C＃ - 通过十字架关闭Form2后无法看到Form1

Question

I'm fairly new at C#, and have spent the whole day to find a soultion to this to address the issue I'm having so apologies if this is simple, or has been wlsewhere! I have two Forms, Main and Config. Main loads, and has a button to open the Config form and then hide itself as so:

private void btnConfig_Click(object sender, EventArgs e)
{
    Config config = new Config();
    config.Show(); 
    this.Visible = false;
}

It works just fine and the Config form opens. The Config from has two buttons (a Save and a Close button). In essence, both buttons have the same end effect, close the Config form and re-show the Main form, coded as so:

    private void btnClose_Click(object sender, EventArgs e)
    {
        this.Hide();
        Main main = new Main();
        main.Visible = true;
    }      

The issue is that if I close the Config screen using the 'cross', Config is 'closed' but Main is not displayed and the programcontinues to run. I've tried using OnFormClosing and got stuck in an awful loop! The Cross should do the same as the Save/Close buttons, hide the Config form and open Main again.

Answer 1

If you want to show the config Form and reshow the Main form when the config has changed you normally would want something as a Config Form to show Modal .

To show a Modal Form, you'll to use ShowDialog() . ShowDialog() is also a blocking call, which gives you the ability to pick up where you left of.

In the mainform:

private void btnConfig_Click(object sender, EventArgs e)
{
    var config = new Config(); 

    this.Visible = false;
    // this call blocks!
    var dialogResult = config.ShowDialog();

    // when the configform is closed, the code resumes here
    this.Visible = true;
}

This also gives you the possibitlity, to cancel the config form, by setting DialogResult property of the Config form to DialogResult.Cancel just before closing.

Answer 2

I'm not too sure what you're looking for exactly but this is how I would go about it.

Change your function to the following and have a private Config object under your main form class.

private Config config;
private void btnConfig_Click(object sender, EventArgs e)
{
    if(config==null || config.IsDisposed)
    {
        config = new Config(this); // Pass the main form into the constructor of config
    }
    config.ShowDialog(); 
    this.Visible = false;
}

Create a constructor (for Config) that takes in the main form as a parameter and have the main form as a private object. This allows you to show the original form as apposed to just creating a new one every time.

private Form mainForm;
public Config(Form main)
{
    mainForm = main;
}

And change your close action.

private void btnClose_Click(object sender, EventArgs e)
{
    this.Hide();
    mainForm.Visible = true;
}