Question

I have a great question for you. I searched all the Google and MSDN and didn’t find anything.

I’m trying to do a program that exports a font to single PNG images per character. I’m currently testing it with new Windows font, Segoe UI Symbol. Please note I know the font license terms and I won’t distribute that font in the internet.

Well, the real problem is happening when I call the method DrawString, member of Graphics. I convert the unicode integer value to a char then to a string. I already tried to convert the integer to char with char.ConvertFromUtf32() and with Convert.ToChar().

The program is working good during 26 characters (starting from 57344 = 0xE000), the problem doesn’t appear when I use numeric values until 57370. After this, there is not a single number that is not written with a white box char.

After some search, I found an overload to Font constructor, with the attribute gdiCharset and tried to use its value as 2, but nothing was happened.

I’m showing the source code for you below. Please, if there is someone who can help me, I will be happy.

UPDATE
When I use escape sequences (like "\uE1FF" instead of char conversion it works! But I don’t know how to make escape sequences within a for loop.

        Font segoe = new Font("Segoe UI Symbol", 800, FontStyle.Regular, GraphicsUnit.Pixel, 2);

        Bitmap bmedidor = new Bitmap(1000, 1000, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
        Graphics gmedidor = Graphics.FromImage(bmedidor);
        // This line below doesn't matter, see the method DrawString
        Size tamanho = gmedidor.MeasureString(char.ConvertFromUtf32(57344).ToString(), segoe).ToSize();

        int[] reducoes = new int[6] {512, 256, 128, 64, 32, 16};
        string caminho = "C:\\InoMetro";


        for (int u = 57344; u < 57896; u++)
        {
            Bitmap caractere = new Bitmap(tamanho.Width, tamanho.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
            Graphics criador = Graphics.FromImage(caractere);

            criador.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            criador.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
            criador.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
            criador.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

            // Here we have the problem
            criador.DrawString(Convert.ToChar(u).ToString(), segoe, new SolidBrush(Color.Black), new PointF(0, 0));

            for (int r = 0; r < reducoes.Length; r++)
            {
                int taR = reducoes[r];

                Bitmap reducao = new Bitmap(taR, taR, System.Drawing.Imaging.PixelFormat.Format32bppArgb);
                Graphics redutor = Graphics.FromImage(reducao);

                redutor.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                redutor.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
                redutor.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                redutor.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;

                redutor.DrawImage(caractere, 0, 0, taR, taR);
                reducao.Save(caminho + "\\" + taR.ToString() + "\\" + u.ToString() + ".png", System.Drawing.Imaging.ImageFormat.Png);

            }

        }

Answer 1

U+E000-U+F8FF (57344-63743 decimal) are Private Use Area characters.

Most fonts (including Segoe UI Symbol) don’t provide glyphs for any code points in this range, so the typical fallback behavior is for the font renderer to display a white box () or a question mark in a black diamond (�) when asked to draw one of these code points.

Segoe UI Symbol on Windows 8 only defines glyphs for U+E000-U+E019, then provides no glyphs for U+E01A-U+E051; that’s why white boxes are displayed for 57370 (0xE01A) through 57425 (0xE051).