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Question

两幅图重叠在一起
我想把最上面的那一幅切掉
每次切1/4，而且是从下往上切
应该怎么做呢
我做出来的结果老是从上往下切
大家帮忙看下错在哪里的哦
代码如下
var
  Form1: TForm1;
  SwapStep:integer;
  Swap_Time:integer;
  pausetime:integer;
  swp:integer;
implementation
{$R *.dfm}procedure TForm1.FormCreate(Sender: TObject);
var
i:integer;
begin
   randomize;
   i:=Random(52)+1;
   SwapStep:=1;
   pausetime:=1;
   swap_time:=50;
   swp:=swap_time div 10;
   ratiox:=image2.Width/Swap_Time;
   ratioy:=image2.Height/Swap_Time;
   image1.Picture.Bitmap.LoadFromFile('F:\2\pic\a.bmp');
   image2.Picture.Bitmap.LoadFromFile('F:\2\pic\aa.bmp');
   form1.DoubleBuffered :=true;
end;procedure TForm1.Timer1Timer(Sender: TObject);
begin
    inc(pausetime);
    if  round(ratiox*SwapStep)>=image2.Height then exit;
    if (pausetime<Swap_Time div 5) or ((pausetime>Swap_Time div 5+2*swp) and    (pausetime<Swap_Time div 2)) or (pausetime>Swap_Time div 2+2*swp) then
    begin
      if  round(ratiox*SwapStep)<=96 then
       BitBlt(Canvas.Handle, 160,136, image2.width,round(ratiox*SwapStep) ,image1.Canvas.Handle, 0, 0,SRCCOPY);
      swapstep:=swapstep+1;
    end;
end;procedure TForm1.Button1Click(Sender: TObject);
begin
    timer1.Enabled:=true;
end;

Answer 1

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Image2.AutoSize := False;
  Image2.Height := Image2.Height - Image1.Height div 10;
  Timer1.Enabled := Image2.Height > 0;
end;