Control.PointToClient-Methode
Rechnet die Position des angegebenen Bildschirmpunkts in Clientkoordinaten um.
Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in system.windows.forms.dll)
Syntax
'Declaration
Public Function PointToClient ( _
p As Point _
) As Point
'Usage
Dim instance As Control
Dim p As Point
Dim returnValue As Point
returnValue = instance.PointToClient(p)
public Point PointToClient (
Point p
)
public:
Point PointToClient (
Point p
)
public Point PointToClient (
Point p
)
public function PointToClient (
p : Point
) : Point
Parameter
- p
Der zu konvertierende Bildschirmkoordinaten-Point.
Rückgabewert
Ein Point, der den konvertierten Pointp in Clientkoordinaten darstellt.
Beispiel
Im folgenden Codebeispiel kann der Benutzer ein Bild oder eine Bilddatei in das Formular ziehen und an der Stelle ablegen, an der das Element angezeigt werden soll. Die OnPaint-Methode wird überschrieben, sodass das Bild jedes Mal neu gezeichnet wird, wenn das Formular gezeichnet wird. Andernfalls würde das Bild nur bis zum nächsten Neuzeichnen beibehalten werden. Die DragEnter-Ereignisbehandlungsmethode bestimmt den Datentyp, der in das Formular gezogen wird, und reagiert entsprechend. Die DragDrop-Ereignisbehandlungsmethode zeigt das Bild im Formular an, wenn aus den Daten ein Image erstellt werden kann. Die Werte DragEventArgs.X und DragEventArgs.Y sind Bildschirmkoordinaten. Daher wird im Beispiel die PointToClient-Methode verwendet, um sie in Clientkoordinaten umzuwandeln.
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
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:
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.set_AllowDrop(true);
this.add_DragDrop(new DragEventHandler(this.Form1_DragDrop));
this.add_DragEnter(new DragEventHandler(this.Form1_DragEnter));
} //Form1
protected void OnPaint(PaintEventArgs e)
{
// If there is an image and it has a location,
// paint it when the Form is repainted.
super.OnPaint(e);
if (this.picture != null && !this.pictureLocation.Equals(Point.Empty)) {
e.get_Graphics().DrawImage(this.picture, this.pictureLocation);
}
} //OnPaint
private void Form1_DragDrop(Object sender, DragEventArgs e)
{
// Handle FileDrop data.
if (e.get_Data().GetDataPresent(DataFormats.FileDrop)) {
// Assign the file names to a string array, in
// case the user has selected multiple files.
String files[] = (String[])(e.get_Data().GetData(
DataFormats.FileDrop));
try {
// Assign the first image to the picture variable.
this.picture = Image.FromFile(files.toString());
// Set the picture location equal to the drop point.
this.pictureLocation = this.PointToClient(new Point(e.get_X(),
e.get_Y()));
}
catch (System.Exception ex) {
MessageBox.Show(ex.get_Message());
return;
}
}
// Handle Bitmap data.
if (e.get_Data().GetDataPresent(DataFormats.Bitmap)) {
try {
// Create an Image and assign it to the picture variable.
this.picture = (Image)e.get_Data().GetData(DataFormats.Bitmap);
// Set the picture location equal to the drop point.
this.pictureLocation = this.PointToClient(new Point(e.get_X(),
e.get_Y()));
}
catch (System.Exception ex) {
MessageBox.Show(ex.get_Message());
return;
}
}
// Force the form to be redrawn with the image.
this.Invalidate();
} //Form1_DragDrop
private void Form1_DragEnter(Object sender, DragEventArgs e)
{
// If the data is a file or a bitmap, display the copy cursor.
if (e.get_Data().GetDataPresent(DataFormats.Bitmap) || e.get_Data().
GetDataPresent(DataFormats.FileDrop)) {
e.set_Effect(DragDropEffects.Copy);
}
else {
e.set_Effect(DragDropEffects.None);
}
} //Form1_DragEnter
Plattformen
Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile für Pocket PC, Windows Mobile für Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
.NET Framework unterstützt nicht alle Versionen sämtlicher Plattformen. Eine Liste der unterstützten Versionen finden Sie unter Systemanforderungen.
Versionsinformationen
.NET Framework
Unterstützt in: 2.0, 1.1, 1.0
.NET Compact Framework
Unterstützt in: 2.0, 1.0
Siehe auch
Referenz
Control-Klasse
Control-Member
System.Windows.Forms-Namespace
Point
PointToScreen