Scale By Precent

{ .... }

private
function ScalePercentBmp(bitmp: TBitmap; iPercent: Integer): Boolean;

{ .... }

function TForm1.ScalePercentBmp(bitmp: TBitmap;
iPercent: Integer): Boolean;
var
TmpBmp: TBitmap;
ARect: TRect;
h, w: Real;
hi, wi: Integer;
begin
Result := False;
try
TmpBmp := TBitmap.Create;
try
h := bitmp.Height * (iPercent / 100);
w := bitmp.Width * (iPercent / 100);
hi := StrToInt(FormatFloat('#', h)) + bitmp.Height;
wi := StrToInt(FormatFloat('#', w)) + bitmp.Width;
TmpBmp.Width := wi;
TmpBmp.Height := hi;
ARect := Rect(0, 0, wi, hi);
TmpBmp.Canvas.StretchDraw(ARect, Bitmp);
bitmp.Assign(TmpBmp);
finally
TmpBmp.Free;
end;
Result := True;
except
Result := False;
end;
end;


// Example:
procedure TForm1.Button1Click(Sender: TObject);
begin
ScalePercentBmp(Image1.Picture.Bitmap, 33);
end;