C# - お手軽Windowsアイコン作成ツールをつくってみた

文字と図形（とりあえず４種類）からなるアイコンをサクッと作れるツールを作ってみた。

キャプチャ

アイコンの保存は「エクスポート」から。
設定項目は「テンプレート」から保存／読みだしできます。

注意

• フォントには著作権があるので、作成したアイコンファイルを公開したりすることは問題があるかもしれません。
• アイコンのキャッシュのリフレッシュ処理が環境依存な都合で、Windows10向けになっています。
  Windows7の場合は、ソースコード内のICON_CACHE_CLEAR_EXE_OPTIONの値を"-ClearIconCache"に変更すればOK。

コンパイル方法

csc /unsafe IconMaker.cs IconUtility.cs

ソースコード - IconMaker.cs

IconMaker.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Windows.Forms;
using IconUtility;


[Serializable]
public class SettingsClass
{
    public byte fg1Red;
    public byte fg1Green;
    public byte fg1Blue;
    public byte fg2Red;
    public byte fg2Green;
    public byte fg2Blue;
    public byte bg1Red;
    public byte bg1Green;
    public byte bg1Blue;
    public byte bg2Red;
    public byte bg2Green;
    public byte bg2Blue;
    public bool gradiation;
    public string fontName;
    public string textLine1;
    public string textLine2;
    public Decimal fontSizeLine1;
    public Decimal fontSizeLine2;
    public int yOffsetLine1;
    public int yOffsetLine2;
    public string bgFigureTypeName;
    public int iconSize;
}


class IconMaker:Form
{
    PictureBox pct;
    //int iconSize = 64;
    static readonly int DEFAULT_FONT_SIZE = 14;
    static readonly int CANVAS_SIZE = 256;
    static readonly string ICON_CACHE_CLEAR_EXE_NAME = "ie4uinit.exe";
    static readonly string ICON_CACHE_CLEAR_EXE_OPTION = "-show"; // windows10
    //Windows 10では「ie4uinit.exe -show」、
    //それ以外のバージョンでは「ie4uinit.exe -ClearIconCache」
//    const int ZOOM = 2;

    NumericUpDown nudSizeOfIcon;
    ComboBox cmbBgFigureType;

    TextBox txtLine1;
    TextBox txtLine2;
    NumericUpDown nudFontSizeOfLine1;
    NumericUpDown nudFontSizeOfLine2;
    NumericUpDown nudOffsetYLine1;
    NumericUpDown nudOffsetYLine2;

    TextBox txtFontName;

    Button btnColorForeground1;
    Button btnColorForeground2;
    Button btnColorBackground1;
    Button btnColorBackground2;
    CheckBox chkUseGradation;

    Bitmap bmpToBeSaved;
    Font curFontSizeIndependent;
    int curFontStyle;

    Color colorForeground1;
    Color colorForeground2;
    Color colorBackground1;
    Color colorBackground2;

    Pen curPen;
    Font curFont;
    Brush curBrush; // RedrawPreview呼びたびに更新
    PointF curPoint;
    GraphicsPath curPath;
    Graphics curG;

    bool resumeRedraw;


    IconMaker()
    {
        Text = "Icon Maker";
        resumeRedraw = false;

        colorForeground1 = Color.Blue;
        colorForeground2 = Color.Black;
        colorBackground1 = Color.Red;
        colorBackground2 = Color.Yellow;
        curFontSizeIndependent = new Font("メイリオ", (float)DEFAULT_FONT_SIZE);
        curFontStyle = (int)FontStyle.Regular; // Bold , Italic , Strikeout , Underline の bitOR を設定可能


        var menuStrip1 = new MenuStrip(); // https://dobon.net/vb/dotnet/control/menustrip.html

        SuspendLayout();
        menuStrip1.SuspendLayout();

        var templateMenuItem = new ToolStripMenuItem(){ Text = "テンプレート(&T)"};
        var iconMenuItem = new ToolStripMenuItem(){ Text = "エクスポート(&X)"};
        menuStrip1.Items.Add(templateMenuItem);
        menuStrip1.Items.Add(iconMenuItem);

        templateMenuItem.DropDownItems.Add( new ToolStripMenuItem("開く(&O)...", null, (s,e)=>{OpenTemplateWithDialog();}, Keys.Control | Keys.O) );
        templateMenuItem.DropDownItems.Add( new ToolStripMenuItem("保存(&S)...", null, (s,e)=>{SaveTemplateWithDialog();}, Keys.Control | Keys.S) );

        iconMenuItem.DropDownItems.Add( new ToolStripMenuItem("アイコン(.ico)として保存(&I)...", null, (s,e)=>{SaveImageWithDialog("ico");}, Keys.Control | Keys.I) );
        iconMenuItem.DropDownItems.Add( new ToolStripMenuItem("画像(.png)として保存(&P)...",     null, (s,e)=>{SaveImageWithDialog("png");}, Keys.Control | Keys.P) );

