Control.DoDragDrop Metode
Definisi
Penting
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Overload
| DoDragDrop(Object, DragDropEffects, Bitmap, Point, Boolean) |
Memulai operasi seret. |
| DoDragDrop(Object, DragDropEffects) |
Memulai operasi seret dan letakkan. |
DoDragDrop(Object, DragDropEffects, Bitmap, Point, Boolean)
Memulai operasi seret.
public:
System::Windows::Forms::DragDropEffects DoDragDrop(System::Object ^ data, System::Windows::Forms::DragDropEffects allowedEffects, System::Drawing::Bitmap ^ dragImage, System::Drawing::Point cursorOffset, bool useDefaultDragImage);public System.Windows.Forms.DragDropEffects DoDragDrop (object data, System.Windows.Forms.DragDropEffects allowedEffects, System.Drawing.Bitmap? dragImage, System.Drawing.Point cursorOffset, bool useDefaultDragImage);member this.DoDragDrop : obj * System.Windows.Forms.DragDropEffects * System.Drawing.Bitmap * System.Drawing.Point * bool -> System.Windows.Forms.DragDropEffectsPublic Function DoDragDrop (data As Object, allowedEffects As DragDropEffects, dragImage As Bitmap, cursorOffset As Point, useDefaultDragImage As Boolean) As DragDropEffectsParameter
- data
- Object
- allowedEffects
- DragDropEffects
- dragImage
- Bitmap
- cursorOffset
- Point
- useDefaultDragImage
- Boolean
Mengembalikan
Nilai dari DragDropEffects enumerasi yang mewakili efek akhir yang dilakukan selama operasi seret dan letakkan.
Keterangan
Parameter allowedEffects menentukan operasi seret mana yang dapat terjadi. Jika operasi seret perlu menginteropsi aplikasi dalam proses lain, data harus menjadi kelas terkelola dasar (String, , Bitmapatau Metafile) atau beberapa Object yang mengimplementasikan ISerializable. data juga dapat berupa apa pun Object yang mengimplementasikan IDataObject. dragImage adalah bitmap yang akan ditampilkan selama operasi seret dan cursorOffset menentukan lokasi kursor di dalam dragImage, yang merupakan offset dari sudut kiri atas. Tentukan true untuk useDefaultDragImage menggunakan gambar seret jendela berlapis dengan ukuran 96x96; jika tidak false. Perhatikan tepi dragImage luar dipadukan jika lebar atau tinggi gambar melebihi 300 piksel.
Karena DoDragDrop(Object, DragDropEffects, Bitmap, Point, Boolean) selalu melakukan langkah perkalian RGB dalam menghitung nilai alfa, Anda harus selalu meneruskan Bitmap pencampuran alfa tanpa pencampuran alfa yang telah ditentukan sebelumnya. Tidak ada kesalahan yang akan diakibatkan Bitmap dari melewati dengan campuran alfa yang telah ditentukan sebelumnya, tetapi metode ini akan mengalikannya lagi, menggandakan nilai alfa yang dihasilkan.
Berlaku untuk
DoDragDrop(Object, DragDropEffects)
Memulai operasi seret dan letakkan.
public:
System::Windows::Forms::DragDropEffects DoDragDrop(System::Object ^ data, System::Windows::Forms::DragDropEffects allowedEffects);public System.Windows.Forms.DragDropEffects DoDragDrop (object data, System.Windows.Forms.DragDropEffects allowedEffects);member this.DoDragDrop : obj * System.Windows.Forms.DragDropEffects -> System.Windows.Forms.DragDropEffectsPublic Function DoDragDrop (data As Object, allowedEffects As DragDropEffects) As DragDropEffectsParameter
- data
- Object
Data yang akan diseret.
- allowedEffects
- DragDropEffects
Salah DragDropEffects satu nilai.
Mengembalikan
Nilai dari DragDropEffects enumerasi yang mewakili efek akhir yang dilakukan selama operasi seret dan letakkan.
Contoh
Contoh kode berikut menunjukkan operasi seret dan letakkan di antara dua ListBox kontrol. Contoh memanggil DoDragDrop metode saat tindakan seret dimulai. Tindakan seret dimulai jika mouse telah memindahkan lebih dari SystemInformation.DragSize dari lokasi mouse selama MouseDown peristiwa. Metode IndexFromPoint ini digunakan untuk menentukan indeks item yang akan diseret selama MouseDown peristiwa.
Contoh ini juga menunjukkan penggunaan kursor kustom untuk operasi seret dan letakkan. Contohnya mengharuskan dua file kursor, 3dwarro.cur dan 3dwno.cur, ada di direktori aplikasi, untuk kursor seret dan tanpa jatuhkan kustom. Kursor kustom akan digunakan jika UseCustomCursorsCheckCheckBox dicentang. Kursor kustom diatur dalam penanganan GiveFeedback aktivitas.
Status keyboard dievaluasi di DragOver penanganan aktivitas untuk di sebelah kanan ListBox, untuk menentukan operasi seret berdasarkan status tombol SHIFT, CTRL, ALT, atau CTRL+ALT. Lokasi di ListBox mana penurunan akan terjadi juga ditentukan selama DragOver peristiwa. Jika data yang akan dihilangkan bukan String, maka DragEventArgs.Effect diatur ke None dalam DragDropEffects. Akhirnya, status penurunan ditampilkan di DropLocationLabelLabel.
