CheckBox.ThreeState Property

Definition

Namespace:

System.Windows.Forms

Assembly:

System.Windows.Forms.dll

Source:

CheckBox.cs

Gets or sets a value indicating whether the CheckBox will allow three check states rather than two.

public:
 property bool ThreeState { bool get(); void set(bool value); };

public bool ThreeState { get; set; }

member this.ThreeState : bool with get, set

Public Property ThreeState As Boolean

Property Value

Boolean

true if the CheckBox is able to display three check states; otherwise, false. The default value is false.

Examples

The following code example displays the values of three properties in a label. The ThreeState property alternates between true and false with alternating clicks of the control and the CheckAlign alternates between the MiddleRight and MiddleLeft values of System.Drawing.ContentAlignment. This example shows how the property values change as the ThreeState property changes and the control is checked. This code requires that a CheckBox, Label and Button have all been instantiated on a form and that the label is large enough to display three lines of text, as well as a reference to the System.Drawing namespace. This code should be called in the Click event handler of the control.

private:
   void AdjustMyCheckBoxProperties()
   {
      // Concatenate the property values together on three lines.
      label1->Text = String::Format( "ThreeState: {0}\nChecked: {1}\nCheckState: {2}",
         checkBox1->ThreeState, checkBox1->Checked, checkBox1->CheckState );
      
      // Change the ThreeState and CheckAlign properties on every other click.
      if ( !checkBox1->ThreeState )
      {
         checkBox1->ThreeState = true;
         checkBox1->CheckAlign = ContentAlignment::MiddleRight;
      }
      else
      {
         checkBox1->ThreeState = false;
         checkBox1->CheckAlign = ContentAlignment::MiddleLeft;
      }
   }

private void AdjustMyCheckBoxProperties()
 {
    // Change the ThreeState and CheckAlign properties on every other click.
    if (!checkBox1.ThreeState)
    {
       checkBox1.ThreeState = true;
       checkBox1.CheckAlign = ContentAlignment.MiddleRight;
    }
    else
    {
       checkBox1.ThreeState = false;
       checkBox1.CheckAlign = ContentAlignment.MiddleLeft;
    }

    // Concatenate the property values together on three lines.
    label1.Text = "ThreeState: " + checkBox1.ThreeState.ToString() + "\n" +
                  "Checked: " + checkBox1.Checked.ToString() + "\n" +
                  "CheckState: " + checkBox1.CheckState.ToString(); 
 }

Private Sub AdjustMyCheckBoxProperties()

    ' Change the ThreeState and CheckAlign properties on every other click.
    If Not checkBox1.ThreeState Then
        checkBox1.ThreeState = True
        checkBox1.CheckAlign = ContentAlignment.MiddleRight
    Else
        checkBox1.ThreeState = False
        checkBox1.CheckAlign = ContentAlignment.MiddleLeft
    End If

    ' Concatenate the property values together on three lines.
    label1.Text = "ThreeState: " & checkBox1.ThreeState.ToString() & ControlChars.Cr & _
        "Checked: " & checkBox1.Checked.ToString() & ControlChars.Cr & _
        "CheckState: " & checkBox1.CheckState.ToString()

End Sub

Remarks

If the ThreeState property is set to false, the CheckState property value can only be set to the Indeterminate value of System.Windows.Forms.CheckState in code and not by user interaction.