        Controls.AddRange(new Control[]{
            new Label(){                         Location = new Point( 10, 35),  Size = new Size( 80, 20), Text="アイコンサイズ"},
            nudSizeOfIcon = new NumericUpDown(){ Location = new Point(100, 35),  Size = new Size( 60, 20), Maximum = 256, Value = 64, Minimum = 16, Increment = 4}
        });
        nudSizeOfIcon.ValueChanged += (s,e)=>{
            int iconSize = (int)nudSizeOfIcon.Value;
            pct.Size = new Size(iconSize,iconSize);
            RedrawPreview();
        };
        

        GroupBox grpText = new GroupBox(){
            Location = new Point( 10, 60), Size = new Size(280,95), Text = "テキスト" 
        };
        Controls.Add(grpText);

        grpText.Controls.AddRange(new Control[]{
            new Label(){                              Location = new Point(140, 20), Size = new Size(60, 20), Text = "サイズ"},
            new Label(){                              Location = new Point(210, 20), Size = new Size(65, 20), Text = "位置調整"},
            new Label(){                              Location = new Point( 10, 40), Size = new Size(50, 20), Text = "１行目"},
            txtLine1           = new TextBox(){       Location = new Point( 60, 40), Size = new Size(70, 20), Text = "icon"  },
            nudFontSizeOfLine1 = new NumericUpDown(){ Location = new Point(140, 40), Size = new Size(60, 20), Maximum = 100, Value = 30, Minimum = 1, DecimalPlaces=1 },
            nudOffsetYLine1    = new NumericUpDown(){ Location = new Point(210, 40), Size = new Size(60, 20), Maximum = 256, Value = 0,  Minimum = -256 },
            new Label(){                              Location = new Point( 10, 65), Size = new Size(50, 20), Text = "２行目"},
            txtLine2           = new TextBox(){       Location = new Point( 60, 65), Size = new Size(70, 20), Text = "maker" },
            nudFontSizeOfLine2 = new NumericUpDown(){ Location = new Point(140, 65), Size = new Size(60, 20), Maximum = 100, Value = 15, Minimum = 1, DecimalPlaces=1 },
            nudOffsetYLine2    = new NumericUpDown(){ Location = new Point(210, 65), Size = new Size(60, 20), Maximum = 256, Value = 18, Minimum = -256 }
        });
        txtLine1.TextChanged += (s,e)=>{RedrawPreview();};
        txtLine2.TextChanged += (s,e)=>{RedrawPreview();};
        nudFontSizeOfLine1.ValueChanged += (s,e)=>{RedrawPreview();};
        nudFontSizeOfLine2.ValueChanged += (s,e)=>{RedrawPreview();};
        nudOffsetYLine1.ValueChanged += (s,e)=>{RedrawPreview();};
        nudOffsetYLine2.ValueChanged += (s,e)=>{RedrawPreview();};
        


        GroupBox grpFont = new GroupBox(){
            Location = new Point( 10,165), Size = new Size(280,50), Text = "フォント" 
        };
        Controls.Add(grpFont);

        Button btnSelectFont;
        grpFont.Controls.AddRange(new Control[]{
            txtFontName   = new TextBox(){ Location = new Point( 10, 20), Size = new Size(170,25), Text = curFontSizeIndependent.Name, ReadOnly = true },
            btnSelectFont = new Button(){  Location = new Point(185, 15), Size = new Size( 70,25),  Text = "変更..." }
        });
        btnSelectFont.Click += (s,e)=>{SelectAndUpdateFontWithDialog();};
        

        GroupBox grpColor = new GroupBox(){
            Location = new Point( 10,225), Size = new Size(280,100), Text = "色" 
        };
        Controls.Add(grpColor);

        grpColor.Controls.AddRange(new Control[]{
            new Label(){                         Location = new Point( 10, 30), Size = new Size(40,20), Text = "文字"},
            btnColorForeground1 = new Button(){  Location = new Point( 50, 20), Size = new Size(30,20), FlatStyle = FlatStyle.Flat},
            btnColorForeground2 = new Button(){  Location = new Point( 70, 30), Size = new Size(30,20), FlatStyle = FlatStyle.Flat},
            new Label(){                         Location = new Point( 10, 70), Size = new Size(40,20), Text = "背景"},
            btnColorBackground1 = new Button(){  Location = new Point( 50, 60), Size = new Size(30,20), FlatStyle = FlatStyle.Flat},
            btnColorBackground2 = new Button(){  Location = new Point( 70, 70), Size = new Size(30,20), FlatStyle = FlatStyle.Flat},
            chkUseGradation     = new CheckBox(){Location = new Point(140, 40), Size = new Size(100,25), Text = "グラデーション", Checked = true}
        });

