ListBox.IndexFromPoint 方法

参考

定义

命名空间:: System.Windows.Forms

程序集:: System.Windows.Forms.dll

重要

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返回指定坐标处的项的从零开始的索引。

重载

IndexFromPoint(Point)	返回指定坐标处的项的从零开始的索引。
IndexFromPoint(Int32, Int32)	返回指定坐标处的项的从零开始的索引。

IndexFromPoint(Point)

返回指定坐标处的项的从零开始的索引。

public:
 int IndexFromPoint(System::Drawing::Point p);

public int IndexFromPoint (System.Drawing.Point p);

member this.IndexFromPoint : System.Drawing.Point -> int

Public Function IndexFromPoint (p As Point) As Integer

参数

p: Point

Point 对象，包含用于获取项索引的坐标。

Int32

在指定坐标处找到的项的从零开始的索引；如果找不到匹配项，则返回 ListBox.NoMatches。

示例

下面的代码示例演示如何使用 ListBox 包含要放置到 RichTextBox 控件中的项的控件执行拖放操作。窗体的构造函数将 AllowDrop 属性设置为 true ，以便在中 RichTextBox执行拖放操作。该示例使用 MouseDown 的 ListBox 事件通过调用 DoDragDrop 方法启动拖动操作。该示例使用 DragEnter 事件来确定被拖入的 RichTextBox 项是否为有效的数据类型。 DragDrop事件执行拖动的项到实际放RichTextBox控件中的当前光标位置在RichTextBox。此示例要求 DragDrop 和 DragEnter 事件已连接到示例中定义的事件处理程序。

public:
   Form1()
   {
      InitializeComponent();
      
      // Sets the control to allow drops, and then adds the necessary event handlers.
      this->richTextBox1->AllowDrop = true;
   }

private:
   void listBox1_MouseDown( Object^ sender, System::Windows::Forms::MouseEventArgs^ e )
   {
      // Determines which item was selected.
      ListBox^ lb = (dynamic_cast<ListBox^>(sender));
      Point pt = Point(e->X,e->Y);

      //Retrieve the item at the specified location within the ListBox.
      int index = lb->IndexFromPoint( pt );

      // Starts a drag-and-drop operation.
      if ( index >= 0 )
      {
         // Retrieve the selected item text to drag into the RichTextBox.
         lb->DoDragDrop( lb->Items[ index ]->ToString(), DragDropEffects::Copy );
      }
   }

   void richTextBox1_DragEnter( Object^ /*sender*/, DragEventArgs^ e )
   {
      // If the data is text, copy the data to the RichTextBox control.
      if ( e->Data->GetDataPresent( "Text" ) )
            e->Effect = DragDropEffects::Copy;
   }

   void richTextBox1_DragDrop( Object^ /*sender*/, DragEventArgs^ e )
   {
      // Paste the text into the RichTextBox where at selection location.
      richTextBox1->SelectedText = e->Data->GetData( "System.String", true )->ToString();
   }

public Form1()
{
   InitializeComponent();
   // Sets the control to allow drops, and then adds the necessary event handlers.
   this.richTextBox1.AllowDrop = true;
}
 
private void listBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
   // Determines which item was selected.
   ListBox lb =( (ListBox)sender);
   Point pt = new Point(e.X,e.Y);
   //Retrieve the item at the specified location within the ListBox.
   int index = lb.IndexFromPoint(pt);

   // Starts a drag-and-drop operation.
   if(index>=0) 
   {
      // Retrieve the selected item text to drag into the RichTextBox.
      lb.DoDragDrop(lb.Items[index].ToString(), DragDropEffects.Copy);
   }
}

private void richTextBox1_DragEnter(object sender, DragEventArgs e)
{
   // If the data is text, copy the data to the RichTextBox control.
   if(e.Data.GetDataPresent("Text"))
      e.Effect = DragDropEffects.Copy;
}

private void richTextBox1_DragDrop(object sender, DragEventArgs e) 
{
   // Paste the text into the RichTextBox where at selection location.
   richTextBox1.SelectedText =  e.Data.GetData("System.String", true).ToString();
}

Public Sub New()
   MyBase.New()

   'This call is required by the Windows Form Designer.
   InitializeComponent()

   richTextBox1.AllowDrop = True

End Sub

Private Sub listBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles listBox1.MouseDown
   ' Determines which item was selected.
   Dim lb As ListBox = CType(sender, ListBox)
   Dim pt As New Point(e.X, e.Y)
   'Retrieve the item at the specified location within the ListBox.
   Dim index As Integer = lb.IndexFromPoint(pt)

   ' Starts a drag-and-drop operation.
   If index >= 0 Then
      ' Retrieve the selected item text to drag into the RichTextBox.
      lb.DoDragDrop(lb.Items(index).ToString(), DragDropEffects.Copy)
   End If
End Sub


Private Sub richTextBox1_DragEnter(ByVal sender As Object, ByVal e As DragEventArgs) Handles richTextBox1.DragEnter
   ' If the data is text, copy the data to the RichTextBox control.
   If e.Data.GetDataPresent("Text") Then
      e.Effect = DragDropEffects.Copy
   End If
End Sub

Private Sub richTextBox1_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles richTextBox1.DragDrop
   ' Paste the text into the RichTextBox where at selection location.
   richTextBox1.SelectedText = e.Data.GetData("System.String", True).ToString()
End Sub

