I have two Forms, Form1 which is the main Form and Form2 a secondary Form. Through a Button in Form1 I open Form2 and I pass an Integer and a Bitmap from Form1 to Form2. In Form2 I change the Bitmap based on what that Integer's value is. I display the changed Bitmap in Form2 and with a Button press I pass the changed Bitmap to Form1 and close Form2.

What I am having trouble with is getting that changed Bitmap back to Form1. Can't seem to find a way to do this.

In Form1

    private void Button1_Click(object sender, EventArgs e)
    {
        Form2 f2 = new Form2();
        f2.ReceiveData(integer); //this to pass the integer
        f2.Linear(bmp); //this to pass the Bitmap 
        f2.ShowDialog();
    }

In Form 2

    int integer_f2;
    internal void ReceiveData(int integer)
    {
        integer_f2 = integer;
    }

    public void Linear(Bitmap bmp)
    {
        //-- ALGORITH THAT CHANGES THE IMAGES HERE (sample for testing purposes)--
        Bitmap bmp_f2 = new Bitmap(bmp.Width, bmp.Height);

        for (int x = 0; x < bmp.Width; x  )
        {
            for (int y = 0; y < bmp.Height; y  )
            {
                // basically fill bmp2 with whatever color integer_f2 represents
                Color clr = Color.FromArgb(255, integer_f2, integer_f2, integer_f2);

                bmp_f2.SetPixel(x, y, clr);
            }
        }
    }
    
    private void Button_Cancel_2_Click(object sender, EventArgs e)
    {
        Close();
    }

    private void Button_OK_2_Click(object sender, EventArgs e)
    {
        //-- PASS THE CHANGED BITMAP BACK TO FORM1 HERE --
        Close();
    }

CodePudding user response：

In Form2,

    private class  Form2 : Form
    {
        private Bitmap _bmp;
        public Bitmap bmpResult { get; private set; } = null;
     
        public void Linear(Bitmap bmp)
        {
            //-- ALGORITHM THAT CHANGES THE BITMAP HERE --
            _bmp = bmp;
            // Do what you need to here.
        }

        private void Button_Cancel_2_Click(object sender, EventArgs e)
        {
            DialogResult = DialogResult.Cancel;
        }

        private void Button_OK_2_Click(object sender, EventArgs e)
        {
            bmpResult = _bmp;
            DialogResult = DialogResult.OK;
        }

    }

and then in Form1,

    private void Button1_Click(object sender, EventArgs e)
    {
        Bitmap bmp = null;
        using (Form2 f2 = new Form2())
        {
            f2.ReceiveData(integer); //this to pass the integer
            f2.Linear(bmp); //this to pass the Bitmap 
            if (f2.ShowDialog() == DialogResult.OK)
            {
                bmp = f2.bmpResult;
                //or do whatever you want with the result
            }
        }
    }

CodePudding user response：

One approach would be to overload the ShowDialog method of Form2 to accept the required arguments. Form2 should also have a public property e.g. ChangedBitmap that receives the result of the transform based on the integer.

public partial class Form2 : Form
{
    public Form2() => InitializeComponent();
    public DialogResult ShowDialog(IWin32Window owner, Bitmap bitmapIn, int integer)
    {
        // Set bitmap based on integer
        switch (integer % 2)
        {
            case 0: ChangedBitmap = transform0(bitmapIn); break;
            case 1: ChangedBitmap = transform1(bitmapIn); break;
        }
        // Call base class version
        return base.ShowDialog(owner);
    }

    private Bitmap transform0(Bitmap bitmapIn) =>
        ChangedBitmap = (Bitmap)pictureBoxLeft.Image; // Mock result
    private Bitmap transform1(Bitmap bitmapIn) =>
        ChangedBitmap = (Bitmap)pictureBoxRight.Image; // Mock result

    public Bitmap ChangedBitmap { get; private set; }

    private void buttonOK_Click(object sender, EventArgs e) => 
        DialogResult = DialogResult.OK;

    private void buttonCancel_Click(object sender, EventArgs e) =>
        DialogResult = DialogResult.Cancel;
}

MainForm looks at the DialogResult to determine whether to use ChangedBitmap.

public partial class MainForm : Form
{
    public MainForm() => InitializeComponent();
    private readonly Form2 _form2 = new Form2();
    private int _testCount = 0;
    // Check the result
    private void buttonShowForm2_Click(object sender, EventArgs e)
    {
        var bitmapOut = (Bitmap)pictureBox1.Image;
        switch (_form2.ShowDialog(this, bitmapOut, _testCount))
        {
            case DialogResult.OK:
                // Answer to: "getting that changed Bitmap back to Form1" 
                pictureBox1.Image = _form2.ChangedBitmap;
                _testCount  ;
                break;
            case DialogResult.Cancel:
                break;
        }
    }
    // In MainForm.Designer.cs
    protected override void Dispose(bool disposing)
    {
        if (disposing)
        {
            if (components != null)
            {
                components.Dispose();
            }
            // Modal dialog requires disposal when done.
            _form2.Dispose();
        }
        // Modal dialog requires dispose when done.
        base.Dispose(disposing);
    }
}