        SetFlatButtonColor(btnColorForeground1, colorForeground1);
        SetFlatButtonColor(btnColorForeground2, colorForeground2);
        SetFlatButtonColor(btnColorBackground1, colorBackground1);
        SetFlatButtonColor(btnColorBackground2, colorBackground2);
        btnColorForeground1.Click += (s,e)=>{SelectAndUpdateColorWithDialog((Button)s, ref colorForeground1);};
        btnColorForeground2.Click += (s,e)=>{SelectAndUpdateColorWithDialog((Button)s, ref colorForeground2);};
        btnColorBackground1.Click += (s,e)=>{SelectAndUpdateColorWithDialog((Button)s, ref colorBackground1);};
        btnColorBackground2.Click += (s,e)=>{SelectAndUpdateColorWithDialog((Button)s, ref colorBackground2);};
        chkUseGradation.Click += (s,e)=>{
            ReflectGradationCheckToControls();
            RedrawPreview();
        };
        ReflectGradationCheckToControls();

        Controls.Add(
            pct = new PictureBox(){
                Location = new Point(350, 20),
                Size = new Size(CANVAS_SIZE, CANVAS_SIZE),
                Image = new Bitmap(CANVAS_SIZE, CANVAS_SIZE),
            }
        );


        Controls.Add(
            cmbBgFigureType = new ComboBox(){ Location = new Point( 20, 350),  Size = new Size( 80, 20),   DropDownStyle = ComboBoxStyle.DropDownList }
        );
        cmbBgFigureType.Items.AddRange(new string[]{"なし", "六角形", "角丸", "丸", "四角"});
        cmbBgFigureType.SelectedIndex = 1;
        cmbBgFigureType.SelectedIndexChanged += (s,e)=>{RedrawPreview();};


        ClientSize = new Size(350+CANVAS_SIZE, 400);

        Load+=(sender,e)=>{RedrawPreview();};

        curPen = Pens.Black;
        curBrush = Brushes.White; // とりあえず初期化しておく

        Controls.Add(menuStrip1);
        MainMenuStrip = menuStrip1;
        menuStrip1.ResumeLayout(false);
        menuStrip1.PerformLayout();
        ResumeLayout(false);
        PerformLayout();
    }

    void SetFlatButtonColor(Button btn, Color c)
    {
        btn.BackColor = c;
        btn.FlatAppearance.MouseOverBackColor = c;
        btn.FlatAppearance.MouseDownBackColor = c;
    }

    void SelectAndUpdateFontWithDialog()
    {
        FontDialog fd = new FontDialog();

        fd.Font = curFontSizeIndependent;
        fd.MaxSize = DEFAULT_FONT_SIZE;
        fd.MinSize = DEFAULT_FONT_SIZE;
        fd.FontMustExist = true;
        fd.AllowVerticalFonts = true;
        //fd.ShowColor = true;
        fd.ShowEffects = true;
        fd.FixedPitchOnly = false;
        fd.AllowVectorFonts = true;

        //ダイアログを表示する
        if (fd.ShowDialog() != DialogResult.Cancel) {
            curFontSizeIndependent = fd.Font;
            txtFontName.Text = curFontSizeIndependent.Name;
            RedrawPreview();
        }
    }


    void SelectAndUpdateColorWithDialog(Button sender, ref Color c)
    {
        ColorDialog cd = new ColorDialog();

        cd.Color = c;
        cd.FullOpen = true;
        if (cd.ShowDialog() == DialogResult.OK) {
            c = cd.Color;
            SetFlatButtonColor(sender, c);
            RedrawPreview();
        }
    }

    void ReflectGradationCheckToControls()
    {
        bool tmp = chkUseGradation.Checked;
        btnColorForeground2.Visible = tmp;
        btnColorBackground2.Visible = tmp;
    }

    void moveto(float x, float y)
    {
        curPoint.X = x;
        curPoint.Y = y;
    }

    void rmoveto(float rx, float ry)
    {
        curPoint.X += rx;
        curPoint.Y += ry;
    }

    void lineto(float x, float y)
    {
        curPath.AddLine(curPoint.X, curPoint.Y, x, y);
        curPoint.X = x;
        curPoint.Y = y;
    }

    void rlineto(float rx, float ry)
    {
        curPath.AddLine(curPoint.X, curPoint.Y, curPoint.X+rx, curPoint.Y+ry);
        curPoint.X += rx;
        curPoint.Y += ry;
    }