Data yang akan dihilangkan untuk hak ListBox ditentukan dalam DragDrop penanganan aktivitas dan String nilai ditambahkan di tempat yang sesuai di ListBox. Jika operasi seret bergerak di luar batas formulir, maka operasi seret dan letakkan dibatalkan di penanganan QueryContinueDrag aktivitas.
using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
namespace Snip_DragNDrop
{
public ref class Form1: public System::Windows::Forms::Form
{
private:
System::Windows::Forms::ListBox^ ListDragSource;
System::Windows::Forms::ListBox^ ListDragTarget;
System::Windows::Forms::CheckBox^ UseCustomCursorsCheck;
System::Windows::Forms::Label ^ DropLocationLabel;
Int32 indexOfItemUnderMouseToDrag;
Int32 indexOfItemUnderMouseToDrop;
Rectangle dragBoxFromMouseDown;
Point screenOffset;
System::Windows::Forms::Cursor^ MyNoDropCursor;
System::Windows::Forms::Cursor^ MyNormalCursor;
public:
Form1()
{
this->ListDragSource = gcnew System::Windows::Forms::ListBox;
this->ListDragTarget = gcnew System::Windows::Forms::ListBox;
this->UseCustomCursorsCheck = gcnew System::Windows::Forms::CheckBox;
this->DropLocationLabel = gcnew System::Windows::Forms::Label;
this->SuspendLayout();
// ListDragSource
array<Object^>^temp0 = {"five","six","seven","eight","nine","ten"};
this->ListDragSource->Items->AddRange( temp0 );
this->ListDragSource->Location = System::Drawing::Point( 10, 17 );
this->ListDragSource->Size = System::Drawing::Size( 120, 225 );
this->ListDragSource->MouseDown += gcnew System::Windows::Forms::MouseEventHandler( this, &Form1::ListDragSource_MouseDown );
this->ListDragSource->QueryContinueDrag += gcnew System::Windows::Forms::QueryContinueDragEventHandler( this, &Form1::ListDragSource_QueryContinueDrag );
this->ListDragSource->MouseUp += gcnew System::Windows::Forms::MouseEventHandler( this, &Form1::ListDragSource_MouseUp );
this->ListDragSource->MouseMove += gcnew System::Windows::Forms::MouseEventHandler( this, &Form1::ListDragSource_MouseMove );
this->ListDragSource->GiveFeedback += gcnew System::Windows::Forms::GiveFeedbackEventHandler( this, &Form1::ListDragSource_GiveFeedback );
// ListDragTarget
this->ListDragTarget->AllowDrop = true;
this->ListDragTarget->Location = System::Drawing::Point( 154, 17 );
this->ListDragTarget->Size = System::Drawing::Size( 120, 225 );
this->ListDragTarget->DragOver += gcnew System::Windows::Forms::DragEventHandler( this, &Form1::ListDragTarget_DragOver );
this->ListDragTarget->DragDrop += gcnew System::Windows::Forms::DragEventHandler( this, &Form1::ListDragTarget_DragDrop );
this->ListDragTarget->DragEnter += gcnew System::Windows::Forms::DragEventHandler( this, &Form1::ListDragTarget_DragEnter );
this->ListDragTarget->DragLeave += gcnew System::EventHandler( this, &Form1::ListDragTarget_DragLeave );
// UseCustomCursorsCheck
this->UseCustomCursorsCheck->Location = System::Drawing::Point( 10, 243 );
this->UseCustomCursorsCheck->Size = System::Drawing::Size( 137, 24 );
this->UseCustomCursorsCheck->Text = "Use Custom Cursors";
// DropLocationLabel
this->DropLocationLabel->Location = System::Drawing::Point( 154, 245 );
this->DropLocationLabel->Size = System::Drawing::Size( 137, 24 );
this->DropLocationLabel->Text = "None";
// Form1
this->ClientSize = System::Drawing::Size( 292, 270 );
array<System::Windows::Forms::Control^>^formControls = {this->ListDragSource,this->ListDragTarget,this->UseCustomCursorsCheck,this->DropLocationLabel};
this->Controls->AddRange( formControls );
this->Text = "drag-and-drop Example";
this->ResumeLayout( false );
}
private:
void ListDragSource_MouseDown( Object^ /*sender*/, System::Windows::Forms::MouseEventArgs^ e )
{
// Get the index of the item the mouse is below.
indexOfItemUnderMouseToDrag = this->ListDragSource->IndexFromPoint( e->X, e->Y );
if ( indexOfItemUnderMouseToDrag != ListBox::NoMatches )
{
// Remember the point where the mouse down occurred. The DragSize indicates
// the size that the mouse can move before a drag event should be started.
System::Drawing::Size dragSize = SystemInformation::DragSize;
// Create a rectangle using the DragSize, with the mouse position being
// at the center of the rectangle.
dragBoxFromMouseDown = Rectangle(Point(e->X - (dragSize.Width / 2),e->Y - (dragSize.Height / 2)),dragSize);
}
else
dragBoxFromMouseDown = Rectangle::Empty;
// Reset the rectangle if the mouse is not over an item in the ListBox.
}
void ListDragSource_MouseUp( Object^ /*sender*/, System::Windows::Forms::MouseEventArgs^ /*e*/ )
{
// Reset the drag rectangle when the mouse button is raised.
dragBoxFromMouseDown = Rectangle::Empty;
}
void ListDragSource_MouseMove( Object^ /*sender*/, System::Windows::Forms::MouseEventArgs^ e )
{
if ( (e->Button & ::MouseButtons::Left) == ::MouseButtons::Left )
{
// If the mouse moves outside the rectangle, start the drag.
if ( dragBoxFromMouseDown != Rectangle::Empty && !dragBoxFromMouseDown.Contains( e->X, e->Y ) )
{
// Create custom cursors for the drag-and-drop operation.
try
{
MyNormalCursor = gcnew System::Windows::Forms::Cursor( "3dwarro.cur" );
MyNoDropCursor = gcnew System::Windows::Forms::Cursor( "3dwno.cur" );
}
catch ( Exception^ )
{
// An error occurred while attempting to load the cursors, so use
// the standard cursors.
this->UseCustomCursorsCheck->Checked = false;
}
__finally
{
// The screenOffset is used to account for any desktop bands
// that may be at the top or left side of the screen when
// determining when to cancel the drag drop operation.
screenOffset = SystemInformation::WorkingArea.Location;
// Proceed with the drag-and-drop, passing in the list item.
