angular-elastic-input.js

/**
 * angular-elastic-input
 * A directive for AngularJS which automatically resizes the width of input field according to the content, while typing.
 * @author: Jacek Pulit <jacek.pulit@gmail.com>
 * @license: MIT License
 */

'use strict';

angular.module('puElasticInput', []).directive('puElasticInput', ['$document', '$window', function($document, $window) {

    var wrapper = angular.element('<div style="position:fixed; top:-999px; left:0;"></div>');
    angular.element($document[0].body).append(wrapper);

    function getStyle(oElm, css3Prop){
        var strValue = "";

        if(window.getComputedStyle){
            strValue = getComputedStyle(oElm).getPropertyValue(css3Prop);

        } else if (oElm.currentStyle){ //IE
            try {
                strValue = oElm.currentStyle[css3Prop];
            } catch (e) {}
        }
        return strValue;
    }

    function getParentWidth(element) {

        var parent = element[0], width;

        do {
            parent = parent.parentNode;
            width = parseInt(getStyle(parent, 'width'), 10) - parseInt(getStyle(parent, 'padding-left'), 10) - parseInt(getStyle(parent, 'padding-right'), 10);

        } while( getStyle(parent, 'display') != 'block' && parent.nodeName.toLowerCase() != 'body' );

        return width + 'px';
    }

    function setMirrorStyle(mirror, element, attrs) {
        var style = $window.getComputedStyle(element[0]);
        var defaultMaxWidth = style.maxWidth === 'none' ? getParentWidth(element) : style.maxWidth;
        element.css('minWidth', attrs.puElasticInputMinwidth || style.minWidth);
        element.css('maxWidth', attrs.puElasticInputMaxwidth || defaultMaxWidth);

        angular.forEach(['fontFamily', 'fontSize', 'fontWeight', 'fontStyle',
            'letterSpacing', 'textTransform', 'wordSpacing'], function(value) {
            mirror.css(value, style[value]);
        });

        mirror.css('paddingLeft', style.textIndent);

        if (style.boxSizing === 'border-box') {
            angular.forEach(['paddingLeft', 'paddingRight',
                'borderLeftStyle', 'borderLeftWidth',
                'borderRightStyle', 'borderRightWidth'], function(value) {
                mirror.css(value, style[value]);
            });
        } else if (style.boxSizing === 'padding-box') {
            angular.forEach(['paddingLeft', 'paddingRight'], function(value) {
                mirror.css(value, style[value]);
            });
        }
    }

    return {
        restrict: 'A',
        link: function postLink(scope, element, attrs) {

            // Disable trimming inputs by default
            attrs.$set('ngTrim', attrs.ngTrim === 'true' ? 'true' : 'false');

            // Initial value of mirror is null character what should trigger initial width update
            var mirror = angular.element('<span style="white-space:pre;">&#000;</span>');
            setMirrorStyle(mirror, element, attrs);

            wrapper.append(mirror);

            function update() {

                var newValue = element.val() || attrs.placeholder || '';

                // If new value is the same value as previous one there is no need to update the styling
                if ( mirror.text() == newValue ) return;

                mirror.text( newValue );

                var delta = parseInt(attrs.puElasticInputWidthDelta) || 1;
                element.css('width', mirror.prop('offsetWidth') + delta + 'px');
            }

            update();

            scope.$watch(attrs.ngModel, update);
            element.on('keydown keyup focus input propertychange change', update);

            scope.$on('$destroy', function() {
                mirror.remove();
            });
        }
    };
}]);