创建另一个表单问题的表单对象？

Question

I have got the following error message when I trying to create the form object of another form. any one can help me, What is the solution for this error?

the Training_form which needs to be created as object is:

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

using Emgu.CV.UI;
using Emgu.CV;
using Emgu.CV.Structure;
using Emgu.CV.CvEnum;

using System.IO;
using System.Drawing.Imaging;
using System.Xml;
using System.Threading;


namespace Face_Recognition
{
    public partial class Training_Form : Form
    {
        #region Variables
        //Camera specific
        Capture grabber;

        //Images for finding face
        Image<Bgr, Byte> currentFrame;
        Image<Gray, byte> result = null;
        Image<Gray, byte> gray_frame = null;

        //Classifier
        CascadeClassifier Face;

        //For aquiring 10 images in a row
        List<Image<Gray, byte>> resultImages = new List<Image<Gray, byte>>();
        int results_list_pos = 0;
        int num_faces_to_aquire = 10;
        bool RECORD = false;

        //Saving Jpg
        List<Image<Gray, byte>> ImagestoWrite = new List<Image<Gray, byte>>();
        EncoderParameters ENC_Parameters = new EncoderParameters(1);
        EncoderParameter ENC = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100);
        ImageCodecInfo Image_Encoder_JPG;

        //Saving XAML Data file
        List<string> NamestoWrite = new List<string>();
        List<string> NamesforFile = new List<string>();
        XmlDocument docu = new XmlDocument();

        //Variables
        Form1 Parent;
        #endregion

        public Training_Form(Form1 _Parent)
        {
            InitializeComponent();
            Parent = _Parent;
            Face = Parent.Face;
            //Face = new HaarCascade(Application.StartupPath + "/Cascades/haarcascade_frontalface_alt2.xml");
            ENC_Parameters.Param[0] = ENC;
            Image_Encoder_JPG = GetEncoder(ImageFormat.Jpeg);
            initialise_capture();
        }

        private void Training_Form_FormClosing(object sender, FormClosingEventArgs e)
        {
            stop_capture();
            Parent.retrain();
            Parent.initialise_capture();
        }

        //Camera Start Stop
        public void initialise_capture()
        {
            grabber = new Capture();
            grabber.QueryFrame();
            //Initialize the FrameGraber event
            Application.Idle += new EventHandler(FrameGrabber);
        }
        private void stop_capture()
        {
            Application.Idle -= new EventHandler(FrameGrabber);
            if (grabber != null)
            {
                grabber.Dispose();
            }
            //Initialize the FrameGraber event
        }

        //Process Frame
        void FrameGrabber(object sender, EventArgs e)
        {
            //Get the current frame form capture device
            currentFrame = grabber.QueryFrame().Resize(320, 240, Emgu.CV.CvEnum.INTER.CV_INTER_CUBIC);

            //Convert it to Grayscale
            if (currentFrame != null)
            {
                gray_frame = currentFrame.Convert<Gray, Byte>();

                //Face Detector
                //MCvAvgComp[][] facesDetected = gray_frame.DetectHaarCascade(Face, 1.2, 10, Emgu.CV.CvEnum.HAAR_DETECTION_TYPE.DO_CANNY_PRUNING, new Size(20, 20)); //old method
                Rectangle[] facesDetected = Face.DetectMultiScale(gray_frame, 1.2, 10, new Size(50, 50), Size.Empty);

                //Action for each element detected
                for(int i = 0; i< facesDetected.Length; i++)// (Rectangle face_found in facesDetected)
                {
                    //This will focus in on the face from the haar results its not perfect but it will remove a majoriy
                    //of the background noise
                    facesDetected[i].X += (int)(facesDetected[i].Height * 0.15);
                    facesDetected[i].Y += (int)(facesDetected[i].Width * 0.22);
                    facesDetected[i].Height -= (int)(facesDetected[i].Height * 0.3);
                    facesDetected[i].Width -= (int)(facesDetected[i].Width * 0.35);

                    result = currentFrame.Copy(facesDetected[i]).Convert<Gray, byte>().Resize(100, 100, Emgu.CV.CvEnum.INTER.CV_INTER_CUBIC);
                    result._EqualizeHist();
                    face_PICBX.Image = result.ToBitmap();
                    //draw the face detected in the 0th (gray) channel with blue color
                    currentFrame.Draw(facesDetected[i], new Bgr(Color.Red), 2);

