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Control.PointToClient Method

Computes the location of the specified screen point into client coordinates.

[Visual Basic]
Public Function PointToClient( _
   ByVal p As Point _
) As Point
[C#]
public Point PointToClient(
 Point p
);
[C++]
public: Point PointToClient(
 Point p
);
[JScript]
public function PointToClient(
   p : Point
) : Point;

Parameters

p
The screen coordinate Point to convert.

Return Value

A Point that represents the converted Point, p, in client coordinates.

Example

[Visual Basic, C#, C++] The following 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. 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. The DragEnter event-handling method determines the type of data being dragged into the form and provides the appropriate feedback. The DragDrop event-handling method displays the image on the form, if an Image can be created from the data. Because the DragEventArgs.X and DragEventArgs.Y values are screen coordinates, the example uses the PointToClient method to convert them to client coordinates.

[Visual Basic] 
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 Not (Me.picture Is 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

[C#] 
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;
   }
}

[C++] 
private:
   Image*  picture;
   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::Form1_DragDrop);
      this->DragEnter += new DragEventHandler(this, &Form1::Form1_DragEnter);
   }

protected:
   void OnPaint(PaintEventArgs* e) {
      // If there is an image and it has a location,
      // paint it when the Form is repainted.
      Form::OnPaint(e);
      if (this->picture != 0 && 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( 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;
         }
   }

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework

See Also

Control Class | Control Members | System.Windows.Forms Namespace | Point | PointToScreen

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