前几天，使用DataGridView来进行动态数据显示，但是发现左边的滚动条会显示不正确。
比如设置显示第100行了，但是滚动条的位置还是在最顶端，
如果你去点击一下滚动条，它又立即更新，并且跳到正确的位置显示。

一开始认为界面没有更新，找了Refresh()函数，又调用窗口更新函数，
最后还使用下面代码反向映射获取滚动条：
ScrollBar vsbar = (ScrollBar)typeof(DataGridView).GetProperty("VerticalScrollBar", BindingFlags.NonPublic | BindingFlags.Public | BindingFlags.Instance).GetValue(datagridview1, null);
并设置对应的位置，但是还是没有正确地显示。

到这个时候，已经找了一天半时间了，又去翻MSDN的文档，又去百度，还去bing。
但是还没有解决。

最后发现了一个函数PerformLayout()，它是立即强制界面刷新，并且进行重新设置。
后来通过调用这个函数，就可以解决滚动更新位置不正确的问题了。

例子如下：

using System.Windows.Forms;
using System.Drawing;public class LayoutForm :System.Windows.Forms.Form{public LayoutForm() : base(){InitializeComponent();}internal System.Windows.Forms.Button Button1;internal System.Windows.Forms.Button Button2;internal LayoutControl LayoutControl1;internal System.Windows.Forms.Button Button3;private void InitializeComponent(){this.Button1 = new System.Windows.Forms.Button();this.Button2 = new System.Windows.Forms.Button();this.Button3 = new System.Windows.Forms.Button();this.LayoutControl1 = new LayoutControl();this.SuspendLayout();this.Button1.Location = new System.Drawing.Point(16, 16);this.Button1.Name = "Button1";this.Button1.Size = new System.Drawing.Size(120, 32);this.Button1.TabIndex = 0;this.Button1.Text = "Center textbox on control";this.Button2.Location = new System.Drawing.Point(152, 16);this.Button2.Name = "Button2";this.Button2.Size = new System.Drawing.Size(104, 32);this.Button2.TabIndex = 3;this.Button2.Text = "Shrink user control";this.Button3.Location = new System.Drawing.Point(96, 232);this.Button3.Name = "Button3";this.Button3.TabIndex = 5;this.Button3.Text = "Reset";this.LayoutControl1.BackColor = System.Drawing.SystemColors.ControlDark;this.LayoutControl1.Location = new System.Drawing.Point(72, 64);this.LayoutControl1.Name = "LayoutControl1";this.LayoutControl1.Size = new System.Drawing.Size(150, 160);this.LayoutControl1.TabIndex = 6;this.ClientSize = new System.Drawing.Size(292, 266);this.Controls.Add(this.Button3);this.Controls.Add(this.Button2);this.Controls.Add(this.Button1);this.Controls.Add(this.LayoutControl1);this.Name = "Form1";this.Text = "Form1";this.ResumeLayout(false);this.Button1.Click += new System.EventHandler(Button1_Click);this.Button2.Click += new System.EventHandler(Button2_Click);this.Button3.Click += new System.EventHandler(Button3_Click);}[System.STAThread]public static void Main(){Application.Run(new LayoutForm());}// This method explicitly calls raises the layout event on // LayoutControl1, changing the Bounds property.private void Button1_Click(System.Object sender, System.EventArgs e){LayoutControl1.PerformLayout(LayoutControl1, "Bounds");}// This resize of LayoutControl1 implicitly triggers the layout event. //  Changing the size of the control affects its Bounds property.private void Button2_Click(System.Object sender, System.EventArgs e){LayoutControl1.Size = new System.Drawing.Size(100, 100);}// This method explicitly calls PerformLayout with no parameters, // which raises the Layout event with the LayoutEventArgs properties// equal to Nothing.private void Button3_Click(System.Object sender, System.EventArgs e){LayoutControl1.PerformLayout();}
}// This custom control has the Layout event implented so that when 
// PerformLayout(AffectedControl, AffectedProperty) is called 
// on the control, where AffectedProperty equals "Bounds" the 
// textbox is centered on the control.
public class LayoutControl :System.Windows.Forms.UserControl
{internal System.Windows.Forms.TextBox TextBox1;public LayoutControl() : base(){InitializeComponent();}private void InitializeComponent(){this.TextBox1 = new System.Windows.Forms.TextBox();this.SuspendLayout();this.TextBox1.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle;this.TextBox1.Name = "TextBox1";this.TextBox1.TabIndex = 0;this.BackColor = System.Drawing.SystemColors.ControlDark;this.Controls.Add(this.TextBox1);this.Name = "LayoutControl";this.ResumeLayout(false);this.Layout += new LayoutEventHandler(LayoutControl_Layout);}// This method is called when the Layout event is fired. // This happens by during the initial load, by calling PerformLayout// or by resizing, adding or removing controls or other actions that // affect how the control is laid out. This method checks the // value of e.AffectedProperty and changes the look of the // control accordingly. private void LayoutControl_Layout(object sender,System.Windows.Forms.LayoutEventArgs e){if (e.AffectedProperty != null){if (e.AffectedProperty.Equals("Bounds")){TextBox1.Left = (this.Width - TextBox1.Width) / 2;TextBox1.Top = (this.Height - TextBox1.Height) / 2;}}else{this.Size = new System.Drawing.Size(150, 160);TextBox1.Location = new System.Drawing.Point(16, 24);}TextBox1.Text = "Left = " + TextBox1.Left + " Top = " + TextBox1.Top;}
}