    void charpath(string s)
    {
        var sf = new StringFormat();
        sf.Alignment     = StringAlignment.Center;    // 横方向の中央
        sf.LineAlignment = StringAlignment.Center;    // 縦方向の中央
        FontFamily ff = curFont.FontFamily;
        curPath.AddString(s, ff, curFontStyle, curFont.Size, curPoint, sf);
    }

    void newpath()
    {
        curPath.Reset();
        curPath.StartFigure();
    }

    void closepath()
    {
        curPath.CloseFigure();
    }

    void stroke()
    {
        if ( curG != null ) {
            curG.DrawPath(curPen, curPath);
        }
    }
    void fill()
    {
        if ( curG != null ) {
            curPath.FillMode = FillMode.Winding;
            curG.FillPath(curBrush, curPath);
        }
    }
    /*
    void eofill()
    {
        if ( curG != null ) {
            curPath.FillMode = FillMode.Alternate;
            curG.FillPath(curBrush, curPath);
        }
    }
    */

    float cos(float degree)
    {
        return (float)Math.Cos((degree/180.0)*Math.PI);
    }
    float sin(float degree)
    {
        return (float)Math.Sin((degree/180.0)*Math.PI);
    }


    void RedrawPreview()
    {
        if(resumeRedraw){return;}

        int iconSize = (int)nudSizeOfIcon.Value;
        bmpToBeSaved = CreateTransparentBitmap(iconSize, iconSize);
        curPath = new GraphicsPath();
        curG = Graphics.FromImage(bmpToBeSaved);
        curG.SmoothingMode = SmoothingMode.AntiAlias;

        try {
            if (chkUseGradation.Checked) {
                curBrush = new LinearGradientBrush(new Point(0, 0), new Point(iconSize, iconSize), colorBackground1, colorBackground2);
            }
            else {
                curBrush = new SolidBrush(colorBackground1);
            }

            DrawFigure();

            if (chkUseGradation.Checked) {
                curBrush = new LinearGradientBrush(new Point(0, 0), new Point(iconSize, iconSize), colorForeground1, colorForeground2);
            }
            else {
                curBrush = new SolidBrush(colorForeground1);
            }

            curFont = new Font(curFontSizeIndependent.Name, (float)nudFontSizeOfLine1.Value);
            newpath();
            moveto(iconSize/2, iconSize/2 + (int)nudOffsetYLine1.Value);
            charpath(txtLine1.Text);
            closepath();
            fill();

            if ( txtLine2.Text != "" ) {
                curFont = new Font(curFontSizeIndependent.Name, (float)nudFontSizeOfLine2.Value);
                newpath();
                moveto(iconSize/2, iconSize/2 + (int)nudOffsetYLine2.Value);
                charpath(txtLine2.Text);
                closepath();
                fill();
            }
        }
        finally {
            curG.Dispose();
            curG = null;
        }

        int zoom = 1;// 2;
        Graphics g = Graphics.FromImage(pct.Image);
        g.FillRectangle(Brushes.White, 0, 0, bmpToBeSaved.Width*zoom, bmpToBeSaved.Height*zoom); // pct.Image.Width, pct.Image.Height);
        g.DrawImage(bmpToBeSaved, 0, 0, bmpToBeSaved.Width*zoom, bmpToBeSaved.Height*zoom);
        g.Dispose();

        pct.Refresh();
    }


    void DrawFigure()
    {
        int iconSize = (int)nudSizeOfIcon.Value;
        
        string figureType = cmbBgFigureType.Text;
        
        if ( figureType == "六角形" ) {
            newpath();
            for ( int deg=0 ; deg<360 ; deg+=60 ) {
                float x = iconSize/2 + (iconSize/2 - 1)*cos(deg);
                float y = iconSize/2 + (iconSize/2 - 1)*sin(deg);
                if ( deg == 0 ) { moveto(x,y); } else { lineto(x,y); }
            }
            closepath();
            fill();
        }
        else if ( figureType == "丸" ) {
            newpath();
            curPath.AddArc(0, 0, iconSize, iconSize, 0, 360);
            closepath();
            fill();
        }
        else if ( figureType == "四角" ) {
            newpath();
            curPath.AddRectangle(new Rectangle(0, 0, iconSize, iconSize));
            closepath();
            fill();
        }
        else if ( figureType == "角丸" ) {
            int cornerSize = iconSize/2;
            newpath();
            curPath.AddArc(0,                   0,                   cornerSize, cornerSize, 180, 90);
            curPath.AddArc(iconSize-cornerSize, 0,                   cornerSize, cornerSize, 270, 90);
            curPath.AddArc(iconSize-cornerSize, iconSize-cornerSize, cornerSize, cornerSize,   0, 90);
            curPath.AddArc(0,                   iconSize-cornerSize, cornerSize, cornerSize,  90, 90);
            closepath();
            fill();
        }
    }


