Xin chào các bạn, bài viết hôm nay mình chia sẻ các bạn phần mềm PDF Split, dùng để tách tập tin PDF thành nhiều trang theo tùy chọn.

[Tool] Phần mềm tách một file tập tin pdf thành nhiều file.

Giao diện demo ứng dụng C#:

Phần mềm cho phép bạn tách file pdf theo trang chẵn, hoặc theo trang lẻ, hoặc nhập số 2 vào.

Tùy chọn xuất 1 file vào 1 folder, hoặc tất cả vào chung 1 folder.

Source code C#:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using iTextSharp.text;
using iTextSharp.text.pdf;

namespace PDFSplitterApp
{
    public partial class FormMain : Form
    {
        private List<string> selectedPDFPaths = new List<string>();
        private string outputFolderPath = string.Empty;
        private string inputFolderPath = string.Empty;

        public FormMain()
        {
            InitializeComponent();
        }

        private void InitializeComponent()
        {
            System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(FormMain));
            this.btnSelectPDF = new System.Windows.Forms.Button();
            this.btnSelectOutputFolder = new System.Windows.Forms.Button();
            this.btnSplitPDF = new System.Windows.Forms.Button();
            this.lblInputFiles = new System.Windows.Forms.Label();
            this.lblOutputFolder = new System.Windows.Forms.Label();
            this.txtOutputPrefix = new System.Windows.Forms.TextBox();
            this.lblOutputPrefix = new System.Windows.Forms.Label();
            this.rbSplitEvenPages = new System.Windows.Forms.RadioButton();
            this.rbSplitOddPages = new System.Windows.Forms.RadioButton();
            this.rbSplitCustomPages = new System.Windows.Forms.RadioButton();
            this.txtCustomPages = new System.Windows.Forms.TextBox();
            this.lblCustomPagesHelp = new System.Windows.Forms.Label();
            this.statusStrip = new System.Windows.Forms.StatusStrip();
            this.statusLabel = new System.Windows.Forms.ToolStripStatusLabel();
            this.progressBar = new System.Windows.Forms.ToolStripProgressBar();
            this.lvResults = new System.Windows.Forms.ListView();
            this.colOutFileName = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.colOutFilePath = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.colPages = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.groupBoxSplitOptions = new System.Windows.Forms.GroupBox();
            this.lvInputFiles = new System.Windows.Forms.ListView();
            this.colFileName = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.colFilePath = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.colPageCount = ((System.Windows.Forms.ColumnHeader)(new System.Windows.Forms.ColumnHeader()));
            this.btnRemoveFiles = new System.Windows.Forms.Button();
            this.btnOpenInputFolder = new System.Windows.Forms.Button();
            this.groupBoxOutputOptions = new System.Windows.Forms.GroupBox();
            this.rbSeparateFolders = new System.Windows.Forms.RadioButton();
            this.rbSingleFolder = new System.Windows.Forms.RadioButton();
            this.statusStrip.SuspendLayout();
            this.groupBoxSplitOptions.SuspendLayout();
            this.groupBoxOutputOptions.SuspendLayout();
            this.SuspendLayout();
            // 
            // btnSelectPDF
            // 
            this.btnSelectPDF.Location = new System.Drawing.Point(12, 12);
            this.btnSelectPDF.Name = "btnSelectPDF";
            this.btnSelectPDF.Size = new System.Drawing.Size(130, 30);
            this.btnSelectPDF.TabIndex = 0;
            this.btnSelectPDF.Text = "Chọn File PDF";
            this.btnSelectPDF.UseVisualStyleBackColor = true;
            this.btnSelectPDF.Click += new System.EventHandler(this.btnSelectPDF_Click);
            // 
            // btnSelectOutputFolder
            // 
            this.btnSelectOutputFolder.Location = new System.Drawing.Point(12, 48);
