unit UnitMain;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Math, StdCtrls, jpeg, ExtCtrls, ComCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Image1: TImage;
    Button2: TButton;
    Image2: TImage;
    TrackBar1: TTrackBar;
    Button3: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    procedure bmp_rotate(src,dst:tbitmap;angle:extended);
  public
    { Public declarations }
  end;

  procedure rotate(sur:pchar;bmp:Tbitmap;cx,cy:integer;angle:integer);
	procedure RotateBmp(bmp: TBitmap; Center: TPoint; angle: Integer);

var
  Form1: TForm1;

implementation

uses UnitBitmapRotate;

{$R *.dfm}



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.Button1Click(Sender: TObject);
var
    bmp:TBitMap;
    a: pbytearray;
    Center: TPoint;
begin
    bmp:=TBitMap.create;
    bmp.Assign(Image1.Picture.Graphic);
		//AntiAlias(Bmp);
    Center.X := Bmp.Width div 2;
    Center.Y := Bmp.Height div 2;
    RotateBmp(Bmp, Center, 10);
    Image1.Picture.Assign(Bmp);
    Bmp.free;
end;

procedure rotate(sur:pchar;bmp:Tbitmap;cx,cy:integer;angle:integer);
var
x1,y1,x3,y3 :integer; //x1,y1 為平移坐標 x3,y3為旋轉的新坐標
x,y,h,w,widthbytes,dst,v:integer;
hcos,hsin:double;
tmp:Pcolor;
hu:double;
begin
  hu:=angle*3.1415/180;
  hcos:=cos(hu); hsin:=sin(hu);
  h:=bmp.Height; w:=bmp.Width ;
  widthbytes:=integer(bmp.scanline[0])-integer(bmp.scanline[1]);
  dst:=integer(bmp.ScanLine[h-1]);
  fillchar(pchar(dst)^,widthbytes*h,0); //使圖像全黑
  for y:=0 to h-1 do
        begin
        y1:=y -(h-cy);  //平移下的y
        for x:=0 to W-1 do
           begin
              x1:=x-cx; //平移下的x
              x3:=round(x1*hcos-y1*hsin);
              y3:=round(x1*hsin+y1*hcos); //平移下的新坐標
              x3:=x3+cx;
              y3:=y3+(h-cy);   //轉換回原坐標
              if (x3>=0) and (x3<w-1) and (y3>=0) and (y3<h-1) then
              pcolor(dst+x*3+y*widthbytes)^:=
                  pcolor(integer(sur)+x3*3+y3*widthbytes)^;
            end;
        end;
end;
//angle為旋轉的角度，cx、cy為旋轉中心, cx=width div 2,cy=height div 2即以圖像的中心為旋轉中心。此程序處理速度快，可處理大圖片。

procedure TForm1.Button2Click(Sender: TObject);
var
	Bmp: TBitmap;
begin
	Button2.Enabled := False;
	Bmp := TBitmap.Create();
  Bmp.Width := Image1.Width ;
  Bmp.Height := Image1.Height;
	Bmp.Assign(Image1.Picture.Bitmap);
  Bmp.SaveToFile('1.bmp');
	bmp_rotate(Image1.Picture.Bitmap, Bmp, 10 - TrackBar1.Position);
  Image1.Picture.Bitmap.Assign(Bmp);
  Bmp.Free();
  Button2.Enabled := True;;
end;

procedure RotateBmp(bmp: TBitmap; Center: TPoint; angle: Integer);
var
  tmpbmp: TBitmap;
  i, j, x, y, px, py: Integer;
  cAngle, sAngle: extended;
  p1, p2: Pchar;
begin
  while angle < 0 do
    angle := angle + 360;
  angle := angle mod 360;
  sAngle := sin(- angle * pi / 180);
  cAngle := cos(- angle * pi / 180);
  tmpbmp := tbitmap.create;
  tmpbmp.assign(bmp);
  for i := 0 to tmpbmp.height - 1 do
  begin
    p1 := pchar(tmpbmp.scanline[i]);
    py := 2 * (i - center.y) - 1;
    for j := 0 to tmpbmp.width - 1 do
    begin
      px := 2 * (j - center.x) - 1;
      x := (round(px * cAngle - py * sAngle) - 1) div 2 + center.x;
      y := (round(px * sAngle + py * cAngle) - 1) div 2 + center.y;
      if (x>=0) and (x<tmpbmp.width) and (y>=0) and (y<=tmpbmp.height) then
      begin
        p2 := pchar(bmp.scanline[y]) + x * 3;
        move(p1^, p2^, 3);
      end;
      inc(p1, 3);
    end;
  end;
end;



end.