    bool OpenTemplateWithDialog()
    {
        OpenFileDialog ofd = new OpenFileDialog();
        ofd.FileName = "テンプレート.xml";
        ofd.Filter = "XMLファイル(*.xml)|*.xml";
        // ofd.Filter = "XMLファイル(*.xml)|*.xml|すべてのファイル(*.*)|*.*";
        // ofd.FilterIndex = 1;
        // ofd.Title = "開くファイルを選択してください";
        ofd.RestoreDirectory = true;
        // ofd.CheckFileExists = true;
        // ofd.CheckPathExists = true;

        if (ofd.ShowDialog() == DialogResult.OK) {
            return LoadSettingsFromXml(ofd.FileName);
        }
        else {
            return false;
        }
    }

    bool SaveTemplateWithDialog()
    {
        SaveFileDialog sfd = new SaveFileDialog();
        sfd.FileName = "新しいIconMakerテンプレート.xml";
        // sfd.InitialDirectory = @"C:\";
        sfd.Filter = "XMLファイル(*.xml)|*.xml";
        sfd.Title = "保存先のファイルを選択してください";
        sfd.RestoreDirectory = true;
        // sfd.OverwritePrompt = true;
        // sfd.CheckPathExists = true;

        //ダイアログを表示する
        if (sfd.ShowDialog() == DialogResult.OK) {
            return SaveSettingsToXml(sfd.FileName);
        }
        else {
            return false;
        }
    }
    
    bool SaveImageWithDialog(string fmt)
    {
        SaveFileDialog sfd = new SaveFileDialog();
        // sfd.InitialDirectory = @"C:\";
        if ( fmt == "ico" ) {
            sfd.FileName = "新しいアイコン.ico";
            sfd.Filter = "アイコンファイル(*.ico)|*.ico";
        }
        else if ( fmt == "png" ) {
            sfd.FileName = "新しい画像.png";
            sfd.Filter = "画像ファイル(*.png)|*.png";
        }
        else {
            return false;
        }
        sfd.Title = "保存先のファイルを選択してください";
        sfd.RestoreDirectory = true;
        // sfd.OverwritePrompt = true;
        // sfd.CheckPathExists = true;

        //ダイアログを表示する
        if (sfd.ShowDialog() == DialogResult.OK) {
            bool saveResult = false;
            if ( fmt == "ico" ) {
                saveResult = SaveAsIcon(sfd.FileName);
                if ( saveResult ) {
                    RunClearCache();
                }
            }
            else if ( fmt == "png" ) {
                saveResult = SaveAsPng(sfd.FileName);
            }
            return saveResult;
        }
        else {
            return false;
        }
    }

    bool SaveAsIcon(string destPath)
    {
        Icons icons;
        icons = new Icons();
        icons.AddIcon(bmpToBeSaved);
        try {
            icons.SaveToFile(destPath);
            return true;
        }
        catch (IOException e) {
            MessageBox.Show(e.ToString());
        }
        return false;
    }

    bool SaveAsPng(string destPath)
    {
        try {
            bmpToBeSaved.Save(destPath, System.Drawing.Imaging.ImageFormat.Png);
            return true;
        }
        catch (IOException e) {
            MessageBox.Show(e.ToString());
        }
        return false;
    }

    void RunClearCache()
    {
        try {
            System.Diagnostics.Process.Start(ICON_CACHE_CLEAR_EXE_NAME, ICON_CACHE_CLEAR_EXE_OPTION);
        }
        catch (System.ComponentModel.Win32Exception e) {
            Console.WriteLine(e);
        }
    }

    bool SaveSettingsToXml(string destPath)
    {
        var t = new SettingsClass()
        {
            fg1Red   = colorForeground1.R,
            fg1Green = colorForeground1.G,
            fg1Blue  = colorForeground1.B,
            fg2Red   = colorForeground2.R,
            fg2Green = colorForeground2.G,
            fg2Blue  = colorForeground2.B,
            bg1Red   = colorBackground1.R,
            bg1Green = colorBackground1.G,
            bg1Blue  = colorBackground1.B,
            bg2Red   = colorBackground2.R,
            bg2Green = colorBackground2.G,
            bg2Blue  = colorBackground2.B,
            gradiation = chkUseGradation.Checked,
            fontName   = curFontSizeIndependent.Name,
            fontSizeLine1 = nudFontSizeOfLine1.Value,
            fontSizeLine2 = nudFontSizeOfLine2.Value,
            yOffsetLine1 = (int)nudOffsetYLine1.Value,
            yOffsetLine2 = (int)nudOffsetYLine2.Value,
            textLine1  = txtLine1.Text,
            textLine2  = txtLine2.Text,
            iconSize =  (int)nudSizeOfIcon.Value,
            bgFigureTypeName = cmbBgFigureType.Text,
        };

