扩展Ext2类 Extending Ext2 Class

Tutorial:Extending Ext2 Class (Chinese)

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Summary: 本文为您介绍扩展EXT组件类所需的几个步骤。

Author: Jozef Sakalos(译者：Frank Chueng)

Published: January 2, 2008

Ext Version: 2.0+

Languages:

English

Korean

Chinese

[hide]

实现的目的

预期将是这样的IconCombo

要创建的扩展是一个在文字前面能够显示图标的这么一个Ext.form.Combobox。将其中一个功能举例来说，就是要在一块选择里，国家名称连同国旗一并出现。

我们先给扩展起个名字，就叫Ext.ux.IconCombo。

A note for those who were used to Ext 1.x

Extending Ext classes has not been difficult in Ext 1.x but it is even easier in Ext 2.x and the whole matter has not dramatically changed. You can even use the same procedure in Ext 2.x as you have used in Ext 1.x. However, every line of code you don't need to type contributes to code maintainability, readability and reduces number of possible bugs. Therefore, I'll show the easiest, simplest and shortest method here.

文件的创建

首要的步骤是准备好开发中将会使用的文件。需下列文件：

iconcombo.html: 新扩展将会使用的 html markup
iconcombo.js: 程序javascript代码
Ext.ux.IconCombo.js: 扩展的javascript文件
Ext.ux.IconCombo.css: 扩展样式表

iconcombo.html

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
    "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    <link rel="stylesheet" type="text/css" href="../extjs/resources/css/ext-all.css">
    <link rel="stylesheet" type="text/css" href="Ext.ux.IconCombo.css">
    <script type="text/javascript" src="../extjs/adapter/ext/ext-base.js"></script>
    <script type="text/javascript" src="../extjs/ext-all-debug.js"></script>
    <script type="text/javascript" src="Ext.ux.IconCombo.js"></script>
    <script type="text/javascript" src="iconcombo.js"></script>
    <!-- A Localization Script File comes here -->
    <script type="text/javascript">Ext.onReady(iconcombo.init, iconcombo);</script>
    <title>Ext.ux.IconCombo Tutorial</title>
</head>
<body>
<div style="position:relative;300px;top:24px;left:64px;font-size:11px">
    <div>Icon combo:</div>
    <div id="combo-ct"></div>
</div>
</body>
</html>

该文件来自教程Ext程序规划入门的轻微修改。

iconcombo.js

/**
  * Ext.ux.IconCombo Tutorial
  * by Jozef Sakalos, aka Saki
  * http://extjs.com/learn/Tutorial:Extending_Ext_Class
  */
 
// 引用本地空白文件
Ext.BLANK_IMAGE_URL = '../extjs/resources/images/default/s.gif';
 
// 创建程序
iconcombo = function() {
 
    // 公共空间
    return {
        // public properties, e.g. strings to translate
 
        // public methods
        init: function() {
            var icnCombo = new Ext.ux.IconCombo({
                store: new Ext.data.SimpleStore({
                    fields: ['countryCode', 'countryName', 'countryFlag'],
                    data: [
                        ['US', 'United States', 'x-flag-us'],
                        ['DE', 'Germany', 'x-flag-de'],
                        ['FR', 'France', 'x-flag-fr']
                    ]
                }),
                valueField: 'countryCode',
                displayField: 'countryName',
                iconClsField: 'countryFlag',
                triggerAction: 'all',
                mode: 'local',
                 160
            });
            icnCombo.render('combo-ct');
            icnCombo.setValue('DE');
        }
    };
}(); // end of app
 
// end of file

我们在这个文件中创建IconCombo，以便可以进行扩展和测试。

Ext.ux.IconCombo.js

// Create创建用户的扩展（User eXtensions namespace (Ext.ux)）
Ext.namespace('Ext.ux');
 
/**
  * Ext.ux.IconCombo 扩展类
  *
  * @author Jozef Sakalos, aka Saki
  * @version 1.0
  *
  * @class Ext.ux.IconCombo
  * @extends Ext.form.ComboBox
  * @constructor
  * @param {Object} config 配置项参数
  */
Ext.ux.IconCombo = function(config) {
 
    // 调用父类的构建函数
    Ext.ux.IconCombo.superclass.constructor.call(this, config);
 
} // Ext.ux.IconCombo构建器的底部
 
// 进行扩展
Ext.extend(Ext.ux.IconCombo, Ext.form.ComboBox, {
 
}); // 扩展完毕
 
// 文件底部

运行到这一步，实际这是一个没有对Ext.form.ComboBox新加任何东西的空扩展。我们正是需要这个完成好的空扩展，再继续下一步。

Ext.ux.IconCombo.css

.x-flag-us {
    background-image: url(../img/flags/us.png);
}
.x-flag-de {
    background-image: url(../img/flags/de.png);
}
.x-flag-fr {
    background-image: url(../img/flags/fr.png);
}

路径可能根据你所在的国旗放置目录有所不同。国旗的资源可在here下载。

Let's go

So far so good！如果你浏览iconcombo.html应该会发现一个包含三个选项的标准combo,而德国的那个是选中的...是吧？不过还没有图标...

