Delphi10.3如何将ListBox1项，拖动 到 右边Memo1当前输入项

01]ListBox1的DragMode设置为dmAutomatic

02】Memo1的OnGragOver事件和OnDragDrop事件

 

procedure TForm8.Memo1DragOver(Sender, Source: TObject; X, Y: Integer;
  State: TDragState; var Accept: Boolean);
begin
if TListBox(Source)=ListBox1 then Accept:=true;
end;

procedure TForm8.Memo1DragDrop(Sender, Source: TObject; X, Y: Integer);
begin
  if ListBox1.ItemIndex>-1 then
  Memo1.SelText :=Listbox1.Items[ListBox1.ItemIndex];
end;

 更复杂的，请参考https://prog.hu/tudastar/90383/drag-and-drop-tmemo

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    ListBox1: TListBox;
    Memo1: TMemo;
    Label1: TLabel;
    procedure Memo1DragDrop(Sender, Source: TObject; X, Y: Integer);
    procedure Memo1DragOver(Sender, Source: TObject; X, Y: Integer;      State: TDragState; var Accept: Boolean);
    procedure Memo1MouseMove(Sender: TObject; Shift: TShiftState; X,      Y: Integer);
  private
      function CharPosInMemo(aMemo: TMemo; X, Y: integer): integer;
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function TForm1.CharPosInMemo(aMemo: TMemo; X, Y: integer): integer;
// Get the current character position (0-based) in the TMemo aMemo
// corresponding to the client coordinates X, Y.  Returns -1 if there
// is no corresponding character.
begin
  result := LoWord(SendMessage(aMemo.Handle, EM_CHARFROMPOS, 0, MAKELPARAM(X, Y)));
end;

procedure TForm1.Memo1DragDrop(Sender, Source: TObject; X, Y: Integer);
var
  aCharPos: integer;
  droptext:string;
begin

aCharPos := CharPosInMemo(Memo1, X, Y);
 if (aCharPos <> -1) then
  begin
    droptext:=(Source as TListBox).Items[(Source as TListBox).ItemIndex];
     Memo1.Perform(EM_REPLACESEL, integer(true), integer(PChar(dropText)));
     Memo1.SelStart := aCharPos+length(dropText);
     Memo1.SelLength := 0;
     end;
 end;

procedure TForm1.Memo1DragOver(Sender, Source: TObject; X, Y: Integer;  State: TDragState; var Accept: Boolean);
var
    aCharPos: integer;
begin
        Memo1.SetFocus;
      // Get the current position
        aCharPos := CharPosInMemo(Memo1, X, Y);
        // If it makes sense, then put the caret there.
          if (aCharPos <> -1) then
            begin
             Memo1.selStart := aCharPos;
             Memo1.selLength := 0;
            end;
     If Source is TListBox then Accept:=True;
end;

procedure TForm1.Memo1MouseMove(Sender: TObject; Shift: TShiftState; X,  Y: Integer);
var
  ret: Longint;
begin
  ret := memo1.perform(EM_CHARFROMPOS, 0, MakeLParam(X, Y));
 // label1.caption := format('row: %d, character index: %d', [HiWord(ret),    LoWord(ret)]);
end;

end.