How can I use TDropTarget in Delphi?

TDropTarget is a built-in component in Delphi that allows you to enable drag-and-drop functionality for your application. To use TDropTarget in Delphi, you can follow these steps:

Place a TDropTarget component on your form, either from the component palette or by dragging it from the Tool Palette.
Set the properties of the TDropTarget component, such as AllowDrag and AllowDrop.
Connect the TDropTarget component to other components or events on your form, for example, you can connect it to a TListBox to enable drag-and-drop functionality for the list box.

Here is an example of how you can use TDropTarget in Delphi:

procedure TForm1.DropTarget1Drop(Sender: TObject; ShiftState: TShiftState; Point: TPoint; var Effect: Integer);
begin
  ListBox1.Items.Add(DropTarget1.Data);
end;

procedure TForm1.DropTarget1Drop(Sender: TObject; ShiftState: TShiftState; Point: TPoint; var Effect: Integer);

begin

ListBox1.Items.Add(DropTarget1.Data);

end;

In this example, the TDropTarget component is named DropTarget1 and the TListBox component is named ListBox1. The OnDrop event of the TDropTarget component is used to get the dropped data and add it to the list box.

Here is the explanation of the events of TDropTarget:

OnEnter: This event is triggered when the user moves the mouse pointer over the target component with a dragged object.
OnLeave: This event is triggered when the user moves the mouse pointer out of the target component while dragging an object.
OnDragOver: This event is triggered when the user moves the mouse pointer over the target component while dragging an object.
OnDragDrop: This event is triggered when the user drops the dragged object on the target component.
OnDrop: This event is similar to OnDragDrop but the event is triggered after the object is dropped.

You can use these events to perform different actions when the user enters, leaves, or drops an object on the target component.

You can check the documentation and examples that come with Delphi for more information on how to use the TDropTarget component and its properties and events.

You can use the TDropTarget.Data property to read the file names of the dropped files. The Data property returns the data of the dropped object as a Variant type. You can then use the VarArrayToArrayOf function to convert the Variant data to an array of file names.

Here is an example of how you can read the file names of the dropped files in a TDropTarget component:

procedure TForm1.DropTarget1Drop(Sender: TObject; ShiftState: TShiftState; Point: TPoint; var Effect: Integer);
var
  FileNames: TStringDynArray;
begin
  FileNames := VarArrayToArrayOf(DropTarget1.Data);
  // FileNames is an array of strings, where each string is a file name
  for var i := 0 to High(FileNames) do
    ListBox1.Items.Add(FileNames[i]);
end;

procedure TForm1.DropTarget1Drop(Sender: TObject; ShiftState: TShiftState; Point: TPoint; var Effect: Integer);

var

FileNames: TStringDynArray;

begin

FileNames := VarArrayToArrayOf(DropTarget1.Data);

// FileNames is an array of strings, where each string is a file name

for var i := 0 to High(FileNames) do

ListBox1.Items.Add(FileNames[i]);

end;

The VarArrayToArrayOf function is a helper function provided by Delphi and can be used to convert the Variant data to an array of strings, where each string is a file name.

Note that you should check if the dropped data is a file or not before attempting to read the file name, you can use the TDragObject.Files property to check if the data is files or not

You can check the documentation and examples that come with Delphi for more information on how to use the TDropTarget component and its properties and events for reading dropped files.

How can I use TDropTarget in Delphi?

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