ListBox.IndexFromPoint 方法
定义
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)
- Source:
- ListBox.cs
- Source:
- ListBox.cs
- Source:
- ListBox.cs
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
返回
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)
- Source:
- ListBox.cs
- Source:
- ListBox.cs
- Source:
- ListBox.cs
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。
返回
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
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。