ComboBoxRenderer.DrawDropDownButton Méthode

Définition

Espace de noms:

System.Windows.Forms

Assembly:

System.Windows.Forms.dll

Source:

ComboBoxRenderer.cs

Dessine une flèche déroulante avec le style visuel actuel du système d’exploitation.

public:
 static void DrawDropDownButton(System::Drawing::Graphics ^ g, System::Drawing::Rectangle bounds, System::Windows::Forms::VisualStyles::ComboBoxState state);

public static void DrawDropDownButton(System.Drawing.Graphics g, System.Drawing.Rectangle bounds, System.Windows.Forms.VisualStyles.ComboBoxState state);

static member DrawDropDownButton : System.Drawing.Graphics * System.Drawing.Rectangle * System.Windows.Forms.VisualStyles.ComboBoxState -> unit

Public Shared Sub DrawDropDownButton (g As Graphics, bounds As Rectangle, state As ComboBoxState)

Paramètres

g

Graphics

Graphics Utilisé pour dessiner la flèche déroulante.

bounds

Rectangle

Qui Rectangle spécifie les limites de la flèche déroulante.

state

ComboBoxState

Une des ComboBoxState valeurs qui spécifie l’état visuel de la flèche déroulante.

Exceptions

InvalidOperationException

Le système d’exploitation ne prend pas en charge les styles visuels.

- ou -

Les styles visuels sont désactivés par l’utilisateur dans le système d’exploitation.

- ou -

Les styles visuels ne sont pas appliqués à la zone cliente des fenêtres d’application.

Exemples

L’exemple de code suivant utilise la méthode dans la DrawDropDownButton méthode d’un OnPaint contrôle personnalisé pour dessiner une flèche déroulante dans l’état déterminé par l’emplacement du pointeur de la souris. Cet exemple de code fait partie d’un exemple plus grand fourni pour la ComboBoxRenderer classe.

      // Draw the combo box in the current state.
protected:
    virtual void OnPaint(PaintEventArgs^ e) override 
    {
        Control::OnPaint(e);

        if (!ComboBoxRenderer::IsSupported)
        {
            this->Parent->Text = "Visual Styles Disabled";
            return;
        }

        this->Parent->Text = "CustomComboBox Enabled";

        // Always draw the main text box and drop down arrow in their
        // current states
        ComboBoxRenderer::DrawTextBox(e->Graphics, topTextBoxRectangle,
            this->Text, this->Font, textBoxState);
        ComboBoxRenderer::DrawDropDownButton(e->Graphics, arrowRectangle,
            arrowState);

        // Only draw the bottom text box if the arrow has been clicked
        if (isActivated)
        {
            ComboBoxRenderer::DrawTextBox(e->Graphics,
                bottomTextBoxRectangle, bottomText, this->Font,
                textBoxState);
        }
    }

protected:
    virtual void OnMouseDown(MouseEventArgs^ e) override 
    {
        Control::OnMouseDown(e);

        // Check whether the user clicked the arrow.
        if (arrowRectangle.Contains(e->Location) &&
            ComboBoxRenderer::IsSupported)
        {
            // Draw the arrow in the pressed state.
            arrowState = ComboBoxState::Pressed;

            // The user has activated the combo box.
            if (!isActivated)
            {
                this->Text = "Clicked!";
                textBoxState = ComboBoxState::Pressed;
                isActivated = true;
            }

            // The user has deactivated the combo box.
            else
            {
                this->Text = "Click here";
                textBoxState = ComboBoxState::Normal;
                isActivated = false;
            }

            // Redraw the control.
            Invalidate();
        }
    }

// Draw the combo box in the current state.
protected override void OnPaint(PaintEventArgs e)
{
    base.OnPaint(e);

    if (!ComboBoxRenderer.IsSupported)
    {
        this.Parent.Text = "Visual Styles Disabled";
        return;
    }

    this.Parent.Text = "CustomComboBox Enabled";

    // Always draw the main text box and drop down arrow in their 
    // current states
    ComboBoxRenderer.DrawTextBox(e.Graphics, topTextBoxRectangle,
        this.Text, this.Font, textBoxState);
    ComboBoxRenderer.DrawDropDownButton(e.Graphics, arrowRectangle,
        arrowState);

    // Only draw the bottom text box if the arrow has been clicked
    if (isActivated)
    {
        ComboBoxRenderer.DrawTextBox(e.Graphics,
            bottomTextBoxRectangle, bottomText, this.Font,
            textBoxState);
    }
}

protected override void OnMouseDown(MouseEventArgs e)
{
    base.OnMouseDown(e);

    // Check whether the user clicked the arrow.
    if (arrowRectangle.Contains(e.Location) &&
        ComboBoxRenderer.IsSupported)
    {
        // Draw the arrow in the pressed state.
        arrowState = ComboBoxState.Pressed;

        // The user has activated the combo box.
        if (!isActivated)
        {
            this.Text = "Clicked!";
            textBoxState = ComboBoxState.Pressed;
            isActivated = true;
        }

        // The user has deactivated the combo box.
        else
        {
            this.Text = "Click here";
            textBoxState = ComboBoxState.Normal;
            isActivated = false;
        }

        // Redraw the control.
        Invalidate();
    }
}

' Draw the combo box in the current state.
Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
    MyBase.OnPaint(e)

    If Not ComboBoxRenderer.IsSupported Then
        Me.Parent.Text = "Visual Styles	Disabled"
        Return
    End If

    Me.Parent.Text = "CustomComboBox Enabled"

    ' Always draw the main text box and drop down arrow in their 
    ' current states.
    ComboBoxRenderer.DrawTextBox(e.Graphics, topTextBoxRectangle, _
        Me.Text, Me.Font, textBoxState)
    ComboBoxRenderer.DrawDropDownButton(e.Graphics, arrowRectangle, _
        arrowState)

    ' Only draw the bottom text box if the arrow has been clicked.
    If isActivated Then
        ComboBoxRenderer.DrawTextBox(e.Graphics, _
            bottomTextBoxRectangle, bottomText, Me.Font, textBoxState)
    End If
End Sub

Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs)
    MyBase.OnMouseDown(e)

    ' Check whether the user clicked the arrow.
    If arrowRectangle.Contains(e.Location) And _
        ComboBoxRenderer.IsSupported Then

        ' Draw the arrow in the pressed state.
        arrowState = ComboBoxState.Pressed

        ' The user has activated the combo box.
        If Not isActivated Then
            Me.Text = "Clicked!"
            textBoxState = ComboBoxState.Pressed
            isActivated = True

        ' The user has deactivated the combo box.
        Else
            Me.Text = "Click here"
            textBoxState = ComboBoxState.Normal
            isActivated = False
        End If

        ' Redraw the control.
        Invalidate()
    End If
End Sub

Remarques

Avant d’appeler cette méthode, vous devez vérifier que la IsSupported propriété retourne true.