ActivityDesigner.OnPaint(ActivityDesignerPaintEventArgs) 方法

定义

命名空间:

System.Workflow.ComponentModel.Design

程序集:

System.Workflow.ComponentModel.dll

在设计时绘制活动的可视表示形式。

protected:
 virtual void OnPaint(System::Workflow::ComponentModel::Design::ActivityDesignerPaintEventArgs ^ e);

protected virtual void OnPaint (System.Workflow.ComponentModel.Design.ActivityDesignerPaintEventArgs e);

abstract member OnPaint : System.Workflow.ComponentModel.Design.ActivityDesignerPaintEventArgs -> unit
override this.OnPaint : System.Workflow.ComponentModel.Design.ActivityDesignerPaintEventArgs -> unit

Protected Overridable Sub OnPaint (e As ActivityDesignerPaintEventArgs)

参数

e

ActivityDesignerPaintEventArgs

包含事件数据的 ActivityDesignerPaintEventArgs。

例外

ArgumentNullException

e 包含空引用（在 Visual Basic 中为 Nothing）。

示例

下面的示例演示一个自定义 ActivityDesigner，它根据一个布尔值确定将绘制职责委托给基类还是自行绘制。 如果 useBasePaint 为 false，该自定义活动将使用 ActivityDesignerPaint 类的各种方法自行绘制。

private bool expanded = true;
private bool useBasePaint = false;

public bool UseBasePaint
{
    get { return this.useBasePaint; }
    set { this.useBasePaint = value; }
}

public bool Expanded
{
    get { return this.expanded; }
    set { this.expanded = value; }
}

protected override void OnPaint(ActivityDesignerPaintEventArgs e)
{
    if (this.UseBasePaint == true)
    {
        base.OnPaint(e);
        return;
    }

    DrawCustomActivity(e);
}

private void DrawCustomActivity(ActivityDesignerPaintEventArgs e)
{
    Graphics graphics = e.Graphics;

    CompositeDesignerTheme compositeDesignerTheme = (CompositeDesignerTheme)e.DesignerTheme;

    ActivityDesignerPaint.DrawRoundedRectangle(graphics, compositeDesignerTheme.BorderPen, this.Bounds, compositeDesignerTheme.BorderWidth);

    string text = this.Text;
    Rectangle textRectangle = this.TextRectangle;
    if (!string.IsNullOrEmpty(text) && !textRectangle.IsEmpty)
    {
        ActivityDesignerPaint.DrawText(graphics, compositeDesignerTheme.Font, text, textRectangle, StringAlignment.Center, e.AmbientTheme.TextQuality, compositeDesignerTheme.ForegroundBrush);
    }

    System.Drawing.Image image = this.Image;
    Rectangle imageRectangle = this.ImageRectangle;
    if (image != null && !imageRectangle.IsEmpty)
    {
        ActivityDesignerPaint.DrawImage(graphics, image, imageRectangle, DesignerContentAlignment.Fill);
    }

    ActivityDesignerPaint.DrawExpandButton(graphics,
        new Rectangle(this.Location.X, this.Location.Y, 10, 10),
        this.Expanded,
        compositeDesignerTheme);
}

Private expandedValue As Boolean = True
Private useBasePaintValue As Boolean = False

Public Property UseBasePaint() As Boolean
    Get
        Return Me.useBasePaintValue
    End Get

    Set(ByVal value As Boolean)
        Me.useBasePaintValue = value
    End Set
End Property

Public Property Expanded() As Boolean
    Get
        Return Me.expandedValue
    End Get
    Set(ByVal value As Boolean)
        Me.expandedValue = value
    End Set
End Property


Protected Overrides Sub OnPaint(ByVal e As ActivityDesignerPaintEventArgs)
    If Me.UseBasePaint = True Then
        MyBase.OnPaint(e)
        Return
    End If

    DrawCustomActivity(e)
End Sub

Private Sub DrawCustomActivity(ByVal e As ActivityDesignerPaintEventArgs)
    Dim graphics As Graphics = e.Graphics

    Dim compositeDesignerTheme As CompositeDesignerTheme = CType(e.DesignerTheme, CompositeDesignerTheme)

    ActivityDesignerPaint.DrawRoundedRectangle(graphics, compositeDesignerTheme.BorderPen, Me.Bounds, compositeDesignerTheme.BorderWidth)

    Dim text As String = Me.Text
    Dim TextRectangle As Rectangle = Me.TextRectangle
    If Not String.IsNullOrEmpty(text) And Not TextRectangle.IsEmpty Then
        ActivityDesignerPaint.DrawText(graphics, compositeDesignerTheme.Font, text, TextRectangle, StringAlignment.Center, e.AmbientTheme.TextQuality, compositeDesignerTheme.ForegroundBrush)
    End If

    Dim Image As System.Drawing.Image = Me.Image
    Dim ImageRectangle As Rectangle = Me.ImageRectangle
    If Image IsNot Nothing And Not ImageRectangle.IsEmpty Then
        ActivityDesignerPaint.DrawImage(graphics, Image, ImageRectangle, DesignerContentAlignment.Fill)
    End If

    ActivityDesignerPaint.DrawExpandButton(graphics, _
        New Rectangle(Me.Location.X, Me.Location.Y, 10, 10), _
        Me.Expanded, _
        compositeDesignerTheme)
End Sub