Roo/util/TextMetrics.js

diff --git a/Roo/util/TextMetrics.js b/Roo/util/TextMetrics.js
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+/*
+ * Based on:
+ * Ext JS Library 1.1.1
+ * Copyright(c) 2006-2007, Ext JS, LLC.
+ *
+ * Originally Released Under LGPL - original licence link has changed is not relivant.
+ *
+ * Fork - LGPL
+ * <script type="text/javascript">
+ */
+
+ 
+/**
+ * @class Roo.util.TextMetrics
+ * Provides precise pixel measurements for blocks of text so that you can determine exactly how high and
+ * wide, in pixels, a given block of text will be.
+ * @singleton
+ */
+Roo.util.TextMetrics = function(){
+    var shared;
+    return {
+        /**
+         * Measures the size of the specified text
+         * @param {String/HTMLElement} el The element, dom node or id from which to copy existing CSS styles
+         * that can affect the size of the rendered text
+         * @param {String} text The text to measure
+         * @param {Number} fixedWidth (optional) If the text will be multiline, you have to set a fixed width
+         * in order to accurately measure the text height
+         * @return {Object} An object containing the text's size {width: (width), height: (height)}
+         */
+        measure : function(el, text, fixedWidth){
+            if(!shared){
+                shared = Roo.util.TextMetrics.Instance(el, fixedWidth);
+            }
+            shared.bind(el);
+            shared.setFixedWidth(fixedWidth || 'auto');
+            return shared.getSize(text);
+        },
+
+        /**
+         * Return a unique TextMetrics instance that can be bound directly to an element and reused.  This reduces
+         * the overhead of multiple calls to initialize the style properties on each measurement.
+         * @param {String/HTMLElement} el The element, dom node or id that the instance will be bound to
+         * @param {Number} fixedWidth (optional) If the text will be multiline, you have to set a fixed width
+         * in order to accurately measure the text height
+         * @return {Roo.util.TextMetrics.Instance} instance The new instance
+         */
+        createInstance : function(el, fixedWidth){
+            return Roo.util.TextMetrics.Instance(el, fixedWidth);
+        }
+    };
+}();
+
+ 
+
+Roo.util.TextMetrics.Instance = function(bindTo, fixedWidth){
+    var ml = new Roo.Element(document.createElement('div'));
+    document.body.appendChild(ml.dom);
+    ml.position('absolute');
+    ml.setLeftTop(-1000, -1000);
+    ml.hide();
+
+    if(fixedWidth){
+        ml.setWidth(fixedWidth);
+    }
+     
+    var instance = {
+        /**
+         * Returns the size of the specified text based on the internal element's style and width properties
+         * @memberOf Roo.util.TextMetrics.Instance#
+         * @param {String} text The text to measure
+         * @return {Object} An object containing the text's size {width: (width), height: (height)}
+         */
+        getSize : function(text){
+            ml.update(text);
+            var s = ml.getSize();
+            ml.update('');
+            return s;
+        },
+
+        /**
+         * Binds this TextMetrics instance to an element from which to copy existing CSS styles
+         * that can affect the size of the rendered text
+         * @memberOf Roo.util.TextMetrics.Instance#
+         * @param {String/HTMLElement} el The element, dom node or id
+         */
+        bind : function(el){
+            ml.setStyle(
+                Roo.fly(el).getStyles('font-size','font-style', 'font-weight', 'font-family','line-height')
+            );
+        },
+
+        /**
+         * Sets a fixed width on the internal measurement element.  If the text will be multiline, you have
+         * to set a fixed width in order to accurately measure the text height.
+         * @memberOf Roo.util.TextMetrics.Instance#
+         * @param {Number} width The width to set on the element
+         */
+        setFixedWidth : function(width){
+            ml.setWidth(width);
+        },
+
+        /**
+         * Returns the measured width of the specified text
+         * @memberOf Roo.util.TextMetrics.Instance#
+         * @param {String} text The text to measure
+         * @return {Number} width The width in pixels
+         */
+        getWidth : function(text){
+            ml.dom.style.width = 'auto';
+            return this.getSize(text).width;
+        },
+
+        /**
+         * Returns the measured height of the specified text.  For multiline text, be sure to call
+         * {@link #setFixedWidth} if necessary.
+         * @memberOf Roo.util.TextMetrics.Instance#
+         * @param {String} text The text to measure
+         * @return {Number} height The height in pixels
+         */
+        getHeight : function(text){
+            return this.getSize(text).height;
+        }
+    };
+
+    instance.bind(bindTo);
+
+    return instance;
+};
+
+// backwards compat
+Roo.Element.measureText = Roo.util.TextMetrics.measure;
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