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php爱好者> php文档>.NET快速开发实践之应用IExtenderProvider实现控件焦点跳转

.NET快速开发实践之应用IExtenderProvider实现控件焦点跳转

时间:2010-08-17  来源:魏琼东

         我在前面的.NET快速开发实践中的IExtenderProvider扩展组件和其他两篇Post介绍了IExtenderProvider扩展编程模式和应用IExtenderProvider实现实体与对象的做法与例子,下面我为介绍一下在管理信息系统开发中一个常用的功能,控件的输入焦点跳转,我们知道,系统为我们提供了Tab和Shift+Tab切换输入焦点的功能,但是这里面有一个问题,即最终操作者最不习惯于使用Tab进行切换输入焦点,因为都已经习惯于无鼠标操作,常使用回车,上下方向键进行操作以实现焦点切换。

         那么我们如何实现这样的功能,最普通的方法是处理输入控件的KeyDown事件,判读按键是否满足跳转:例如

        private void tbName_KeyDown(object sender, KeyEventArgs e)
        {
            if(e.KeyCode == Keys.Enter) //回车向下一焦点跳转
                        {
                this.tbInputCode1.Focus();
                        }
            else if(e.KeyCode == Keys.Up) //向上键向上一焦点跳转
                        {
                this.tbCode.Focus();
        }

         这样的做法,我们就必须重写所有输入控件的KeyDown事件,效率低下,也影响代码的美观,我们可以通过应用应用IExtenderProvider实现另一种方式,即把这样的功能封装在一个名字叫ControlFocus的组件中:

    [ToolboxItem(true)]
    [Description("控制焦点跳转组件")]
        [ProvideProperty( "NextControl", typeof(Control)) ]
    [ProvideProperty("PreviousControl", typeof(Control))]
        public class ControlFocus:Component, IExtenderProvider
        {
        Dictionary<Control, Control> _NextFocus = new Dictionary<Control, Control>();
        Dictionary<Control, Control> _PreviousFocus = new Dictionary<Control, Control>();

        private Keys [] nextKeys;
        private Keys[] previousKeys;

                public ControlFocus()
                {
                        
                }
        
        public ControlFocus(System.ComponentModel.IContainer container)
        {
            container.Add(this);
        }

        [Category("焦点跳转")]
        [Description("获取/设置向前跳转按键集合")]
        public Keys[] NextKeys
        {
            get
            {
                return this.nextKeys;
            }
            set
            {
                this.nextKeys = value;
            }
        }

        [Category("焦点跳转")]
        [Description("获取/设置向后跳转按键集合")]
        public Keys[] PreviousKeys
        {
            get
            {
                return this.previousKeys;
            }
            set
            {
                this.previousKeys = value;
            }
        }

        [Category("焦点跳转")]
        [Description("获取/设置向前跳转控件")]
        public System.Windows.Forms.Control GetNextControl(Control control)
        {
            if (_NextFocus.ContainsKey(control))
            {
                return _NextFocus[control];
            }
            return null;
        }

        public void SetNextControl(Control control, Control nextControl)
                {
            if (_NextFocus.ContainsKey(control) != true)
                        {
                                _NextFocus.Add(control,nextControl);
                control.KeyDown += new KeyEventHandler(Control_KeyDown);
                        }
                        else
                        {
                                _NextFocus[control] = nextControl;
                        }
                }

        [Category("焦点跳转")]
        [Description("获取/设置向后跳转控件")]
        public Control GetPreviousControl(Control control)
        {
            if (_PreviousFocus.ContainsKey(control))
            {
                return (System.Windows.Forms.Control)_PreviousFocus[control];
            }
            return null;
        }

        public void SetPreviousControl(Control control, Control previousControl)
                {
            if (_PreviousFocus.ContainsKey(control) != true)
                        {
                                _PreviousFocus.Add(control,previousControl);
                control.KeyDown += new KeyEventHandler(Control_KeyDown);
                        }
                        else
                        {
                                _PreviousFocus[control] = previousControl;
                        }
                }        

                private void Control_KeyDown(object sender, KeyEventArgs e)
                {
                        if(NextKeysContains(e.KeyCode))
                        {
                          Control nextControl = this.GetNextControl((Control)sender);
                                if(nextControl != null && nextControl.CanFocus)
                                        nextControl.Focus();
                        }
            else if (PreviousKeysContains(e.KeyCode))
                        {
                           Control previousControl = this.GetPreviousControl((Control)sender);
                                if(previousControl != null && previousControl.CanFocus)
                                        previousControl.Focus();
                        }            
                }

        internal bool NextKeysContains(Keys k)
        {
            if (this.nextKeys == null)
                return false;

            for (int i = 0; i < this.nextKeys.Length; i++)
            {
                if (this.nextKeys[i] == k)
                    return true;
            }

            return false;
        }

        internal bool PreviousKeysContains(Keys k)
        {
            if (this.previousKeys == null)
                return false;

            for (int i = 0; i < this.previousKeys.Length; i++)
            {
                if (this.previousKeys[i] == k)
                    return true;
            }

            return false;
        }

        #region IExtenderProvider 成员

        bool IExtenderProvider.CanExtend(object component)
        {
            if (component is Control && !(component is Form))
            {
                return true;
            }

            return false;
        }

        #endregion
    }

         下面我们来看看如何应用ControlFocus,拖出一个ControlFocus设置跳转按键值,可以通过属性窗口,也可以通过代码:

        public DiagnosisEditor()
        {
            InitializeComponent();
            
            this.controlFocus1.NextKeys = new Keys[] {Keys.Enter,Keys.PageDown};
            this.controlFocus1.PreviousKeys = new Keys [] {Keys.PageUp};
        }

         下面设置输入控件的焦点跳转顺序,需要为每个控件设置下一个焦点控件和前一焦点控件:

         我做了一个简单的demo,请下载Exam.DataUIMapper.rar。

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