【WinForm窗体控件开发】之二 简单的窗体控件

我们做一个简单的例子：

下面是继承自Control类的自定义窗体控件的代码：

 

FirstControl继承控件代码

using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms;

namespace 之二简单的窗体控件Demo
{
public class FirstControl:Control
{
/// <summary>
/// Constructor
/// </summary>
public FirstControl() { }

#region FirstControl 使用该属性来设置从 Control 继承的 Text 属性的显示格式
// ContentAlignment is an enumeration defined in the System.Drawing
// namespace that specifies the alignment of content on a drawing
// surface.
private ContentAlignment alignmentValue = ContentAlignment.MiddleLeft;

[
Category( " Alignment " ),
Description( " Specifies the alignment of text. " )
]
public ContentAlignment TextAlignment
{
get
{
return alignmentValue;
}
set
{
alignmentValue = value;

// The Invalidate method invokes the OnPaint method described
// in step 3.

// 在设置更改控件可视显示的属性时，必须调用 Invalidate 方法来重新绘制该控件。
// Invalidate 是在 Control 基类中定义的。
Invalidate();
}
}
#endregion


/// <summary>
/// 重写从 Control 继承的受保护的 OnPaint 方法，以便为控件提供呈现逻辑。
/// 如果不改写 OnPaint，您的控件将无法自行绘制。
/// 在下面的代码片段中，OnPaint 方法显示从 Control 继承的 Text 属性，并使用 alignmentValue 字段指定的对齐方式。
/// </summary>
protected override void OnPaint(PaintEventArgs e)
{
base .OnPaint(e);

StringFormat style = new StringFormat();
style.Alignment = StringAlignment.Near;

switch (alignmentValue)
{
case ContentAlignment.MiddleLeft:
style.Alignment = StringAlignment.Near;
break ;
case ContentAlignment.MiddleRight:
style.Alignment = StringAlignment.Far;
break ;
case ContentAlignment.MiddleCenter:
style.Alignment = StringAlignment.Center;
break ;
}

// Call the DrawString method of the System.Drawing class to write text.
// Text and ClientRectangle are properties inherited from Control.
e.Graphics.DrawString(
Text,
Font,
new SolidBrush(ForeColor),
ClientRectangle, style);

}
}
}

 

 

 

窗体代码：

namespace 之二简单的窗体控件Demo
{
partial class Form1
{
/// <summary>
/// Required designer variable.
/// </summary>
private System.ComponentModel.IContainer components = null ;

/// <summary>
/// Clean up any resources being used.
/// </summary>
/// <param name="disposing"> true if managed resources should be disposed; otherwise, false. </param>
protected override void Dispose( bool disposing)
{
if (disposing && (components != null ))
{
components.Dispose();
}
base .Dispose(disposing);
}

#region Windows Form Designer generated code

/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
private void InitializeComponent()
{
this .firstControl1 = new 之二简单的窗体控件Demo.FirstControl();
this .firstControl2 = new 之二简单的窗体控件Demo.FirstControl();
this .firstControl3 = new 之二简单的窗体控件Demo.FirstControl();
this .SuspendLayout();
//
// firstControl1
//
this .firstControl1.Location = new System.Drawing.Point( 12 , 24 );
this .firstControl1.Name = " firstControl1 " ;
this .firstControl1.Size = new System.Drawing.Size( 122 , 21 );
this .firstControl1.TabIndex = 0 ;
this .firstControl1.Text = " firstControl1 " ;
this .firstControl1.TextAlignment = System.Drawing.ContentAlignment.MiddleLeft;
//
// firstControl2
//
this .firstControl2.Location = new System.Drawing.Point( 12 , 51 );
this .firstControl2.Name = " firstControl2 " ;
this .firstControl2.Size = new System.Drawing.Size( 122 , 23 );
this .firstControl2.TabIndex = 1 ;
this .firstControl2.Text = " firstControl2 " ;
this .firstControl2.TextAlignment = System.Drawing.ContentAlignment.MiddleCenter;
//
// firstControl3
//
this .firstControl3.Location = new System.Drawing.Point( 12 , 80 );
this .firstControl3.Name = " firstControl3 " ;
this .firstControl3.Size = new System.Drawing.Size( 122 , 23 );
this .firstControl3.TabIndex = 2 ;
this .firstControl3.Text = " firstControl3 " ;
this .firstControl3.TextAlignment = System.Drawing.ContentAlignment.MiddleRight;
//
// Form1
//
this .AutoScaleDimensions = new System.Drawing.SizeF(6F, 12F);
this .AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
this .ClientSize = new System.Drawing.Size( 214 , 182 );
this .Controls.Add( this .firstControl3);
this .Controls.Add( this .firstControl2);
this .Controls.Add( this .firstControl1);
this .Name = " Form1 " ;
this .Text = " Form1 " ;
this .Load += new System.EventHandler( this .Form1_Load);
this .ResumeLayout( false );

}

#endregion

private FirstControl firstControl1;
private FirstControl firstControl2;
private FirstControl firstControl3;
}
}

效果图：

控件编译后会在Toolbox工具箱中出现一个齿轮样子的小工具，直接在Form窗体上使用即可；

注意属性栏中最下面一个TextAligment属性，这是我们自己为FirstControl控件添加的属性

关于控件的常用的Attribute的详细介绍我们在下一节中进行详细介绍。

 

转载于:https://www.cnblogs.com/bobbychencj/archive/2010/11/29/1891564.html