                }
                if (RECORD && facesDetected.Length > 0 && resultImages.Count < num_faces_to_aquire)
                {
                    resultImages.Add(result);
                    count_lbl.Text = "Count: " + resultImages.Count.ToString();
                    if (resultImages.Count == num_faces_to_aquire)
                    {
                        ADD_BTN.Enabled = true;
                        NEXT_BTN.Visible = true;
                        PREV_btn.Visible = true;
                        count_lbl.Visible = false;
                        Single_btn.Visible = true;
                        ADD_ALL.Visible = true;
                        RECORD = false;
                        Application.Idle -= new EventHandler(FrameGrabber);
                    }
                }

                image_PICBX.Image = currentFrame.ToBitmap();
            }
        }

        //Saving The Data
        private bool save_training_data(Image face_data)
        {
            try
            {
                Random rand = new Random();
                bool file_create = true;
                string facename = "face_" + NAME_PERSON.Text + "_" + rand.Next().ToString() + ".jpg";
                while (file_create)
                {

                    if (!File.Exists(Application.StartupPath + "/TrainedFaces/" + facename))
                    {
                        file_create = false;
                    }
                    else
                    {
                        facename = "face_" + NAME_PERSON.Text + "_" + rand.Next().ToString() + ".jpg";
                    }
                }


                if(Directory.Exists(Application.StartupPath + "/TrainedFaces/"))
                {
                    face_data.Save(Application.StartupPath + "/TrainedFaces/" + facename, ImageFormat.Jpeg);
                }
                else
                {
                    Directory.CreateDirectory(Application.StartupPath + "/TrainedFaces/");
                    face_data.Save(Application.StartupPath + "/TrainedFaces/" + facename, ImageFormat.Jpeg);
                }
                if (File.Exists(Application.StartupPath + "/TrainedFaces/TrainedLabels.xml"))
                {
                    //File.AppendAllText(Application.StartupPath + "/TrainedFaces/TrainedLabels.txt", NAME_PERSON.Text + "\n\r");
                    bool loading = true;
                    while (loading)
                    {
                        try
                        {
                            docu.Load(Application.StartupPath + "/TrainedFaces/TrainedLabels.xml");
                            loading = false;
                        }
                        catch
                        {
                            docu = null;
                            docu = new XmlDocument();
                            Thread.Sleep(10);
                        }
                    }

                    //Get the root element
                    XmlElement root = docu.DocumentElement;

                    XmlElement face_D = docu.CreateElement("FACE");
                    XmlElement name_D = docu.CreateElement("NAME");
                    XmlElement file_D = docu.CreateElement("FILE");

                    //Add the values for each nodes
                    //name.Value = textBoxName.Text;
                    //age.InnerText = textBoxAge.Text;
                    //gender.InnerText = textBoxGender.Text;
                    name_D.InnerText = NAME_PERSON.Text;
                    file_D.InnerText = facename;

                    //Construct the Person element
                    //person.Attributes.Append(name);
                    face_D.AppendChild(name_D);
                    face_D.AppendChild(file_D);

                    //Add the New person element to the end of the root element
                    root.AppendChild(face_D);

                    //Save the document
                    docu.Save(Application.StartupPath + "/TrainedFaces/TrainedLabels.xml");
                    //XmlElement child_element = docu.CreateElement("FACE");
                    //docu.AppendChild(child_element);
                    //docu.Save("TrainedLabels.xml");
                }
                else
                {
                    FileStream FS_Face = File.OpenWrite(Application.StartupPath + "/TrainedFaces/TrainedLabels.xml");
                    using (XmlWriter writer = XmlWriter.Create(FS_Face))
                    {
                        writer.WriteStartDocument();
                        writer.WriteStartElement("Faces_For_Training");

                        writer.WriteStartElement("FACE");
                        writer.WriteElementString("NAME", NAME_PERSON.Text);
                        writer.WriteElementString("FILE", facename);
                        writer.WriteEndElement();

                        writer.WriteEndElement();
                        writer.WriteEndDocument();
                    }
                    FS_Face.Close();
                }

                return true;
            }
            catch (Exception ex)
            {
                return false;
            }

        }
        private ImageCodecInfo GetEncoder(ImageFormat format)
        {
            ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
            foreach (ImageCodecInfo codec in codecs)
            {
                if (codec.FormatID == format.Guid)
                {
                    return codec;
                }
            }
            return null;
        }

        //Delete all the old training data by simply deleting the folder
        private void Delete_Data_BTN_Click(object sender, EventArgs e)
        {
            if (Directory.Exists(Application.StartupPath + "/TrainedFaces/"))
            {
                Directory.Delete(Application.StartupPath + "/TrainedFaces/", true);
                Directory.CreateDirectory(Application.StartupPath + "/TrainedFaces/");
            }
        }

