SystemInformation.DragSize SystemInformation.DragSize SystemInformation.DragSize SystemInformation.DragSize Property

Definizione

Ottiene la larghezza e l'altezza di un rettangolo allineato al centro rispetto al punto in cui è stato premuto il pulsante del mouse, all'interno del quale non verrà avviata un'operazione di trascinamento.Gets the width and height of a rectangle centered on the point the mouse button was pressed, within which a drag operation will not begin.

public:
 static property System::Drawing::Size DragSize { System::Drawing::Size get(); };
public static System.Drawing.Size DragSize { get; }
member this.DragSize : System.Drawing.Size
Public Shared ReadOnly Property DragSize As Size

Valore della proprietà

Oggetto Size che specifica l'area, in pixel, di un rettangolo allineato al centro rispetto al punto in cui è stato premuto il pulsante del mouse, all'interno del quale non verrà avviata un'operazione di trascinamento.A Size that specifies the area of a rectangle, in pixels, centered on the point the mouse button was pressed, within which a drag operation will not begin.

Esempi

Nell'esempio di codice seguente vengono elencate tutte le SystemInformation proprietà della classe ListBox in un oggetto e viene visualizzato il valore corrente della TextBox proprietà in un oggetto quando viene selezionato un elemento dell'elenco.The following code example lists all properties of the SystemInformation class in a ListBox and displays the current value of the property in a TextBox when a list item selected.

#using <System.Windows.Forms.dll>
#using <System.Drawing.dll>
#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::ComponentModel;
using namespace System::Drawing;
using namespace System::Reflection;
using namespace System::Windows::Forms;
public ref class SystemInfoBrowserForm: public System::Windows::Forms::Form
{
private:
   System::Windows::Forms::ListBox^ listBox1;
   System::Windows::Forms::TextBox^ textBox1;

public:
   SystemInfoBrowserForm()
   {
      this->SuspendLayout();
      InitForm();
      
      // Add each property of the SystemInformation class to the list box.
      Type^ t = System::Windows::Forms::SystemInformation::typeid;
      array<PropertyInfo^>^pi = t->GetProperties();
      for ( int i = 0; i < pi->Length; i++ )
         listBox1->Items->Add( pi[ i ]->Name );
      textBox1->Text = String::Format( "The SystemInformation class has {0} properties.\r\n", pi->Length );
      
      // Configure the list item selected handler for the list box to invoke a 
      // method that displays the value of each property.
      listBox1->SelectedIndexChanged += gcnew EventHandler( this, &SystemInfoBrowserForm::listBox1_SelectedIndexChanged );
      this->ResumeLayout( false );
   }


private:
   void listBox1_SelectedIndexChanged( Object^ /*sender*/, EventArgs^ /*e*/ )
   {
      
      // Return if no list item is selected.
      if ( listBox1->SelectedIndex == -1 )
            return;

      
      // Get the property name from the list item.
      String^ propname = listBox1->Text;
      if ( propname->Equals( "PowerStatus" ) )
      {
         
         // Cycle and display the values of each property of the PowerStatus property.
         textBox1->Text = String::Concat( textBox1->Text, "\r\nThe value of the PowerStatus property is:" );
         Type^ t = System::Windows::Forms::PowerStatus::typeid;
         array<PropertyInfo^>^pi = t->GetProperties();
         for ( int i = 0; i < pi->Length; i++ )
         {
            Object^ propval = pi[ i ]->GetValue( SystemInformation::PowerStatus, nullptr );
            textBox1->Text = String::Format( "{0}\r\n    PowerStatus.{1} is: {2}", textBox1->Text, pi[ i ]->Name, propval );

         }
      }
      else
      {
         
         // Display the value of the selected property of the SystemInformation type.
         Type^ t = System::Windows::Forms::SystemInformation::typeid;
         array<PropertyInfo^>^pi = t->GetProperties();
         PropertyInfo^ prop = nullptr;
         for ( int i = 0; i < pi->Length; i++ )
            if ( pi[ i ]->Name == propname )
            {
               prop = pi[ i ];
               break;
            }
         Object^ propval = prop->GetValue( nullptr, nullptr );
         textBox1->Text = String::Format( "{0}\r\nThe value of the {1} property is: {2}", textBox1->Text, propname, propval );
      }
   }