            this.btnSelectOutputFolder.Name = "btnSelectOutputFolder";
            this.btnSelectOutputFolder.Size = new System.Drawing.Size(130, 30);
            this.btnSelectOutputFolder.TabIndex = 2;
            this.btnSelectOutputFolder.Text = "Chọn Thư Mục Lưu";
            this.btnSelectOutputFolder.UseVisualStyleBackColor = true;
            this.btnSelectOutputFolder.Click += new System.EventHandler(this.btnSelectOutputFolder_Click);
            // 
            // btnSplitPDF
            // 
            this.btnSplitPDF.Font = new System.Drawing.Font("Microsoft Sans Serif", 9.75F, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, ((byte)(0)));
            this.btnSplitPDF.Location = new System.Drawing.Point(12, 440);
            this.btnSplitPDF.Name = "btnSplitPDF";
            this.btnSplitPDF.Size = new System.Drawing.Size(630, 40);
            this.btnSplitPDF.TabIndex = 9;
            this.btnSplitPDF.Text = "TÁCH FILE PDF";
            this.btnSplitPDF.UseVisualStyleBackColor = true;
            this.btnSplitPDF.Click += new System.EventHandler(this.btnSplitPDF_Click);
            // 
            // lblInputFiles
            // 
            this.lblInputFiles.AutoSize = true;
            this.lblInputFiles.Location = new System.Drawing.Point(148, 21);
            this.lblInputFiles.Name = "lblInputFiles";
            this.lblInputFiles.Size = new System.Drawing.Size(120, 13);
            this.lblInputFiles.TabIndex = 1;
            this.lblInputFiles.Text = "Chưa chọn file PDF nào";
            // 
            // lblOutputFolder
            // 
            this.lblOutputFolder.AutoSize = true;
            this.lblOutputFolder.Location = new System.Drawing.Point(148, 57);
            this.lblOutputFolder.Name = "lblOutputFolder";
            this.lblOutputFolder.Size = new System.Drawing.Size(117, 13);
            this.lblOutputFolder.TabIndex = 3;
            this.lblOutputFolder.Text = "Chưa chọn thư mục lưu";
            // 
            // txtOutputPrefix
            // 
            this.txtOutputPrefix.Location = new System.Drawing.Point(101, 85);
            this.txtOutputPrefix.Name = "txtOutputPrefix";
            this.txtOutputPrefix.Size = new System.Drawing.Size(200, 20);
            this.txtOutputPrefix.TabIndex = 5;
            this.txtOutputPrefix.Text = "PDFSplit";
            // 
            // lblOutputPrefix
            // 
            this.lblOutputPrefix.AutoSize = true;
            this.lblOutputPrefix.Location = new System.Drawing.Point(12, 88);
            this.lblOutputPrefix.Name = "lblOutputPrefix";
            this.lblOutputPrefix.Size = new System.Drawing.Size(80, 13);
            this.lblOutputPrefix.TabIndex = 4;
            this.lblOutputPrefix.Text = "Tên file xuất ra:";
            // 
            // rbSplitEvenPages
            // 
            this.rbSplitEvenPages.AutoSize = true;
            this.rbSplitEvenPages.Location = new System.Drawing.Point(20, 30);
            this.rbSplitEvenPages.Name = "rbSplitEvenPages";
            this.rbSplitEvenPages.Size = new System.Drawing.Size(128, 17);
            this.rbSplitEvenPages.TabIndex = 0;
            this.rbSplitEvenPages.Text = "Tách theo trang chẵn";
            this.rbSplitEvenPages.UseVisualStyleBackColor = true;
            // 
            // rbSplitOddPages
            // 
            this.rbSplitOddPages.AutoSize = true;
            this.rbSplitOddPages.Location = new System.Drawing.Point(20, 55);
            this.rbSplitOddPages.Name = "rbSplitOddPages";
            this.rbSplitOddPages.Size = new System.Drawing.Size(112, 17);
            this.rbSplitOddPages.TabIndex = 1;
            this.rbSplitOddPages.Text = "Tách theo trang lẻ";
            this.rbSplitOddPages.UseVisualStyleBackColor = true;
            // 
            // rbSplitCustomPages
            // 
            this.rbSplitCustomPages.AutoSize = true;
            this.rbSplitCustomPages.Checked = true;
            this.rbSplitCustomPages.Location = new System.Drawing.Point(20, 80);
