Example Delphi - Rotate Bitmap.pdf

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Rotate Bitmap   2008-04-03 07:52:59
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//This is how we can rotate bitmap
 //for this example we need to use components below:
 //OpenDialog1 (TopenDialog)
 //Button1 (TBUtton)
 //Button2 (TBUtton)
 //Image1 (TImage)
 //Put them to the form painter and try this script
 
 unit Unit1;
 
 interface
 
 uses
   Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls,
Forms,
   Dialogs, StdCtrls, ExtCtrls;
 
 type
   TForm1 = class(TForm)
     Image1: TImage;
     OpenDialog1: TOpenDialog;
     Button1: TButton;
     Button2: TButton;
     procedure Button1Click(Sender: TObject);
     procedure Button2Click(Sender: TObject);
   private
     { Private declarations }
   public
     { Public declarations }
   end;
 
 var
   Form1: TForm1;
 
 implementation
 
 uses
   Math, StrUtils;
 
 {$R *.dfm}
 
 function Vektor(FromP, Top: TPoint): TPoint;
 begin
   Result.x := Top.x - FromP.x;
   Result.y := Top.y - FromP.y;
 end;
 
 function xComp(Vektor: TPoint; Angle: Extended): Integer;
 begin
   Result := Round(Vektor.x * cos(Angle) - (Vektor.y) * sin(Angle));
 end;
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 function yComp(Vektor: TPoint; Angle: Extended): Integer;
 begin
   Result := Round((Vektor.x) * (sin(Angle)) + (vektor.y) * cos(Angle));
 end;
 
 
 function RotImage(srcbit: TBitmap; Angle: Extended; FPoint: TPoint;
   Background: TColor): TBitmap;
 var
   highest, lowest, mostleft, mostright: TPoint;
   topoverh, leftoverh: integer;
   x, y, newx, newy: integer;
 begin
   Result := TBitmap.Create;
 
   while Angle >= (2 * pi) do
   begin
     angle := Angle - (2 * pi);
   end;
 
   if (angle    begin
     highest := Point(0,0);                        //OL
     Lowest := Point(Srcbit.Width, Srcbit.Height); //UR
     mostleft := Point(0,Srcbit.Height);            //UL
     mostright := Point(Srcbit.Width, 0);             //OR
   end 
   else if (angle    begin
     highest := Point(0,Srcbit.Height);
     Lowest := Point(Srcbit.Width, 0);
     mostleft := Point(Srcbit.Width, Srcbit.Height);
     mostright := Point(0,0);
   end 
   else if (Angle    begin
     highest := Point(Srcbit.Width, Srcbit.Height);
     Lowest := Point(0,0);
     mostleft := Point(Srcbit.Width, 0);
     mostright := Point(0,Srcbit.Height);
   end 
   else
   begin
     highest := Point(Srcbit.Width, 0);
     Lowest := Point(0,Srcbit.Height);
     mostleft := Point(0,0);
     mostright := Point(Srcbit.Width, Srcbit.Height);
   end;
 
   topoverh := yComp(Vektor(FPoint, highest), Angle);
   leftoverh := xComp(Vektor(FPoint, mostleft), Angle);
   Result.Height := Abs(yComp(Vektor(FPoint, lowest), Angle)) +
Abs(topOverh);
   Result.Width  := Abs(xComp(Vektor(FPoint, mostright), Angle)) +
Abs(leftoverh);
 
   Topoverh := TopOverh + FPoint.y;
   Leftoverh := LeftOverh + FPoint.x;
 
   Result.Canvas.Brush.Color := Background;
   Result.Canvas.pen.Color   := background;
   Result.Canvas.Fillrect(Rect(0,0,Result.Width, Result.Height));
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   for y := 0 to srcbit.Height - 1 do
   begin                     
     for x := 0 to srcbit.Width - 1 do
     begin                 
       newX := xComp(Vektor(FPoint, Point(x, y)), Angle);
       newY := yComp(Vektor(FPoint, Point(x, y)), Angle);
       newX := FPoint.x + newx - leftoverh;
       newy := FPoint.y + newy - topoverh;
       // Move beacause of new size
       Result.Canvas.Pixels[newx, newy] := srcbit.Canvas.Pixels[x, y];
       // also fil lthe pixel beside to prevent empty pixels
       if ((angle          ((angle > pi) and
         (angle        begin
         Result.Canvas.Pixels[newx, newy + 1] := srcbit.Canvas.Pixels[x,
y];
       end 
       else 
       begin
         Result.Canvas.Pixels[newx + 1,newy] := srcbit.Canvas.Pixels[x,
y];
       end;
     end;
   end;
 end;
 
 
 procedure TForm1.Button1Click(Sender: TObject);
 begin
   if OpenDialog1.Execute then
   begin
     if RightStr(OpenDialog1.FileName,3) = 'bmp' then
     begin
       Image1.Picture.LoadFromFile(OpenDialog1.FileName);
     end
     else
     showmessage('Please open bitmap file (bmp)');
   end;
 end;
 
 procedure TForm1.Button2Click(Sender: TObject);
 var
   BitRot : TBitmap;
 begin
   BitRot := TBitmap.Create;
   try
     if assigned(image1.Picture.Bitmap) then
     begin
       BitRot := RotImage(image1.Picture.Bitmap,                        
{Source}
                          DegToRad(90),                                 
         {90 degree to rotate}
                          Point(image1.Picture.Bitmap.Width div 2,      
 {x point for center rotate}
                          image1.Picture.Bitmap.Height div 2),          
   {y point for center rotate}
                          clBlack);                                     
             {background Color for rotated image}
       Image1.Picture.Assign(BitRot);
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     end;
   finally
     BitRot.Free;
   end;
 end;
 
 end.
 
 
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