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# Example Delphi - Rotate Bitmap by suganux

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```									                                    Example Delphi - http://exampledelphi.com

Rotate Bitmap 2008-04-03 07:52:59

//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;

Example Delphi - http://exampledelphi.com

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));

Example Delphi - http://exampledelphi.com

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
end
else
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}
{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);

Example Delphi - http://exampledelphi.com

end;
finally
BitRot.Free;
end;
end;

end.