            this.rbSplitCustomPages.Name = "rbSplitCustomPages";
            this.rbSplitCustomPages.Size = new System.Drawing.Size(140, 17);
            this.rbSplitCustomPages.TabIndex = 2;
            this.rbSplitCustomPages.TabStop = true;
            this.rbSplitCustomPages.Text = "Tách theo trang tự chọn";
            this.rbSplitCustomPages.UseVisualStyleBackColor = true;
            this.rbSplitCustomPages.CheckedChanged += new System.EventHandler(this.rbSplitCustomPages_CheckedChanged);
            // 
            // txtCustomPages
            // 
            this.txtCustomPages.Location = new System.Drawing.Point(166, 80);
            this.txtCustomPages.Name = "txtCustomPages";
            this.txtCustomPages.Size = new System.Drawing.Size(95, 20);
            this.txtCustomPages.TabIndex = 3;
            this.txtCustomPages.Text = "2";
            // 
            // lblCustomPagesHelp
            // 
            this.lblCustomPagesHelp.AutoSize = true;
            this.lblCustomPagesHelp.Location = new System.Drawing.Point(267, 83);
            this.lblCustomPagesHelp.Name = "lblCustomPagesHelp";
            this.lblCustomPagesHelp.Size = new System.Drawing.Size(268, 13);
            this.lblCustomPagesHelp.TabIndex = 4;
            this.lblCustomPagesHelp.Text = "Số trang trong mỗi file (vd: 2 trang thì 20 trang ra 10 file)";
            // 
            // statusStrip
            // 
            this.statusStrip.Items.AddRange(new System.Windows.Forms.ToolStripItem[] {
            this.statusLabel,
            this.progressBar});
            this.statusStrip.Location = new System.Drawing.Point(0, 654);
            this.statusStrip.Name = "statusStrip";
            this.statusStrip.Size = new System.Drawing.Size(654, 22);
            this.statusStrip.TabIndex = 11;
            this.statusStrip.Text = "statusStrip1";
            // 
            // statusLabel
            // 
            this.statusLabel.Name = "statusLabel";
            this.statusLabel.Size = new System.Drawing.Size(54, 17);
            this.statusLabel.Text = "Sẵn sàng";
            // 
            // progressBar
            // 
            this.progressBar.Name = "progressBar";
            this.progressBar.Size = new System.Drawing.Size(200, 16);
            // 
            // lvResults
            // 
            this.lvResults.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
            this.colOutFileName,
            this.colOutFilePath,
            this.colPages});
            this.lvResults.FullRowSelect = true;
            this.lvResults.GridLines = true;
            this.lvResults.HideSelection = false;
            this.lvResults.Location = new System.Drawing.Point(12, 490);
            this.lvResults.Name = "lvResults";
            this.lvResults.Size = new System.Drawing.Size(630, 150);
            this.lvResults.TabIndex = 10;
            this.lvResults.UseCompatibleStateImageBehavior = false;
            this.lvResults.View = System.Windows.Forms.View.Details;
            // 
            // colOutFileName
            // 
            this.colOutFileName.Text = "Tên File";
            this.colOutFileName.Width = 150;
            // 
            // colOutFilePath
            // 
            this.colOutFilePath.Text = "Đường Dẫn";
            this.colOutFilePath.Width = 380;
            // 
            // colPages
            // 
            this.colPages.Text = "Số Trang";
            this.colPages.Width = 80;
            // 
            // groupBoxSplitOptions
            // 
            this.groupBoxSplitOptions.Controls.Add(this.rbSplitEvenPages);
            this.groupBoxSplitOptions.Controls.Add(this.rbSplitOddPages);
            this.groupBoxSplitOptions.Controls.Add(this.rbSplitCustomPages);
            this.groupBoxSplitOptions.Controls.Add(this.txtCustomPages);
            this.groupBoxSplitOptions.Controls.Add(this.lblCustomPagesHelp);
            this.groupBoxSplitOptions.Location = new System.Drawing.Point(12, 270);
