如何：创建自定义图像按钮控件
更新：2007 年 11 月
若要创建具有图像的按钮，必须创建从 Windows 窗体 Control 类派生的自定义控件。
创建具有图像的按钮
创建一个从 System.Windows.Forms.Control 派生的类。
在类中为显示按下和未按下状态的按钮图像定义属性。
使用 Invalidate 方法使窗体在单击按钮时重绘。
重写 OnPaint 方法以绘制具有适当图像的自定义控件。
示例
此示例包含一个定义 PictureButton 自定义控件的类。它创建窗体上的控件的一个实例并定义该控件使用的位图。
Imports System
Imports System.Drawing
Imports System.Windows.Forms
Public Class PictureButtonDemo
Inherits System.Windows.Forms.Form
Friend WithEvents PictureButton1 As New PictureButton
Public Sub New()
' Display the OK close button.
Me.MinimizeBox = False
Me.Text = "Picture Button Demo"
' Create an instance of the PictureButton custom control.
With PictureButton1
.Parent = Me
.Bounds = New Rectangle(10, 30, 150, 30)
.ForeColor = Color.White
.BackgroundImageValue = MakeBitmap(Color.Blue, _
PictureButton1.Width, PictureButton1.Height)
.PressedImageValue = MakeBitmap(Color.LightBlue, _
PictureButton1.Width, PictureButton1.Height)
.Text = "Click Me"
End With
End Sub
' Clean up any resources being used.
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
MyBase.Dispose(disposing)
End Sub
' Create a bitmap object and fill it with the specified color.
' To make it look like a custom image, draw an ellipse in it.
Function MakeBitmap(ByVal ButtonColor As Color, ByVal width As Integer, _
ByVal height As Integer) As Bitmap
Dim bmp As New Bitmap(width, height)
Dim g As Graphics = Graphics.FromImage(bmp)
g.FillRectangle(New SolidBrush(ButtonColor), 0, 0, bmp.Width, bmp.Height)
g.DrawEllipse(New Pen(Color.LightGray), 3, 3, width - 6, height - 6)
g.Dispose()
Return bmp
End Function
Shared Sub Main()
Application.Run(New PictureButtonDemo)
End Sub
' Because PictureButton inherits from Control,
' you can use the default Click event.
Private Sub PictureButton1_Click(ByVal sender As Object, ByVal e As EventArgs) _
Handles PictureButton1.Click
'Add code here to respond to button click.
End Sub
End Class
'Button with an image custom control.
Public Class PictureButton
Inherits Control
Private backgroundImg As Image
Private pressedImg As Image
Private pressed As Boolean = False
' Property for the background image to be drawn behind the button text.
Public Property BackgroundImageValue() As Image
Get
Return Me.backgroundImg
End Get
Set(ByVal Value As Image)
Me.backgroundImg = Value
End Set
End Property
' Property for the background image to be drawn behind the button text when
' the button is pressed.
Public Property PressedImageValue() As Image
Get
Return Me.pressedImg
End Get
Set(ByVal Value As Image)
Me.pressedImg = Value
End Set
End Property
' When the mouse button is pressed, set the "pressed" flag to true
' and ivalidate the form to cause a repaint. The .NET Compact Framework
' sets the mouse capture automatically.
Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs)
Me.pressed = True
Me.Invalidate()
MyBase.OnMouseDown(e)
End Sub
' When the mouse is released, reset the "pressed" flag
' and invalidate to redraw the button in the unpressed state.
Protected Overrides Sub OnMouseUp(ByVal e As MouseEventArgs)
Me.pressed = False
Me.Invalidate()
MyBase.OnMouseUp(e)
End Sub
' Override the OnPaint method to draw the background image and the text.
Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
If Me.pressed AndAlso (Me.pressedImg IsNot Nothing) Then
e.Graphics.DrawImage(Me.pressedImg, 0, 0)
Else
e.Graphics.DrawImage(Me.backgroundImg, 0, 0)
End If
' Draw the text if there is any.