        var serializer = new System.Xml.Serialization.XmlSerializer(typeof(SettingsClass));
        try {
            var sw = new System.IO.StreamWriter(destPath, false, new System.Text.UTF8Encoding(false));
            try {
                serializer.Serialize(sw, t);
            }
            finally {
                sw.Close();
            }
            return true;
        }
        catch( IOException e ) {
            MessageBox.Show(e.ToString());
            return false;
        }
    }


    bool LoadSettingsFromXml(string srcPath)
    {
        // https://www.atmarkit.co.jp/ait/articles/1704/19/news021.html

        var xmlSerializer = new System.Xml.Serialization.XmlSerializer(typeof(SettingsClass));
        SettingsClass t;
        //var xmlSettings = new System.Xml.XmlReaderSettings();

        try {
            using (var streamReader = new StreamReader(srcPath, System.Text.Encoding.UTF8))
            using (var xmlReader = System.Xml.XmlReader.Create(streamReader)) //, xmlSettings))
            {
                t = (SettingsClass)xmlSerializer.Deserialize(xmlReader);
            }
        }
        catch (IOException e) {
            MessageBox.Show(e.ToString());
            return false;
        }
        catch (InvalidOperationException e) {
            MessageBox.Show(e.ToString());
            return false;
        }

        resumeRedraw = true;
        try {
            colorForeground1 = Color.FromArgb(t.fg1Red, t.fg1Green, t.fg1Blue);
            colorForeground2 = Color.FromArgb(t.fg2Red, t.fg2Green, t.fg2Blue);
            colorBackground1 = Color.FromArgb(t.bg1Red, t.bg1Green, t.bg1Blue);
            colorBackground2 = Color.FromArgb(t.bg2Red, t.bg2Green, t.bg2Blue);
            SetFlatButtonColor(btnColorForeground1, colorForeground1);
            SetFlatButtonColor(btnColorForeground2, colorForeground2);
            SetFlatButtonColor(btnColorBackground1, colorBackground1);
            SetFlatButtonColor(btnColorBackground2, colorBackground2);

            chkUseGradation.Checked = t.gradiation;
            ReflectGradationCheckToControls();

            txtLine1.Text = t.textLine1;
            txtLine2.Text = t.textLine2;
            nudFontSizeOfLine1.Value = t.fontSizeLine1;
            nudFontSizeOfLine2.Value = t.fontSizeLine2;
            nudOffsetYLine1.Value = t.yOffsetLine1;
            nudOffsetYLine2.Value = t.yOffsetLine2;
            cmbBgFigureType.Text = t.bgFigureTypeName;
            nudSizeOfIcon.Value = t.iconSize;

            curFontSizeIndependent = new Font(t.fontName, (float)DEFAULT_FONT_SIZE);
            txtFontName.Text = curFontSizeIndependent.Name;
        }
        finally {
            resumeRedraw = false;
        }
        RedrawPreview();
        return true;
    }


    // 透過色で初期化
    Bitmap CreateTransparentBitmap(int width, int height)
    {
        Bitmap bmp = new Bitmap(width, height, PixelFormat.Format32bppArgb);
        BitmapData bd = bmp.LockBits(new Rectangle(0,0,width,height), ImageLockMode.WriteOnly, PixelFormat.Format32bppArgb);

        try {
            unsafe {
                // 書き込み
                byte* ptr = (byte*)bd.Scan0;
                for ( int y=0 ; y<height ; y++ ) {
                    for ( int x=0 ; x<width ; x++ ) {
                        ptr[y*bd.Stride + 4*x    ] = 0;// B
                        ptr[y*bd.Stride + 4*x + 1] = 0;// G
                        ptr[y*bd.Stride + 4*x + 2] = 0;// R
                        ptr[y*bd.Stride + 4*x + 3] = 0;// alpha = 0 (透過)
                    }
                }
            }
        }
        finally {
            bmp.UnlockBits(bd);
        }

        return bmp;
    }


    [STAThread]
    static void Main()
    {
        Application.Run(new IconMaker());
    }
}

ソースコード - IconUtility.cs

IconUtility.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Reflection;
using System.Runtime.InteropServices;


namespace IconUtility
{
    public class Icons
    {
        class IconEntry
        {
            [StructLayout(LayoutKind.Sequential)]
            public struct IconDir
            {
                public short  icoReserved; // must be 0
                public short  icoResourceType; //must be 1 for icon
                public short  icoResourceCount;

                public IconDir(int n)
                {
                    icoReserved = 0;
                    icoResourceType = 1;
                    icoResourceCount = (short)n;
                }
            }