DragDropEffects dropEffect = this->ListDragSource->DoDragDrop( ListDragSource->Items[ indexOfItemUnderMouseToDrag ], static_cast<DragDropEffects>(DragDropEffects::All | DragDropEffects::Link) );
// If the drag operation was a move then remove the item.
if ( dropEffect == DragDropEffects::Move )
{
ListDragSource->Items->RemoveAt( indexOfItemUnderMouseToDrag );
// Selects the previous item in the list as long as the list has an item.
if ( indexOfItemUnderMouseToDrag > 0 )
ListDragSource->SelectedIndex = indexOfItemUnderMouseToDrag - 1;
else
if ( ListDragSource->Items->Count > 0 )
// Selects the first item.
ListDragSource->SelectedIndex = 0;
}
// Dispose of the cursors since they are no longer needed.
if ( MyNormalCursor != nullptr )
delete MyNormalCursor;
if ( MyNoDropCursor != nullptr )
delete MyNoDropCursor;
}
}
}
}
void ListDragSource_GiveFeedback( Object^ /*sender*/, System::Windows::Forms::GiveFeedbackEventArgs^ e )
{
// Use custom cursors if the check box is checked.
if ( UseCustomCursorsCheck->Checked )
{
// Sets the custom cursor based upon the effect.
e->UseDefaultCursors = false;
if ( (e->Effect & DragDropEffects::Move) == DragDropEffects::Move )
::Cursor::Current = MyNormalCursor;
else
::Cursor::Current = MyNoDropCursor;
}
}
void ListDragTarget_DragOver( Object^ /*sender*/, System::Windows::Forms::DragEventArgs^ e )
{
// Determine whether string data exists in the drop data. If not, then
// the drop effect reflects that the drop cannot occur.
if ( !e->Data->GetDataPresent( System::String::typeid ) )
{
e->Effect = DragDropEffects::None;
DropLocationLabel->Text = "None - no string data.";
return;
}
// Set the effect based upon the KeyState.
if ( (e->KeyState & (8 + 32)) == (8 + 32) && ((e->AllowedEffect & DragDropEffects::Link) == DragDropEffects::Link) )
{
// KeyState 8 + 32 = CTRL + ALT
// Link drag-and-drop effect.
e->Effect = DragDropEffects::Link;
}
else
if ( (e->KeyState & 32) == 32 && ((e->AllowedEffect & DragDropEffects::Link) == DragDropEffects::Link) )
{
// ALT KeyState for link.
e->Effect = DragDropEffects::Link;
}
else
if ( (e->KeyState & 4) == 4 && ((e->AllowedEffect & DragDropEffects::Move) == DragDropEffects::Move) )
{
// SHIFT KeyState for move.
e->Effect = DragDropEffects::Move;
}
else
if ( (e->KeyState & 8) == 8 && ((e->AllowedEffect & DragDropEffects::Copy) == DragDropEffects::Copy) )
{
// CTRL KeyState for copy.
e->Effect = DragDropEffects::Copy;
}
else
if ( (e->AllowedEffect & DragDropEffects::Move) == DragDropEffects::Move )
{
// By default, the drop action should be move, if allowed.
e->Effect = DragDropEffects::Move;
}
else
e->Effect = DragDropEffects::None;
// Get the index of the item the mouse is below.
// The mouse locations are relative to the screen, so they must be
// converted to client coordinates.
indexOfItemUnderMouseToDrop = ListDragTarget->IndexFromPoint( ListDragTarget->PointToClient( Point(e->X,e->Y) ) );
// Updates the label text.
if ( indexOfItemUnderMouseToDrop != ListBox::NoMatches )
{
DropLocationLabel->Text = String::Concat( "Drops before item # ", (indexOfItemUnderMouseToDrop + 1) );
}
else
DropLocationLabel->Text = "Drops at the end.";
}
void ListDragTarget_DragDrop( Object^ /*sender*/, System::Windows::Forms::DragEventArgs^ e )
{
// Ensure that the list item index is contained in the data.
if ( e->Data->GetDataPresent( System::String::typeid ) )
{
Object^ item = dynamic_cast<Object^>(e->Data->GetData( System::String::typeid ));
// Perform drag-and-drop, depending upon the effect.
if ( e->Effect == DragDropEffects::Copy || e->Effect == DragDropEffects::Move )
{
// Insert the item.
if ( indexOfItemUnderMouseToDrop != ListBox::NoMatches )
ListDragTarget->Items->Insert( indexOfItemUnderMouseToDrop, item );
else
ListDragTarget->Items->Add( item );
}
}
// Reset the label text.
DropLocationLabel->Text = "None";
}
void ListDragSource_QueryContinueDrag( Object^ sender, System::Windows::Forms::QueryContinueDragEventArgs^ e )
{
// Cancel the drag if the mouse moves off the form.
