add function to load Cp437Grid from str

crates/servicepoint/src/command.rs

@@ -4,18 +4,13 @@ use crate::{
     command_code::CommandCode,
     compression::into_decompressed,
     packet::{Header, Packet},
-    Brightness, BrightnessGrid, CompressionCode, Origin, PixelGrid, Pixels,
-    PrimitiveGrid, SpBitVec, Tiles, TILE_SIZE,
+    Brightness, BrightnessGrid, CompressionCode, Cp437Grid, Origin, PixelGrid,
+    Pixels, PrimitiveGrid, SpBitVec, Tiles, TILE_SIZE,
 };
 
 /// Type alias for documenting the meaning of the u16 in enum values
 pub type Offset = usize;
 
-/// A grid containing codepage 437 characters.
-///
-/// The encoding is currently not enforced.
-pub type Cp437Grid = PrimitiveGrid<u8>;
-
 /// A low-level display command.
 ///
 /// This struct and associated functions implement the UDP protocol for the display.
@@ -92,9 +87,8 @@ pub enum Command {
     ///
     /// ```rust
     /// # use servicepoint::{Command, Connection, Cp437Grid, Origin};
-    /// # let connection = Connection::open("127.0.0.1:2342").unwrap();
-    /// let chars = ['H', 'e', 'l', 'l', 'o', 'W', 'o', 'r', 'l', 'd'].map(move |c| c as u8);
-    /// let grid = Cp437Grid::load(5, 2, &chars);
+    /// # let connection = Connection::Fake;
+    /// let grid = Cp437Grid::load_ascii("Hello\nWorld", 5, false).unwrap();
     /// connection.send(Command::Cp437Data(Origin::new(2, 2), grid)).unwrap();
     /// ```
     Cp437Data(Origin<Tiles>, Cp437Grid),

crates/servicepoint/src/cp437.rs

@@ -0,0 +1,100 @@
+use crate::cp437::Cp437LoadError::InvalidChar;
+use crate::{Grid, PrimitiveGrid};
+
+/// A grid containing codepage 437 characters.
+///
+/// The encoding is currently not enforced.
+pub type Cp437Grid = PrimitiveGrid<u8>;
+
+#[derive(Debug)]
+pub enum Cp437LoadError {
+    InvalidChar { index: usize, char: char },
+}
+
+impl Cp437Grid {
+    /// Load an ASCII-only [&str] into a [Cp437Grid] of specified width.
+    ///
+    /// # Panics
+    ///
+    /// - for width == 0
+    /// - on empty strings
+    pub fn load_ascii(
+        value: &str,
+        width: usize,
+        wrap: bool,
+    ) -> Result<Self, Cp437LoadError> {
+        assert!(width > 0);
+        assert!(!value.is_empty());
+
+        let mut chars = {
+            let mut x = 0;
+            let mut y = 0;
+
+            for (index, char) in value.chars().enumerate() {
+                if !char.is_ascii() {
+                    return Err(InvalidChar { index, char });
+                }
+
+                let is_lf = char == '\n';
+                if is_lf || (wrap && x == width) {
+                    y += 1;
+                    x = 0;
+                    if is_lf {
+                        continue;
+                    }
+                }
+
+                x += 1;
+            }
+
+            Cp437Grid::new(width, y + 1)
+        };
+
+        let mut x = 0;
+        let mut y = 0;
+        for char in value.chars().map(move |c| c as u8) {
+            let is_lf = char == b'\n';
+            if is_lf || (wrap && x == width) {
+                y += 1;
+                x = 0;
+                if is_lf {
+                    continue;
+                }
+            }
+
+            if wrap || x < width {
+                chars.set(x, y, char);
+            }
+            x += 1;
+        }
+
+        Ok(chars)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn load_ascii_nowrap() {
+        let chars = ['H', 'e', 'l', 'l', 'o', 'W', 'o', 'r', 'l', 'd']
+            .map(move |c| c as u8);
+        let expected = Cp437Grid::load(5, 2, &chars);
+
+        let actual = Cp437Grid::load_ascii("Hello,\nWorld!", 5, false).unwrap();
+        // comma will be removed because line is too long and wrap is off
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn load_ascii_wrap() {
+        let chars = ['H', 'e', 'l', 'l', 'o', 'W', 'o', 'r', 'l', 'd']
+            .map(move |c| c as u8);
+        let expected = Cp437Grid::load(5, 2, &chars);
+
+        let actual = Cp437Grid::load_ascii("HelloWorld", 5, true).unwrap();
+        // line break will be added
+        assert_eq!(actual, expected);
+    }
+}

crates/servicepoint/src/lib.rs

@@ -41,9 +41,10 @@ pub use bitvec;
 use bitvec::prelude::{BitVec, Msb0};
 
 pub use crate::brightness::{Brightness, BrightnessGrid};
-pub use crate::command::{Command, Cp437Grid, Offset};
+pub use crate::command::{Command, Offset};
 pub use crate::compression_code::CompressionCode;
 pub use crate::connection::Connection;
+pub use crate::cp437::Cp437Grid;
 pub use crate::data_ref::DataRef;
 pub use crate::grid::Grid;
 pub use crate::origin::{Origin, Pixels, Tiles};
@@ -58,6 +59,7 @@ mod command_code;
 mod compression;
 mod compression_code;
 mod connection;
+mod cp437;
 mod data_ref;
 mod grid;
 mod origin;

crates/servicepoint_binding_c/src/cp437_grid.rs

@@ -40,7 +40,9 @@ pub unsafe extern "C" fn sp_cp437_grid_new(
     width: usize,
     height: usize,
 ) -> *mut SPCp437Grid {
-    Box::into_raw(Box::new(SPCp437Grid(servicepoint::Cp437Grid::new(width, height))))
+    Box::into_raw(Box::new(SPCp437Grid(servicepoint::Cp437Grid::new(
+        width, height,
+    ))))
 }
 
 /// Loads a `SPCp437Grid` with the specified dimensions from the provided data.
@@ -67,7 +69,9 @@ pub unsafe extern "C" fn sp_cp437_grid_load(
     data_length: usize,
 ) -> *mut SPCp437Grid {
     let data = std::slice::from_raw_parts(data, data_length);
-    Box::into_raw(Box::new(SPCp437Grid(servicepoint::Cp437Grid::load(width, height, data))))
+    Box::into_raw(Box::new(SPCp437Grid(servicepoint::Cp437Grid::load(
+        width, height, data,
+    ))))
 }
 
 /// Clones a `SPCp437Grid`.