            [StructLayout(LayoutKind.Sequential)]
            public struct IconDirEntry
            {
                byte   _Width;
                byte   _Height;
                public byte   ColorCount;
                public byte   reserved1;
                public short  reserved2;
                public short  reserved3;
                public int    icoDIBSize;
                public int    icoDIBOffset;

                public int Width{get{return (_Width>0)?_Width:256;}}
                public int Height{get{return (_Height>0)?_Height:256;}}

                public IconDirEntry(int w, int h)
                {
                    if ( w<0 || w>256 || h<0 || h>256 ) {
                        throw new Exception("Size parameter error");
                    }
                    _Width  = (byte)w;
                    _Height = (byte)h;
                    ColorCount=0;
                    reserved1=0;
                    reserved2=0;
                    reserved3=0;
                    icoDIBSize=0;
                    icoDIBOffset=0;
                }
            }

            [StructLayout(LayoutKind.Sequential)]
            struct BitmapInfoHeader
            {
                public int    biSize; // must be 40
                public int    biWidth;
                public int    biHeight;
                public short  biPlanes; // must be 1
                public short  biBitCount; // color
                public int    biCompression; // 0:not compress
                public int    biSizeImage;
                public int    biXPixPerMeter;
                public int    biYPixPerMeter;
                public int    biClrUsed;
                public int    biClrImportant;

                public BitmapInfoHeader(int w, int h)
                {
                    biSize = 40;
                    biWidth = w;
                    biHeight = h*2; // 本体とmaskを含むため2倍とする決まりらしい
                    biPlanes = 1;
                    biBitCount = 32;
                    biCompression=0;
                    biSizeImage=0;
                    biXPixPerMeter=0;
                    biYPixPerMeter=0;
                    biClrUsed=0;
                    biClrImportant=0;
                }
            }

            IconDirEntry     iconDirEntry;
            BitmapInfoHeader bitmapInfoHeader;
            byte[] bitmapBody;
            byte[] bitmapMask;

            public System.Drawing.Size Size{get{return new System.Drawing.Size(iconDirEntry.Width, iconDirEntry.Height);}}
            public int Width{get{return iconDirEntry.Width;}}
            public int Height{get{return iconDirEntry.Height;}}
            int BitPerPixel{get{return bitmapInfoHeader.biBitCount;}}

            int CalcDIBSize()
            {
                return Marshal.SizeOf(typeof(BitmapInfoHeader)) + bitmapBody.Length + bitmapMask.Length;
            }

            public int UpdateIconDirEntry(int icoDIBOffset)
            {
                iconDirEntry.icoDIBOffset = icoDIBOffset;
                iconDirEntry.icoDIBSize   = CalcDIBSize();
                return iconDirEntry.icoDIBSize;
            }

            public void WriteIconDirEntryTo(BinaryWriter writer)
            {
                Icons.CopyDataToByteArray<IconDirEntry>(writer, iconDirEntry);
            }

            public void WriteDataTo(BinaryWriter writer)
            {
                Icons.CopyDataToByteArray<BitmapInfoHeader>(writer, bitmapInfoHeader);
                writer.Write(bitmapBody);
                writer.Write(bitmapMask);
            }

            IconEntry(IconDirEntry _iconDirEntry, BitmapInfoHeader _bitmapInfoHeader, byte[] _bitmapBody, byte[] _bitmapMask)
            {
                iconDirEntry = _iconDirEntry;
                bitmapInfoHeader = _bitmapInfoHeader;
                bitmapBody = _bitmapBody;
                bitmapMask = _bitmapMask;
            }

            // 本体
            public IconEntry(Bitmap bmp, Color? alphaColor)
            {
                int w = bmp.Width;
                int h = bmp.Height;

                if ( w>256 || h>256 ) {
                    throw new Exception("size parameter error");
                }

                iconDirEntry = new IconDirEntry(w, h);
                bitmapInfoHeader = new BitmapInfoHeader(w, h);
                bitmapBody = new byte[Icons.GetBitmapBodySize(w, h, bitmapInfoHeader.biBitCount)];
                bitmapMask = new byte[Icons.GetBitmapMaskSize(w, h)];

                Draw32bppBitmapToData(bmp, alphaColor);
            }

            void Draw32bppBitmapToData(Bitmap bmp, Color? alphaColor)
            {
                Array.Clear(bitmapMask, 0, bitmapMask.Length);
                Array.Clear(bitmapBody, 0, bitmapBody.Length);

