UIElement.ReleasePointerCapture(Pointer) Metode
Definisi
Penting
Beberapa informasi terkait produk prarilis yang dapat diubah secara signifikan sebelum dirilis. Microsoft tidak memberikan jaminan, tersirat maupun tersurat, sehubungan dengan informasi yang diberikan di sini.
public:
virtual void ReleasePointerCapture(Pointer ^ value) = ReleasePointerCapture;
void ReleasePointerCapture(Pointer const& value);
public void ReleasePointerCapture(Pointer value);
function releasePointerCapture(value)
Public Sub ReleasePointerCapture (value As Pointer)
Parameter
- value
- Pointer
Referensi penunjuk. Gunakan referensi yang disimpan dari tangkapan sebelumnya, atau data peristiwa penunjuk, untuk mendapatkan referensi ini.
Contoh
Contoh ini menunjukkan panggilan ReleasePointerCapture berdasarkan penanganan PointerReleased.
Ini juga menunjukkan kode untuk menangkap pointer pada awalnya, dan pola untuk melacak dan menghitung referensi pointer.
int _pointerCount;
public Scenario2()
{
this.InitializeComponent();
bEnteredExited.PointerEntered += bEnteredExited_PointerEntered;
bEnteredExited.PointerExited += bEnteredExited_PointerExited;
bEnteredExited.PointerPressed += bEnteredExited_PointerPressed;
bEnteredExited.PointerReleased += bEnteredExited_PointerReleased;
bEnteredExited.PointerMoved += bEnteredExited_PointerMoved;
// To code for multiple Pointers (that is, fingers),
// we track how many entered/exited.
_pointerCount = 0;
}
private void bEnteredExited_PointerMoved(object sender,
PointerRoutedEventArgs e)
{
Scenario2UpdateVisuals(sender as Border, "Moved");
}
private void bEnteredExited_PointerReleased(object sender,
PointerRoutedEventArgs e)
{
((Border)sender).ReleasePointerCapture(e.Pointer);
txtCaptureStatus.Text = string.Empty;
}
//Can only get capture on PointerPressed (i.e. touch down, mouse click, pen press)
private void bEnteredExited_PointerPressed(object sender,
PointerRoutedEventArgs e)
{
if (tbPointerCapture.IsOn)
{
bool _hasCapture = ((Border)sender).CapturePointer(e.Pointer);
txtCaptureStatus.Text = "Got Capture: " + _hasCapture;
}
}
private void bEnteredExited_PointerExited(object sender,
PointerRoutedEventArgs e)
{
_pointerCount--;
Scenario2UpdateVisuals(sender as Border, "Exited");
}
private void bEnteredExited_PointerEntered(object sender,
PointerRoutedEventArgs e)
{
_pointerCount++;
Scenario2UpdateVisuals(sender as Border, "Entered");
}
private void Scenario2UpdateVisuals(Border border,
String eventDescription)
{
switch (eventDescription.ToLower())
{
case "exited":
if (_pointerCount <= 0)
{
border.Background = new SolidColorBrush(Colors.Red);
bEnteredExitedTextBlock.Text = eventDescription;
}
break;
case "moved":
RotateTransform rt =
(RotateTransform)bEnteredExitedTimer.RenderTransform;
rt.Angle += 2;
if (rt.Angle > 360) rt.Angle -= 360;
break;
default:
border.Background = new SolidColorBrush(Colors.Green);
bEnteredExitedTextBlock.Text = eventDescription;
break;
}
}
private void Scenario2Reset(object sender, RoutedEventArgs e)
{
Scenario2Reset();
}
private void Scenario2Reset()
{
bEnteredExited.Background = new SolidColorBrush(Colors.Green);
bEnteredExitedTextBlock.Text = string.Empty;
}
Private _pointerCount As Integer
Public Sub New()
Me.InitializeComponent()
AddHandler bEnteredExited.PointerEntered, AddressOf bEnteredExited_PointerEntered
AddHandler bEnteredExited.PointerExited, AddressOf bEnteredExited_PointerExited
AddHandler bEnteredExited.PointerPressed, AddressOf bEnteredExited_PointerPressed
AddHandler bEnteredExited.PointerReleased, AddressOf bEnteredExited_PointerReleased
AddHandler bEnteredExited.PointerMoved, AddressOf bEnteredExited_PointerMoved
'To code for multiple Pointers (i.e. Fingers) we track how many entered/exited.