            this.groupBoxSplitOptions.Name = "groupBoxSplitOptions";
            this.groupBoxSplitOptions.Size = new System.Drawing.Size(630, 120);
            this.groupBoxSplitOptions.TabIndex = 8;
            this.groupBoxSplitOptions.TabStop = false;
            this.groupBoxSplitOptions.Text = "Tùy chọn tách";
            // 
            // lvInputFiles
            // 
            this.lvInputFiles.Columns.AddRange(new System.Windows.Forms.ColumnHeader[] {
            this.colFileName,
            this.colFilePath,
            this.colPageCount});
            this.lvInputFiles.FullRowSelect = true;
            this.lvInputFiles.GridLines = true;
            this.lvInputFiles.HideSelection = false;
            this.lvInputFiles.Location = new System.Drawing.Point(12, 120);
            this.lvInputFiles.Name = "lvInputFiles";
            this.lvInputFiles.Size = new System.Drawing.Size(630, 100);
            this.lvInputFiles.TabIndex = 6;
            this.lvInputFiles.UseCompatibleStateImageBehavior = false;
            this.lvInputFiles.View = System.Windows.Forms.View.Details;
            // 
            // colFileName
            // 
            this.colFileName.Text = "Tên File";
            this.colFileName.Width = 150;
            // 
            // colFilePath
            // 
            this.colFilePath.Text = "Đường Dẫn";
            this.colFilePath.Width = 380;
            // 
            // colPageCount
            // 
            this.colPageCount.Text = "Số Trang";
            this.colPageCount.Width = 80;
            // 
            // btnRemoveFiles
            // 
            this.btnRemoveFiles.Enabled = false;
            this.btnRemoveFiles.Location = new System.Drawing.Point(12, 226);
            this.btnRemoveFiles.Name = "btnRemoveFiles";
            this.btnRemoveFiles.Size = new System.Drawing.Size(130, 30);
            this.btnRemoveFiles.TabIndex = 7;
            this.btnRemoveFiles.Text = "Xóa File Đã Chọn";
            this.btnRemoveFiles.UseVisualStyleBackColor = true;
            this.btnRemoveFiles.Click += new System.EventHandler(this.btnRemoveFiles_Click);
            // 
            // btnOpenInputFolder
            // 
            this.btnOpenInputFolder.Enabled = false;
            this.btnOpenInputFolder.Location = new System.Drawing.Point(512, 12);
            this.btnOpenInputFolder.Name = "btnOpenInputFolder";
            this.btnOpenInputFolder.Size = new System.Drawing.Size(130, 30);
            this.btnOpenInputFolder.TabIndex = 12;
            this.btnOpenInputFolder.Text = "Mở Thư Mục Nhập";
            this.btnOpenInputFolder.UseVisualStyleBackColor = true;
            this.btnOpenInputFolder.Click += new System.EventHandler(this.btnOpenInputFolder_Click);
            // 
            // groupBoxOutputOptions
            // 
            this.groupBoxOutputOptions.Controls.Add(this.rbSeparateFolders);
            this.groupBoxOutputOptions.Controls.Add(this.rbSingleFolder);
            this.groupBoxOutputOptions.Location = new System.Drawing.Point(12, 396);
            this.groupBoxOutputOptions.Name = "groupBoxOutputOptions";
            this.groupBoxOutputOptions.Size = new System.Drawing.Size(630, 38);
            this.groupBoxOutputOptions.TabIndex = 13;
            this.groupBoxOutputOptions.TabStop = false;
            this.groupBoxOutputOptions.Text = "Tùy chọn xuất";
            // 
            // rbSeparateFolders
            // 
            this.rbSeparateFolders.AutoSize = true;
            this.rbSeparateFolders.Location = new System.Drawing.Point(276, 15);
            this.rbSeparateFolders.Name = "rbSeparateFolders";
            this.rbSeparateFolders.Size = new System.Drawing.Size(196, 17);
            this.rbSeparateFolders.TabIndex = 1;
            this.rbSeparateFolders.Text = "Tạo thư mục riêng cho từng file PDF";
            this.rbSeparateFolders.UseVisualStyleBackColor = true;
            // 
            // rbSingleFolder
