preview panel [still more like a POC than a full feature]

3 files changed, 175 insertions, 0 deletions

diff --git a/src/hex/byte.rs b/src/hex/byte.rs
new file mode 100644
index 0000000..1195ff4
--- /dev/null
+++ b/src/hex/byte.rs
@@ -0,0 +1,60 @@
+use {
+    crate::{
+        skin::StyleMap,
+    },
+    termimad::CompoundStyle,
+};
+
+pub enum ByteCategory {
+    Null,
+    AsciiGraphic,
+    AsciiWhitespace,
+    AsciiOther,
+    NonAscii,
+}
+
+#[derive(Clone, Copy)]
+pub struct Byte(u8);
+
+impl From<u8> for Byte {
+    fn from(u: u8) -> Self {
+        Self(u)
+    }
+}
+
+impl Byte {
+    pub fn category(self) -> ByteCategory {
+        if self.0 == 0x00 {
+            ByteCategory::Null
+        } else if self.0.is_ascii_graphic() {
+            ByteCategory::AsciiGraphic
+        } else if self.0.is_ascii_whitespace() {
+            ByteCategory::AsciiWhitespace
+        } else if self.0.is_ascii() {
+            ByteCategory::AsciiOther
+        } else {
+            ByteCategory::NonAscii
+        }
+    }
+
+    pub fn style(self, styles: & StyleMap) -> & CompoundStyle {
+        match self.category() {
+            ByteCategory::Null => &styles.hex_null,
+            ByteCategory::AsciiGraphic => &styles.hex_ascii_graphic,
+            ByteCategory::AsciiWhitespace => &styles.hex_ascii_whitespace,
+            ByteCategory::AsciiOther => &styles.hex_ascii_other,
+            ByteCategory::NonAscii => &styles.hex_non_ascii,
+        }
+    }
+
+    pub fn as_char(self) -> char {
+        match self.category() {
+            ByteCategory::Null => '0',
+            ByteCategory::AsciiGraphic => self.0 as char,
+            ByteCategory::AsciiWhitespace if self.0 == 0x20 => ' ',
+            ByteCategory::AsciiWhitespace => '_',
+            ByteCategory::AsciiOther => '•',
+            ByteCategory::NonAscii => '×',
+        }
+    }
+}
diff --git a/src/hex/hex_view.rs b/src/hex/hex_view.rs
new file mode 100644
index 0000000..fd9eea9
--- /dev/null
+++ b/src/hex/hex_view.rs
@@ -0,0 +1,106 @@
+
+use {
+    super::{
+        byte::Byte,
+    },
+    crate::{
+        display::{CropWriter, LONG_SPACE, Screen, W},
+        errors::ProgramError,
+        skin::PanelSkin,
+    },
+    crossterm::{
+        cursor,
+        QueueableCommand,
+    },
+    memmap::Mmap,
+    std::{
+        fs::File,
+        io,
+        path::PathBuf,
+    },
+    termimad::{Area},
+};
+
+
+pub struct HexLine {
+    pub bytes: Vec<u8>, // from 1 to 16 bytes
+}
+
+pub struct HexView {
+    pub path: PathBuf,
+    pub scroll: usize,
+    pub len: usize,
+}
+
+impl HexView {
+    pub fn new(path: PathBuf) -> io::Result<Self> {
+        let len = path.metadata()?.len() as usize;
+        Ok(Self {
+            path,
+            scroll: 0,
+            len,
+        })
+    }
+    pub fn line_count(&self) -> usize {
+        self.len / 16
+    }
+    pub fn get_page(&mut self, start_line_idx: usize, line_count: usize) -> io::Result<Vec<HexLine>> {
+        // I'm not sure a memmap is the best solution here but at least it's easy
+        let file = File::open(&self.path)?;
+        let mmap = unsafe { Mmap::map(&file)? };
+        let new_len = mmap.len();
+        if new_len != self.len {
+            warn!("previewed file len changed from {} to {}", self.len, new_len);
+            self.len = new_len;
+        }
+        let mut lines = Vec::new();
+        let mut start_idx = 16 * start_line_idx;
+        while start_idx < self.len {
+            let line_len = 16.min(self.len - start_idx);
+            let mut bytes: Vec<u8> = vec![0; line_len];
+            bytes[0..line_len].copy_from_slice(&mmap[start_idx..start_idx+line_len]);
+            lines.push(HexLine{bytes});
+            if lines.len() >= line_count {
+                break;
+            }
+            start_idx += line_len;
+        }
+        Ok(lines)
+    }
+    pub fn display(
+        &mut self,
+        w: &mut W,
+        _screen: &Screen,
+        panel_skin: &PanelSkin,
+        area: &Area,
+    ) -> Result<(), ProgramError> {
+        let line_count = area.height as usize;
+        let page = self.get_page(self.scroll, line_count)?;
+        let styles = &panel_skin.styles;
+        let mut show_middle_space = false;
+        if area.width > 50 {
+            show_middle_space = true;
+        }
+        for y in 0..line_count {
+            w.queue(cursor::MoveTo(area.left, y as u16 + area.top))?;
+            let mut cw = CropWriter::new(w, area.width as usize);
+            let cw = &mut cw;
+            if y < page.len() {
+                let line = &page[y];
+                for x in 0..16 {
+                    if x==8 && show_middle_space {
+                        cw.queue_char(&styles.default, ' ')?;
+                    }
+                    if let Some(b) = line.bytes.get(x) {
+                        let byte = Byte::from(*b);
+                        cw.queue_string(byte.style(styles), format!(" {:02x}", b))?;
+                    } else {
+                        cw.queue_str(&styles.default, "   ")?;
+                    }
+                }
+                cw.fill(&styles.default, LONG_SPACE)?;
+            }
+        }
+        Ok(())
+    }
+}
diff --git a/src/hex/mod.rs b/src/hex/mod.rs
new file mode 100644
index 0000000..378e56f
--- /dev/null
+++ b/src/hex/mod.rs
@@ -0,0 +1,9 @@
+
+
+mod byte;
+mod hex_view;
+
+pub use {
+    hex_view::HexView,
+};
+