Control.Invalidate 方法

参考

定义

命名空间:: System.Windows.Forms

程序集:: System.Windows.Forms.dll

重要

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使控件的特定区域无效并向控件发送绘制消息。

重载

Invalidate(Region, Boolean)	使控件的指定区域无效（将其添加到控件的更新区域，下次绘制操作时将重新绘制更新区域），并向控件发送绘制消息。还可以使分配给该控件的子控件无效。
Invalidate(Rectangle, Boolean)	使控件的指定区域无效（将其添加到控件的更新区域，下次绘制操作时将重新绘制更新区域），并向控件发送绘制消息。还可以使分配给该控件的子控件无效。
Invalidate(Region)	使控件的指定区域无效（将其添加到控件的更新区域，下次绘制操作时将重新绘制更新区域），并向控件发送绘制消息。
Invalidate(Boolean)	使控件的特定区域无效并向控件发送绘制消息。还可以使分配给该控件的子控件无效。
Invalidate()	使控件的整个图面无效并导致重绘控件。
Invalidate(Rectangle)	使控件的指定区域无效（将其添加到控件的更新区域，下次绘制操作时将重新绘制更新区域），并向控件发送绘制消息。

Invalidate(Region, Boolean)

使控件的指定区域无效（将其添加到控件的更新区域，下次绘制操作时将重新绘制更新区域），并向控件发送绘制消息。还可以使分配给该控件的子控件无效。

public:
 void Invalidate(System::Drawing::Region ^ region, bool invalidateChildren);

public void Invalidate (System.Drawing.Region region, bool invalidateChildren);

public void Invalidate (System.Drawing.Region? region, bool invalidateChildren);

member this.Invalidate : System.Drawing.Region * bool -> unit

Public Sub Invalidate (region As Region, invalidateChildren As Boolean)

参数

region: Region

要使之无效的 Region。

invalidateChildren: Boolean

若要使控件的子控件无效，则为 true；否则为 false。

注解

Invalidate调用方法不强制同步绘制;若要强制同步绘制，请在Update调用 Invalidate 方法后调用方法。在没有参数的情况下调用此方法时，会将整个工作区添加到更新区域。

另请参阅

适用于

Invalidate(Rectangle, Boolean)

public:
 void Invalidate(System::Drawing::Rectangle rc, bool invalidateChildren);

public void Invalidate (System.Drawing.Rectangle rc, bool invalidateChildren);

member this.Invalidate : System.Drawing.Rectangle * bool -> unit

Public Sub Invalidate (rc As Rectangle, invalidateChildren As Boolean)

参数

rc: Rectangle

一个 Rectangle，表示要使之无效的区域。

invalidateChildren: Boolean

若要使控件的子控件无效，则为 true；否则为 false。

注解

另请参阅

适用于

Invalidate(Region)

使控件的指定区域无效（将其添加到控件的更新区域，下次绘制操作时将重新绘制更新区域），并向控件发送绘制消息。

public:
 void Invalidate(System::Drawing::Region ^ region);

public void Invalidate (System.Drawing.Region region);

public void Invalidate (System.Drawing.Region? region);

member this.Invalidate : System.Drawing.Region -> unit

Public Sub Invalidate (region As Region)

参数

region: Region

要使之无效的 Region。

注解

另请参阅

适用于

Invalidate(Boolean)

使控件的特定区域无效并向控件发送绘制消息。还可以使分配给该控件的子控件无效。

public:
 void Invalidate(bool invalidateChildren);

public void Invalidate (bool invalidateChildren);

member this.Invalidate : bool -> unit

Public Sub Invalidate (invalidateChildren As Boolean)

参数

invalidateChildren: Boolean

若要使控件的子控件无效，则为 true；否则为 false。

注解

另请参阅

适用于

Invalidate()

使控件的整个图面无效并导致重绘控件。

public:
 void Invalidate();

public void Invalidate ();

member this.Invalidate : unit -> unit

Public Sub Invalidate ()

