Control.Invalidate 方法

定义

使控件的特定区域无效并向控件发送绘制消息。Invalidates a specific region of the control and causes a paint message to be sent to the control.

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。Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control. 还可以使分配给该控件的子控件无效。Optionally, invalidates the child controls assigned to the control.

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。Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control. 还可以使分配给该控件的子控件无效。Optionally, invalidates the child controls assigned to the control.

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。Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control.

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。Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control.

Invalidate(Boolean)

使控件的特定区域无效并向控件发送绘制消息。Invalidates a specific region of the control and causes a paint message to be sent to the control. 还可以使分配给该控件的子控件无效。Optionally, invalidates the child controls assigned to the control.

Invalidate()

使控件的整个图面无效并导致重绘控件。Invalidates the entire surface of the control and causes the control to be redrawn.

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。Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control. 还可以使分配给该控件的子控件无效。Optionally, invalidates the child controls assigned to the control.

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

参数

region
Region

要使之无效的 RegionThe Region to invalidate.

invalidateChildren
Boolean

若要使控件的子控件无效,则为 true;否则为 falsetrue to invalidate the control's child controls; otherwise, false.

注解

调用 Invalidate 方法不会强制执行同步绘制;若要强制执行同步画图,请在调用 Invalidate 方法后调用 Update 方法。Calling the Invalidate method does not force a synchronous paint; to force a synchronous paint, call the Update method after calling the Invalidate method. 如果在没有参数的情况下调用此方法,则会将整个工作区添加到更新区域。When this method is called with no parameters, the entire client area is added to the update region.

另请参阅

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。Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control. 还可以使分配给该控件的子控件无效。Optionally, invalidates the child controls assigned to the control.

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。A Rectangle that represents the region to invalidate.

invalidateChildren
Boolean

若要使控件的子控件无效,则为 true;否则为 falsetrue to invalidate the control's child controls; otherwise, false.

注解

调用 Invalidate 方法不会强制执行同步绘制;若要强制执行同步画图,请在调用 Invalidate 方法后调用 Update 方法。Calling the Invalidate method does not force a synchronous paint; to force a synchronous paint, call the Update method after calling the Invalidate method. 如果在没有参数的情况下调用此方法,则会将整个工作区添加到更新区域。When this method is called with no parameters, the entire client area is added to the update region.

另请参阅

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。Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control.

public:
 void Invalidate(System::Drawing::Region ^ region);
public void Invalidate (System.Drawing.Region region);
member this.Invalidate : System.Drawing.Region -> unit

参数

region
Region

要使之无效的 RegionThe Region to invalidate.

注解

调用 Invalidate 方法不会强制执行同步绘制;若要强制执行同步画图,请在调用 Invalidate 方法后调用 Update 方法。Calling the Invalidate method does not force a synchronous paint; to force a synchronous paint, call the Update method after calling the Invalidate method. 如果在没有参数的情况下调用此方法,则会将整个工作区添加到更新区域。When this method is called with no parameters, the entire client area is added to the update region.

另请参阅

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。Invalidates the specified region of the control (adds it to the control's update region, which is the area that will be repainted at the next paint operation), and causes a paint message to be sent to the control.

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。A Rectangle that represents the region to invalidate.

注解

调用 Invalidate 方法不会强制执行同步绘制;若要强制执行同步画图,请在调用 Invalidate 方法后调用 Update 方法。Calling the Invalidate method does not force a synchronous paint; to force a synchronous paint, call the Update method after calling the Invalidate method. 如果在没有参数的情况下调用此方法,则会将整个工作区添加到更新区域。When this method is called with no parameters, the entire client area is added to the update region.

另请参阅

Invalidate(Boolean)

使控件的特定区域无效并向控件发送绘制消息。Invalidates a specific region of the control and causes a paint message to be sent to the control. 还可以使分配给该控件的子控件无效。Optionally, invalidates the child controls assigned to the control.

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 falsetrue to invalidate the control's child controls; otherwise, false.

注解

调用 Invalidate 方法不会强制执行同步绘制;若要强制执行同步画图,请在调用 Invalidate 方法后调用 Update 方法。Calling the Invalidate method does not force a synchronous paint; to force a synchronous paint, call the Update method after calling the Invalidate method. 如果在没有参数的情况下调用此方法,则会将整个工作区添加到更新区域。When this method is called with no parameters, the entire client area is added to the update region.

另请参阅

Invalidate()

使控件的整个图面无效并导致重绘控件。Invalidates the entire surface of the control and causes the control to be redrawn.

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,并在删除它时显示它。The following code example enables the user to drag an image or image file onto the form, and have it be displayed at the point on it is dropped. 重写 OnPaint 方法,以便在每次绘制窗体时重绘图像;否则,只有在下一次重画时才会保留图像。The OnPaint method is overridden to repaint the image each time the form is painted; otherwise the image would only persist until the next repainting. DragEnter 事件处理方法确定要拖动到窗体中的数据的类型,并提供相应的反馈。The DragEnter event-handling method determines the type of data being dragged into the form and provides the appropriate feedback. 如果可从数据创建 Image,则 DragDrop 事件处理方法将显示窗体上的图像。The DragDrop event-handling method displays the image on the form, if an Image can be created from the data. 由于 DragEventArgs.XDragEventArgs.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。Because the DragEventArgs.X and DragEventArgs.Y values are screen coordinates, the example uses the PointToClient method to convert them to client coordinates.

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

调用 Invalidate 方法不会强制执行同步绘制;若要强制执行同步画图,请在调用 Invalidate 方法后调用 Update 方法。Calling the Invalidate method does not force a synchronous paint; to force a synchronous paint, call the Update method after calling the Invalidate method. 如果在没有参数的情况下调用此方法,则会将整个工作区添加到更新区域。When this method is called with no parameters, the entire client area is added to the update region.

另请参阅

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