Control.Invalidate 方法

參考

定義

命名空間:: System.Windows.Forms

組件:: System.Windows.Forms.dll

重要

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使控制項的特定區域失效，並且造成傳送繪製訊息至控制項。

多載

Invalidate(Region, Boolean)	使控制項的指定區域失效 (將它加入控制項的更新區域，而這個區域會在下一個繪製作業中重新繪製)，並使繪製訊息傳送至控制項。選擇性使指派至控制項的子控制項失效。
Invalidate(Rectangle, Boolean)	使控制項的指定區域失效 (將它加入控制項的更新區域，而這個區域會在下一個繪製作業中重新繪製)，並使繪製訊息傳送至控制項。選擇性使指派至控制項的子控制項失效。
Invalidate(Region)	使控制項的指定區域失效 (將它加入控制項的更新區域，而這個區域會在下一個繪製作業中重新繪製)，並使繪製訊息傳送至控制項。
Invalidate(Boolean)	使控制項的特定區域失效，並且造成傳送繪製訊息至控制項。選擇性使指派至控制項的子控制項失效。
Invalidate()	讓控制項的整個介面失效，並重新繪製控制項。
Invalidate(Rectangle)	使控制項的指定區域失效 (將它加入控制項的更新區域，而這個區域會在下一個繪製作業中重新繪製)，並使繪製訊息傳送至控制項。

Invalidate(Region, Boolean)

使控制項的指定區域失效 (將它加入控制項的更新區域，而這個區域會在下一個繪製作業中重新繪製)，並使繪製訊息傳送至控制項。選擇性使指派至控制項的子控制項失效。

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)

參數

region: Region

要使其失效的 Region。

invalidateChildren: Boolean

true 會使控制項的子控制項失效，否則為 false。

備註

Invalidate呼叫方法並不會強制同步繪製;若要強制同步繪製，請在呼叫 Invalidate 方法之後呼叫 Update 方法。在沒有參數的情況下呼叫此方法時，會將整個工作區新增至更新區域。

另請參閱

適用於

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)

參數

rc: Rectangle

Rectangle，表示要使其失效的區域。

invalidateChildren: Boolean

true 會使控制項的子控制項失效，否則為 false。

備註

另請參閱

適用於

Invalidate(Region)

使控制項的指定區域失效 (將它加入控制項的更新區域，而這個區域會在下一個繪製作業中重新繪製)，並使繪製訊息傳送至控制項。

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)

參數

region: Region

要使其失效的 Region。

備註

另請參閱

適用於

Invalidate(Boolean)

使控制項的特定區域失效，並且造成傳送繪製訊息至控制項。選擇性使指派至控制項的子控制項失效。

public:
 void Invalidate(bool invalidateChildren);

public void Invalidate (bool invalidateChildren);

member this.Invalidate : bool -> unit

Public Sub Invalidate (invalidateChildren As Boolean)

參數

invalidateChildren: Boolean

true 會使控制項的子控制項失效，否則為 false。

備註

另請參閱

適用於

Invalidate()

讓控制項的整個介面失效，並重新繪製控制項。

public:
 void Invalidate();

public void Invalidate ();

member this.Invalidate : unit -> unit

Public Sub Invalidate ()

範例

下列程式碼範例可讓使用者將影像或影像檔拖曳到表單上，並將其顯示在卸載的點。系統會 OnPaint 覆寫方法，在每次繪製表單時重新繪製影像;否則，影像只會持續到下一次重新繪製為止。 DragEnter事件處理方法會決定要拖曳到表單中的資料類型，並提供適當的意見反應。如果 Image 可以從資料建立，事件 DragDrop 處理方法會顯示表單上的影像。 DragEventArgs.X由於和 DragEventArgs.Y 值是螢幕座標，所以此範例會使用 PointToClient 方法來將它們轉換成用戶端座標。

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

備註

另請參閱

適用於

Invalidate(Rectangle)

使控制項的指定區域失效 (將它加入控制項的更新區域，而這個區域會在下一個繪製作業中重新繪製)，並使繪製訊息傳送至控制項。

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)

參數

rc: Rectangle

Rectangle，表示要使其失效的區域。

備註

另請參閱

適用於

Control.Invalidate 方法

定義

多載

Invalidate(Region, Boolean)

參數

備註

另請參閱

適用於

Invalidate(Rectangle, Boolean)

參數

備註

另請參閱

適用於

Invalidate(Region)

參數

備註

另請參閱

適用於

Invalidate(Boolean)

參數

備註

另請參閱

適用於

Invalidate()

範例

備註

另請參閱

適用於

Invalidate(Rectangle)

參數

備註

另請參閱

適用於

意見反應

其他資源