper.offset();
 		this.position = { left: curleft, top: curtop };
 
+		if ( !this._helper ) {
+			calculatedSize = this._calculateAdjustedElementDimensions( el );
+		}
+
 		this.size = this._helper ? {
 				width: this.helper.width(),
 				height: this.helper.height()
 			} : {
-				width: el.width(),
-				height: el.height()
+				width: calculatedSize.width,
+				height: calculatedSize.height
 			};
 
 		this.originalSize = this._helper ? {
 				width: el.outerWidth(),
 				height: el.outerHeight()
 			} : {
-				width: el.width(),
-				height: el.height()
+				width: calculatedSize.width,
+				height: calculatedSize.height
 			};
 
 		this.sizeDiff = {
@@ -690,6 +700,52 @@ $.widget( "ui.resizable", $.ui.mouse, {
 		};
 	},
 
+	_calculateAdjustedElementDimensions: function( element ) {
+		var elWidth, elHeight, paddingBorder,
+			ce = element.get( 0 );
+
+		if ( element.css( "box-sizing" ) !== "content-box" ||
+			( !this._hasScroll( ce ) && !this._hasScroll( ce, "left" ) ) ) {
+				return {
+					height: parseFloat( element.css( "height" ) ),
+					width: parseFloat( element.css( "width" ) )
+				};
+		}
+
+		// Check if CSS inline styles are set and use those (usually from previous resizes)
+		elWidth = parseFloat( ce.style.width );
+		elHeight = parseFloat( ce.style.height );
+
+		paddingBorder = this._getPaddingPlusBorderDimensions( element );
+		elWidth = isNaN( elWidth ) ?
+			this._getElementTheoreticalSize( element, paddingBorder, "width" ) :
+			elWidth;
+		elHeight = isNaN( elHeight ) ?
+			this._getElementTheoreticalSize( element, paddingBorder, "height" ) :
+			elHeight;
+
+		return {
+			height: elHeight,
+			width: elWidth
+		};
+	},
+
+	_getElementTheoreticalSize: function( element, extraSize, dimension ) {
+
+		// offsetWidth/offsetHeight is a rounded sum of content, padding, scroll gutter, and border
+		var size = Math.max( 0, Math.ceil(
+			element.get( 0 )[ "offset" + dimension[ 0 ].toUpperCase() + dimension.slice( 1 ) ] -
+			extraSize[ dimension ] -
+			0.5
+
+		// If offsetWidth/offsetHeight is unknown, then we can't determine theoretical size.
+		// Use an explicit zero to avoid NaN.
+		// See https://github.com/jquery/jquery/issues/3964
+		) ) || 0;
+
+		return size;
+	},
+
 	_proportionallyResize: function() {
 
 		if ( !this._proportionallyResizeElements.length ) {
@@ -1044,9 +1100,11 @@ $.ui.plugin.add( "resizable", "alsoResize", {
 			o = that.options;
 
 		$( o.alsoResize ).each( function() {
-			var el = $( this );
+			var el = $( this ),
+				elSize = that._calculateAdjustedElementDimensions( el );
+
 			el.data( "ui-resizable-alsoresize", {
-				width: parseFloat( el.css( "width" ) ), height: parseFloat( el.css( "height" ) ),
+				width: elSize.width, height: elSize.height,
 				left: parseFloat( el.css( "left" ) ), top: parseFloat( el.css( "top" ) )
 			} );
 		} );