_pointerCount = 0
End Sub
''' <summary>
''' Invoked when this page is about to be displayed in a Frame.
''' </summary>
''' <param name="e">Event data that describes how this page was reached. The Parameter
''' property is typically used to configure the page.</param>
Protected Overrides Sub OnNavigatedTo(e As NavigationEventArgs)
End Sub
Private Sub bEnteredExited_PointerMoved(sender As Object, e As PointerRoutedEventArgs)
Scenario2UpdateVisuals(TryCast(sender, Border), "Moved")
End Sub
Private Sub bEnteredExited_PointerReleased(sender As Object, e As PointerRoutedEventArgs)
DirectCast(sender, Border).ReleasePointerCapture(e.Pointer)
txtCaptureStatus.Text = String.Empty
End Sub
'Can only get capture on PointerPressed (i.e. touch down, mouse click, pen press)
Private Sub bEnteredExited_PointerPressed(sender As Object, e As PointerRoutedEventArgs)
If tbPointerCapture.IsOn Then
Dim _hasCapture As Boolean = DirectCast(sender, Border).CapturePointer(e.Pointer)
txtCaptureStatus.Text = "Got Capture: " & _hasCapture
End If
End Sub
Private Sub bEnteredExited_PointerExited(sender As Object, e As PointerRoutedEventArgs)
_pointerCount -= 1
Scenario2UpdateVisuals(TryCast(sender, Border), "Exited")
End Sub
Private Sub bEnteredExited_PointerEntered(sender As Object, e As PointerRoutedEventArgs)
_pointerCount += 1
Scenario2UpdateVisuals(TryCast(sender, Border), "Entered")
End Sub
Private Sub Scenario2UpdateVisuals(border As Border, eventDescription As String)
Select Case eventDescription.ToLower()
Case "exited"
If _pointerCount <= 0 Then
border.Background = New SolidColorBrush(Colors.Red)
bEnteredExitedTextBlock.Text = eventDescription
End If
Exit Select
Case "moved"
Dim rt As RotateTransform = DirectCast(bEnteredExitedTimer.RenderTransform, RotateTransform)
rt.Angle += 2
If rt.Angle > 360 Then
rt.Angle -= 360
End If
Exit Select
Case Else
border.Background = New SolidColorBrush(Colors.Green)
bEnteredExitedTextBlock.Text = eventDescription
Exit Select
End Select
End Sub
Private Sub Scenario2ResetMethod(sender As Object, e As RoutedEventArgs)
Reset()
End Sub
Private Sub Reset()
bEnteredExited.Background = New SolidColorBrush(Colors.Green)
bEnteredExitedTextBlock.Text = String.Empty
End Sub
Keterangan
Melepaskan penangkapan penunjuk secara terprogram dengan ReleasePointerCapture bukanlah satu-satunya cara elemen mungkin kehilangan penunjuk. Misalnya, peristiwa berbasis pengguna seperti merilis pointer (titik sentuh ke atas, tombol mouse dilepaskan) dapat menyebabkan penangkapan pointer dibatalkan.
Anda dapat mendengarkan peristiwa PointerCaptureLostuntuk menentukan kapan hal ini terjadi.
Cara lain penangkapan pointer mungkin dibatalkan adalah jika pointer bergerak keluar dari satu aplikasi dan ke aplikasi lain sementara kedua aplikasi berdampingan.
Anda seharusnya hanya memanggil ReleasePointerCapture jika kode aplikasi Anda sebelumnya disebut CapturePointer, dan memiliki referensi ke instans Pointer tertentu tempat Anda ingin merilis tangkapan pointer. Anda biasanya akan mendapatkan referensi Pointer tersebut melalui peristiwa seperti PointerReleased atau mungkin PointerMoved.
Kode aplikasi Anda mungkin memanggil CapturePointer dari UIElement yang berbeda dari yang memiliki pengambilan pointer saat ini. Jika demikian, itu membatalkan tangkapan pointer yang sebelumnya dibuat oleh elemen lain.
UIElementdapat menangkap beberapa pointer untuk menangani beberapa titik sentuh seperti untuk manipulasi, tetapi hanya satu UIElementdalam aplikasi yang dapat memiliki tangkapan pointer kapan saja. Untuk informasi selengkapnya, lihat Menangani input penunjuk.