两个跟踪栏镜像

Question

我想知道如何使我的第二个 trackbar.position 镜像到与 trackbar1.position 相反的方向。例如。范围从 1 到 100。

所以当TrackBar1.Position := 2，那么trackbar2.Position := 99无论轨道条朝哪个方向走，我都想朝相反的方向镜像。

这是我到目前为止的代码：（对使用键执行此操作不感兴趣），只是鼠标交互。

Direction : string; 
Skip : boolean;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
if TrackBar1.Position = TrackBar2.Position then
begin
if Direction = 'up' then   TrackBar2.Position := TrackBar2.Position + 1;
if Direction = 'down' then TrackBar2.Position := TrackBar2.Position - 1;
skip := true;
end;

if TrackBar1.Position < TrackBar2.Position then
begin 
if skip = false then
begin
TrackBar2.Position := TrackBar2.Position - 1;
Direction := 'down';
end;
end
else
begin
if skip = false then
begin
TrackBar2.Position := TrackBar2.Position + 1;
Direction := 'up';
end;
end;
end;

我可能做得太过分了。也许有一种更简单的方法。我更喜欢更简单的方法。谢谢

本

Answer 1

2 个

跟踪栏OnChange事件链接到以下代码：

procedure TForm1.TrackBarChange(Sender: TObject);
var
  tbSource, tbTarget: TTrackBar;
begin
  if Sender = TrackBar1 then // Check the Trackbar which triggers the event
  begin
    tbSource := TrackBar1;
    tbTarget := TrackBar2;
  end
  else
  begin
    tbSource := TrackBar2;
    tbTarget := TrackBar1;
  end;
  tbTarget.OnChange := nil;                           // disable the event on the other trackbar
  tbTarget.Position := tbSource.Max + tbSource.Min - tbSource.Position; // set the position on the other trackbar
  tbTarget.OnChange := TrackBarChange;                // define the event back to the other trackbar
  // Call a function or whatever after this line if you need to do something when it changes
//  lbl1.Caption := IntToStr(TrackBar1.Position);
//  lbl2.Caption := IntToStr(TrackBar2.Position);
end;

 

替代开始（由Ken White建议和我的评论;o））：

procedure TForm1.TrackBarChange(Sender: TObject);
var
  tbSource, tbTarget: TTrackBar;
begin
//  if Sender is TTrackBar then      // is it called 'from' a trackbar?
//  begin
    tbSource := TTrackBar(Sender); // Set the source
    if tbSource = TrackBar1 then   // Check the Trackbar which triggers the event
      tbTarget := TrackBar2
    else
      tbTarget := TrackBar1;
    tbTarget.OnChange := nil;                                             // disable the event on the other trackbar
    tbTarget.Position := tbSource.Max + tbSource.Min - tbSource.Position; // set the position on the other trackbar
    tbTarget.OnChange := TrackBarChange;                                  // define the event back to the other trackbar
    // Call a function or whatever after this line if you need to do something when it changes
//    lbl1.Caption := IntToStr(TrackBar1.Position);
//    lbl2.Caption := IntToStr(TrackBar2.Position);
//  end;
end;