unit unitImage;

interface

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

type
  TForm1 = class(TForm)
    Image1: TImage;
    Image2: TImage;
    Image3: TImage;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Image4: TImage;
    Button1: TButton;
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
  private
    { Private declarations }
    procedure bmp_rotate(src, dst: tbitmap; angle: extended);
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

{ TForm1 }

procedure TForm1.bmp_rotate(src, dst: tbitmap; angle: extended);
var
  c1x, c1y, c2x, c2y: integer;
  p1x, p1y, p2x, p2y: integer;
  radius, n: integer;
  alpha: extended;
  c0, c1, c2, c3: tcolor;
begin
  //將角度轉換為PI值
  angle := (angle / 180) * pi;
  // 計算中心點，你可以修改它
  c1x := src.width div 2;
  c1y := src.height div 2;
  c2x := dst.width div 2;
  c2y := dst.height div 2;

  // 步驟數值number
  if c2x < c2y then
    n := c2y
  else
    n := c2x;
  dec(n, 1);

  // 開始旋轉
  for p2x := 0 to n do begin
      for p2y := 0 to n do begin
          if p2x = 0 then
            alpha := pi / 2
          else
            alpha := arctan2(p2y, p2x);
          radius := round(sqrt((p2x * p2x) + (p2y * p2y)));
          p1x := round(radius * cos(angle + alpha));
          p1y := round(radius * sin(angle + alpha));

          c0 := src.canvas.pixels[c1x + p1x, c1y + p1y];
          c1 := src.canvas.pixels[c1x - p1x, c1y - p1y];
          c2 := src.canvas.pixels[c1x + p1y, c1y - p1x];
          c3 := src.canvas.pixels[c1x - p1y, c1y + p1x];

          dst.canvas.pixels[c2x + p2x, c2y + p2y] := c0;
          dst.canvas.pixels[c2x - p2x, c2y - p2y] := c1;
          dst.canvas.pixels[c2x + p2y, c2y - p2x] := c2;
          dst.canvas.pixels[c2x - p2y, c2y + p2x] := c3;
        end;
      application.processmessages
    end;
end;


procedure TForm1.Button2Click(Sender: TObject);
var
  i, j: integer;
begin
  //確定旋轉后位圖的大小
  image2.Picture.Bitmap.Height := image1.picture.width;
  image2.Picture.Bitmap.Width := image1.picture.height;
  for i := 0 to image1.Height do
    for j := 0 to image1.Width do
      image2.canvas.Pixels[(-i + image1.Height),
        j] := image1.canvas.Pixels[j, i];
end;


procedure TForm1.Button3Click(Sender: TObject);
var
  i, j: integer;
begin
  //確定旋轉后位圖的大小
  image3.Picture.Bitmap.Height := image1.picture.Height;
  image3.Picture.Bitmap.Width := image1.picture.Width;
  for i := 0 to image1.Height do
    for j := 0 to image1.Width do
      image3.canvas.Pixels[(image1.Width
        - j), (image1.Height - i)] := image1.canvas.Pixels[j, i];
end;


procedure TForm1.Button4Click(Sender: TObject);
var
  i, j: integer;
begin
  //確定旋轉后位圖的大小
  image4.Picture.Bitmap.Height := image1.picture.Width;
  image4.Picture.Bitmap.Width := image1.picture.Height;
  for i := 0 to image1.Height do
    for j := 0 to image1.Width do
      image4.canvas.Pixels[i, (image1.Width-j)] := image1.canvas.Pixels[j, i];
end;



end.