将Stretch控件的ToolStrip属性设置为true时，控件会从头到尾填充其容器，并在其容器调整大小时调整自身大小。 在这种配置中，你可能会发现将控件中的项（例如 ToolStripTextBox）拉伸以填充可用空间，并在控件调整大小时随之调整大小是很有用的。 例如，如果要实现类似于 Microsoft internet® Explorer 中地址栏的外观和行为，此拉伸非常有用。
示例：
下面的代码示例展示一个从 ToolStripTextBox 派生并被命名为 ToolStripSpringTextBox 的类。 此类重写GetPreferredSize方法，用于计算在减去所有其他项的组合宽度后父ToolStrip控件的可用宽度。 此代码示例还提供一个 Form 类和一个 Program 类来演示新行为。
using System;
using System.Drawing;
using System.Windows.Forms;
public class ToolStripSpringTextBox : ToolStripTextBox
{
public override Size GetPreferredSize(Size constrainingSize)
{
// Use the default size if the text box is on the overflow menu
// or is on a vertical ToolStrip.
if (IsOnOverflow || Owner.Orientation == Orientation.Vertical)
{
return DefaultSize;
}
// Declare a variable to store the total available width as
// it is calculated, starting with the display width of the
// owning ToolStrip.
Int32 width = Owner.DisplayRectangle.Width;
// Subtract the width of the overflow button if it is displayed.
if (Owner.OverflowButton.Visible)
{
width = width - Owner.OverflowButton.Width -
Owner.OverflowButton.Margin.Horizontal;
}
// Declare a variable to maintain a count of ToolStripSpringTextBox
// items currently displayed in the owning ToolStrip.
Int32 springBoxCount = 0;
foreach (ToolStripItem item in Owner.Items)
{
// Ignore items on the overflow menu.
if (item.IsOnOverflow) continue;
if (item is ToolStripSpringTextBox)
{
// For ToolStripSpringTextBox items, increment the count and
// subtract the margin width from the total available width.
springBoxCount++;
width -= item.Margin.Horizontal;
}
else
{
// For all other items, subtract the full width from the total
// available width.
width = width - item.Width - item.Margin.Horizontal;
}
}
// If there are multiple ToolStripSpringTextBox items in the owning
// ToolStrip, divide the total available width between them.
if (springBoxCount > 1) width /= springBoxCount;
// If the available width is less than the default width, use the
// default width, forcing one or more items onto the overflow menu.
if (width < DefaultSize.Width) width = DefaultSize.Width;
// Retrieve the preferred size from the base class, but change the
// width to the calculated width.
Size size = base.GetPreferredSize(constrainingSize);
size.Width = width;
return size;
}
}
public class Form1 : Form
{
public Form1()
{
ToolStrip toolStrip1 = new ToolStrip();
toolStrip1.Dock = DockStyle.Top;
toolStrip1.Items.Add(new ToolStripLabel("Address"));
toolStrip1.Items.Add(new ToolStripSpringTextBox());
toolStrip1.Items.Add(new ToolStripButton("Go"));
Controls.Add(toolStrip1);
Text = "ToolStripSpringTextBox demo";
}
}
static class Program
{
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}
}
Imports System.Drawing
Imports System.Windows.Forms
Public Class ToolStripSpringTextBox
Inherits ToolStripTextBox
Public Overrides Function GetPreferredSize( _
ByVal constrainingSize As Size) As Size
' Use the default size if the text box is on the overflow menu
' or is on a vertical ToolStrip.
If IsOnOverflow Or Owner.Orientation = Orientation.Vertical Then
Return DefaultSize
End If
' Declare a variable to store the total available width as
' it is calculated, starting with the display width of the
' owning ToolStrip.
Dim width As Int32 = Owner.DisplayRectangle.Width
' Subtract the width of the overflow button if it is displayed.
If Owner.OverflowButton.Visible Then
width = width - Owner.OverflowButton.Width - _
Owner.OverflowButton.Margin.Horizontal()
End If
' Declare a variable to maintain a count of ToolStripSpringTextBox
' items currently displayed in the owning ToolStrip.
Dim springBoxCount As Int32 = 0
For Each item As ToolStripItem In Owner.Items
' Ignore items on the overflow menu.
If item.IsOnOverflow Then Continue For
If TypeOf item Is ToolStripSpringTextBox Then
' For ToolStripSpringTextBox items, increment the count and
' subtract the margin width from the total available width.
springBoxCount += 1
width -= item.Margin.Horizontal
Else
' For all other items, subtract the full width from the total
' available width.
width = width - item.Width - item.Margin.Horizontal
End If
Next
' If there are multiple ToolStripSpringTextBox items in the owning
' ToolStrip, divide the total available width between them.
If springBoxCount > 1 Then width = CInt(width / springBoxCount)
' If the available width is less than the default width, use the
' default width, forcing one or more items onto the overflow menu.
If width < DefaultSize.Width Then width = DefaultSize.Width
' Retrieve the preferred size from the base class, but change the
' width to the calculated width.
Dim preferredSize As Size = MyBase.GetPreferredSize(constrainingSize)
preferredSize.Width = width
Return preferredSize
End Function
End Class
Public Class Form1
Inherits Form
Public Sub New()
Dim toolStrip1 As New ToolStrip()
With toolStrip1
.Dock = DockStyle.Top
.Items.Add(New ToolStripLabel("Address"))
.Items.Add(New ToolStripSpringTextBox())
.Items.Add(New ToolStripButton("Go"))
End With
Controls.Add(toolStrip1)
Text = "ToolStripSpringTextBox demo"
End Sub
End Class
Public Class Program
<STAThread()> Public Shared Sub Main()
Application.EnableVisualStyles()
Application.SetCompatibleTextRenderingDefault(False)
Application.Run(New Form1())
End Sub
End Class
编译代码
此示例需要：
- 对 System、System.Drawing 和 System.Windows.Forms 程序集的引用。
