我正在编写一个程序,其中一部分是在CP437中呈现位图字体。
在一个函数中,当我渲染文本时,我想能够在编码转换之前检查char
在CP437中是否可用,例如:
public static void DrawCharacter(this Graphics g, char c)
{
if (char_exist_in_encoding(Encoding.GetEncoding(437), c) {
byte[] src = Encoding.Unicode.GetBytes(c.ToString());
byte[] dest = Encoding.Convert(Encoding.Unicode, Encoding.GetEncoding(437), src);
DrawCharacter(g, dest[0]); // Call the void(this Graphics, byte) overload
}
}
如果没有检查,任何CP437之外的字符都会导致一个问号(63,0x3F)。我想完全隐藏任何无效字符。是否有实现char_exist_in_encoding
的方法,除了下面这种愚蠢的方法?
private static bool char_exist_in_encoding(Encoding e, char c)
{
if (c == '?')
return true;
byte[] src = Encoding.Unicode.GetBytes(c.ToString());
byte[] dest = Encoding.Convert(Encoding.Unicode, e, src);
if (dest[0] == 0x3F)
return false;
return true;
}
也许与主题不太相关,但是位图是这样创建的:
Bitmap b = new Bitmap(256 * 8, 16);
Graphics g = Graphics.FromImage(b);
g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SingleBitPerPixelGridFit;
Font f = new Font("Whatever 8x16 bitmap font", 16, GraphicsUnit.Pixel);
for (byte i = 0; i < 255; i++)
{
byte[] arr = Encoding.Convert(Encoding.GetEncoding(437), Encoding.Unicode, new byte[] { i });
char c = Encoding.Unicode.GetChars(arr)[0];
g.DrawString(c.ToString(), f, Brushes.Black, i * 8 - 3, 0); // Don't know why it needs a 3px offset
}
b.Save(@"D:\chars.png");
EncoderFallback
? - Vlad