Add new braille character table and color schemes (#247)

* Add new braille character table and color schemes

* Add character for tab and change color for 0x7f

---------

Co-authored-by: David Peter <mail@david-peter.de>

src/lib.rs

@@ -43,6 +43,24 @@ pub enum CharacterTable {
     /// Uses code page 437 (for non-ASCII bytes).
     #[value(name = "codepage-437")]
     CP437,
+
+    /// Uses braille characters for non-printable bytes.
+    Braille,
+}
+
+#[derive(Copy, Clone, Debug, Default, ValueEnum)]
+#[non_exhaustive]
+pub enum ColorScheme {
+    /// Show the default colors: bright black for NULL bytes, green for ASCII
+    /// space characters and non-printable ASCII, cyan for printable ASCII characters,
+    /// and yellow for non-ASCII bytes.
+    #[default]
+    Default,
+
+    /// Show bright black for NULL bytes, cyan for printable ASCII characters, a gradient
+    /// from pink to violet for non-printable ASCII characters and a heatmap-like gradient
+    /// from red to yellow to white for non-ASCII bytes.
+    Gradient,
 }
 
 #[derive(Copy, Clone, Debug, Default, ValueEnum)]
@@ -81,14 +99,29 @@ impl Byte {
         }
     }
 
-    fn color(self) -> &'static [u8] {
+    fn color(self, color_scheme: ColorScheme) -> &'static [u8] {
         use crate::ByteCategory::*;
-        match self.category() {
-            Null => COLOR_NULL.as_bytes(),
-            AsciiPrintable => COLOR_ASCII_PRINTABLE.as_bytes(),
-            AsciiWhitespace => COLOR_ASCII_WHITESPACE.as_bytes(),
-            AsciiOther => COLOR_ASCII_OTHER.as_bytes(),
-            NonAscii => COLOR_NONASCII.as_bytes(),
+        match color_scheme {
+            ColorScheme::Default => match self.category() {
+                Null => COLOR_NULL.as_bytes(),
+                AsciiPrintable => COLOR_ASCII_PRINTABLE.as_bytes(),
+                AsciiWhitespace => COLOR_ASCII_WHITESPACE.as_bytes(),
+                AsciiOther => COLOR_ASCII_OTHER.as_bytes(),
+                NonAscii => COLOR_NONASCII.as_bytes(),
+            },
+            ColorScheme::Gradient => match self.category() {
+                Null => COLOR_NULL_RGB,
+                AsciiWhitespace if self.0 == b' ' => &COLOR_GRADIENT_ASCII_PRINTABLE[0],
+                AsciiPrintable => &COLOR_GRADIENT_ASCII_PRINTABLE[(self.0 - b' ') as usize],
+                AsciiWhitespace | AsciiOther => {
+                    if self.0 == 0x7f {
+                        COLOR_DEL
+                    } else {
+                        &COLOR_GRADIENT_ASCII_NONPRINTABLE[self.0 as usize - 1]
+                    }
+                }
+                NonAscii => &COLOR_GRADIENT_NONASCII[(self.0 - 128) as usize],
+            },
         }
     }
 
@@ -113,6 +146,37 @@ impl Byte {
             },
             CharacterTable::CP1047 => CP1047[self.0 as usize],
             CharacterTable::CP437 => CP437[self.0 as usize],
+            CharacterTable::Braille => match self.category() {
+                // null is important enough to get its own symbol
+                Null => '⋄',
+                AsciiPrintable => self.0 as char,
+                AsciiWhitespace if self.0 == b' ' => ' ',
+                // `\t`, `\n` and `\r` are important enough to get their own symbols
+                AsciiWhitespace if self.0 == b'\t' => '→',
+                AsciiWhitespace if self.0 == b'\n' => '↵',
+                AsciiWhitespace if self.0 == b'\r' => '←',
+                AsciiWhitespace | AsciiOther | NonAscii => {
+                    /// Adjust the bits from the original number to a new number.
+                    ///
+                    /// Bit positions in braille are adjusted as follows:
+                    ///
+                    /// ```text
+                    /// 0 3 => 0 1
+                    /// 1 4 => 2 3
+                    /// 2 5 => 4 5
+                    /// 6 7 => 6 7
+                    /// ```
+                    fn to_braille_bits(byte: u8) -> u8 {
+                        let mut out = 0;
+                        for (from, to) in [0, 3, 1, 4, 2, 5, 6, 7].into_iter().enumerate() {
+                            out |= (byte >> from & 1) << to;
+                        }
+                        out
+                    }
+
+                    char::from_u32(0x2800 + to_braille_bits(self.0) as u32).unwrap()
+                }
+            },
         }
     }
 }
@@ -203,6 +267,7 @@ pub struct PrinterBuilder<'a, Writer: Write> {
     base: Base,
     endianness: Endianness,
     character_table: CharacterTable,
+    color_scheme: ColorScheme,
 }
 
 impl<'a, Writer: Write> PrinterBuilder<'a, Writer> {
@@ -219,6 +284,7 @@ impl<'a, Writer: Write> PrinterBuilder<'a, Writer> {
             base: Base::Hexadecimal,
             endianness: Endianness::Big,
             character_table: CharacterTable::Default,
+            color_scheme: ColorScheme::Default,
         }
     }
 
