MeasureItemEventArgs.ItemWidth 屬性
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
取得或設定 Index 所指定的項目寬度。
public:
property int ItemWidth { int get(); void set(int value); };public int ItemWidth { get; set; }member this.ItemWidth : int with get, setPublic Property ItemWidth As Integer屬性值
測得的項目寬度。
範例
下列程式碼範例示範如何使用 Graphics 屬性來執行 中 ListBox 專案的自訂繪圖。
public ref class Form1: public System::Windows::Forms::Form
{
private:
System::Windows::Forms::ListBox^ listBox1;
System::ComponentModel::Container^ components;
public:
~Form1()
{
if ( components != nullptr )
{
delete components;
}
}
private:
/// <summary>
/// Required method for Designer support - do not modify
/// the contents of this method with the code editor.
/// </summary>
void InitializeComponent()
{
this->listBox1 = gcnew System::Windows::Forms::ListBox;
this->SuspendLayout();
//
// listBox1
//
this->listBox1->DrawMode = System::Windows::Forms::DrawMode::OwnerDrawVariable;
this->listBox1->Location = System::Drawing::Point( 16, 48 );
this->listBox1->Name = "listBox1";
this->listBox1->SelectionMode = System::Windows::Forms::SelectionMode::MultiExtended;
this->listBox1->Size = System::Drawing::Size( 256, 134 );
this->listBox1->TabIndex = 0;
this->listBox1->MeasureItem += gcnew System::Windows::Forms::MeasureItemEventHandler( this, &Form1::listBox1_MeasureItem );
this->listBox1->DrawItem += gcnew System::Windows::Forms::DrawItemEventHandler( this, &Form1::listBox1_DrawItem );
//
// Form1
//
this->ClientSize = System::Drawing::Size( 292, 273 );
array<System::Windows::Forms::Control^>^temp0 = {this->listBox1};
this->Controls->AddRange( temp0 );
this->Name = "Form1";
this->Text = "Form1";
this->ResumeLayout( false );
}
void listBox1_MeasureItem( Object^ /*sender*/, MeasureItemEventArgs^ e )
{
System::Drawing::Font^ font = (dynamic_cast<ListBoxFontItem^>(listBox1->Items[ e->Index ]))->Font;
SizeF stringSize = e->Graphics->MeasureString( font->Name, font );
// Set the height and width of the item
e->ItemHeight = (int)stringSize.Height;
e->ItemWidth = (int)stringSize.Width;
}
// For efficiency, cache the brush to use for drawing.
SolidBrush^ foreColorBrush;
void listBox1_DrawItem( Object^ /*sender*/, DrawItemEventArgs^ e )
{
Brush^ brush;
// Create the brush using the ForeColor specified by the DrawItemEventArgs
if ( foreColorBrush == nullptr )
foreColorBrush = gcnew SolidBrush( e->ForeColor );
else
if ( foreColorBrush->Color != e->ForeColor )
{
// The control's ForeColor has changed, so dispose of the cached brush and
// create a new one.
delete foreColorBrush;
foreColorBrush = gcnew SolidBrush( e->ForeColor );
}
// Select the appropriate brush depending on if the item is selected.
// Since State can be a combinateion (bit-flag) of enum values, you can't use
// "==" to compare them.
if ( (e->State & DrawItemState::Selected) == DrawItemState::Selected )
brush = SystemBrushes::HighlightText;
else
brush = foreColorBrush;
// Perform the painting.
System::Drawing::Font^ font = (dynamic_cast<ListBoxFontItem^>(listBox1->Items[ e->Index ]))->Font;
e->DrawBackground();
e->Graphics->DrawString( font->Name, font, brush, e->Bounds );
e->DrawFocusRectangle();
}
public:
/// <summary>
/// A wrapper class for use with storing Fonts in a ListBox. Since ListBox uses the
/// ToString() of its items for the text it displays, this class is needed to return
/// the name of the font, rather than its ToString() value.