            // 
            this.rbSingleFolder.AutoSize = true;
            this.rbSingleFolder.Checked = true;
            this.rbSingleFolder.Location = new System.Drawing.Point(20, 15);
            this.rbSingleFolder.Name = "rbSingleFolder";
            this.rbSingleFolder.Size = new System.Drawing.Size(175, 17);
            this.rbSingleFolder.TabIndex = 0;
            this.rbSingleFolder.TabStop = true;
            this.rbSingleFolder.Text = "Xuất tất cả file vào một thư mục";
            this.rbSingleFolder.UseVisualStyleBackColor = true;
            // 
            // FormMain
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(654, 676);
            this.Controls.Add(this.groupBoxOutputOptions);
            this.Controls.Add(this.btnOpenInputFolder);
            this.Controls.Add(this.statusStrip);
            this.Controls.Add(this.lvResults);
            this.Controls.Add(this.btnSplitPDF);
            this.Controls.Add(this.groupBoxSplitOptions);
            this.Controls.Add(this.btnRemoveFiles);
            this.Controls.Add(this.lvInputFiles);
            this.Controls.Add(this.txtOutputPrefix);
            this.Controls.Add(this.lblOutputPrefix);
            this.Controls.Add(this.lblOutputFolder);
            this.Controls.Add(this.btnSelectOutputFolder);
            this.Controls.Add(this.lblInputFiles);
            this.Controls.Add(this.btnSelectPDF);
            this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
            this.Icon = ((System.Drawing.Icon)(resources.GetObject("$this.Icon")));
            this.MaximizeBox = false;
            this.Name = "FormMain";
            this.StartPosition = System.Windows.Forms.FormStartPosition.CenterScreen;
            this.Text = "Ứng Dụng Tách File PDF";
            this.statusStrip.ResumeLayout(false);
            this.statusStrip.PerformLayout();
            this.groupBoxSplitOptions.ResumeLayout(false);
            this.groupBoxSplitOptions.PerformLayout();
            this.groupBoxOutputOptions.ResumeLayout(false);
            this.groupBoxOutputOptions.PerformLayout();
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        private System.Windows.Forms.Button btnSelectPDF;
        private System.Windows.Forms.Button btnSelectOutputFolder;
        private System.Windows.Forms.Button btnSplitPDF;
        private System.Windows.Forms.Label lblInputFiles;
        private System.Windows.Forms.Label lblOutputFolder;
        private System.Windows.Forms.TextBox txtOutputPrefix;
        private System.Windows.Forms.Label lblOutputPrefix;
        private System.Windows.Forms.RadioButton rbSplitEvenPages;
        private System.Windows.Forms.RadioButton rbSplitOddPages;
        private System.Windows.Forms.RadioButton rbSplitCustomPages;
        private System.Windows.Forms.TextBox txtCustomPages;
        private System.Windows.Forms.Label lblCustomPagesHelp;
        private System.Windows.Forms.GroupBox groupBoxSplitOptions;
        private System.Windows.Forms.StatusStrip statusStrip;
        private System.Windows.Forms.ToolStripStatusLabel statusLabel;
        private System.Windows.Forms.ToolStripProgressBar progressBar;
        private System.Windows.Forms.ListView lvResults;
        private System.Windows.Forms.ColumnHeader colOutFileName;
        private System.Windows.Forms.ColumnHeader colOutFilePath;
        private System.Windows.Forms.ColumnHeader colPages;
        private System.Windows.Forms.ListView lvInputFiles;
        private System.Windows.Forms.ColumnHeader colFileName;
        private System.Windows.Forms.ColumnHeader colFilePath;
        private System.Windows.Forms.ColumnHeader colPageCount;
        private System.Windows.Forms.Button btnRemoveFiles;
        private System.Windows.Forms.Button btnOpenInputFolder;
        private System.Windows.Forms.GroupBox groupBoxOutputOptions;
        private System.Windows.Forms.RadioButton rbSeparateFolders;
        private System.Windows.Forms.RadioButton rbSingleFolder;

