ToolStripRenderer.OnRenderToolStripBackground 方法

定义

命名空间:

System.Windows.Forms

程序集:

System.Windows.Forms.dll

引发 RenderToolStripBackground 事件。

protected:
 virtual void OnRenderToolStripBackground(System::Windows::Forms::ToolStripRenderEventArgs ^ e);

protected virtual void OnRenderToolStripBackground (System.Windows.Forms.ToolStripRenderEventArgs e);

abstract member OnRenderToolStripBackground : System.Windows.Forms.ToolStripRenderEventArgs -> unit
override this.OnRenderToolStripBackground : System.Windows.Forms.ToolStripRenderEventArgs -> unit

Protected Overridable Sub OnRenderToolStripBackground (e As ToolStripRenderEventArgs)

参数

e

ToolStripRenderEventArgs

包含事件数据的 ToolStripRenderEventArgs。

示例

下面的代码示例演示如何重写 方法， OnRenderToolStripBackground 以在控件的背景 ToolStrip 中绘制渐变。 此代码示例是为 ToolStripRenderer 类提供的一个更大示例的一部分。

// This method renders the GridStrip control's background.
protected override void OnRenderToolStripBackground(
    ToolStripRenderEventArgs e)
{
    base.OnRenderToolStripBackground(e);

    // This late initialization is a workaround. The gradient
    // depends on the bounds of the GridStrip control. The bounds 
    // are dependent on the layout engine, which hasn't fully
    // performed layout by the time the Initialize method runs.
    if (this.backgroundBrush == null)
    {
        this.backgroundBrush = new LinearGradientBrush(
           e.ToolStrip.ClientRectangle,
           SystemColors.ControlLightLight,
           SystemColors.ControlDark,
           90,
           true);
    }

    // Paint the GridStrip control's background.
    e.Graphics.FillRectangle(
        this.backgroundBrush, 
        e.AffectedBounds);
}

' This method renders the GridStrip control's background.
Protected Overrides Sub OnRenderToolStripBackground(e As ToolStripRenderEventArgs)
   MyBase.OnRenderToolStripBackground(e)
   
   ' This late initialization is a workaround. The gradient
   ' depends on the bounds of the GridStrip control. The bounds 
   ' are dependent on the layout engine, which hasn't fully
   ' performed layout by the time the Initialize method runs.
   If Me.backgroundBrush Is Nothing Then
      Me.backgroundBrush = New LinearGradientBrush(e.ToolStrip.ClientRectangle, SystemColors.ControlLightLight, SystemColors.ControlDark, 90, True)
   End If
   
   ' Paint the GridStrip control's background.
   e.Graphics.FillRectangle(Me.backgroundBrush, e.AffectedBounds)
  End Sub

注解

引发事件时，将通过委托调用事件处理程序。 有关详细信息，请参阅 处理和引发事件。

OnRenderToolStripBackground 方法还允许派生类对事件进行处理而不必附加委托。 这是在派生类中处理事件的首选技术。

继承者说明

在派生类中重写 OnRenderToolStripBackground(ToolStripRenderEventArgs) 时，一定要调用基类的 OnRenderToolStripBackground(ToolStripRenderEventArgs) 方法，以便已注册的委托对事件进行接收。

另请参阅

• 如何：实现自定义 ToolStripRenderer