Question

我有两个表单，我想从第二个表单更改第一个表单的backGround。我已经在form2中为form1和button1选择了backGround图像，但没有任何反应。提前（Windows窗体）第一种形式：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Form2 frm2 = new Form2();
            frm2.ShowDialog();
        }
    }
}

第二表格：

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Form1 frm1 = new Form1();
            frm1.BackgroundImage = button1.BackgroundImage;
        }
    }
}

Answer 1

在第二种形式中，添加一个私有成员，该成员将保留对第一个表单的引用：

private Form _form1 = null;

然后在Form2的构造函数中，允许传入该引用：

public Form2(Form form1)
{
    InitializeComponent();
    _form1 = form1;
}

现在，在该按钮单击处理程序中，您可以：

private void button1_Click(Object sender, EventArgs e)
{
    _form1.BackgroundImage = button1.BackgroundImage;
}

另一种方法是向Form1添加一个接收要设置为背景的图像的方法。假设Form2中存在相同的_form1引用，您将其添加到Form1：

public void ChangeBGImage(Image bgImage)
{
    this.BackgroundImage = bgImage;
}

从Form2中，您可以称之为：

private void button1_Click(Object sender, EventArgs e)
{
    _form1.ChangeBGImage(button1.BackgroundImage);
}

Answer 2

问题是您无法从form1访问form2进行更改。如果您想更改form1中的内容，则不应创建Form1的新实例。你应该在构造函数中获取实例。

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

    private void button1_Click(object sender, EventArgs e)
    {
        Form2 frm2 = new Form2(this);
        frm2.ShowDialog();
    }
}
public partial class Form2 : Form
{
    Form1 frm1; 
    public Form2(Form1 frm1)
    {
        InitializeComponent();
        this.frm1 = frm1; 
    }

    private void button1_Click(object sender, EventArgs e)
    {
        frm1.BackgroundImage = button1.BackgroundImage;
    }
}

Answer 3

试试这个，

FOrm 1

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Form2 frm2 = new Form2();

            //check if button1 clicked and then change the background
            if(frm2.ShowDialog() == System.Windows.Forms.DialogResult.OK)
            {
                  this.BackgroundImage = frm2.GetBackImage();
            }
        }
    }
}

表格2

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form2 : Form
    {
        public Form2()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //Form1 frm1 = new Form1();
            //frm1.BackgroundImage = button1.BackgroundImage;
            this.DialogResult = System.Windows.Forms.DialogResult.OK;
        }

       public Image GetBackImage()
       {
           return this.button1.BackgroundImage;
       }
    }
}

如何从其他表单更改backGround图像？

3 个答案: