datagridview-image-button-column ソースコード全文

<Solution>
  <Project Path="DataGridView_ImageButtonColumn/DataGridView_ImageButtonColumn.csproj" />
</Solution>

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>WinExe</OutputType>
    <TargetFramework>net10.0-windows</TargetFramework>
    <Nullable>enable</Nullable>
    <UseWindowsForms>true</UseWindowsForms>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

  <ItemGroup>
    <None Update="Images\search.png">
      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
    </None>
  </ItemGroup>

</Project>

<?xml version="1.0" encoding="utf-8"?>
<Project ToolsVersion="Current" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
    <ItemGroup>
        <Compile Update="Form1.cs">
            <SubType>Form</SubType>
        </Compile>
    </ItemGroup>
</Project>

using System.Data;

namespace DataGridView_ImageButtonColumn
{
    public partial class Form1 : Form
    {
        private DataTable _dataTable = new DataTable();

        // 読み込んだ画像オブジェクトを使い回す（キャッシュする）ための変数
        private Bitmap? _searchIcon;

        public Form1()
        {
            InitializeComponent();
            LoadFileIcon(); // 起動時に一度だけ画像を読み込む
            InitializeDataGridView();
        }

        /// <summary>
        /// 出力ディレクトリにコピーされたファイルから画像を読み込む
        /// </summary>
        private void LoadFileIcon()
        {
            try
            {
                // 実行ファイルがあるフォルダ（StartupPath）内の「Images/search.png」の絶対パスを結合
                string imagePath = Path.Combine(Application.StartupPath, "Images", "search.png");

                if (File.Exists(imagePath))
                {
                    // ファイルから24x24のBitmapを生成してキャッシュ
                    _searchIcon = new Bitmap(imagePath);
                }
                else
                {
                    MessageBox.Show($"画像ファイルが見つかりません。想定パス: {imagePath}",
                                    "エラー", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show($"画像の読み込み中にエラーが発生しました:\n{ex.Message}",
                                "エラー", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }

        private void InitializeDataGridView()
        {
            // 1. テストデータの準備
            _dataTable.Columns.Add("Keywords", typeof(string));
            _dataTable.Columns.Add("Target", typeof(string));
            _dataTable.Rows.Add("C# 画面遷移", "Google");
            _dataTable.Rows.Add("DataGridView 描画", "Bing");

            dataGridView1.DataSource = _dataTable;

            // 2. 検索ボタン列を手動で追加
            var btnColumn = new DataGridViewButtonColumn();
            btnColumn.Name = "SearchBtn";
            btnColumn.HeaderText = "検索実行";
            btnColumn.Text = ""; // ボタン上のテキストは空にして画像だけにする
            btnColumn.UseColumnTextForButtonValue = true;
            btnColumn.Width = 100; // 24x24のアイコンが余裕を持って収まる列幅

            dataGridView1.Columns.Insert(0, btnColumn);

            dataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;

            // 24x24のアイコンが上下に見切れないよう、行高さを少し広めに設定（推奨: 32以上）
            dataGridView1.RowTemplate.Height = 38;

            // 3. セルの描画イベント（CellPainting）を購読
            dataGridView1.CellPainting += DataGridView1_CellPainting;

            // 4. ボタンのクリックイベント（CellContentClick）を購読
            dataGridView1.CellContentClick += DataGridView1_CellContentClick;
        }

        /// <summary>
        /// セルの描画が行われるときに呼び出されるイベント（画像の描画）
        /// </summary>
        private void DataGridView1_CellPainting(object? sender, DataGridViewCellPaintingEventArgs e)
        {
            // ヘッダー行や、目的のボタン列以外の列は処理対象外にする
            if (e.RowIndex < 0 || e.ColumnIndex < 0) return;

            if (dataGridView1.Columns[e.ColumnIndex].Name == "SearchBtn")
            {
                // A. ボタンの背景・枠線だけを通常通りシステムに描画させる（文字用のForegroundは除外）
                e.Paint(e.CellBounds, DataGridViewPaintParts.All & ~DataGridViewPaintParts.ContentForeground);

                // B. キャッシュしておいた 24x24 のアイコンを中央寄せで描画
                if (_searchIcon != null)
                {
                    // セルの幅・高さから、中央寄せになるX, Y座標を算出
                    int x = e.CellBounds.Left + (e.CellBounds.Width - _searchIcon.Width) / 2;
                    int y = e.CellBounds.Top + (e.CellBounds.Height - _searchIcon.Height) / 2;

                    e.Graphics.DrawImage(_searchIcon, x, y);
                }

                // C. システムによる標準のテキスト重ね描きなどをキャンセル
                e.Handled = true;
            }
        }

        /// <summary>
        /// セルの中身（今回の場合はボタン）がクリックされたときに呼び出されるイベント
        /// </summary>
        private void DataGridView1_CellContentClick(object? sender, DataGridViewCellEventArgs e)
        {
            // 列ヘッダーのクリックや、目的のボタン列以外のクリックは無視する
            if (e.RowIndex < 0 || e.ColumnIndex < 0) return;

            if (dataGridView1.Columns[e.ColumnIndex].Name == "SearchBtn")
            {
                // クリックされた行のデータを取得
                string keywords = dataGridView1.Rows[e.RowIndex].Cells["Keywords"].Value?.ToString() ?? "";
                string target = dataGridView1.Rows[e.RowIndex].Cells["Target"].Value?.ToString() ?? "";

                // イベントハンドリングの証明として、メッセージボックスを表示
                MessageBox.Show($"「{target}」でキーワード「{keywords}」の検索を実行します。",
                                "検索イベント感知", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
        }

        protected override void OnFormClosed(FormClosedEventArgs e)
        {
            base.OnFormClosed(e);

            // ファイルから生成した画像リソースを明示的に解放
            // これを怠るとWindowsによってファイルがロックされ続け、アプリ実行中に画像を上書き・削除できなくなります
            _searchIcon?.Dispose();
        }
    }
}

namespace DataGridView_ImageButtonColumn
{
    partial class Form1
    {
        /// <summary>
        ///  Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        ///  Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        ///  Required method for Designer support - do not modify
        ///  the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            dataGridView1 = new DataGridView();
            ((System.ComponentModel.ISupportInitialize)dataGridView1).BeginInit();
            SuspendLayout();
            //
            // dataGridView1
            //
            dataGridView1.ColumnHeadersHeightSizeMode = DataGridViewColumnHeadersHeightSizeMode.AutoSize;
            dataGridView1.Dock = DockStyle.Fill;
            dataGridView1.Location = new Point(0, 0);
            dataGridView1.Name = "dataGridView1";
            dataGridView1.RowHeadersWidth = 62;
            dataGridView1.Size = new Size(800, 450);
            dataGridView1.TabIndex = 0;
            //
            // Form1
            //
            AutoScaleDimensions = new SizeF(10F, 25F);
            AutoScaleMode = AutoScaleMode.Font;
            ClientSize = new Size(800, 450);
            Controls.Add(dataGridView1);
            Name = "Form1";
            Text = "Form1";
            ((System.ComponentModel.ISupportInitialize)dataGridView1).EndInit();
            ResumeLayout(false);
        }

        #endregion

        private DataGridView dataGridView1;
    }
}

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namespace DataGridView_ImageButtonColumn
{
    internal static class Program
    {
        /// <summary>
        ///  The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            // To customize application configuration such as set high DPI settings or default font,
            // see https://aka.ms/applicationconfiguration.
            ApplicationConfiguration.Initialize();
            Application.Run(new Form1());
        }
    }
}