ListBox^ lb = dynamic_cast<ListBox^>(sender);
if ( lb != nullptr )
{
Form^ f = lb->FindForm();
// Cancel the drag if the mouse moves off the form. The screenOffset
// takes into account any desktop bands that may be at the top or left
// side of the screen.
if ( ((Control::MousePosition.X - screenOffset.X) < f->DesktopBounds.Left) || ((Control::MousePosition.X - screenOffset.X) > f->DesktopBounds.Right) || ((Control::MousePosition.Y - screenOffset.Y) < f->DesktopBounds.Top) || ((Control::MousePosition.Y - screenOffset.Y) > f->DesktopBounds.Bottom) )
{
e->Action = DragAction::Cancel;
}
}
}
void ListDragTarget_DragEnter( Object^ /*sender*/, System::Windows::Forms::DragEventArgs^ /*e*/ )
{
// Reset the label text.
DropLocationLabel->Text = "None";
}
void ListDragTarget_DragLeave( Object^ /*sender*/, System::EventArgs^ /*e*/ )
{
// Reset the label text.
DropLocationLabel->Text = "None";
}
};
}
/// The main entry point for the application.
[STAThread]
int main()
{
Application::Run( gcnew Snip_DragNDrop::Form1 );
}
using System;
using System.Drawing;
using System.Windows.Forms;
namespace Snip_DragNDrop
{
public class Form1 : Form
{
private ListBox ListDragSource;
private ListBox ListDragTarget;
private CheckBox UseCustomCursorsCheck;
private Label DropLocationLabel;
private int indexOfItemUnderMouseToDrag;
private int indexOfItemUnderMouseToDrop;
private Rectangle dragBoxFromMouseDown;
private Point screenOffset;
private Cursor MyNoDropCursor;
private Cursor MyNormalCursor;
// The main entry point for the application.
[STAThread]
static void Main()
{
Application.Run(new Form1());
}
public Form1()
{
this.ListDragSource = new ListBox();
this.ListDragTarget = new ListBox();
this.UseCustomCursorsCheck = new CheckBox();
this.DropLocationLabel = new Label();
this.SuspendLayout();
// ListDragSource
this.ListDragSource.Items.AddRange(new object[] {"one", "two", "three", "four",
"five", "six", "seven", "eight",
"nine", "ten"});
this.ListDragSource.Location = new Point(10, 17);
this.ListDragSource.Size = new Size(120, 225);
this.ListDragSource.MouseDown += this.ListDragSource_MouseDown;
this.ListDragSource.QueryContinueDrag += this.ListDragSource_QueryContinueDrag;
this.ListDragSource.MouseUp += this.ListDragSource_MouseUp;
this.ListDragSource.MouseMove += this.ListDragSource_MouseMove;
this.ListDragSource.GiveFeedback += this.ListDragSource_GiveFeedback;
// ListDragTarget
this.ListDragTarget.AllowDrop = true;
this.ListDragTarget.Location = new Point(154, 17);
this.ListDragTarget.Size = new Size(120, 225);
this.ListDragTarget.DragOver += this.ListDragTarget_DragOver;
this.ListDragTarget.DragDrop += this.ListDragTarget_DragDrop;
this.ListDragTarget.DragEnter += this.ListDragTarget_DragEnter;
this.ListDragTarget.DragLeave += this.ListDragTarget_DragLeave;
// UseCustomCursorsCheck
this.UseCustomCursorsCheck.Location = new Point(10, 243);
this.UseCustomCursorsCheck.Size = new Size(137, 24);
this.UseCustomCursorsCheck.Text = "Use Custom Cursors";
// DropLocationLabel
this.DropLocationLabel.Location = new Point(154, 245);
this.DropLocationLabel.Size = new Size(137, 24);
this.DropLocationLabel.Text = "None";
// Form1
this.ClientSize = new Size(292, 270);
this.Controls.AddRange(new Control[] {
this.ListDragSource,
this.ListDragTarget,
this.UseCustomCursorsCheck,
this.DropLocationLabel});
this.Text = "drag-and-drop Example";
this.ResumeLayout(false);
}
private void ListDragSource_MouseDown(object sender, MouseEventArgs e)
{
// Get the index of the item the mouse is below.
indexOfItemUnderMouseToDrag = ListDragSource.IndexFromPoint(e.X, e.Y);
if (indexOfItemUnderMouseToDrag != ListBox.NoMatches)
{
// Remember the point where the mouse down occurred. The DragSize indicates
// the size that the mouse can move before a drag event should be started.
Size dragSize = SystemInformation.DragSize;
// Create a rectangle using the DragSize, with the mouse position being
// at the center of the rectangle.
dragBoxFromMouseDown = new Rectangle(
new Point(e.X - (dragSize.Width / 2),
e.Y - (dragSize.Height / 2)),
dragSize);
}
else
{
// Reset the rectangle if the mouse is not over an item in the ListBox.
dragBoxFromMouseDown = Rectangle.Empty;
}
}
private void ListDragSource_MouseUp(object sender, MouseEventArgs e)
{
// Reset the drag rectangle when the mouse button is raised.
dragBoxFromMouseDown = Rectangle.Empty;
}
private void ListDragSource_MouseMove(object sender, MouseEventArgs e)
{
if ((e.Button & MouseButtons.Left) == MouseButtons.Left)
{
// If the mouse moves outside the rectangle, start the drag.
if (dragBoxFromMouseDown != Rectangle.Empty &&
!dragBoxFromMouseDown.Contains(e.X, e.Y))
{
// Create custom cursors for the drag-and-drop operation.
try
{
MyNormalCursor = new Cursor("3dwarro.cur");
MyNoDropCursor = new Cursor("3dwno.cur");
}
catch
{
// An error occurred while attempting to load the cursors, so use
// standard cursors.
