从子表单控制父表单的进度条。 [英] Controlling progress bar of parent form from the child form.

问题描述

Hello Everyone，



我想从子表单控制父表单上的进度条。父表单有一个按钮和一个进度条。单击该按钮时，将打开子窗体，子窗体将执行其任务一段时间。当任务完成时，我希望进度显示在父表单的进度条上。



我已将修饰符设置为Public并写入这些行代码仍然无法实现。



表格1：

Hello Everyone,

I want to control a progress bar on the parent form from the child form. The parent form has one button and a progress bar. On clicking that button a child form is opened and the child form does its task for some time. As the task is being done, I want the progress to be displayed on the progress bar of the parent form.

I have set the modifiers to Public and wrote these lines of code. Still, couldn't make it possible.

Form 1:

private void button1_Click(object sender, EventArgs e){

Form2 f2 = new Form2();
f2.Show();
}

表格2：

Form 2:

public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
            Form1 f1 = new Form1();
            int j;
            for (j = 0; j < 100; j++)
            {
                f1.progressBar1.Value = j;
                f1.progressBar1.Refresh();
                f1.progressBar1.Update();
                Console.WriteLine("j={0}", j);
            }
        }
    }

我尝试了什么：



还尝试在按钮事件中关联表单2代码。

What I have tried:

Also tried associating the form 2 code in a button event.

public partial class Form2 : Form
    {
        Form1 f1 = new Form1();
        public Form2()
        {
            InitializeComponent();
            
            
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int j;
            for (j = 0; j < 100; j++)
            {
                f1.progressBar1.Value = j;
                f1.progressBar1.Refresh();
                f1.progressBar1.Update();
                Console.WriteLine("j={0}", j);
            }
        }
    }

推荐答案

看看你的代码：

Look at your code:

public Form2()
{
    InitializeComponent();
    Form1 f1 = new Form1();

当你创建一个 new 的任何实例时，这正是你得到的：a'获得新对象。你没有得到现有的副本，你没有得到现有的副本 - 你得到一个全新的。

你不能这样做！



你想要做的是错误的，非常错误的 - 孩子形式不应该;甚至知道父存在：这就是为什么控制私人开始 - 这样你的外面的世界就无法与它们一起玩！



使Form1进展再次禁用私有，并在Form2中创建一个事件，Form1处理该事件以指示进度：转移两种表格之间的信息，第2部分：儿童到父母 [ ^ ]应该提供帮助并提供一个示例。

When you create a new instance of anything, that is exactly what you get: a 't get new object. You don't get a copy of an existing one, you don't get a reference to an existing one - you get an entirely new one.
You can't do it like that!

And what you are trying to do is wrong, very wrong - the "child" form shouldn;t even know that the "parent" exists: that's why controls are private to start with - so that your "outside world" can't play with them!

Make the Form1 progress bar private again, and create an event in Form2 which Form1 handles to indicate progress: Transferring information between two forms, Part 2: Child to Parent[^] should help and provides an example.

尝试



表格1

try

Form 1

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        public void UpdateProgress(int j) { // public method to invoke from the child form
            this.progressBar1.Value = j;
            this.progressBar1.Refresh();
            this.progressBar1.Update(); 
        }

        private void button1_Click(object sender, EventArgs e)
        {
            
            Form2 f2 = new Form2();
            f2.ParentFormObject = this; // pass the parent form object 
            f2.Show();
        }
    }

表格2

Form 2

public Form1 ParentFormObject { get; set; } // to access parent form object
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            int j;
            for (j = 0; j < 100; j++)
                ParentFormObject.UpdateProgress(j); // access the parent form public method
        }

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