示例

下面的代码示例使用户能够将图像或图像文件拖到窗体上，并在删除时将其显示。 OnPaint将重写方法以在每次绘制窗体时重新绘制图像;否则，图像将仅保留到下一次重新绘制。事件 DragEnter 处理方法确定要拖动到窗体中的数据类型，并提供适当的反馈。如果可以从数据创建，Image则DragDrop事件处理方法会在窗体上显示图像。 DragEventArgs.X由于和 DragEventArgs.Y 值是屏幕坐标，因此该示例使用 PointToClient 方法将它们转换为客户端坐标。

private:
   Image^ picture;
   Point pictureLocation;

public:
   Form1()
   {
      
      // Enable drag-and-drop operations and
      // add handlers for DragEnter and DragDrop.
      this->AllowDrop = true;
      this->DragDrop += gcnew DragEventHandler( this, &Form1::Form1_DragDrop );
      this->DragEnter += gcnew DragEventHandler( this, &Form1::Form1_DragEnter );
   }

protected:
   virtual void OnPaint( PaintEventArgs^ e ) override
   {
      
      // If there is an image and it has a location,
      // paint it when the Form is repainted.
      Form::OnPaint( e );
      if ( this->picture != nullptr && this->pictureLocation != Point::Empty )
      {
         e->Graphics->DrawImage( this->picture, this->pictureLocation );
      }
   }

private:
   void Form1_DragDrop( Object^ /*sender*/, DragEventArgs^ e )
   {
      
      // Handle FileDrop data.
      if ( e->Data->GetDataPresent( DataFormats::FileDrop ) )
      {
         // Assign the file names to a String* array, in
         // case the user has selected multiple files.
         array<String^>^files = (array<String^>^)e->Data->GetData( DataFormats::FileDrop );
         try
         {
            // Assign the first image to the picture variable.
            this->picture = Image::FromFile( files[ 0 ] );
            
            // Set the picture location equal to the drop point.
            this->pictureLocation = this->PointToClient( Point(e->X,e->Y) );
         }
         catch ( Exception^ ex ) 
         {
            MessageBox::Show( ex->Message );
            return;
         }

      }
      
      // Handle Bitmap data.
      if ( e->Data->GetDataPresent( DataFormats::Bitmap ) )
      {
         try
         {
            // Create an Image and assign it to the picture variable.
            this->picture = dynamic_cast<Image^>(e->Data->GetData( DataFormats::Bitmap ));

            // Set the picture location equal to the drop point.
            this->pictureLocation = this->PointToClient( Point(e->X,e->Y) );
         }
         catch ( Exception^ ex ) 
         {
            MessageBox::Show( ex->Message );
            return;
         }
      }
      
      // Force the form to be redrawn with the image.
      this->Invalidate();
   }

   void Form1_DragEnter( Object^ /*sender*/, DragEventArgs^ e )
   {
      // If the data is a file or a bitmap, display the copy cursor.
      if ( e->Data->GetDataPresent( DataFormats::Bitmap ) || e->Data->GetDataPresent( DataFormats::FileDrop ) )
      {
         e->Effect = DragDropEffects::Copy;
      }
      else
      {
         e->Effect = DragDropEffects::None;
      }
   }

private Image picture;
private Point pictureLocation;

public Form1()
{
   // Enable drag-and-drop operations and 
   // add handlers for DragEnter and DragDrop.
   this.AllowDrop = true;
   this.DragDrop += new DragEventHandler(this.Form1_DragDrop);
   this.DragEnter += new DragEventHandler(this.Form1_DragEnter);
}

protected override void OnPaint(PaintEventArgs e)
{
   // If there is an image and it has a location, 
   // paint it when the Form is repainted.
   base.OnPaint(e);
   if(this.picture != null && this.pictureLocation != Point.Empty)
   {
      e.Graphics.DrawImage(this.picture, this.pictureLocation);
   }
}

private void Form1_DragDrop(object sender, DragEventArgs e)
{
   // Handle FileDrop data.
   if(e.Data.GetDataPresent(DataFormats.FileDrop) )
   {
      // Assign the file names to a string array, in 
      // case the user has selected multiple files.
      string[] files = (string[])e.Data.GetData(DataFormats.FileDrop);
      try
      {
         // Assign the first image to the picture variable.
         this.picture = Image.FromFile(files[0]);
         // Set the picture location equal to the drop point.
         this.pictureLocation = this.PointToClient(new Point(e.X, e.Y) );
      }
      catch(Exception ex)
      {
         MessageBox.Show(ex.Message);
         return;
      }
   }

