从 Form2 窗口调整 form1 窗口的大小

Question

我正在 VS windowsforms 中编写 C# 代码 我有一个问题，我需要通过单击 Form2 窗口中的按钮来调整 Form1 父窗口的大小。主要问题是我不明白如何访问Form1。我可以通过 (this.Size) 访问 Form2。

我一直在尝试通过 this.Parent.Size 和 this.Owner.Weight，但它抛出一个错误（NullReferenceException 未处理） WindowsFormsApplication8.1.exe 中未处理的“System.NullReferenceException”类型异常）

我有3种形式： 表格一：

namespace WindowsFormsApplication8._1
{
    public partial class MainForm : Form
    {
        public MainForm()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            
        }

        private void выходToolStripMenuItem_Click_1(object sender, EventArgs e)
        {
            Application.Exit();
        }

        private void вводToolStripMenuItem_Click_1(object sender, EventArgs e)
        {
            SecondForm secondForm = new SecondForm();
            secondForm.ShowDialog();
            изменениеToolStripMenuItem.Visible = true;
        }

        private void изменениеToolStripMenuItem_Click_1(object sender, EventArgs e)
        {
            ThirdForm thirdForm = new ThirdForm();
            thirdForm.ShowDialog();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            
        }
    }
}

表格2

namespace WindowsFormsApplication8._1
{
    public partial class SecondForm : Form
    {
        public SecondForm()
        {
            InitializeComponent();
        }
        private void SecondForm_Load(object sender, EventArgs e)
        {

        }

        private void buttonOK_Click_1(object sender, EventArgs e)
        {
            ThirdForm fm2 = new ThirdForm();
            fm2.textBox1.Text = this.textBox1.Text;
            fm2.ShowDialog();
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }

        private void textBox2_TextChanged(object sender, EventArgs e)
        {

        }
    }
}

表格3

{
    public partial class ThirdForm : Form
    {

        public ThirdForm()
        {
            InitializeComponent();

        }

        private void ThirdForm_Load(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            
            int a = int.Parse(textBox1.Text);
            int pixels = 100;
            if (radioButton1.Checked)
            {
                this.Owner.Size = new Size(this.Width + a, this.Height + a);
            }
            else if (radioButton2.Checked)
            {
                this.Size = new Size(this.Width - a, this.Height - a);

            }
        }

        private void textBox1_TextChanged(object sender, EventArgs e)
        {

        }
    }
}

需要从 ThirdForm 更改 Mainform 比例

Answer 1

对于使用当前代码的最快方法，您需要设置表单的 owner，然后沿链传播此所有权 - Form3 的所有者将是 Form1（不是最好的主意）。

在 Form1 中，将代码更改为：

private void вводToolStripMenuItem_Click_1(object sender, EventArgs e)
{
    SecondForm secondForm = new SecondForm();
    secondForm.ShowDialog(this); // <-- This line is changed
    изменениеToolStripMenuItem.Visible = true;
}

在 Form2 中，将代码更改为：

private void buttonOK_Click_1(object sender, EventArgs e)
{
    ThirdForm fm2 = new ThirdForm();
    fm2.textBox1.Text = this.textBox1.Text;
    fm2.ShowDialog(this.Owner); // <-- This line is changed
}

Form3 现在应该可以正常工作，无需进一步更改。

---

您使用的方法不是最好的，因为它将所有表单紧密耦合在一起，如果一个表单发生更改，那么其他表单也必须更新。

更好的选择是使用Events。这样，您可以调整每个表单处理事件的方式，并处理其自身的大小调整和操作，而无需外部代码更改表单的外观或行为。

首先声明一个类似于以下内容的新类：

public class NewSizeEventArgs : EventArgs
{
    public Size Size { get; set; }
    public int Value { get; set; }
}

将 Form3 更改为：

// Add this to the Form3 class
public event EventHandler<NewSizeEventArgs> ChangeSize;

将按钮处理程序更改为如下所示：

if (radioButton1.Checked)
{
    ChangeSize?.Invoke(this, new NewSizeEventArgs {Size = this.Size, Value = a});
    //this.Owner.Size = new Size(this.Width + a, this.Height + a);
}
else if (radioButton2.Checked)
{
    this.Size = new Size(this.Width - a, this.Height - a);
}

将 Form2 更改为：

// Add this to the Form3 class
public event EventHandler<NewSizeEventArgs> ChangeSize;

private void buttonOK_Click_1(object sender, EventArgs e)
{
    ThirdForm fm2 = new ThirdForm();
    fm2.ChangeSize += (o, args) => { ChangeSize?.Invoke(o, args); };
    fm2.textBox1.Text = this.textBox1.Text;
    fm2.ShowDialog(this.Owner); // <-- This line is changed
}

最后将Form1修改为：

private void вводToolStripMenuItem_Click_1(object sender, EventArgs e)
{
    SecondForm secondForm = new SecondForm();
    SecondForm.ChangeSize += SecondFormOnChangeSize;
    secondForm.ShowDialog(this); // <-- This line is changed
    изменениеToolStripMenuItem.Visible = true;
}

private void SecondFormOnChangeSize(object sender, NewSizeEventArgs e)
{
    // Handle the event...
    this.Size = new Size(e.Size.Width + e.Value, e.Size.Height + e.Value);
}