Question

I am doing just for fun a virtual desktop to play Magic The Gathering with friends. I am using Delphi 2010. The cards are represented in the application by TImage components (loading PNG files of the cards loaded from a database). The point here is that in MTG a very common thing to do is to tap a card (rotating it 90º degrees to right). There is a simple way to do this? I really don’t need the “animation”, just the card rotated once is clicked (animation would be nice though). The game should work simultaneously with many cards and they can be moved anywhere in the form. I am thinking in having the image of the card tapped and untapped in the database but this may be an overkill if there is a nice and efficient way to rotate the cards.

Any ideas?

Answer 1

Or you can leave the TImage and use e.g. TPaintBox and GDI+ library. GDI+ has the RotateFlip method directly for doing this. Using the GDI+ Library for Delphi it would look like:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls, ActiveX, GDIPOBJ, GDIPAPI;

type
  TForm1 = class(TForm)
    Button1: TButton;
    PaintBox1: TPaintBox;
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure PaintBox1Paint(Sender: TObject);
  private
    FImage: TGPImage;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.FormCreate(Sender: TObject);
var
  Stream: IStream;
  BlobStream: TMemoryStream;
begin
  BlobStream := TMemoryStream.Create;
  try
    // assuming the BlobStream here has a valid image loaded from a database
    Stream := TStreamAdapter.Create(BlobStream);
    FImage := TGPImage.Create(Stream);
  finally
    BlobStream.Free;
  end;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  FImage.Free;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  FImage.RotateFlip(Rotate90FlipNone);
  PaintBox1.Invalidate;
end;

procedure TForm1.PaintBox1Paint(Sender: TObject);
begin
  with TGPGraphics.Create(PaintBox1.Canvas.Handle) do
  try
    DrawImage(FImage, 0, 0);
  finally
    Free;
  end;
end;

end.

Such an overkill, doesn’t it 😕