UseCustomCursorsCheck.Checked = false;
}
finally
{
// The screenOffset is used to account for any desktop bands
// that may be at the top or left side of the screen when
// determining when to cancel the drag drop operation.
screenOffset = SystemInformation.WorkingArea.Location;
// Proceed with the drag-and-drop, passing in the list item.
DragDropEffects dropEffect = ListDragSource.DoDragDrop(ListDragSource.Items[indexOfItemUnderMouseToDrag], DragDropEffects.All | DragDropEffects.Link);
// If the drag operation was a move then remove the item.
if (dropEffect == DragDropEffects.Move)
{
ListDragSource.Items.RemoveAt(indexOfItemUnderMouseToDrag);
// Selects the previous item in the list as long as the list has an item.
if (indexOfItemUnderMouseToDrag > 0)
ListDragSource.SelectedIndex = indexOfItemUnderMouseToDrag - 1;
else if (ListDragSource.Items.Count > 0)
// Selects the first item.
ListDragSource.SelectedIndex = 0;
}
// Dispose of the cursors since they are no longer needed.
if (MyNormalCursor != null)
MyNormalCursor.Dispose();
if (MyNoDropCursor != null)
MyNoDropCursor.Dispose();
}
}
}
}
private void ListDragSource_GiveFeedback(object sender, GiveFeedbackEventArgs e)
{
// Use custom cursors if the check box is checked.
if (UseCustomCursorsCheck.Checked)
{
// Sets the custom cursor based upon the effect.
e.UseDefaultCursors = false;
if ((e.Effect & DragDropEffects.Move) == DragDropEffects.Move)
Cursor.Current = MyNormalCursor;
else
Cursor.Current = MyNoDropCursor;
}
}
private void ListDragTarget_DragOver(object sender, DragEventArgs e)
{
// Determine whether string data exists in the drop data. If not, then
// the drop effect reflects that the drop cannot occur.
if (!e.Data.GetDataPresent(typeof(System.String)))
{
e.Effect = DragDropEffects.None;
DropLocationLabel.Text = "None - no string data.";
return;
}
// Set the effect based upon the KeyState.
if ((e.KeyState & (8 + 32)) == (8 + 32) &&
(e.AllowedEffect & DragDropEffects.Link) == DragDropEffects.Link)
{
// KeyState 8 + 32 = CTRL + ALT
// Link drag-and-drop effect.
e.Effect = DragDropEffects.Link;
}
else if ((e.KeyState & 32) == 32 &&
(e.AllowedEffect & DragDropEffects.Link) == DragDropEffects.Link)
{
// ALT KeyState for link.
e.Effect = DragDropEffects.Link;
}
else if ((e.KeyState & 4) == 4 &&
(e.AllowedEffect & DragDropEffects.Move) == DragDropEffects.Move)
{
// SHIFT KeyState for move.
e.Effect = DragDropEffects.Move;
}
else if ((e.KeyState & 8) == 8 &&
(e.AllowedEffect & DragDropEffects.Copy) == DragDropEffects.Copy)
{
// CTRL KeyState for copy.
e.Effect = DragDropEffects.Copy;
}
else if ((e.AllowedEffect & DragDropEffects.Move) == DragDropEffects.Move)
{
// By default, the drop action should be move, if allowed.
e.Effect = DragDropEffects.Move;
}
else
{
e.Effect = DragDropEffects.None;
}
// Get the index of the item the mouse is below.
// The mouse locations are relative to the screen, so they must be
// converted to client coordinates.
indexOfItemUnderMouseToDrop =
ListDragTarget.IndexFromPoint(ListDragTarget.PointToClient(new Point(e.X, e.Y)));
// Updates the label text.
if (indexOfItemUnderMouseToDrop != ListBox.NoMatches)
{
DropLocationLabel.Text = "Drops before item #" + (indexOfItemUnderMouseToDrop + 1);
}
else
{
DropLocationLabel.Text = "Drops at the end.";
}
}
private void ListDragTarget_DragDrop(object sender, DragEventArgs e)
{
// Ensure that the list item index is contained in the data.
if (e.Data.GetDataPresent(typeof(System.String)))
{
Object item = e.Data.GetData(typeof(System.String));
// Perform drag-and-drop, depending upon the effect.
if (e.Effect == DragDropEffects.Copy ||
e.Effect == DragDropEffects.Move)
{
// Insert the item.
if (indexOfItemUnderMouseToDrop != ListBox.NoMatches)
ListDragTarget.Items.Insert(indexOfItemUnderMouseToDrop, item);
else
ListDragTarget.Items.Add(item);
}
}
// Reset the label text.
DropLocationLabel.Text = "None";
}
private void ListDragSource_QueryContinueDrag(object sender, QueryContinueDragEventArgs e)
{
// Cancel the drag if the mouse moves off the form.
ListBox lb = sender as ListBox;
if (lb != null)
{
Form f = lb.FindForm();
// Cancel the drag if the mouse moves off the form. The screenOffset
// takes into account any desktop bands that may be at the top or left
// side of the screen.
if (((Control.MousePosition.X - screenOffset.X) < f.DesktopBounds.Left) ||
((Control.MousePosition.X - screenOffset.X) > f.DesktopBounds.Right) ||
((Control.MousePosition.Y - screenOffset.Y) < f.DesktopBounds.Top) ||
((Control.MousePosition.Y - screenOffset.Y) > f.DesktopBounds.Bottom))
{
e.Action = DragAction.Cancel;
}
}
}
private void ListDragTarget_DragEnter(object sender, DragEventArgs e)
{
// Reset the label text.