        private void btnSelectPDF_Click(object sender, EventArgs e)
        {
            using (OpenFileDialog openFileDialog = new OpenFileDialog())
            {
                openFileDialog.Filter = "PDF Files (*.pdf)|*.pdf";
                openFileDialog.Title = "Chọn File PDF";
                openFileDialog.Multiselect = true; // Cho phép chọn nhiều file

                if (openFileDialog.ShowDialog() == DialogResult.OK)
                {
                    // Nếu đây là lần chọn file đầu tiên, lưu thư mục đầu vào
                    if (string.IsNullOrEmpty(inputFolderPath) && openFileDialog.FileNames.Length > 0)
                    {
                        inputFolderPath = Path.GetDirectoryName(openFileDialog.FileNames[0]);
                        btnOpenInputFolder.Enabled = true;
                    }

                    foreach (string fileName in openFileDialog.FileNames)
                    {
                        if (!selectedPDFPaths.Contains(fileName))
                        {
                            selectedPDFPaths.Add(fileName);

                            // Thêm vào ListView
                            ListViewItem item = new ListViewItem(Path.GetFileName(fileName));
                            item.SubItems.Add(fileName);
                            item.SubItems.Add(GetPDFPageCount(fileName).ToString());
                            lvInputFiles.Items.Add(item);
                        }
                    }

                    // Cập nhật status và label
                    lblInputFiles.Text = $"Đã chọn {selectedPDFPaths.Count} file PDF";
                    statusLabel.Text = $"Đã chọn {selectedPDFPaths.Count} file PDF";

                    // Nếu là file đầu tiên, đặt tên xuất ra mặc định
                    if (selectedPDFPaths.Count > 0 && txtOutputPrefix.Text == "PDFSplit")
                    {
                        txtOutputPrefix.Text = Path.GetFileNameWithoutExtension(selectedPDFPaths[0]);
                        if (selectedPDFPaths.Count > 1)
                        {
                            txtOutputPrefix.Text = "PDFSplit";
                        }
                    }

                    btnRemoveFiles.Enabled = selectedPDFPaths.Count > 0;
                }
            }
        }

        private void btnOpenInputFolder_Click(object sender, EventArgs e)
        {
            if (!string.IsNullOrEmpty(inputFolderPath) && Directory.Exists(inputFolderPath))
            {
                System.Diagnostics.Process.Start("explorer.exe", inputFolderPath);
            }
        }

        private void btnSelectOutputFolder_Click(object sender, EventArgs e)
        {
            using (FolderBrowserDialog folderBrowserDialog = new FolderBrowserDialog())
            {
                folderBrowserDialog.Description = "Chọn thư mục lưu file tách";
                folderBrowserDialog.ShowNewFolderButton = true;

                if (folderBrowserDialog.ShowDialog() == DialogResult.OK)
                {
                    outputFolderPath = folderBrowserDialog.SelectedPath;
                    lblOutputFolder.Text = outputFolderPath;
                    statusLabel.Text = "Đã chọn thư mục lưu: " + outputFolderPath;
                }
            }
        }

        private void btnRemoveFiles_Click(object sender, EventArgs e)
        {
            if (lvInputFiles.SelectedItems.Count > 0)
            {
                // Tạo danh sách tạm để xóa (tránh lỗi khi xóa trực tiếp)
                List<ListViewItem> itemsToRemove = new List<ListViewItem>();
                List<string> pathsToRemove = new List<string>();

                foreach (ListViewItem item in lvInputFiles.SelectedItems)
                {
                    itemsToRemove.Add(item);
                    pathsToRemove.Add(item.SubItems[1].Text);
                }

                // Xóa từ ListView và danh sách đường dẫn
                foreach (ListViewItem item in itemsToRemove)
                {
                    lvInputFiles.Items.Remove(item);
                }

                foreach (string path in pathsToRemove)
                {
                    selectedPDFPaths.Remove(path);
                }

                lblInputFiles.Text = $"Đã chọn {selectedPDFPaths.Count} file PDF";
                statusLabel.Text = $"Đã chọn {selectedPDFPaths.Count} file PDF";
                btnRemoveFiles.Enabled = selectedPDFPaths.Count > 0;

