Consider changing the brightblack color and glyph of NULL bytes

[bitraid]

I have a couple of issues with the display of the offset and NULL bytes. They are not such a big deal for me, because I do a manual build and I apply a patch to fix them, but I thought of bringing them up anyway, for the benefit of other users with similar terminal configurations.

• The first one, involves the color. brightblack is the background color of the Solarized Dark color scheme, so it becomes invisible on terminals with that configuration. This is a very popular color scheme, and I’m surprised that it hasn’t been brought up already. I would suggest to be changed to blue, which is a more compatible foreground color, and it’s not used for something else.

• The second, has to do with the choice of the display character for NULL bytes. The "diamond operator" (U+22C4) is not a very common symbol, and it's not present in some popular fonts, like Terminus and Adobe Source Code Pro, so a fallback font is used and it doesn’t look nice. I think a better choice would be a more common symbol, like "subscript zero" (U+2080).

[sharkdp]

Sounds reasonable, thank you. How does that look like (for different terminal schemes)?

[bitraid]

Thanks.

I took a few screenshots of foot terminal, showcasing 8 color schemes and 3 fonts:

• Solarized Dark, Terminus
  

• Solarized Light, Terminus
  

• Dracula, Source Code Pro
  

• Gruvbox Dark, Source Code Pro
  

• Gruvbox Light, Source Code Pro
  

• Monokai Pro, Nimbus Mono
  

• Nord, Nimbus Mono
  

• XTerm, Nimbus Mono
  

I applied this patch (doesn't include the test change):

diff --git a/src/colors.rs b/src/colors.rs
index b76e641..eb5ea0a 100644
--- a/src/colors.rs
+++ b/src/colors.rs
@@ -1,7 +1,7 @@
 use owo_colors::{colors, Color};
 
-pub const COLOR_NULL: &[u8] = colors::BrightBlack::ANSI_FG.as_bytes();
-pub const COLOR_OFFSET: &[u8] = colors::BrightBlack::ANSI_FG.as_bytes();
+pub const COLOR_NULL: &[u8] = colors::Blue::ANSI_FG.as_bytes();
+pub const COLOR_OFFSET: &[u8] = colors::Blue::ANSI_FG.as_bytes();
 pub const COLOR_ASCII_PRINTABLE: &[u8] = colors::Cyan::ANSI_FG.as_bytes();
 pub const COLOR_ASCII_WHITESPACE: &[u8] = colors::Green::ANSI_FG.as_bytes();
 pub const COLOR_ASCII_OTHER: &[u8] = colors::Green::ANSI_FG.as_bytes();
@@ -24,12 +24,12 @@ pub const CP437: [char; 256] = [
     // ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
     // OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     //
-    // modified to use the ⋄ character instead of ␀
+    // modified to use the ₀ character instead of ␀
 
     // use https://en.wikipedia.org/w/index.php?title=Code_page_437&oldid=978947122
     // not ftp://ftp.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/PC/CP437.TXT
     // because we want the graphic versions of 01h–1Fh + 7Fh
-    '⋄','☺','☻','♥','♦','♣','♠','•','◘','○','◙','♂','♀','♪','♫','☼',
+    '₀','☺','☻','♥','♦','♣','♠','•','◘','○','◙','♂','♀','♪','♫','☼',
     '►','◄','↕','‼','¶','§','▬','↨','↑','↓','→','←','∟','↔','▲','▼',
     ' ','!','"','#','$','%','&','\'','(',')','*','+',',','-','.','/',
     '0','1','2','3','4','5','6','7','8','9',':',';','<','=','>','?',
diff --git a/src/lib.rs b/src/lib.rs
index bae2945..10d6b81 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -27,7 +27,7 @@ pub enum ByteCategory {
 #[derive(Copy, Clone, Debug, Default, ValueEnum)]
 #[non_exhaustive]
 pub enum CharacterTable {
-    /// Show printable ASCII characters as-is, '⋄' for NULL bytes, ' ' for
+    /// Show printable ASCII characters as-is, '₀' for NULL bytes, ' ' for
     /// space, '_' for other ASCII whitespace, '•' for other ASCII characters,
     /// and '×' for non-ASCII bytes.
     #[default]
@@ -96,7 +96,7 @@ impl Byte {
         use crate::ByteCategory::*;
         match character_table {
             CharacterTable::Default => match self.category() {
-                Null => '⋄',
+                Null => '₀',
                 AsciiPrintable => self.0 as char,
                 AsciiWhitespace if self.0 == 0x20 => ' ',
                 AsciiWhitespace => '_',
diff --git a/src/main.rs b/src/main.rs
index 2e32cff..eef9dd8 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -494,7 +494,7 @@ fn print_color_table() -> io::Result<()> {
 
     // NULL bytes
     stdout.write_all(COLOR_NULL)?;
-    writeln!(stdout, "⋄ NULL bytes (0x00)")?;
+    writeln!(stdout, "₀ NULL bytes (0x00)")?;
     stdout.write_all(COLOR_RESET)?;
 
     // ASCII printable