   // Handle Bitmap data.
   if(e.Data.GetDataPresent(DataFormats.Bitmap) )
   {
      try
      {
         // Create an Image and assign it to the picture variable.
         this.picture = (Image)e.Data.GetData(DataFormats.Bitmap);
         // Set the picture location equal to the drop point.
         this.pictureLocation = this.PointToClient(new Point(e.X, e.Y) );
      }
      catch(Exception ex)
      {
         MessageBox.Show(ex.Message);
         return;
      }
   }
   // Force the form to be redrawn with the image.
   this.Invalidate();
}

private void Form1_DragEnter(object sender, DragEventArgs e)
{
   // If the data is a file or a bitmap, display the copy cursor.
   if (e.Data.GetDataPresent(DataFormats.Bitmap) || 
      e.Data.GetDataPresent(DataFormats.FileDrop) ) 
   {
      e.Effect = DragDropEffects.Copy;
   }
   else
   {
      e.Effect = DragDropEffects.None;
   }
}

Private picture As Image
Private pictureLocation As Point

Public Sub New()
   ' Enable drag-and-drop operations.
   Me.AllowDrop = True
End Sub

Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
   MyBase.OnPaint(e)

   ' If there is an image and it has a location, 
   ' paint it when the Form is repainted.
   If (Me.picture IsNot Nothing) And _
     Not (Me.pictureLocation.Equals(Point.Empty)) Then
      e.Graphics.DrawImage(Me.picture, Me.pictureLocation)
   End If
End Sub

Private Sub Form1_DragDrop(ByVal sender As Object, _
  ByVal e As DragEventArgs) Handles MyBase.DragDrop
   ' Handle FileDrop data.
   If e.Data.GetDataPresent(DataFormats.FileDrop) Then
      ' Assign the file names to a string array, in 
      ' case the user has selected multiple files.
      Dim files As String() = CType(e.Data.GetData(DataFormats.FileDrop), String())
      Try
         ' Assign the first image to the 'picture' variable.
         Me.picture = Image.FromFile(files(0))
         ' Set the picture location equal to the drop point.
         Me.pictureLocation = Me.PointToClient(New Point(e.X, e.Y))
      Catch ex As Exception
         MessageBox.Show(ex.Message)
         Return
      End Try
   End If

   ' Handle Bitmap data.
   If e.Data.GetDataPresent(DataFormats.Bitmap) Then
      Try
         ' Create an Image and assign it to the picture variable.
         Me.picture = CType(e.Data.GetData(DataFormats.Bitmap), Image)
         ' Set the picture location equal to the drop point.
         Me.pictureLocation = Me.PointToClient(New Point(e.X, e.Y))
      Catch ex As Exception
         MessageBox.Show(ex.Message)
         Return
      End Try
   End If

   ' Force the form to be redrawn with the image.
   Me.Invalidate()
End Sub

Private Sub Form1_DragEnter(ByVal sender As Object, _
  ByVal e As DragEventArgs) Handles MyBase.DragEnter
   ' If the data is a file or a bitmap, display the copy cursor.
   If e.Data.GetDataPresent(DataFormats.Bitmap) _
      Or e.Data.GetDataPresent(DataFormats.FileDrop) Then
      e.Effect = DragDropEffects.Copy
   Else
      e.Effect = DragDropEffects.None
   End If
End Sub

注解

另请参阅

适用于

Invalidate(Rectangle)

使控件的指定区域无效（将其添加到控件的更新区域，下次绘制操作时将重新绘制更新区域），并向控件发送绘制消息。

public:
 void Invalidate(System::Drawing::Rectangle rc);

public void Invalidate (System.Drawing.Rectangle rc);

member this.Invalidate : System.Drawing.Rectangle -> unit

Public Sub Invalidate (rc As Rectangle)

参数

rc: Rectangle

一个 Rectangle，表示要使之无效的区域。

注解

另请参阅

适用于

通过

Control.Invalidate 方法

定义

重载

Invalidate(Region, Boolean)

参数

注解

另请参阅

适用于

Invalidate(Rectangle, Boolean)

参数

注解

另请参阅

适用于

Invalidate(Region)

参数

注解

另请参阅

适用于

Invalidate(Boolean)

参数

注解

另请参阅

适用于

Invalidate()

示例

注解

另请参阅

适用于

Invalidate(Rectangle)

参数

注解

另请参阅

适用于

其他资源