   void InitForm()
   {
      
      // Initialize the form settings
      this->listBox1 = gcnew System::Windows::Forms::ListBox;
      this->textBox1 = gcnew System::Windows::Forms::TextBox;
      this->listBox1->Anchor = (System::Windows::Forms::AnchorStyles)(System::Windows::Forms::AnchorStyles::Top | System::Windows::Forms::AnchorStyles::Bottom | System::Windows::Forms::AnchorStyles::Left | System::Windows::Forms::AnchorStyles::Right);
      this->listBox1->Location = System::Drawing::Point( 8, 16 );
      this->listBox1->Size = System::Drawing::Size( 172, 496 );
      this->listBox1->TabIndex = 0;
      this->textBox1->Anchor = (System::Windows::Forms::AnchorStyles)(System::Windows::Forms::AnchorStyles::Top | System::Windows::Forms::AnchorStyles::Bottom | System::Windows::Forms::AnchorStyles::Right);
      this->textBox1->Location = System::Drawing::Point( 188, 16 );
      this->textBox1->Multiline = true;
      this->textBox1->ScrollBars = System::Windows::Forms::ScrollBars::Vertical;
      this->textBox1->Size = System::Drawing::Size( 420, 496 );
      this->textBox1->TabIndex = 1;
      this->ClientSize = System::Drawing::Size( 616, 525 );
      this->Controls->Add( this->textBox1 );
      this->Controls->Add( this->listBox1 );
      this->Text = "Select a SystemInformation property to get the value of";
   }

};


[STAThread]
int main()
{
   Application::Run( gcnew SystemInfoBrowserForm );
}

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

namespace SystemInfoBrowser
{
    public class SystemInfoBrowserForm : System.Windows.Forms.Form
    {
        private System.Windows.Forms.ListBox listBox1;
        private System.Windows.Forms.TextBox textBox1;        
        
        public SystemInfoBrowserForm()
        {
            this.SuspendLayout();
            InitForm();
            
            // Add each property of the SystemInformation class to the list box.
            Type t = typeof(System.Windows.Forms.SystemInformation);            
            PropertyInfo[] pi = t.GetProperties();            
            for( int i=0; i<pi.Length; i++ )
                listBox1.Items.Add( pi[i].Name );            
            textBox1.Text = "The SystemInformation class has "+pi.Length.ToString()+" properties.\r\n";

            // Configure the list item selected handler for the list box to invoke a 
            // method that displays the value of each property.
            listBox1.SelectedIndexChanged += new EventHandler(listBox1_SelectedIndexChanged);
            this.ResumeLayout(false);
        }
        
        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {
            // Return if no list item is selected.
            if( listBox1.SelectedIndex == -1 ) return;
            // Get the property name from the list item.
            string propname = listBox1.Text;
            
            if( propname == "PowerStatus" )
            {
                // Cycle and display the values of each property of the PowerStatus property.
                textBox1.Text += "\r\nThe value of the PowerStatus property is:";                                
                Type t = typeof(System.Windows.Forms.PowerStatus);
                PropertyInfo[] pi = t.GetProperties();            
                for( int i=0; i<pi.Length; i++ )
                {
                    object propval = pi[i].GetValue(SystemInformation.PowerStatus, null);            
                    textBox1.Text += "\r\n    PowerStatus."+pi[i].Name+" is: "+propval.ToString();
                }
            }
            else
            {
                // Display the value of the selected property of the SystemInformation type.
                Type t = typeof(System.Windows.Forms.SystemInformation);
                PropertyInfo[] pi = t.GetProperties();            
                PropertyInfo prop = null;
                for( int i=0; i<pi.Length; i++ )
                    if( pi[i].Name == propname )
                    {
                        prop = pi[i];
                        break;           
                    }
                object propval = prop.GetValue(null, null);            
                textBox1.Text += "\r\nThe value of the "+propname+" property is: "+propval.ToString();
            }
        }

        private void InitForm()
        {
            // Initialize the form settings
            this.listBox1 = new System.Windows.Forms.ListBox();
            this.textBox1 = new System.Windows.Forms.TextBox();            
            this.listBox1.Anchor = ((System.Windows.Forms.AnchorStyles)((((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) 
                | System.Windows.Forms.AnchorStyles.Left) | System.Windows.Forms.AnchorStyles.Right)));
            this.listBox1.Location = new System.Drawing.Point(8, 16);
            this.listBox1.Size = new System.Drawing.Size(172, 496);
            this.listBox1.TabIndex = 0;            
            this.textBox1.Anchor = ((System.Windows.Forms.AnchorStyles)(((System.Windows.Forms.AnchorStyles.Top | System.Windows.Forms.AnchorStyles.Bottom) 
                | System.Windows.Forms.AnchorStyles.Right)));
            this.textBox1.Location = new System.Drawing.Point(188, 16);
            this.textBox1.Multiline = true;
            this.textBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical;           
            this.textBox1.Size = new System.Drawing.Size(420, 496);
            this.textBox1.TabIndex = 1;            
            this.ClientSize = new System.Drawing.Size(616, 525);            
            this.Controls.Add(this.textBox1);
            this.Controls.Add(this.listBox1);            
            this.Text = "Select a SystemInformation property to get the value of";                   
        }

        [STAThread]
        static void Main() 
        {
            Application.Run(new SystemInfoBrowserForm());
        }
    }
}
Imports System.Collections
Imports System.ComponentModel
Imports System.Drawing
Imports System.Reflection
Imports System.Windows.Forms