注解

使用此方法可以确定哪个项位于控件中的特定位置。可以使用此方法确定当用户右键单击 ListBox时选择列表中的哪个项。可以确定光标的位置并将其传递给 p 方法的 IndexFromPoint 参数，以确定用户右键单击了哪个项。然后，可以向用户显示快捷菜单，以基于特定项提供任务和功能。

适用于

IndexFromPoint(Int32, Int32)

返回指定坐标处的项的从零开始的索引。

public:
 int IndexFromPoint(int x, int y);

public int IndexFromPoint (int x, int y);

member this.IndexFromPoint : int * int -> int

Public Function IndexFromPoint (x As Integer, y As Integer) As Integer

参数

x: Int32

要搜索的位置的 x 坐标。

y: Int32

要搜索的位置的 y 坐标。

Int32

在指定坐标处找到的项的从零开始的索引；如果找不到匹配项，则返回 ListBox.NoMatches。

示例

public:
   Form1()
   {
      InitializeComponent();
      
      // Sets the control to allow drops, and then adds the necessary event handlers.
      this->richTextBox1->AllowDrop = true;
   }

private:
   void listBox1_MouseDown( Object^ sender, System::Windows::Forms::MouseEventArgs^ e )
   {
      // Determines which item was selected.
      ListBox^ lb = (dynamic_cast<ListBox^>(sender));
      Point pt = Point(e->X,e->Y);

      //Retrieve the item at the specified location within the ListBox.
      int index = lb->IndexFromPoint( pt );

      // Starts a drag-and-drop operation.
      if ( index >= 0 )
      {
         // Retrieve the selected item text to drag into the RichTextBox.
         lb->DoDragDrop( lb->Items[ index ]->ToString(), DragDropEffects::Copy );
      }
   }

   void richTextBox1_DragEnter( Object^ /*sender*/, DragEventArgs^ e )
   {
      // If the data is text, copy the data to the RichTextBox control.
      if ( e->Data->GetDataPresent( "Text" ) )
            e->Effect = DragDropEffects::Copy;
   }

   void richTextBox1_DragDrop( Object^ /*sender*/, DragEventArgs^ e )
   {
      // Paste the text into the RichTextBox where at selection location.
      richTextBox1->SelectedText = e->Data->GetData( "System.String", true )->ToString();
   }

public Form1()
{
   InitializeComponent();
   // Sets the control to allow drops, and then adds the necessary event handlers.
   this.richTextBox1.AllowDrop = true;
}
 
private void listBox1_MouseDown(object sender, System.Windows.Forms.MouseEventArgs e)
{
   // Determines which item was selected.
   ListBox lb =( (ListBox)sender);
   Point pt = new Point(e.X,e.Y);
   //Retrieve the item at the specified location within the ListBox.
   int index = lb.IndexFromPoint(pt);

   // Starts a drag-and-drop operation.
   if(index>=0) 
   {
      // Retrieve the selected item text to drag into the RichTextBox.
      lb.DoDragDrop(lb.Items[index].ToString(), DragDropEffects.Copy);
   }
}

private void richTextBox1_DragEnter(object sender, DragEventArgs e)
{
   // If the data is text, copy the data to the RichTextBox control.
   if(e.Data.GetDataPresent("Text"))
      e.Effect = DragDropEffects.Copy;
}

private void richTextBox1_DragDrop(object sender, DragEventArgs e) 
{
   // Paste the text into the RichTextBox where at selection location.
   richTextBox1.SelectedText =  e.Data.GetData("System.String", true).ToString();
}

Public Sub New()
   MyBase.New()

   'This call is required by the Windows Form Designer.
   InitializeComponent()

   richTextBox1.AllowDrop = True

End Sub

Private Sub listBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles listBox1.MouseDown
   ' Determines which item was selected.
   Dim lb As ListBox = CType(sender, ListBox)
   Dim pt As New Point(e.X, e.Y)
   'Retrieve the item at the specified location within the ListBox.
   Dim index As Integer = lb.IndexFromPoint(pt)

   ' Starts a drag-and-drop operation.
   If index >= 0 Then
      ' Retrieve the selected item text to drag into the RichTextBox.
      lb.DoDragDrop(lb.Items(index).ToString(), DragDropEffects.Copy)
   End If
End Sub


Private Sub richTextBox1_DragEnter(ByVal sender As Object, ByVal e As DragEventArgs) Handles richTextBox1.DragEnter
   ' If the data is text, copy the data to the RichTextBox control.
   If e.Data.GetDataPresent("Text") Then
      e.Effect = DragDropEffects.Copy
   End If
End Sub

Private Sub richTextBox1_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles richTextBox1.DragDrop
   ' Paste the text into the RichTextBox where at selection location.
   richTextBox1.SelectedText = e.Data.GetData("System.String", True).ToString()
End Sub

注解

此方法使你能够确定位于控件内特定位置的项。可以使用此方法确定当用户右键单击 ListBox时选择列表中的哪个项。可以确定光标的位置，并将其传递给x并y的参数IndexFromPoint方法，以确定哪一项用户通过右键单击鼠标。然后，可以向用户显示快捷菜单，以基于特定项提供任务和功能。

适用于

通过

ListBox.IndexFromPoint 方法

定义

重载

IndexFromPoint(Point)

参数

返回

示例

注解

适用于

IndexFromPoint(Int32, Int32)

参数

返回

示例

注解

适用于

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