                // Disable nút mở thư mục nếu không còn file nào
                if (selectedPDFPaths.Count == 0)
                {
                    btnOpenInputFolder.Enabled = false;
                    inputFolderPath = string.Empty;
                }
            }
        }

        private int GetPDFPageCount(string pdfPath)
        {
            try
            {
                using (PdfReader reader = new PdfReader(pdfPath))
                {
                    return reader.NumberOfPages;
                }
            }
            catch (Exception)
            {
                return 0;
            }
        }

        private void rbSplitCustomPages_CheckedChanged(object sender, EventArgs e)
        {
            txtCustomPages.Enabled = rbSplitCustomPages.Checked;
        }

        private async void btnSplitPDF_Click(object sender, EventArgs e)
        {
            if (selectedPDFPaths.Count == 0)
            {
                MessageBox.Show("Vui lòng chọn ít nhất một file PDF cần tách!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return;
            }

            if (string.IsNullOrEmpty(outputFolderPath))
            {
                MessageBox.Show("Vui lòng chọn thư mục lưu kết quả!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return;
            }

            if (string.IsNullOrEmpty(txtOutputPrefix.Text))
            {
                MessageBox.Show("Vui lòng nhập tên file xuất ra!", "Thông báo", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                return;
            }

            string mainOutputFolder;

            // Tạo thư mục chính cho kết quả
            if (rbSingleFolder.Checked)
            {
                mainOutputFolder = Path.Combine(outputFolderPath,
                    txtOutputPrefix.Text + "_" + DateTime.Now.ToString("yyyyMMdd_HHmmss"));
                Directory.CreateDirectory(mainOutputFolder);
            }
            else
            {
                mainOutputFolder = outputFolderPath;
            }

            // Disable controls during processing
            SetControlsEnabled(false);

            lvResults.Items.Clear();
            progressBar.Value = 0;

            try
            {
                statusLabel.Text = "Đang xử lý...";

                // Tạo biến tổng số file để xử lý progressBar
                int totalFiles = selectedPDFPaths.Count;
                int filesProcessed = 0;

                // Xử lý từng file PDF trong danh sách
                foreach (string pdfPath in selectedPDFPaths)
                {
                    string baseName = Path.GetFileNameWithoutExtension(pdfPath);
                    string fileOutputFolder;

                    // Xác định thư mục xuất cho file hiện tại
                    if (rbSeparateFolders.Checked)
                    {
                        fileOutputFolder = Path.Combine(mainOutputFolder, baseName + "_" + DateTime.Now.ToString("yyyyMMdd_HHmmss"));
                        Directory.CreateDirectory(fileOutputFolder);
                    }
                    else
                    {
                        fileOutputFolder = mainOutputFolder;
                    }

                    // Cập nhật status
                    this.Invoke((MethodInvoker)delegate {
                        statusLabel.Text = $"Đang xử lý file {baseName}... ({filesProcessed + 1}/{totalFiles})";
                    });

                    await Task.Run(() => {
                        // Tách file
                        SplitPDF(pdfPath, fileOutputFolder, baseName);
                    });

                    filesProcessed++;

                    // Cập nhật progressBar tổng thể
                    this.Invoke((MethodInvoker)delegate {
                        progressBar.Value = Math.Min((filesProcessed * 100) / totalFiles, 100);
                    });
                }

                statusLabel.Text = "Hoàn thành tách file PDF!";
                progressBar.Value = 100;

                string outputMessage = rbSingleFolder.Checked
                     ? $"Đã tách {totalFiles} file PDF thành công!
Các file đã được lưu vào thư mục:
{mainOutputFolder}"
                     : $"Đã tách {totalFiles} file PDF thành công!
Các file đã được lưu vào các thư mục con trong:
{mainOutputFolder}";

                MessageBox.Show(outputMessage, "Thành công", MessageBoxButtons.OK, MessageBoxIcon.Information);

                // Mở thư mục xuất
                System.Diagnostics.Process.Start("explorer.exe", mainOutputFolder);
            }
            catch (Exception ex)
            {
                MessageBox.Show($"Có lỗi xảy ra: {ex.Message}", "Lỗi", MessageBoxButtons.OK, MessageBoxIcon.Error);
                statusLabel.Text = "Tách file thất bại!";
            }
            finally
            {
                // Re-enable controls
                SetControlsEnabled(true);
            }
        }