                BitmapData bd = bmp.LockBits(new Rectangle(0,0,bmp.Width,bmp.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);

                try {
                    IntPtr ptr = bd.Scan0;
                    byte[] pixels = new byte[bd.Stride * bmp.Height];
                    Marshal.Copy(ptr, pixels, 0, pixels.Length);

                    int maskStride = (((Width+7)/8+3)/4)*4;
                    int icoStride = Width*4;

                    for (int y = 0; y < bd.Height; y++) {
                        for (int x = 0; x < bd.Width; x++) {
                            int posIco = y * icoStride + 4*x;

                            int bytePosMask = y * maskStride + x/8;
                            int bitPosMask = 7-(x%8);

                            int pos = (bd.Height-1-y) * bd.Stride + x * 4;
                            bitmapBody[posIco  ] = pixels[pos];   //blue;
                            bitmapBody[posIco+1] = pixels[pos+1]; //green;
                            bitmapBody[posIco+2] = pixels[pos+2]; //red;
                            bitmapBody[posIco+3] = pixels[pos+3]; //alpha

                            if ( pixels[pos+3] == 0 ||
                            (alphaColor != null &&
                                pixels[pos]  ==alphaColor.Value.B &&
                                pixels[pos+1]==alphaColor.Value.G &&
                                pixels[pos+2]==alphaColor.Value.R  )) {
                                //bitmapMask[bytePosMask] |= (byte)(1<<bitPosMask);
                                // 32bit色のiconだとmaskではなくalpha channelが使用されるっぽい
                                bitmapBody[posIco+3] = 0x00;
                            }
                        }
                    }
                }
                finally {
                    bmp.UnlockBits(bd);
                }
            }
        }

        int UpdateIconDirEntries()
        {
            iconDir.icoResourceCount = (short)iconEntries.Count;

            int offset  =  Marshal.SizeOf(typeof(IconEntry.IconDir))  +  iconEntries.Count * Marshal.SizeOf(typeof(IconEntry.IconDirEntry));

            for (int i=0;i<iconEntries.Count;i++) {
                offset += iconEntries[i].UpdateIconDirEntry(offset);
            }
            return offset;
        }

        static int GetBitmapBodySize(int w, int h, int bitCount)
        {
            return ((((w*bitCount + 7)/8)+3)/4)*4 * h;
        }

        static int GetBitmapMaskSize(int w, int h)
        {
            return ((((w+7)/8)+3)/4)*4 * h;
        }

        static TStruct CopyDataToStruct<TStruct> (BinaryReader reader) where TStruct : struct
        {
            var size = Marshal.SizeOf(typeof(TStruct));
            var ptr = IntPtr.Zero;

            try {
                ptr = Marshal.AllocHGlobal(size);
                Marshal.Copy(reader.ReadBytes(size), 0, ptr, size);
                return (TStruct)Marshal.PtrToStructure(ptr, typeof(TStruct));
            }
            finally {
                if (ptr != IntPtr.Zero) {
                    Marshal.FreeHGlobal(ptr);
                }
            }
        }

        static void CopyDataToByteArray<TStruct>(BinaryWriter writer, TStruct s) where TStruct : struct
        {
            var size = Marshal.SizeOf(typeof(TStruct));
            var buffer = new byte[size];
            var ptr = IntPtr.Zero;

            try {
                ptr = Marshal.AllocHGlobal(size);
                Marshal.StructureToPtr(s, ptr, false);
                Marshal.Copy(ptr, buffer, 0, size);
            }
            finally {
                if (ptr != IntPtr.Zero) {
                    Marshal.FreeHGlobal(ptr);
                }
            }
            writer.Write(buffer);
        }



        IconEntry.IconDir iconDir;
        List<IconEntry> iconEntries;

        // ------------------------------------------------------------------------------
        // public members

        public int Count {get{return iconEntries.Count;}}

        public Icons()
        {
            iconDir      = new IconEntry.IconDir(0);
            iconEntries  = new List<IconEntry>();
        }

        public void AddIcon(Bitmap bmp, Color alphaColor)
        {
            iconEntries.Add(new IconEntry(bmp, alphaColor));
            UpdateIconDirEntries();
        }

        public void AddIcon(Bitmap bmp)
        {
            iconEntries.Add(new IconEntry(bmp, null));
            UpdateIconDirEntries();
        }

        public bool SaveToFile(string path)
        {
            //int size = 
            UpdateIconDirEntries();

            using ( var fs = new FileStream(path, FileMode.Create) ) {
                using ( var writer = new BinaryWriter(fs) ) {
                    CopyDataToByteArray<IconEntry.IconDir>(writer, iconDir);

                    foreach(var t in iconEntries) {
                        t.WriteIconDirEntryTo(writer);
                    }

                    foreach(var t in iconEntries) {
                        t.WriteDataTo(writer);
                    }
                }
            }

            return true;
        }
    }
}