从0自学C#05--窗体之间的相互访问.md

如何实现子窗体与父窗体相互访问

在父窗体上，改变CheckBox控件的状态，实现子窗体的打开和关闭。在子窗体上，点击关闭按钮后，父窗体CheckBox控件变为未选中状态。

1.方法

这里用委托事件的方法，实现窗体的相互访问。

2.父窗体（主窗体）

父窗体上放置5个CheckBox控件。并将他们赋值到CheckBox[]数组，以便代码进行循环调用。

CheckBox[] checkBox;

public MainFormBERT()
        {
            InitializeComponent();            
            checkBox = new CheckBox[5];

            checkBox[0] = this.checkBox1;
            checkBox[1] = this.checkBox2;
            checkBox[2] = this.checkBox3;
            checkBox[3] = this.checkBox4;            
            checkBox[4] = this.checkBox5;            
        }

给CheckBox控件添加事件。并定义OpenOrCloseSubFormPPG(int i)方法实现打开或关闭子窗体。该方法调用了子窗体的事件，以相应RecvInfo(int number)方法，设置CheckBox控件为未选中状态：

subFormPPGTx[i].SendToParent += new SubFormPPG.SendFun(RecvInfo);

private void checkBox1_CheckedChanged(object sender, EventArgs e)
        {
            OpenOrCloseSubFormPPG(0);
        }
        
private void checkBox2_CheckedChanged(object sender, EventArgs e)
        {
            OpenOrCloseSubFormPPG(1);
        }
        
private void checkBox3_CheckedChanged(object sender, EventArgs e)
        {
            OpenOrCloseSubFormPPG(2);
        }
        
private void checkBox4_CheckedChanged(object sender, EventArgs e)
        {
            OpenOrCloseSubFormPPG(3);
        }

private void checkBox5_CheckedChanged(object sender, EventArgs e)
        {
            OpenOrCloseSubFormPPG(4);
        }

SubFormPPG[] subFormPPGTx = { null, null, null, null, null};

private void OpenOrCloseSubFormPPG(int i)
        {            
            try
            {
                if (checkBox[i].Checked)
                {
                    string formTitle, formName;

                    if (i < 0 || i > 4)
                    {
                        throw new IndexOutOfRangeException("Channel is out of range");
                    }
                    else if (i == 4)
                    {
                        formTitle = "ParallelWrite";
                        formName = "subFormPPG" + formTitle;
                    }
                    else
                    {
                        formTitle = "Tx" + i;
                        formName = "subFormPPG" + formTitle;
                    }

                    if (subFormPPGTx[i] == null || subFormPPGTx[i].IsDisposed)
                    {
                        subFormPPGTx[i] = new SubFormPPG();
                        subFormPPGTx[i].Text = formTitle;
                        subFormPPGTx[i].Name = formName;
                        subFormPPGTx[i].Tag = i;
                        subFormPPGTx[i].SendToParent += new SubFormPPG.SendFun(RecvInfo);//调用子窗体的事件
                        subFormPPGTx[i].Show(this);
                    }
                    else
                    {
                        subFormPPGTx[i].WindowState = FormWindowState.Normal;
                        subFormPPGTx[i].Activate();
                    }
                }
                else
                {
                    //subFormPPGTx[0].Close();
                    subFormPPGTx[i].Dispose();
                    subFormPPGTx[i] = null;
                }
            }
            catch (IndexOutOfRangeException ex)
            {
                MessageBox.Show(ex.Message);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

private void RecvInfo(int number)
        {
            this.checkBox[number].Checked = false;
        }

3.子窗体

添加事件SendToParent，当子窗体关闭时，响应事件，将信息传递给父窗体。

public delegate void SendFun(int number);

public event SendFun SendToParent;

private void SubFormPPG_FormClosed(object sender, FormClosedEventArgs e)
        {
            if (SendToParent != null)
            {
                SendToParent((int)this.Tag);
            }             
        }