DropLocationLabel.Text = "None";
}
private void ListDragTarget_DragLeave(object sender, EventArgs e)
{
// Reset the label text.
DropLocationLabel.Text = "None";
}
}
}
Imports System.Drawing
Imports System.Windows.Forms
Public NotInheritable Class Form1
Inherits Form
Friend WithEvents ListDragSource As ListBox
Friend WithEvents ListDragTarget As ListBox
Friend WithEvents UseCustomCursorsCheck As CheckBox
Friend WithEvents DropLocationLabel As Label
Private indexOfItemUnderMouseToDrag As Integer
Private indexOfItemUnderMouseToDrop As Integer
Private dragBoxFromMouseDown As Rectangle
Private screenOffset As Point
Private MyNoDropCursor As Cursor
Private MyNormalCursor As Cursor
<STAThread()>
Public Shared Sub Main()
Application.Run(New Form1())
End Sub
Public Sub New()
MyBase.New()
Me.ListDragSource = New ListBox()
Me.ListDragTarget = New ListBox()
Me.UseCustomCursorsCheck = New CheckBox()
Me.DropLocationLabel = New Label()
Me.SuspendLayout()
' ListDragSource
Me.ListDragSource.Items.AddRange(New Object() {"one", "two", "three", "four",
"five", "six", "seven", "eight",
"nine", "ten"})
Me.ListDragSource.Location = New Point(10, 17)
Me.ListDragSource.Size = New Size(120, 225)
' ListDragTarget
Me.ListDragTarget.AllowDrop = True
Me.ListDragTarget.Location = New Point(154, 17)
Me.ListDragTarget.Size = New Size(120, 225)
' UseCustomCursorsCheck
Me.UseCustomCursorsCheck.Location = New Point(10, 243)
Me.UseCustomCursorsCheck.Size = New Size(137, 24)
Me.UseCustomCursorsCheck.Text = "Use Custom Cursors"
' DropLocationLabel
Me.DropLocationLabel.Location = New Point(154, 245)
Me.DropLocationLabel.Size = New Size(137, 24)
Me.DropLocationLabel.Text = "None"
' Form1
Me.ClientSize = New Size(292, 270)
Me.Controls.AddRange(New Control() {Me.ListDragSource,
Me.ListDragTarget,
Me.UseCustomCursorsCheck,
Me.DropLocationLabel})
Me.Text = "drag-and-drop Example"
Me.ResumeLayout(False)
End Sub
Private Sub ListDragSource_MouseDown(ByVal sender As Object, ByVal e As MouseEventArgs) Handles ListDragSource.MouseDown
' Get the index of the item the mouse is below.
indexOfItemUnderMouseToDrag = ListDragSource.IndexFromPoint(e.X, e.Y)
If (indexOfItemUnderMouseToDrag <> ListBox.NoMatches) Then
' Remember the point where the mouse down occurred. The DragSize indicates
' the size that the mouse can move before a drag event should be started.
Dim dragSize As Size = SystemInformation.DragSize
' Create a rectangle using the DragSize, with the mouse position being
' at the center of the rectangle.
dragBoxFromMouseDown = New Rectangle(
New Point(e.X - (dragSize.Width / 2), e.Y - (dragSize.Height / 2)),
dragSize)
Else
' Reset the rectangle if the mouse is not over an item in the ListBox.
dragBoxFromMouseDown = Rectangle.Empty
End If
End Sub
Private Sub ListDragSource_MouseUp(ByVal sender As Object, ByVal e As MouseEventArgs) Handles ListDragSource.MouseUp
' Reset the drag rectangle when the mouse button is raised.
dragBoxFromMouseDown = Rectangle.Empty
End Sub
Private Sub ListDragSource_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs) Handles ListDragSource.MouseMove
If ((e.Button And MouseButtons.Left) = MouseButtons.Left) Then
' If the mouse moves outside the rectangle, start the drag.
If (Rectangle.op_Inequality(dragBoxFromMouseDown, Rectangle.Empty) And
Not dragBoxFromMouseDown.Contains(e.X, e.Y)) Then
' Creates custom cursors for the drag-and-drop operation.
Try
MyNormalCursor = New Cursor("3dwarro.cur")
MyNoDropCursor = New Cursor("3dwno.cur")
Catch
' An error occurred while attempting to load the cursors so use
' standard cursors.
UseCustomCursorsCheck.Checked = False
Finally
' The screenOffset is used to account for any desktop bands
' that may be at the top or left side of the screen when
' determining when to cancel the drag drop operation.
screenOffset = SystemInformation.WorkingArea.Location
' Proceed with the drag-and-drop, passing in the list item.
Dim dropEffect As DragDropEffects = ListDragSource.DoDragDrop(
ListDragSource.Items(indexOfItemUnderMouseToDrag),
DragDropEffects.All Or DragDropEffects.Link)
' If the drag operation was a move then remove the item.
If (dropEffect = DragDropEffects.Move) Then
ListDragSource.Items.RemoveAt(indexOfItemUnderMouseToDrag)
' Select the previous item in the list as long as the list has an item.
If (indexOfItemUnderMouseToDrag > 0) Then
ListDragSource.SelectedIndex = indexOfItemUnderMouseToDrag - 1
ElseIf (ListDragSource.Items.Count > 0) Then
' Selects the first item.
ListDragSource.SelectedIndex = 0
End If
End If
' Dispose the cursors since they are no longer needed.