Public Class SystemInfoBrowserForm
    Inherits System.Windows.Forms.Form
    
    Private listBox1 As System.Windows.Forms.ListBox
    Private textBox1 As System.Windows.Forms.TextBox  
    
    Public Sub New()
        Me.SuspendLayout()
        InitForm()
        
        ' Add each property of the SystemInformation class to the list box.
        Dim t As Type = GetType(System.Windows.Forms.SystemInformation)
        Dim pi As PropertyInfo() = t.GetProperties()
        Dim i As Integer
        For i = 0 To pi.Length - 1
            listBox1.Items.Add(pi(i).Name)
        Next i
        textBox1.Text = "The SystemInformation class has " + pi.Length.ToString() + " properties." + ControlChars.CrLf
        
        ' Configure the list item selected handler for the list box to invoke a 
        ' method that displays the value of each property.
        AddHandler listBox1.SelectedIndexChanged, AddressOf listBox1_SelectedIndexChanged
        
        Me.ResumeLayout(False)
    End Sub    
    
    Private Sub listBox1_SelectedIndexChanged(sender As Object, e As EventArgs)
        ' Return if no list item is selected.
        If listBox1.SelectedIndex = - 1 Then
            Return
        End If         
        ' Get the property name from the list item.
        Dim propname As String = listBox1.Text
        
        If propname = "PowerStatus" Then
            ' Cycle and display the values of each property of the PowerStatus property.
            textBox1.Text += ControlChars.CrLf + "The value of the PowerStatus property is:"
            Dim t As Type = GetType(System.Windows.Forms.PowerStatus)
            Dim pi As PropertyInfo() = t.GetProperties()
            Dim i As Integer
            For i = 0 To pi.Length - 1
                Dim propval As Object = pi(i).GetValue(SystemInformation.PowerStatus, Nothing)
                textBox1.Text += ControlChars.CrLf + "    PowerStatus." + pi(i).Name + " is: " + propval.ToString()
            Next i
        Else
            ' Display the value of the selected property of the SystemInformation type.
            Dim t As Type = GetType(System.Windows.Forms.SystemInformation)
            Dim pi As PropertyInfo() = t.GetProperties()
            Dim prop As PropertyInfo = Nothing
            Dim i As Integer
            For i = 0 To pi.Length - 1
                If pi(i).Name = propname Then
                    prop = pi(i)
                    Exit For
                End If
            Next i
            Dim propval As Object = prop.GetValue(Nothing, Nothing)
            textBox1.Text += ControlChars.CrLf + "The value of the " + propname + " property is: " + propval.ToString()
        End If
    End Sub    
    
    Private Sub InitForm()
        ' Initialize the form settings
        Me.listBox1 = New System.Windows.Forms.ListBox()
        Me.textBox1 = New System.Windows.Forms.TextBox()
        Me.listBox1.Anchor = CType(System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left Or System.Windows.Forms.AnchorStyles.Right, System.Windows.Forms.AnchorStyles)
        Me.listBox1.Location = New System.Drawing.Point(8, 16)
        Me.listBox1.Size = New System.Drawing.Size(172, 496)
        Me.listBox1.TabIndex = 0
        Me.textBox1.Anchor = CType(System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Right, System.Windows.Forms.AnchorStyles)
        Me.textBox1.Location = New System.Drawing.Point(188, 16)
        Me.textBox1.Multiline = True
        Me.textBox1.ScrollBars = System.Windows.Forms.ScrollBars.Vertical
        Me.textBox1.Size = New System.Drawing.Size(420, 496)
        Me.textBox1.TabIndex = 1
        Me.ClientSize = New System.Drawing.Size(616, 525)
        Me.Controls.Add(Me.textBox1)
        Me.Controls.Add(Me.listBox1)
        Me.Text = "Select a SystemInformation property to get the value of"
    End Sub
        
    <STAThread()>  _
    Shared Sub Main()
        Application.Run(New SystemInfoBrowserForm())
    End Sub

End Class

Commenti

La DragSize proprietà indica le dimensioni, in pixel, di un rettangolo centrato intorno al punto in cui è stato premuto il pulsante del mouse.The DragSize property indicates the size, in pixels, of a rectangle centered around the point at which the mouse button was pressed. Windows utilizza il rettangolo come limite all'interno del quale non viene avviata un'operazione di trascinamento.Windows uses the rectangle as a boundary within which it does not start a drag operation.

Un utente può mantenere premuto il pulsante del mouse e spostare il mouse all'interno di quest'area prima che inizi un'operazione di trascinamento, che consente all'utente di fare clic e rilasciare il pulsante del mouse in modo semplice senza avviare accidentalmente un'operazione di trascinamento.A user can hold a mouse button down and move the mouse within this area before a drag operation begins, which enables the user to click and release the mouse button easily without unintentionally starting a drag operation.

Si applica a

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