        //Add the image to training data
        private void ADD_BTN_Click(object sender, EventArgs e)
        {
            if (resultImages.Count == num_faces_to_aquire)
            {
                if (!save_training_data(face_PICBX.Image)) MessageBox.Show("Error", "Error in saving file info. Training data not saved", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
            else
            {
                stop_capture();
                if (!save_training_data(face_PICBX.Image)) MessageBox.Show("Error", "Error in saving file info. Training data not saved", MessageBoxButtons.OK, MessageBoxIcon.Error);
                initialise_capture();
            }
        }
        private void Single_btn_Click(object sender, EventArgs e)
        {
            RECORD = false;
            resultImages.Clear();
            NEXT_BTN.Visible = false;
            PREV_btn.Visible = false;
            Application.Idle += new EventHandler(FrameGrabber);
            Single_btn.Visible = false;
            count_lbl.Text = "Count: 0";
            count_lbl.Visible = true;
        }
        //Get 10 image to train
        private void RECORD_BTN_Click(object sender, EventArgs e)
        {
            if (RECORD)
            {
                RECORD = false;
            }
            else
            {
                if (resultImages.Count == 10)
                {
                    resultImages.Clear();
                    Application.Idle += new EventHandler(FrameGrabber);
                }
                RECORD = true;
                ADD_BTN.Enabled = false;
            }

        }
        private void NEXT_BTN_Click(object sender, EventArgs e)
        {
            if (results_list_pos < resultImages.Count - 1)
            {
                face_PICBX.Image = resultImages[results_list_pos].ToBitmap();
                results_list_pos++;
                PREV_btn.Enabled = true;
            }
            else
            {
                NEXT_BTN.Enabled = false;
            }
        }
        private void PREV_btn_Click(object sender, EventArgs e)
        {
            if (results_list_pos > 0)
            {
                results_list_pos--;
                face_PICBX.Image = resultImages[results_list_pos].ToBitmap();
                NEXT_BTN.Enabled = true;
            }
            else
            {
                PREV_btn.Enabled = false;
            }
        }
        private void ADD_ALL_Click(object sender, EventArgs e)
        {
            for(int i = 0; i<resultImages.Count;i++)
            {
                face_PICBX.Image = resultImages[i].ToBitmap();
                if (!save_training_data(face_PICBX.Image)) MessageBox.Show("Error", "Error in saving file info. Training data not saved", MessageBoxButtons.OK, MessageBoxIcon.Error);
                Thread.Sleep(100);
            }
            ADD_ALL.Visible = false;
            //restart single face detection
            Single_btn_Click(null, null);
        }

        private void Training_Form_Load(object sender, EventArgs e)
        {

        }

    }
}

the form which needs to create the object of Training_Form is:

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

using System.IO;
using System.Xml;
using System.Runtime.InteropServices;
using System.Threading;
using System.Security.Principal;
using System.Threading.Tasks;
using Microsoft.Win32.SafeHandles;

namespace Face_Recognition
{
    public partial class mainwindow : Form
    {
        public mainwindow()
        {
            InitializeComponent();
        }

        private void button2_Click(object sender, EventArgs e)
        {
            Form1 childf = new Form1();
            childf.ShowDialog();
        }

        private void mainwindow_Load(object sender, EventArgs e)
        {

        }

        private void button3_Click(object sender, EventArgs e)
        {
            Training_Form TF = new Training_Form(this);
            TF.Show();

        }
    }
}

Answer 1

It seems that this does not refer to an instance of Form1 but a different Form -type Face_Recognition . But the constructor of Training_Form only accepts Form1 as parameter. So you either have to pass an instance of Form1 if you have one or change the signature of the constructor.

Maybe it's sufficient to use a Form :

public Training_Form(Form _Parent)
{
    InitializeComponent();
    Parent = _Parent;
    Face = Parent.Face;
    //Face = new HaarCascade(Application.StartupPath + "/Cascades/haarcascade_frontalface_alt2.xml");
    ENC_Parameters.Param[0] = ENC;
    Image_Encoder_JPG = GetEncoder(ImageFormat.Jpeg);
    initialise_capture();
}

If you need the Form1 you have to pass an instance. You are creating one in button2_Click but just as local variable. You could store it in a field:

Form1 childf = null;

private void button2_Click(object sender, EventArgs e)
{
    if(childf == null) childf = new Form1();
    childf.ShowDialog();
}

private void button3_Click(object sender, EventArgs e)
{
    if(childf == null) childf = new Form1();
    Training_Form TF = new Training_Form(childf);
    TF.Show();
}

Answer 2

Your Training_Form expects a parameter of type Form1 .

While in your code you are trying to supply it with the keyword this . this being the object you are currently in. Since you are calling it from mainwindow you are trying to put a mainwindow type in it, because in this case mainwindow is equal to this .

You probably, by reading your code, mean to put the childf in, or at least, that has the right type. That would work, but you would have to declare the childf parameter more globally.

Or you should change the type you expect in your constructor to mainwindow that would work as well.

Answer 3

You are sending training form an argument of "this" from your program which is a reference to program so you are getting an invalid argument. You either need to make the call to display the TrainingForm from within Form1 or make Form1 a private instantiated member of the program so you can pass it into the TrainingForm constructor.