Help out with this code please. Image from datagridview to desktop

Question

i am displaying images into datagridview, is working fine without any problem, but when i wan to download a single image it keeps on showing me problems that i have to (Select a single cell from Attachment column). Please the code is detailed. one can try it and help out with a solution. thank you using

using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Windows.Forms;

namespace ImageThumbnailDataGridView
{
    public partial class FormMain : Form
    {
        private List<string> files = null;
        private int numberPreviewImages = 100;
        private int imageSize = 90;
        private int currentStartImageIndex = 0;
        private int currentEndImageIndex = 0;

        //Dictionary will store the attachments
        Dictionary<int, byte[]> myAttachments;

        public FormMain()
        {
            InitializeComponent();
        }

        private void btnLoadImages_Click(object sender, EventArgs e)
        {
            if (openFileDialog.ShowDialog(this) != DialogResult.OK)
            {
                return;
            }

            files = new List<string>();
            files.AddRange(openFileDialog.FileNames);
            files.Sort();

            if (numberPreviewImages == 1)
            {
                currentStartImageIndex = 0;
                currentEndImageIndex = 1;
            }
            else
            {
                currentEndImageIndex = currentStartImageIndex + numberPreviewImages - 1;
            }

            this.LoadImages();
        }

        private void LoadImages()
        {
            try
            {
                if (files == null)
                {
                    return;
                }

                if (this.WindowState == FormWindowState.Minimized)
                {
                    return;
                }

                dataViewImages.Rows.Clear();
                dataViewImages.Columns.Clear();

                int numColumnsForWidth = (dataViewImages.Width - 10) / (imageSize + 20);
                int numRows = 0;

                int numImagesRequired = 0;

                if (currentEndImageIndex > files.Count)
                {
                    // Are we requesting to display more images than we actually have? If so then reduce
                    if (currentStartImageIndex == 0)
                    {
                        numImagesRequired = files.Count;
                    }
                    else
                    {
                        numImagesRequired = (currentEndImageIndex - currentStartImageIndex) - (currentEndImageIndex - _files.Count);
                    }
                }
                else
                {
                    // Calculated the number of rows we will need for normal use
                    numImagesRequired = currentEndImageIndex - currentStartImageIndex; 
                }

                numRows = numImagesRequired / numColumnsForWidth;

                if (numImagesRequired % numColumnsForWidth > 0)
                {
                    numRows += 1;
                }

                if (numImagesRequired < numColumnsForWidth)
                {
                    numColumnsForWidth = numImagesRequired;
                }

                int numGeneratedCells = numRows * numColumnsForWidth;

                // Dynamically creating the columns
                for (int index = 0; index < numColumnsForWidth; index++)
                {
                    DataGridViewImageColumn dataGridViewColumn = new DataGridViewImageColumn();

                    dataViewImages.Columns.Add(dataGridViewColumn);
                    dataViewImages.Columns[index].Width = imageSize + 20;
                }

                // Creating the rows
                for (int index = 0; index < numRows; index++)
                {
                    dataViewImages.Rows.Add();
                    dataViewImages.Rows[index].Height = imageSize + 20;
                }

                int columnIndex = 0;
                int rowIndex = 0;

                for (int index = currentStartImageIndex; index < currentStartImageIndex + numImagesRequired; index++)
                {
                    // Load the image from the file and add to the DataGridView
                    Image image = Helper.ResizeImage(files[index], imageSize, imageSize, false);
                    dataViewImages.Rows[rowIndex].Cells[columnIndex].Value = image;
                    dataViewImages.Rows[rowIndex].Cells[columnIndex].ToolTipText = Path.GetFileName(files[index]);

                    // Have we reached the end column? if so then start on the next row
                    if (columnIndex == numColumnsForWidth - 1)
                    {
                        rowIndex++;
                        columnIndex = 0;
                    }
                    else
                    {
                        columnIndex++;
                    }
                }

