Add simple text rendering

src/font.rs

@@ -78,7 +78,7 @@ fn letter(character: char) -> [u8; 8] {
         ],
         'r' => [
             0b11111111, 0b10000001, 0b10000001, 0b11111111, 0b11111100, 0b10000010, 0b10000001,
-            0b00000001,
+            0b10000001,
         ],
         's' => [
             0b01111111, 0b10000000, 0b10000000, 0b01111110, 0b00000001, 0b00000001, 0b00000001,
@@ -112,10 +112,55 @@ fn letter(character: char) -> [u8; 8] {
             0b11111111, 0b00000111, 0b00001100, 0b00011000, 0b00110000, 0b01100000, 0b11000000,
             0b11111111,
         ],
+        '!' => [
+            0b01000000, 0b01000000, 0b01000000, 0b01000000, 0b01000000, 0b01000000, 0b00000000,
+            0b01000000,
+        ],
+        ',' => [
+            0b00000000, 0b00000000, 0b00000000, 0b00000000, 0b00000000, 0b00000000, 0b01000000,
+            0b10000000,
+        ],
         _ => [0; 8],
     }
 }
 
+pub fn draw_text<T: DelayNs, DCPin: PinOps, RSTPin: PinOps>(
+    display: &mut Display<T, DCPin, RSTPin>,
+    text: &str,
+    fg: Rgb565,
+    bg: Rgb565,
+    position: Vec2,
+    scale: u16,
+) {
+    let mut curr_pos = position;
+
+    let kerning = 9 * scale;
+    let original_x = position.x;
+
+    for c in text.chars() {
+        if c == '\n' {
+            curr_pos.y += kerning;
+            continue;
+        }
+        if c == ' ' {
+            curr_pos.x += kerning;
+            continue;
+        }
+        if curr_pos.x + kerning > 240 {
+            curr_pos.x = original_x;
+            curr_pos.y += kerning;
+        }
+        if curr_pos.y + kerning > 240 {
+            curr_pos.y = 0;
+        }
+
+        Letter::from(c, fg, bg)
+            .iter()
+            .draw(display, curr_pos, scale);
+        curr_pos.x += kerning;
+    }
+}
+
 pub struct Letter {
     base: [u8; 8],
     pub fg: Rgb565,
@@ -160,7 +205,7 @@ impl<'a> Iterator for LetterIter<'a> {
 
     fn next(&mut self) -> Option<Self::Item> {
         let byte_idx = self.idx / 8;
-        let bit_idx = self.idx % 8;
+        let bit_idx = 7 - (self.idx % 8);
         if byte_idx >= 8 {
             None
         } else {

src/main.rs

@@ -19,7 +19,7 @@ use panic_halt as _;
 
 use crate::{
     display::{Display, Rgb565, Vec2},
-    font::Letter,
+    font::{Letter, draw_text},
     graphics::{Image, LARGE_CAT_UNSAFE, PRESS_BTN_UNSAFE, draw_image},
     peripherals::Button,
 };
@@ -94,7 +94,14 @@ fn main() -> ! {
 
     let letter = Letter::from('h', Rgb565::white(), Rgb565::black());
 
-    letter.iter().draw(&mut display, Vec2 { x: 10, y: 10 }, 4);
+    draw_text(
+        &mut display,
+        "hello there!",
+        Rgb565::white(),
+        Rgb565::red(),
+        Vec2 { x: 10, y: 10 },
+        3,
+    );
 
     loop {
         if button.poll() {