If (Not MyNormalCursor Is Nothing) Then _
MyNormalCursor.Dispose()
If (Not MyNoDropCursor Is Nothing) Then _
MyNoDropCursor.Dispose()
End Try
End If
End If
End Sub
Private Sub ListDragSource_GiveFeedback(ByVal sender As Object, ByVal e As GiveFeedbackEventArgs) Handles ListDragSource.GiveFeedback
' Use custom cursors if the check box is checked.
If (UseCustomCursorsCheck.Checked) Then
' Set the custom cursor based upon the effect.
e.UseDefaultCursors = False
If ((e.Effect And DragDropEffects.Move) = DragDropEffects.Move) Then
Cursor.Current = MyNormalCursor
Else
Cursor.Current = MyNoDropCursor
End If
End If
End Sub
Private Sub ListDragTarget_DragOver(ByVal sender As Object, ByVal e As DragEventArgs) Handles ListDragTarget.DragOver
' Determine whether string data exists in the drop data. If not, then
' the drop effect reflects that the drop cannot occur.
If Not (e.Data.GetDataPresent(GetType(System.String))) Then
e.Effect = DragDropEffects.None
DropLocationLabel.Text = "None - no string data."
Return
End If
' Set the effect based upon the KeyState.
If ((e.KeyState And (8 + 32)) = (8 + 32) And
(e.AllowedEffect And DragDropEffects.Link) = DragDropEffects.Link) Then
' KeyState 8 + 32 = CTRL + ALT
' Link drag-and-drop effect.
e.Effect = DragDropEffects.Link
ElseIf ((e.KeyState And 32) = 32 And
(e.AllowedEffect And DragDropEffects.Link) = DragDropEffects.Link) Then
' ALT KeyState for link.
e.Effect = DragDropEffects.Link
ElseIf ((e.KeyState And 4) = 4 And
(e.AllowedEffect And DragDropEffects.Move) = DragDropEffects.Move) Then
' SHIFT KeyState for move.
e.Effect = DragDropEffects.Move
ElseIf ((e.KeyState And 8) = 8 And
(e.AllowedEffect And DragDropEffects.Copy) = DragDropEffects.Copy) Then
' CTRL KeyState for copy.
e.Effect = DragDropEffects.Copy
ElseIf ((e.AllowedEffect And DragDropEffects.Move) = DragDropEffects.Move) Then
' By default, the drop action should be move, if allowed.
e.Effect = DragDropEffects.Move
Else
e.Effect = DragDropEffects.None
End If
' Gets the index of the item the mouse is below.
' The mouse locations are relative to the screen, so they must be
' converted to client coordinates.
indexOfItemUnderMouseToDrop =
ListDragTarget.IndexFromPoint(ListDragTarget.PointToClient(New Point(e.X, e.Y)))
' Updates the label text.
If (indexOfItemUnderMouseToDrop <> ListBox.NoMatches) Then
DropLocationLabel.Text = "Drops before item #" & (indexOfItemUnderMouseToDrop + 1)
Else
DropLocationLabel.Text = "Drops at the end."
End If
End Sub
Private Sub ListDragTarget_DragDrop(ByVal sender As Object, ByVal e As DragEventArgs) Handles ListDragTarget.DragDrop
' Ensures that the list item index is contained in the data.
If (e.Data.GetDataPresent(GetType(System.String))) Then
Dim item As Object = CType(e.Data.GetData(GetType(System.String)), System.Object)
' Perform drag-and-drop, depending upon the effect.
If (e.Effect = DragDropEffects.Copy Or
e.Effect = DragDropEffects.Move) Then
' Insert the item.
If (indexOfItemUnderMouseToDrop <> ListBox.NoMatches) Then
ListDragTarget.Items.Insert(indexOfItemUnderMouseToDrop, item)
Else
ListDragTarget.Items.Add(item)
End If
End If
' Reset the label text.
DropLocationLabel.Text = "None"
End If
End Sub
Private Sub ListDragSource_QueryContinueDrag(ByVal sender As Object, ByVal e As QueryContinueDragEventArgs) Handles ListDragSource.QueryContinueDrag
' Cancel the drag if the mouse moves off the form.
Dim lb As ListBox = CType(sender, ListBox)
If (lb IsNot Nothing) Then
Dim f As Form = lb.FindForm()
' Cancel the drag if the mouse moves off the form. The screenOffset
' takes into account any desktop bands that may be at the top or left
' side of the screen.
If (((Control.MousePosition.X - screenOffset.X) < f.DesktopBounds.Left) Or
((Control.MousePosition.X - screenOffset.X) > f.DesktopBounds.Right) Or
((Control.MousePosition.Y - screenOffset.Y) < f.DesktopBounds.Top) Or
((Control.MousePosition.Y - screenOffset.Y) > f.DesktopBounds.Bottom)) Then
e.Action = DragAction.Cancel
End If
End If
End Sub
Private Sub ListDragTarget_DragEnter(ByVal sender As Object, ByVal e As DragEventArgs) Handles ListDragTarget.DragEnter
' Reset the label text.
DropLocationLabel.Text = "None"
End Sub
Private Sub ListDragTarget_DragLeave(ByVal sender As Object, ByVal e As EventArgs) Handles ListDragTarget.DragLeave
' Reset the label text.