If Me.Text.Length > 0 Then
Dim size As SizeF = e.Graphics.MeasureString(Me.Text, Me.Font)
' Center the text inside the client area of the PictureButton.
e.Graphics.DrawString(Me.Text, Me.Font, New SolidBrush(Me.ForeColor), _
(Me.ClientSize.Width - size.Width) / 2, _
(Me.ClientSize.Height - size.Height) / 2)
End If
' Draw a border around the outside of the
' control to look like Pocket PC buttons.
e.Graphics.DrawRectangle(New Pen(Color.Black), 0, 0, _
Me.ClientSize.Width - 1, Me.ClientSize.Height - 1)
MyBase.OnPaint(e)
End Sub
End Class
using System;
using System.Drawing;
using System.Windows.Forms;
namespace PictureButton
{
public class PictureButtonDemo : System.Windows.Forms.Form
{
int clickCount = 0;
// Create a bitmap object and fill it with the specified color.
// To make it look like a custom image, draw an ellipse in it.
Bitmap MakeBitmap(Color color, int width, int height)
{
Bitmap bmp = new Bitmap(width, height);
Graphics g = Graphics.FromImage(bmp);
g.FillRectangle(new SolidBrush(color), 0, 0, bmp.Width, bmp.Height);
g.DrawEllipse(new Pen(Color.DarkGray), 3, 3, width - 6, height - 6);
g.Dispose();
return bmp;
}
// Create a new PictureButton control and hook up its properties.
public PictureButtonDemo()
{
InitializeComponent();
// Display the OK close button.
this.MinimizeBox = false;
PictureButton button = new PictureButton();
button.Parent = this;
button.Bounds = new Rectangle(10, 30, 150, 30);
button.ForeColor = Color.White;
button.BackgroundImage = MakeBitmap(Color.Blue, button.Width, button.Height);
button.PressedImage = MakeBitmap(Color.LightBlue, button.Width, button.Height);
button.Text = "click me";
button.Click +=new EventHandler(button_Click);
}
protected override void Dispose( bool disposing )
{
base.Dispose( disposing );
}
private void InitializeComponent()
{
this.Text = "Picture Button Demo";
}
static void Main()
{
Application.Run(new PictureButtonDemo());
}
// Since PictureButton inherits from Control, we can just use the default
// Click event that Control supports.
private void button_Click(object sender, EventArgs e)
{
this.Text = "Click Count = " + ++this.clickCount;
}
}
// This code shows a simple way to have a
// button-like control that has a background image.
public class PictureButton : Control
{
Image backgroundImage, pressedImage;
bool pressed = false;
// Property for the background image to be drawn behind the button text.
public Image BackgroundImage
{
get
{
return this.backgroundImage;
}
set
{
this.backgroundImage = value;
}
}
// Property for the background image to be drawn behind the button text when
// the button is pressed.
public Image PressedImage
{
get
{
return this.pressedImage;
}
set
{
this.pressedImage = value;
}
}
// When the mouse button is pressed, set the "pressed" flag to true
// and invalidate the form to cause a repaint. The .NET Compact Framework
// sets the mouse capture automatically.
protected override void OnMouseDown(MouseEventArgs e)
{
this.pressed = true;
this.Invalidate();
base.OnMouseDown (e);
}
// When the mouse is released, reset the "pressed" flag
// and invalidate to redraw the button in the unpressed state.
protected override void OnMouseUp(MouseEventArgs e)
{
this.pressed = false;
this.Invalidate();
base.OnMouseUp (e);
}
// Override the OnPaint method to draw the background image and the text.
protected override void OnPaint(PaintEventArgs e)
{
if(this.pressed && this.pressedImage != null)
e.Graphics.DrawImage(this.pressedImage, 0, 0);
else
e.Graphics.DrawImage(this.backgroundImage, 0, 0);
// Draw the text if there is any.
if(this.Text.Length > 0)
{
SizeF size = e.Graphics.MeasureString(this.Text, this.Font);
// Center the text inside the client area of the PictureButton.
e.Graphics.DrawString(this.Text,
this.Font,
new SolidBrush(this.ForeColor),
(this.ClientSize.Width - size.Width) / 2,
(this.ClientSize.Height - size.Height) / 2);
}
// Draw a border around the outside of the
// control to look like Pocket PC buttons.
e.Graphics.DrawRectangle(new Pen(Color.Black), 0, 0,
this.ClientSize.Width - 1, this.ClientSize.Height - 1);
base.OnPaint(e);
}
}
}
编译代码
此示例需要引用下面的命名空间：