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。