DropLocationLabel.Text = "None"
End Sub
End Class
Contoh kode berikut menunjukkan cara menggunakan DragDropEffects enumerasi untuk menentukan bagaimana data harus ditransfer antara kontrol yang terlibat dalam operasi seret dan letakkan. Contoh ini mengharuskan formulir Anda menyertakan RichTextBox kontrol dan ListBox kontrol dan ListBox kontrol diisi dengan daftar nama file yang valid. Saat pengguna menyeret nama file ke RichTextBox kontrol, peristiwa kontrol DragEnter dinaikkan. Dalam penanganan aktivitas, Effect properti diinisialisasi DragEventArgs untuk DragDropEffects menunjukkan bahwa data yang direferensikan oleh jalur file harus disalin ke RichTextBox kontrol.
private:
void Form1_Load( Object^ /*sender*/, EventArgs^ /*e*/ )
{
// Sets the AllowDrop property so that data can be dragged onto the control.
richTextBox1->AllowDrop = true;
// Add code here to populate the ListBox1 with paths to text files.
}
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);
int index = lb->IndexFromPoint( pt );
// Starts a drag-and-drop operation with that item.
if ( index >= 0 )
{
lb->DoDragDrop( lb->Items[ index ], DragDropEffects::Link );
}
}
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 )
{
// Loads the file into the control.
richTextBox1->LoadFile( dynamic_cast<String^>(e->Data->GetData( "Text" )), System::Windows::Forms::RichTextBoxStreamType::RichText );
}
private void Form1_Load(object sender, EventArgs e)
{
// Sets the AllowDrop property so that data can be dragged onto the control.
richTextBox1.AllowDrop = true;
// Add code here to populate the ListBox1 with paths to text files.
}
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);
int index = lb.IndexFromPoint(pt);
// Starts a drag-and-drop operation with that item.
if(index>=0)
{
lb.DoDragDrop(lb.Items[index].ToString(), DragDropEffects.Link);
}
}
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)
{
// Loads the file into the control.
richTextBox1.LoadFile((String)e.Data.GetData("Text"), System.Windows.Forms.RichTextBoxStreamType.RichText);
}
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
' Sets the AllowDrop property so that data can be dragged onto the control.
RichTextBox1.AllowDrop = True
' Add code here to populate the ListBox1 with paths to text files.
End Sub
Private Sub RichTextBox1_DragEnter(ByVal sender As Object, ByVal e As System.Windows.Forms.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 Overloads Sub RichTextBox1_DragDrop(ByVal sender As Object, ByVal e As System.Windows.Forms.DragEventArgs) Handles RichTextBox1.DragDrop
' Loads the file into the control.
RichTextBox1.LoadFile(e.Data.GetData("Text"), System.Windows.Forms.RichTextBoxStreamType.RichText)
End Sub
Private Sub ListBox1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles ListBox1.MouseDown
Dim Lb As ListBox
Dim Pt As New Point(e.X, e.Y)
Dim Index As Integer
' Determines which item was selected.
Lb = sender
Index = Lb.IndexFromPoint(Pt)
' Starts a drag-and-drop operation with that item.
If Index >= 0 Then
Lb.DoDragDrop(Lb.Items(Index), DragDropEffects.Link)
End If
End Sub
Keterangan
Parameter allowedEffects menentukan operasi seret mana yang dapat terjadi. Jika operasi seret perlu beroperasi dengan aplikasi dalam proses lain, data harus menjadi kelas terkelola dasar (String, , Bitmapatau Metafile), atau objek yang mengimplementasikan ISerializable atau IDataObject.
Berikut ini menjelaskan bagaimana dan kapan peristiwa yang terkait dengan operasi seret dan letakkan dinaikkan.
Metode DoDragDrop menentukan kontrol di bawah lokasi kursor saat ini. Kemudian memeriksa untuk melihat apakah kontrol adalah target penurunan yang valid.
Jika kontrol adalah target penurunan yang valid, GiveFeedback peristiwa dinaikkan dengan efek seret dan letakkan yang ditentukan. Untuk daftar efek seret dan letakkan, lihat DragDropEffects enumerasi.
Perubahan posisi kursor mouse, status keyboard, dan status tombol mouse dilacak.
Jika pengguna keluar dari jendela, DragLeave peristiwa akan dinaikkan.
Jika mouse memasuki kontrol lain, untuk kontrol tersebut DragEnter akan dinaikkan.
Jika mouse bergerak tetapi tetap berada dalam kontrol yang sama, DragOver peristiwa akan dinaikkan.
Jika ada perubahan dalam status tombol keyboard atau mouse, QueryContinueDrag peristiwa dinaikkan dan menentukan apakah akan melanjutkan seret, untuk menghilangkan data, atau membatalkan operasi berdasarkan nilai Action properti acara QueryContinueDragEventArgs.
Jika nilai DragAction adalah
Continue, DragOver peristiwa dinaikkan untuk melanjutkan operasi dan GiveFeedback peristiwa dinaikkan dengan efek baru sehingga umpan balik visual yang sesuai dapat diatur. Untuk daftar efek penurunan yang valid, lihat DragDropEffects enumerasi.Catatan
Peristiwa DragOver dan GiveFeedback dipasangkan sehingga saat mouse bergerak melintasi target penurunan, pengguna diberi umpan balik terbaru tentang posisi mouse.
Jika nilai DragAction adalah
Drop, nilai efek penurunan dikembalikan ke sumber, sehingga aplikasi sumber dapat melakukan operasi yang sesuai pada data sumber; misalnya, memotong data jika operasi adalah pemindahan.Jika nilai DragAction adalah
Cancel, DragLeave peristiwa dinaikkan.
Catatan
Metode ini DoDragDrop menangkap semua pengecualian dan hanya menumbuhkan kembali pengecualian keamanan atau kritis berikut:
SecurityException
NullReferenceException
Pengecualian StackOverflow
OutOfMemoryException
ThreadAbortException
ExecutionEngineException
IndexOutOfRangeException
AccessViolationException
Lihat juga
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