        private void SetControlsEnabled(bool enabled)
        {
            btnSelectPDF.Enabled = enabled;
            btnSelectOutputFolder.Enabled = enabled;
            btnSplitPDF.Enabled = enabled;
            btnRemoveFiles.Enabled = enabled && selectedPDFPaths.Count > 0;
            btnOpenInputFolder.Enabled = enabled && !string.IsNullOrEmpty(inputFolderPath);
            txtOutputPrefix.Enabled = enabled;
            rbSplitEvenPages.Enabled = enabled;
            rbSplitOddPages.Enabled = enabled;
            rbSplitCustomPages.Enabled = enabled;
            txtCustomPages.Enabled = enabled && rbSplitCustomPages.Checked;
            lvInputFiles.Enabled = enabled;
            rbSingleFolder.Enabled = enabled;
            rbSeparateFolders.Enabled = enabled;
        }

        private void SplitPDF(string pdfPath, string outputFolder, string baseName)
        {
            // Mở file PDF nguồn
            PdfReader reader = new PdfReader(pdfPath);
            int totalPages = reader.NumberOfPages;

            List<int> pagesToExtract = new List<int>();

            // Xác định trang cần tách theo tùy chọn
            if (rbSplitEvenPages.Checked)
            {
                // Tách trang chẵn
                for (int i = 2; i <= totalPages; i += 2)
                {
                    pagesToExtract.Add(i);
                }
            }
            else if (rbSplitOddPages.Checked)
            {
                // Tách trang lẻ
                for (int i = 1; i <= totalPages; i += 2)
                {
                    pagesToExtract.Add(i);
                }
            }
            else if (rbSplitCustomPages.Checked)
            {
                // Tách theo số trang tự chọn
                int pagesPerFile = 1;

                // Invoke để lấy giá trị từ UI thread
                this.Invoke((MethodInvoker)delegate {
                    if (!int.TryParse(txtCustomPages.Text, out pagesPerFile) || pagesPerFile < 1)
                    {
                        pagesPerFile = 1;
                    }
                });

                // Tạo các file với số trang được chỉ định
                int currentPage = 1;
                int fileCount = 0;

                while (currentPage <= totalPages)
                {
                    fileCount++;
                    string outputFilePath = Path.Combine(outputFolder, $"{baseName}_{fileCount}.pdf");

                    Document document = new Document(reader.GetPageSizeWithRotation(1));
                    PdfCopy copy = new PdfCopy(document, new FileStream(outputFilePath, FileMode.Create));
                    document.Open();

                    int pageCount = 0;
                    while (currentPage <= totalPages && pageCount < pagesPerFile)
                    {
                        copy.AddPage(copy.GetImportedPage(reader, currentPage));
                        currentPage++;
                        pageCount++;
                    }

                    document.Close();
                    copy.Close();

                    // Update UI
                    int filePageCount = pageCount;
                    string fileName = Path.GetFileName(outputFilePath);

                    this.Invoke((MethodInvoker)delegate {
                        ListViewItem item = new ListViewItem(fileName);
                        item.SubItems.Add(outputFilePath);
                        item.SubItems.Add(filePageCount.ToString());
                        lvResults.Items.Add(item);
                    });
                }

                reader.Close();
                return;
            }

            // Xử lý tách theo trang chẵn hoặc lẻ
            if (pagesToExtract.Count > 0)
            {
                int fileCount = 0;
                foreach (int pageNum in pagesToExtract)
                {
                    fileCount++;
                    string outputFilePath = Path.Combine(outputFolder, $"{baseName}_{fileCount}.pdf");

                    Document document = new Document(reader.GetPageSizeWithRotation(pageNum));
                    PdfCopy copy = new PdfCopy(document, new FileStream(outputFilePath, FileMode.Create));
                    document.Open();

                    copy.AddPage(copy.GetImportedPage(reader, pageNum));

                    document.Close();
                    copy.Close();

                    // Update UI
                    string fileName = Path.GetFileName(outputFilePath);

                    this.Invoke((MethodInvoker)delegate {
                        ListViewItem item = new ListViewItem(fileName);
                        item.SubItems.Add(outputFilePath);
                        item.SubItems.Add("1");
                        lvResults.Items.Add(item);
                    });
                }
            }

            reader.Close();
        }
    }
}

Thanks for watching!

DOWNLOAD SOURCE