现在正是开始工作。在调用父类构建器之后加入下列行：

this.tpl = config.tpl ||
      '<div class="x-combo-list-item">'
    + '<table><tbody><tr>'
    + '<td>'
    + '<div class="{' + this.iconClsField + '} x-icon-combo-icon"></div></td>'
    + '<td>{' + this.displayField + '}</td>'
    + '</tr></tbody></table>'
    + '</div>'
;

在这一步，我们将默认combox box的模版重写为iconClsField模版。

现在加入Ext.ux.IconCombo.css中的样式文件：

.x-icon-combo-icon {
    background-repeat: no-repeat;
    background-position: 0 50%;
    width: 18px;
    height: 14px;
}

不错！可以测试一下了，刷新的页面，还好吧！？嗯，列表展开时那些漂亮的图标就出来了。。还有。。我们不是要在关闭时也出现图标的吗？

在构建器中加入创建模版的过程：

this.on({
    render:{scope:this, fn:function() {
        var wrap = this.el.up('div.x-form-field-wrap');
        this.wrap.applyStyles({position:'relative'});
        this.el.addClass('x-icon-combo-input');
        this.flag = Ext.DomHelper.append(wrap, {
            tag: 'div', style:'position:absolute'
        });
    }}
});

加入 事件render的侦听器，用于调整元素样式和创建国旗的div容器。如后按照下列方式进行扩展：

// 进行扩展
Ext.extend(Ext.ux.IconCombo, Ext.form.ComboBox, {
 
    setIconCls: function() {
        var rec = this.store.query(this.valueField, this.getValue()).itemAt(0);
        if(rec) {
            this.flag.className = 'x-icon-combo-icon ' + rec.get(this.iconClsField);
        }
    },
 
    setValue: function(value) {
        Ext.ux.IconCombo.superclass.setValue.call(this, value);
        this.setIconCls();
    }
 
}); // 扩展完毕

新增 setIconCls函数并重写setValue函数。我们还是需要父类的setValue的方法来调用一下，接着再调用setIconCls的函数。最后，我们应该在文件Ext.ux.IconCombo.css加入下列代码：

.x-icon-combo-input {
    padding-left: 26px;
}
.x-form-field-wrap .x-icon-combo-icon {
    top: 3px;
    left: 6px;
}

完成

最后再刷新一下，如果一切顺利，那这个就是新的Ext.ux.IconCombo扩展！希望你能在此基础上扩展更多的组件！

谢谢Brian Moeskau提醒，使得能进一步精简Ext.ux.IconCombo 代码，才称得上最终版本。最终代码和CSS为：

Ext.ux.IconCombo.js

// Create user extensions namespace (Ext.ux)
Ext.namespace('Ext.ux');
 
/**
  * Ext.ux.IconCombo Extension Class
  *
  * @author  Jozef Sakalos
  * @version 1.0
  *
  * @class Ext.ux.IconCombo
  * @extends Ext.form.ComboBox
  * @constructor
  * @param {Object} config Configuration options
  */
Ext.ux.IconCombo = function(config) {
 
    // call parent constructor
    Ext.ux.IconCombo.superclass.constructor.call(this, config);
 
    this.tpl = config.tpl ||
          '<div class="x-combo-list-item x-icon-combo-item {' 
        + this.iconClsField 
        + '}">{' 
        + this.displayField 
        + '}</div>'
    ;
 
    this.on({
        render:{scope:this, fn:function() {
            var wrap = this.el.up('div.x-form-field-wrap');
            this.wrap.applyStyles({position:'relative'});
            this.el.addClass('x-icon-combo-input');
            this.flag = Ext.DomHelper.append(wrap, {
                tag: 'div', style:'position:absolute'
            });
        }}
    });
} // end of Ext.ux.IconCombo constructor
 
// extend
Ext.extend(Ext.ux.IconCombo, Ext.form.ComboBox, {
 
    setIconCls: function() {
        var rec = this.store.query(this.valueField, this.getValue()).itemAt(0);
        if(rec) {
            this.flag.className = 'x-icon-combo-icon ' + rec.get(this.iconClsField);
        }
    },
 
    setValue: function(value) {
        Ext.ux.IconCombo.superclass.setValue.call(this, value);
        this.setIconCls();
    }
 
}); // end of extend
 
// end of file

Ext.ux.IconCombo.css

/* application specific styles */
.x-flag-us {
    background-image:url(../img/flags/us.png);
}
.x-flag-de {
    background-image:url(../img/flags/de.png);
}
.x-flag-fr {
    background-image:url(../img/flags/fr.png);
}
 
/* Ext.ux.IconCombo mandatory styles */
.x-icon-combo-icon {
    background-repeat: no-repeat;
    background-position: 0 50%;
    width: 18px;
    height: 14px;
}
.x-icon-combo-input {
    padding-left: 25px;
}
.x-form-field-wrap .x-icon-combo-icon {
    top: 3px;
    left: 5px;
}
.x-icon-combo-item {
    background-repeat: no-repeat;
    background-position: 3px 50%;
    padding-left: 24px;
}

Retrieved from "http://extjs.com/learn/Tutorial:Extending_Ext2_Class_%28Chinese%29"

扩展Ext2类 Extending Ext2 Class

Tutorial:Extending Ext2 Class (Chinese)

From Learn About the Ext JavaScript Library

Contents

实现的目的

A note for those who were used to Ext 1.x

文件的创建

iconcombo.html

iconcombo.js

Ext.ux.IconCombo.js

Ext.ux.IconCombo.css

Let's go

完成

Ext.ux.IconCombo.js

Ext.ux.IconCombo.css