c# – 无法计算所有者绘制文本中的位置

I’ve done this successfully before in C++.我在C#中尝试了很多方法,但还没有准确定位插入符号.最初,我尝试使用.NET类来确定正确的位置,但后来我尝试直接访问Windows API.在某些情况下,我走近了,但过了一段时间后,我仍然无法准确地放置插入符号.

我创建了一个小测试程序,并在下面发布了关键部分.我还发布了整个项目here.

使用的确切字体对我来说并不重要;但是,我的应用程序采用单倍间距字体.任何帮助表示赞赏.

Form1.cs的
这是我的主要形式.

public partial class Form1 : Form
{
    private string TestString;
    private int AveCharWidth;
    private int Position;

    public Form1()
    {
        InitializeComponent();
        TestString = "123456789012345678901234567890123456789012345678901234567890";
        AveCharWidth = GetFontWidth();
        Position = 0;
    }

    private void Form1_Load(object sender,EventArgs e)
    {
        Font = new Font(FontFamily.GenericMonospace,12,FontStyle.Regular,GraphicsUnit.Pixel);
    }

    protected override void OnGotFocus(EventArgs e)
    {
        Windows.CreateCaret(Handle,(IntPtr)0,2,(int)Font.Height);
        Windows.ShowCaret(Handle);
        UpdateCaretPosition();
        base.OnGotFocus(e);
    }

    protected void UpdateCaretPosition()
    {
        Windows.SetCaretPos(Padding.Left + (Position * AveCharWidth),Padding.Top);
    }

    protected override void OnLostFocus(EventArgs e)
    {
        Windows.HideCaret(Handle);
        Windows.DestroyCaret();
        base.OnLostFocus(e);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        e.Graphics.DrawString(TestString,Font,SystemBrushes.WindowText,new PointF(Padding.Left,Padding.Top));
    }

    protected override bool IsInputKey(Keys keyData)
    {
        switch (keyData)
        {
            case Keys.Right:
            case Keys.Left:
                return true;
        }
        return base.IsInputKey(keyData);
    }

    protected override void OnKeyDown(KeyEventArgs e)
    {
        switch (e.KeyCode)
        {
            case Keys.Left:
                Position = Math.Max(Position - 1,0);
                UpdateCaretPosition();
                break;
            case Keys.Right:
                Position = Math.Min(Position + 1,TestString.Length);
                UpdateCaretPosition();
                break;
        }
        base.OnKeyDown(e);
    }

    protected int GetFontWidth()
    {
        int AverageCharWidth = 0;

        using (var graphics = this.CreateGraphics())
        {
            try
            {
                Windows.TEXTMETRIC tm;
                var hdc = graphics.GetHdc();
                IntPtr hFont = this.Font.ToHfont();
                IntPtr hOldFont = Windows.SelectObject(hdc,hFont);
                var a = Windows.GetTextMetrics(hdc,out tm);
                var b = Windows.SelectObject(hdc,hOldFont);
                var c = Windows.DeleteObject(hFont);
                AverageCharWidth = tm.tmAveCharWidth;
            }
            catch
            {
            }
            finally
            {
                graphics.ReleaseHdc();
            }
        }
        return AverageCharWidth;
    }
}

Windows.cs
这是我的Windows API声明.

public static class Windows
{
    [Serializable,StructLayout(LayoutKind.Sequential,CharSet = CharSet.Auto)]
    public struct TEXTMETRIC
    {
        public int tmHeight;
        public int tmAscent;
        public int tmDescent;
        public int tmInternalLeading;
        public int tmExternalLeading;
        public int tmAveCharWidth;
        public int tmMaxCharWidth;
        public int tmWeight;
        public int tmOverhang;
        public int tmDigitizedAspectX;
        public int tmDigitizedAspectY;
        public short tmFirstChar;
        public short tmLastChar;
        public short tmDefaultChar;
        public short tmBreakChar;
        public byte tmItalic;
        public byte tmUnderlined;
        public byte tmStruckOut;
        public byte tmPitchAndFamily;
        public byte tmCharSet;
    }

    [DllImport("user32.dll")]
    public static extern bool CreateCaret(IntPtr hWnd,IntPtr hBitmap,int nWidth,int nHeight);
    [DllImport("User32.dll")]
    public static extern bool SetCaretPos(int x,int y);
    [DllImport("User32.dll")]
    public static extern bool DestroyCaret();
    [DllImport("User32.dll")]
    public static extern bool ShowCaret(IntPtr hWnd);
    [DllImport("User32.dll")]
    public static extern bool HideCaret(IntPtr hWnd);
    [DllImport("gdi32.dll",CharSet = CharSet.Auto)]
    public static extern bool GetTextMetrics(IntPtr hdc,out TEXTMETRIC lptm);
    [DllImport("gdi32.dll")]
    public static extern IntPtr SelectObject(IntPtr hdc,IntPtr hgdiobj);
    [DllImport("GDI32.dll")]
    public static extern bool DeleteObject(IntPtr hObject);
}

编辑

我发布的代码有一个问题,使其更加不准确.这是尝试许多不同方法的结果,有些方法比这更准确.我正在寻找的是一个使其“完全准确”的修复,就像在我的MFC Hex Editor Control in C++中一样.