/// </summary>
ref class ListBoxFontItem
{
public:
System::Drawing::Font^ Font;
ListBoxFontItem( System::Drawing::Font^ f )
{
Font = f;
}
virtual String^ ToString() override
{
return Font->Name;
}
};
};
[STAThread]
int main()
{
Application::Run( gcnew Form1 );
}
public class Form1 : System.Windows.Forms.Form
{
private System.Windows.Forms.ListBox listBox1;
private System.ComponentModel.Container components = null;
protected override void Dispose(bool disposing)
{
if( disposing )
{
if ( components != null )
components.Dispose();
if ( foreColorBrush != null )
foreColorBrush.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.listBox1 = new System.Windows.Forms.ListBox();
this.SuspendLayout();
//
// listBox1
//
this.listBox1.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawVariable;
this.listBox1.Location = new System.Drawing.Point(16, 48);
this.listBox1.Name = "listBox1";
this.listBox1.SelectionMode = System.Windows.Forms.SelectionMode.MultiExtended;
this.listBox1.Size = new System.Drawing.Size(256, 134);
this.listBox1.TabIndex = 0;
this.listBox1.MeasureItem += new System.Windows.Forms.MeasureItemEventHandler(this.listBox1_MeasureItem);
this.listBox1.DrawItem += new System.Windows.Forms.DrawItemEventHandler(this.listBox1_DrawItem);
//
// Form1
//
this.ClientSize = new System.Drawing.Size(292, 273);
this.Controls.AddRange(new System.Windows.Forms.Control[] {
this.listBox1});
this.Name = "Form1";
this.Text = "Form1";
this.ResumeLayout(false);
}
#endregion
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
private void listBox1_MeasureItem(object sender, System.Windows.Forms.MeasureItemEventArgs e)
{
Font font = ((ListBoxFontItem)listBox1.Items[e.Index]).Font;
SizeF stringSize = e.Graphics.MeasureString(font.Name, font);
// Set the height and width of the item
e.ItemHeight = (int)stringSize.Height;
e.ItemWidth = (int)stringSize.Width;
}
// For efficiency, cache the brush to use for drawing.
private SolidBrush foreColorBrush;
private void listBox1_DrawItem(object sender, System.Windows.Forms.DrawItemEventArgs e)
{
Brush brush;
// Create the brush using the ForeColor specified by the DrawItemEventArgs
if ( foreColorBrush == null )
{
foreColorBrush = new SolidBrush(e.ForeColor);
}
else if ( foreColorBrush.Color != e.ForeColor )
{
// The control's ForeColor has changed, so dispose of the cached brush and
// create a new one.
foreColorBrush.Dispose();
foreColorBrush = new SolidBrush(e.ForeColor);
}
// Select the appropriate brush depending on if the item is selected.
// Since State can be a combinateion (bit-flag) of enum values, you can't use
// "==" to compare them.
if ( (e.State & DrawItemState.Selected) == DrawItemState.Selected )
brush = SystemBrushes.HighlightText;
else
brush = foreColorBrush;
// Perform the painting.
Font font = ((ListBoxFontItem)listBox1.Items[e.Index]).Font;
e.DrawBackground();
e.Graphics.DrawString(font.Name, font, brush, e.Bounds);
e.DrawFocusRectangle();
}
/// <summary>
/// A wrapper class for use with storing Fonts in a ListBox. Since ListBox uses the
/// ToString() of its items for the text it displays, this class is needed to return
/// the name of the font, rather than its ToString() value.
/// </summary>
public class ListBoxFontItem
{
public Font Font;
public ListBoxFontItem(Font f)
{
Font = f;
}
public override string ToString()
{
return Font.Name;
}
}
}
Public Class Form1
Inherits System.Windows.Forms.Form
Private WithEvents listBox1 As System.Windows.Forms.ListBox
Private components As System.ComponentModel.Container = Nothing
Private FontSize As Single = 12.0F
'
' This sample displays a ListBox that contains a list of all the fonts
' installed on the system and draws each item in its respective font.
