C＃中怎样设置trackbar每次滑动的长度

Question

当用鼠标拖动其滑动指针时，该指针每次移动滑动标尺上的一个刻度，这样当用用截取手机铃声时就不太精准了。请问怎样设置以后当鼠标指在哪儿，该指针就停在哪儿。

Answer 1

类定义：
public partial class Form1 : Form
{
private Point lastPoint = Point.Empty;

public Form1()
{
InitializeComponent();
}

private void trackBar1_MouseDown(object sender, MouseEventArgs e)
{
lastPoint.X = e.X;
lastPoint.Y = e.Y;
if (e.X > this.trackBar1.Minimum && e.X < this.trackBar1.Maximum)
this.trackBar1.Value = e.X;
else if (e.X > this.trackBar1.Maximum)
this.trackBar1.Value = this.trackBar1.Maximum;
else
this.trackBar1.Value = this.trackBar1.Minimum;
}

private void trackBar1_MouseUp(object sender, EventArgs e)
{
lastPoint = Point.Empty;
}

private void trackBar1_MouseMove(object sender, MouseEventArgs e)
{
if (!lastPoint.IsEmpty)
{
if (e.X > this.trackBar1.Minimum && e.X < this.trackBar1.Maximum)
this.trackBar1.Value = e.X;
else if (e.X > this.trackBar1.Maximum)
this.trackBar1.Value = this.trackBar1.Maximum;
else
this.trackBar1.Value = this.trackBar1.Minimum;
}
}
}

关于TrackBar的Form1类设计器的代码段

this.trackBar1.Location = new System.Drawing.Point(123, 112);
this.trackBar1.Maximum = 300;
this.trackBar1.Minimum = 2;
this.trackBar1.Name = "trackBar1";
this.trackBar1.Size = new System.Drawing.Size(325, 45);
this.trackBar1.SmallChange = 2;
this.trackBar1.TabIndex = 0;
this.trackBar1.TickFrequency = 2;
this.trackBar1.Value = 2;
this.trackBar1.MouseUp += new System.Windows.Forms.MouseEventHandler(this.trackBar1_MouseUp);
this.trackBar1.MouseDown += new System.Windows.Forms.MouseEventHandler(this.trackBar1_MouseDown);
this.trackBar1.MouseMove += new System.Windows.Forms.MouseEventHandler(this.trackBar1_MouseMove);

TrackBar的Maximum应该动态修改，根据对象不同而不同，如果是音频和视频的话，TickFrequency设为以百分之一秒为单位，Maximum的值就是时间（以秒为单位）*100/TickFrequency。