                // Blank the unused cells
                if (numGeneratedCells > numImagesRequired)
                {
                    for (int index = 0; index < numGeneratedCells - numImagesRequired; index++)
                    {
                        DataGridViewCellStyle dataGridViewCellStyle = new DataGridViewCellStyle();
                        dataGridViewCellStyle.NullValue = null;
                        dataGridViewCellStyle.Tag = "BLANK";
                        dataViewImages.Rows[rowIndex].Cells[columnIndex + index].Style = dataGridViewCellStyle;
                    }
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void dataViewImages_Resize(object sender, EventArgs e)
        {
            this.LoadImages();
        }

        private void FormMain_Load(object sender, EventArgs e)
        {
            imageSize = 90;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            if (dataViewImages.SelectedRows.Count == 1 && dataViewImages.SelectedCells[0].ColumnIndex == 1 && dataViewImages.SelectedCells[0].Value != null)
            {
                DownloadAttachment(dataViewImages.SelectedCells[0]);
            }
            else
                MessageBox.Show("Select a single cell from Attachment column", "Error uploading file", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
        private void DownloadAttachment(DataGridViewCell dgvCell)
        {
            string fileName = Convert.ToString(dgvCell.Value);

            //Return if the cell is empty
            if (fileName == string.Empty)
                return;

            FileInfo fileInfo = new FileInfo(fileName);
            string fileExtension = fileInfo.Extension;

            byte[] byteData = null;

            //show save as dialog
            using (SaveFileDialog saveFileDialog1 = new SaveFileDialog())
            {
                //Set Save dialog properties
                saveFileDialog1.Filter = "Files (*" + fileExtension + ")|*" + fileExtension;
                saveFileDialog1.Title = "Save File as";
                saveFileDialog1.CheckPathExists = true;
                saveFileDialog1.FileName = fileName;

                if (saveFileDialog1.ShowDialog() == DialogResult.OK)
                {
                    byteData = myAttachments[dgvCell.RowIndex];
                    File.WriteAllBytes(saveFileDialog1.FileName, byteData);
                }
            }
        }
    }
}

Answer 1

The problem is in this line:

if (dataViewImages.SelectedRows.Count == 1 && dataViewImages.SelectedCells[0].ColumnIndex == 1 && dataViewImages.SelectedCells[0].Value != null)  

dataViewImages.SelectedRows.Count == 1 and dataViewImages.SelectedCells[0].ColumnIndex == 1 cannot be satisfied at the same time.

If dataViewImages.SelectedRows.Count == 1 is true, you must select the row, then dataViewImages.SelectedCells[0].ColumnIndex must be 0.

If you select a cell, then dataViewImages.SelectedRows.Count must be 0.

In addition, I checked your DownloadAttachment method, it has some problems.

1. string fileName = Convert.ToString(dgvCell.Value); The result will be System.Drawing.Bitmap, the type of the object instead of the path, you cannot get a correct FileInfo based on it. Try to convert it to Image and add a method to get its extension.

          Image image = (Image)dgvCell.Value;  
       string fileExtension = GetImageType(image);  
   
       public string GetImageType(Image image)  
       {  
           if (image.RawFormat.Equals(ImageFormat.Bmp))  
           {  
               return "Bmp";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.MemoryBmp))  
           {  
               return "BMP";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.Wmf))  
           {  
               return "Emf";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.Wmf))  
           {  
               return "Wmf";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.Gif))  
           {  
               return "Gif";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.Jpeg))  
           {  
               return "Jpeg";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.Png))  
           {  
               return "Png";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.Tiff))  
           {  
               return "Tiff";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.Exif))  
           {  
               return "Exif";  
           }  
           else if (image.RawFormat.Equals(ImageFormat.Icon))  
           {  
               return "Ico";  
           }  
   
           return "Not an image.";  
       }  
   

2. byteData = myAttachments[dgvCell.RowIndex]; In the current code you provided, myAttachments is not initialized, and no value is added to it anywhere. I am not very clear about its usefulness, so I do not use it in my current code.

       private void DownloadAttachment(DataGridViewCell dgvCell)  
       {  
           Image image = (Image)dgvCell.Value;  
           string fileExtension = GetImageType(image);  
           //show save as dialog  
           using (SaveFileDialog saveFileDialog1 = new SaveFileDialog())  
           {  
               //Set Save dialog properties  
               saveFileDialog1.Filter = "Files (*" + fileExtension + ")|*" + fileExtension;  
               saveFileDialog1.Title = "Save File as";  
               saveFileDialog1.CheckPathExists = true;  
               saveFileDialog1.FileName = "1."+fileExtension;  
   
               if (saveFileDialog1.ShowDialog() == DialogResult.OK)  
               {  
                   image.Save(saveFileDialog1.FileName);  
               }  
           }  
       }  
   

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