//等比例缩小

uses Math;

var

Zoom:Extended;

W,H:integer;

bmp:Tbitmap;

begin

  bmp:=Tbitmap.Create;

  bmp.LoadFromFile('c:\aa.bmp');

  Zoom:=Image1.Width/Max(bmp.Width,bmp.Height); //获得比例值

  W:=Trunc(bmp.Width*Zoom);

  H:=Trunc(bmp.Height*Zoom);

  //居中显示缩小后的图片

  Image1.Canvas.StretchDraw(Rect(Trunc((Image1.width-W)/2),Trunc((Image1.Height-H)/2),Trunc((Image1.width-W)/2)+W,Trunc((Image1.Height-H)/2)+H),Bmp);

  bmp.free;

end;