'
Public Sub New()
InitializeComponent()
' Populate control with the fonts installed on the system.
Dim families As FontFamily() = FontFamily.Families
Dim family As FontFamily
For Each family In families
Dim style As FontStyle = FontStyle.Regular
' Monotype Corsiva is only available in italic
If family.Name = "Monotype Corsiva" Then
style = style Or FontStyle.Italic
End If
listBox1.Items.Add(New ListBoxFontItem(New Font(family.Name, FontSize, style, GraphicsUnit.Point)))
Next family
End Sub
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
If disposing Then
If (components IsNot Nothing) Then
components.Dispose()
End If
If (foreColorBrush IsNot Nothing) Then
foreColorBrush.Dispose()
End If
End If
MyBase.Dispose(disposing)
End Sub
Private Sub InitializeComponent()
Me.listBox1 = New System.Windows.Forms.ListBox()
Me.SuspendLayout()
'
' listBox1
'
Me.listBox1.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawVariable
Me.listBox1.Location = New System.Drawing.Point(16, 48)
Me.listBox1.Name = "listBox1"
Me.listBox1.SelectionMode = System.Windows.Forms.SelectionMode.MultiExtended
Me.listBox1.Size = New System.Drawing.Size(256, 134)
Me.listBox1.TabIndex = 0
'
' Form1
'
Me.ClientSize = New System.Drawing.Size(292, 273)
Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.listBox1})
Me.Name = "Form1"
Me.Text = "Form1"
Me.ResumeLayout(False)
End Sub
<STAThread()> Shared Sub Main()
Application.Run(New Form1())
End Sub
Private Sub listBox1_MeasureItem(ByVal sender As Object, ByVal e As System.Windows.Forms.MeasureItemEventArgs) Handles listBox1.MeasureItem
Dim font As Font = CType(listBox1.Items(e.Index), ListBoxFontItem).Font
Dim stringSize As SizeF = e.Graphics.MeasureString(font.Name, font)
' Set the height and width of the item
e.ItemHeight = CInt(stringSize.Height)
e.ItemWidth = CInt(stringSize.Width)
End Sub
' For efficiency, cache the brush used for drawing.
Private foreColorBrush As SolidBrush
Private Sub listBox1_DrawItem(ByVal sender As Object, ByVal e As System.Windows.Forms.DrawItemEventArgs) Handles listBox1.DrawItem
Dim brush As Brush
' Create the brush using the ForeColor specified by the DrawItemEventArgs
If foreColorBrush Is Nothing Then
foreColorBrush = New SolidBrush(e.ForeColor)
Else
If Not foreColorBrush.Color.Equals(e.ForeColor) Then
' The control's ForeColor has changed, so dispose of the cached brush and
' create a new one.
foreColorBrush.Dispose()
foreColorBrush = New SolidBrush(e.ForeColor)
End If
End If
' Select the appropriate brush depending on if the item is selected.
' Since State can be a combinateion (bit-flag) of enum values, you can't use
' "==" to compare them.
If (e.State And DrawItemState.Selected) = DrawItemState.Selected Then
brush = SystemBrushes.HighlightText
Else
brush = foreColorBrush
End If
' Perform the painting.
Dim font As Font = CType(listBox1.Items(e.Index), ListBoxFontItem).Font
e.DrawBackground()
e.Graphics.DrawString(font.Name, font, brush, e.Bounds.X, e.Bounds.Y)
e.DrawFocusRectangle()
End Sub
'
' A wrapper class for use with storing Fonts in a ListBox. Since ListBox uses the
' ToString() of its items for the text it displays, this class is needed to return
' the name of the font, rather than its ToString() value.
'
Public Class ListBoxFontItem
Public Font As Font
Public Sub New(ByVal f As Font)
Font = f
End Sub
Public Overrides Function ToString() As String
Return Font.Name
End Function
End Class
End Class
備註
這個成員只能由 MenuItem 使用。 您可以使用這個屬性來確保功能表至少與功能表清單中的最寬功能表項目一樣寬。