Drag and drop unicode TText in DelphiXe4

问题

I am trying to make a chessboard gui in DelphiXE4 with TRectangle & TText using unicode chess pieces (see StackOverflow Delphi chess unicode linkand drag and drop but I cannot get DND to work properly! My test project is FireMonkey FMX. I have tried various code additions to DragDrop/DragOver Events including using Accept & Source in code but to no result.

I set dragdrop to auto on TRectangle & TText components & can get drag function but no drop function! What code do I need to enter in Events DragDrop DragOver on target TRectangle to accept the drop event? (I am very confused with this & cannot find clear instruction on Google search anywhere!)

Here is my basic test code (on Form):

unit Unit1;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Rtti, System.Classes,
  System.Variants, FMX.Types, FMX.Controls, FMX.Forms, FMX.Dialogs,
  FMX.StdCtrls, FMX.Objects;

type
  TForm1 = class(TForm)
    Rectangle1: TRectangle;
    Rectangle2: TRectangle;
    Rectangle3: TRectangle;
    Rectangle4: TRectangle;
    Rectangle5: TRectangle;
    Rectangle6: TRectangle;
    Rectangle7: TRectangle;
    Rectangle8: TRectangle;
    Rectangle9: TRectangle;
    Text1: TText;
    procedure Rectangle7DragOver(Sender: TObject; const Data: TDragObject;
      const Point: TPointF; var Accept: Boolean);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.fmx}

procedure TForm1.Rectangle7DragOver(Sender: TObject; const Data: TDragObject;
  const Point: TPointF; var Accept: Boolean);
begin
  if Sender is TText then 
    Accept := True;
end;

end.

Most grateful for help & look forward to replies-thanks

EDIT/UPDATE

Here is code from bummi:

unit Unit3;

interface

uses
  System.SysUtils, System.Types, System.UITypes, System.Rtti, System.Classes,
  System.Variants, FMX.Types, FMX.Controls, FMX.Forms, FMX.Dialogs,
  FMX.Objects, FMX.Edit;

type
  TForm3 = class(TForm)
    Rectangle1: TRectangle;
    Text1: TText;
    Edit1: TEdit;
    procedure Rectangle1DragOver(Sender: TObject; const Data: TDragObject;
      const Point: TPointF; var Accept: Boolean);
  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

var
  Form3: TForm3;

implementation    
{$R *.fmx}    
procedure TForm3.Rectangle1DragOver(Sender: TObject;
  const Data: TDragObject; const Point: TPointF; var Accept: Boolean);
begin
  Caption := Data.Source.ClassName ;
  Accept := Data.Source is TText;       
end;    
end.

However even with this I still cannot get my chess example to work for me! Oh dear aaargh!

回答1:

You will have to Accept if the Source of then TDragObject is TText.

 Accept := Data.Source is TText;

Sender would be your Rectangle7, or any component Rectangle7DragOver is assigned to.

来源：https://stackoverflow.com/questions/17232577/drag-and-drop-unicode-ttext-in-delphixe4

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Delphi

drag-and-drop

delphi-xe4