@@ -272,6 +338,11 @@ impl<'a, Writer: Write> PrinterBuilder<'a, Writer> {
         self
     }
 
+    pub fn color_scheme(mut self, color_scheme: ColorScheme) -> Self {
+        self.color_scheme = color_scheme;
+        self
+    }
+
     pub fn build(self) -> Printer<'a, Writer> {
         Printer::new(
             self.writer,
@@ -285,6 +356,7 @@ impl<'a, Writer: Write> PrinterBuilder<'a, Writer> {
             self.base,
             self.endianness,
             self.character_table,
+            self.color_scheme,
         )
     }
 }
@@ -298,6 +370,7 @@ pub struct Printer<'a, Writer: Write> {
     show_position_panel: bool,
     show_color: bool,
     curr_color: Option<&'static [u8]>,
+    color_scheme: ColorScheme,
     border_style: BorderStyle,
     byte_hex_panel: Vec<String>,
     byte_char_panel: Vec<String>,
@@ -329,6 +402,7 @@ impl<'a, Writer: Write> Printer<'a, Writer> {
         base: Base,
         endianness: Endianness,
         character_table: CharacterTable,
+        color_scheme: ColorScheme,
     ) -> Printer<'a, Writer> {
         Printer {
             idx: 0,
@@ -338,6 +412,7 @@ impl<'a, Writer: Write> Printer<'a, Writer> {
             show_position_panel,
             show_color,
             curr_color: None,
+            color_scheme,
             border_style,
             byte_hex_panel: (0u8..=u8::MAX)
                 .map(|i| match base {
@@ -481,9 +556,10 @@ impl<'a, Writer: Write> Printer<'a, Writer> {
             Squeezer::Print | Squeezer::Delete => self.writer.write_all(b" ")?,
             Squeezer::Ignore | Squeezer::Disabled => {
                 if let Some(&b) = self.line_buf.get(i as usize) {
-                    if self.show_color && self.curr_color != Some(Byte(b).color()) {
-                        self.writer.write_all(Byte(b).color())?;
-                        self.curr_color = Some(Byte(b).color());
+                    if self.show_color && self.curr_color != Some(Byte(b).color(self.color_scheme))
+                    {
+                        self.writer.write_all(Byte(b).color(self.color_scheme))?;
+                        self.curr_color = Some(Byte(b).color(self.color_scheme));
                     }
                     self.writer
                         .write_all(self.byte_char_panel[b as usize].as_bytes())?;
@@ -550,9 +626,9 @@ impl<'a, Writer: Write> Printer<'a, Writer> {
                 if i % (self.group_size as usize) == 0 {
                     self.writer.write_all(b" ")?;
                 }
-                if self.show_color && self.curr_color != Some(Byte(b).color()) {
-                    self.writer.write_all(Byte(b).color())?;
-                    self.curr_color = Some(Byte(b).color());
+                if self.show_color && self.curr_color != Some(Byte(b).color(self.color_scheme)) {
+                    self.writer.write_all(Byte(b).color(self.color_scheme))?;
+                    self.curr_color = Some(Byte(b).color(self.color_scheme));
                 }
                 self.writer
                     .write_all(self.byte_hex_panel[b as usize].as_bytes())?;
@@ -780,6 +856,7 @@ mod tests {
             Base::Hexadecimal,
             Endianness::Big,
             CharacterTable::Default,
+            ColorScheme::Default,
         );
 
         printer.print_all(input).unwrap();
@@ -836,6 +913,7 @@ mod tests {
             Base::Hexadecimal,
             Endianness::Big,
             CharacterTable::Default,
+            ColorScheme::Default,
         );
         printer.display_offset(0xdeadbeef);
 
@@ -871,6 +949,7 @@ mod tests {
             Base::Hexadecimal,
             Endianness::Big,
             CharacterTable::Default,
+            ColorScheme::Default,
         );
 
         printer.print_all(input).unwrap();
@@ -932,6 +1011,7 @@ mod tests {
             Base::Hexadecimal,
             Endianness::Big,
             CharacterTable::Default,
+            ColorScheme::Default,
         );
 
         printer.print_all(input).unwrap();