最近看到一些 winform 控件的写法里面，在设定 DockStyle 或者增减子控件的时候，往往先调用 SuspendLayout 方法，操作完毕之后调用一下 ResumeLayout. 不太明白其中的道理。所以用 Reflector 来看一下。
代码在 System.Windows.Forms.Control 中。
做一个简单的记录如下：
public void SuspendLayout()
{
this.layoutSuspendCount = (byte) (this.layoutSuspendCount + 1);
}public void ResumeLayout()
{
this.ResumeLayout(true);
} public void ResumeLayout(bool performLayout)
{
if (this.layoutSuspendCount > 0)
{
this.layoutSuspendCount = (byte) (this.layoutSuspendCount - 1);
if (((this.layoutSuspendCount == 0) && ((this.state & 0x200) != 0)) && performLayout)
{
this.PerformLayout();
}
}
if (!performLayout)
{
Control.ControlCollection collection1 = (Control.ControlCollection) this.Properties.GetObject(Control.PropControlsCollection);
if (collection1 != null)
{
for (int num1 = 0; num1 < collection1.Count; num1++)
{
Control.LayoutManager.UpdateAnchorInfo(collection1[num1]);
}
}
}
}
[EditorBrowsable(EditorBrowsableState.Advanced)]
public void PerformLayout()
{
this.PerformLayout(null, null);
}
[EditorBrowsable(EditorBrowsableState.Advanced)]
public void PerformLayout(Control affectedControl, string affectedProperty)
{
if (!this.GetAnyDisposingInHierarchy())
{
if (this.layoutSuspendCount > 0)
{
this.state |= 0x200;
}
else
{
this.layoutSuspendCount = 1;
try
{
this.OnLayout(new LayoutEventArgs(affectedControl, affectedProperty));
}
finally
{
this.state &= -513;
this.layoutSuspendCount = 0;
}
}
}
}
