Use embedded-graphics crate to draw shapes and text

Cargo.lock

@@ -133,6 +133,12 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d468802bab17cbc0cc575e9b053f41e72aa36bfa6b7f55e3529ffa43161b97fa"
 
+[[package]]
+name = "az"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7b7e4c2464d97fe331d41de9d5db0def0a96f4d823b8b32a2efd503578988973"
+
 [[package]]
 name = "bincode"
 version = "1.3.3"
@@ -270,6 +276,29 @@ dependencies = [
  "cfg-if",
 ]
 
+[[package]]
+name = "embedded-graphics"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0649998afacf6d575d126d83e68b78c0ab0e00ca2ac7e9b3db11b4cbe8274ef0"
+dependencies = [
+ "az",
+ "byteorder",
+ "embedded-graphics-core",
+ "float-cmp",
+ "micromath",
+]
+
+[[package]]
+name = "embedded-graphics-core"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ba9ecd261f991856250d2207f6d8376946cd9f412a2165d3b75bc87a0bc7a044"
+dependencies = [
+ "az",
+ "byteorder",
+]
+
 [[package]]
 name = "errno"
 version = "0.3.8"
@@ -344,6 +373,15 @@ dependencies = [
  "log",
 ]
 
+[[package]]
+name = "float-cmp"
+version = "0.9.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "98de4bbd547a563b716d8dfa9aad1cb19bfab00f4fa09a6a4ed21dbcf44ce9c4"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "funty"
 version = "2.0.0"
@@ -537,6 +575,7 @@ name = "kernel"
 version = "0.1.0"
 dependencies = [
  "bootloader_api",
+ "embedded-graphics",
 ]
 
 [[package]]
@@ -588,6 +627,21 @@ version = "2.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "523dc4f511e55ab87b694dc30d0f820d60906ef06413f93d4d7a1385599cc149"
 
+[[package]]
+name = "micromath"
+version = "2.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c3c8dda44ff03a2f238717214da50f65d5a53b45cd213a7370424ffdb6fae815"
+
+[[package]]
+name = "num-traits"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "39e3200413f237f41ab11ad6d161bc7239c84dcb631773ccd7de3dfe4b5c267c"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "ovmf-prebuilt"
 version = "0.1.0-alpha.1"

kernel/Cargo.toml

@@ -10,3 +10,4 @@ bench = false
 
 [dependencies]
 bootloader_api = "0.11.0"
+embedded-graphics = "0.8.1"

kernel/src/framebuffer.rs

@@ -1,4 +1,66 @@
 use bootloader_api::info::{FrameBuffer, PixelFormat};
+use embedded_graphics::{
+    draw_target::DrawTarget,
+    geometry::{self, Point},
+    pixelcolor::{Rgb888, RgbColor},
+    Pixel,
+};
+
+pub struct Display {
+    framebuffer: &'static mut FrameBuffer,
+}
+
+impl Display {
+    pub fn new(framebuffer: &'static mut FrameBuffer) -> Display {
+        Self { framebuffer }
+    }
+
+    fn draw_pixel(&mut self, coordinates: Point, color: Rgb888) {
+        // ignore any pixels that are out of bounds.
+        let (width, height) = {
+            let info = self.framebuffer.info();
+            (info.width, info.height)
+        };
+
+        let position = match (coordinates.x.try_into(), coordinates.y.try_into()) {
+            (Ok(x), Ok(y)) if x < width && y < height => Position { x, y },
+            _ => return, // ignore out-of-bounds pixel
+        };
+        let color = Color {
+            red: color.r(),
+            green: color.g(),
+            blue: color.b(),
+        };
+        set_pixel_in(self.framebuffer, position, color);
+    }
+}
+
+impl DrawTarget for Display {
+    type Color = Rgb888;
+
+    /// Drawing operations can never fail.
+    type Error = core::convert::Infallible;
+
+    fn draw_iter<I>(&mut self, pixels: I) -> Result<(), Self::Error>
+    where
+        I: IntoIterator<Item = Pixel<Self::Color>>,
+    {
+        for Pixel(coordinates, color) in pixels.into_iter() {
+            self.draw_pixel(coordinates, color);
+        }
+        Ok(())
+    }
+}
+
+impl geometry::OriginDimensions for Display {
+    fn size(&self) -> geometry::Size {
+        let info = self.framebuffer.info();
+        geometry::Size::new(
+            info.width.try_into().unwrap(),
+            info.height.try_into().unwrap(),
+        )
+    }
+}
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct Position {

kernel/src/main.rs

@@ -1,9 +1,18 @@
 #![no_std]
 #![no_main]
 
-use core::panic::PanicInfo;
+use core::{convert::Infallible, panic::PanicInfo};
 
 use bootloader_api::BootInfo;
+use embedded_graphics::{
+    draw_target::DrawTarget,
+    geometry::Point,
+    mono_font::{self, MonoTextStyle},
+    pixelcolor::{Rgb888, RgbColor, WebColors},
+    primitives::{Circle, PrimitiveStyle, StyledDrawable},
+    text::Text,
+    Drawable,
+};
 
 mod framebuffer;
 
@@ -11,20 +20,16 @@ bootloader_api::entry_point!(kernel_main);
 
 fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
     if let Some(framebuffer) = boot_info.framebuffer.as_mut() {
-        let color = framebuffer::Color {
+        let mut display = framebuffer::Display::new(framebuffer);
-            red: 0,
+        display.clear(Rgb888::RED).unwrap_or_else(infallible);
-            green: 0,
+        let style = PrimitiveStyle::with_fill(Rgb888::YELLOW);
-            blue: 255,
+        Circle::new(Point::new(50, 50), 400)
-        };
+            .draw_styled(&style, &mut display)
-        for x in 0..100 {
+            .unwrap_or_else(infallible);
-            for y in 0..100 {
+
-                let position = framebuffer::Position {
+        let character_style = MonoTextStyle::new(&mono_font::ascii::FONT_10X20, Rgb888::BLUE);
-                    x: 20 + x,
+        let text = Text::new("Hello, world!", Point::new(190, 250), character_style);
-                    y: 100 + y,
+        text.draw(&mut display).unwrap_or_else(infallible);
-                };
-                framebuffer::set_pixel_in(framebuffer, position, color);
-            }
-        }
     }
     loop {}
 }
@@ -34,3 +39,7 @@ fn kernel_main(boot_info: &'static mut BootInfo) -> ! {
 fn panic(_info: &PanicInfo) -> ! {
     loop {}
 }
+
+fn infallible<T>(v: Infallible) -> T {
+    match v {}
+}