Delphi TrackBar停止 [英] Delphi TrackBar On Stop

问题描述

我正在制作一个基本的音乐播放器，并使用TTrackBar作为歌曲的进度.我也想制作它，以便您可以拖动该栏并快进歌曲.

I am making a basic music player and am using a TTrackBar as the progress in the song. As well I want to make it so u can drag the bar and fast forward the song.

当前，我有一个带有以下行的OnChange事件:

Currently I have an OnChange event with the following line:

MediaPlayer1.position := TrackBar1.value... (with proper casting)

但是发生的是，在拖动过程中某些随机点播放歌曲时，当我拖动它发出断断续续的声音时，它会跳过歌曲.

but what happens is that it skips the song along as I drag making a choppy sound as it plays the song at certain random points along the way.

我真正想要的是当用户停止拖动歌曲时应该更改的内容.这是什么事onStopDrop甚至无法解决问题.

What I really want is for when the user stops dragging the song should change. What event is this? The onStopDrop even doesn't do the trick..

推荐答案

滚动通知消息通过WM_HSCROLL或WM_VSCROLL到达，具体取决于轨迹栏的方向. VCL中的这些表面控制为CN_HSCROLL和CN_VSCROLL.您需要处理这些消息，并忽略滚动代码为TB_THUMBTRACK的消息，以防止控件在用户拖动滑块时触发OnChange事件.

The scroll notification messages arrive though WM_HSCROLL or WM_VSCROLL, depending on the orientation of your track bar. These surface in the VCL control as CN_HSCROLL and CN_VSCROLL. You need to handle these messages and ignore message for which the scroll code is TB_THUMBTRACK to prevent the control to fire the OnChange event when the user drags the slider.

例如，这是一个插入控件，可以完成您需要的操作:

For example, here is an interposer control that does what you need:

type
  TTrackBar = class(Vcl.ComCtrls.TTrackBar)
  protected
    procedure CNHScroll(var Message: TWMHScroll); message CN_HSCROLL;
    procedure CNVScroll(var Message: TWMVScroll); message CN_VSCROLL;
  end;

implementation

procedure TTrackBar.CNHScroll(var Message: TWMHScroll);
begin
  if Message.ScrollCode = TB_THUMBTRACK then
    Message.Result := 0
  else
    inherited;
end;

procedure TTrackBar.CNVScroll(var Message: TWMVScroll);
begin
  if Message.ScrollCode = TB_THUMBTRACK then
    Message.Result := 0
  else
    inherited;
end;

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