add screenshot generator tool

Cargo.toml

@@ -26,6 +26,7 @@ members = [
     "emulator/mgba",
     "emulator/mgba-sys",
     "emulator/test-runner",
+    "emulator/screenshot-generator",
     "website/backtrace",
 ]
 

emulator/screenshot-generator/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "screenshot-generator"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+mgba = { path = "../mgba" }
+clap = { version = "4", features = ["derive"] }
+anyhow = "1"
+image = { version = "0.24", default-features = false, features = [ "png", "bmp" ] }
+agb-gbafix = { path = "../../agb-gbafix" }

emulator/screenshot-generator/src/image_generate.rs

@@ -0,0 +1,23 @@
+use image::{DynamicImage, GenericImage, Rgba};
+
+const WIDTH: usize = 240;
+const HEIGHT: usize = 160;
+
+pub fn generate_image(video_buffer: &[u32]) -> DynamicImage {
+    let mut dynamic_image = DynamicImage::new(
+        WIDTH.try_into().unwrap(),
+        HEIGHT.try_into().unwrap(),
+        image::ColorType::Rgba8,
+    );
+    for y in 0..HEIGHT {
+        for x in 0..WIDTH {
+            let video_pixel = video_buffer[x + y * WIDTH];
+            let mut pixels = video_pixel.to_le_bytes();
+            pixels[3] = 255;
+
+            dynamic_image.put_pixel(x.try_into().unwrap(), y.try_into().unwrap(), Rgba(pixels));
+        }
+    }
+
+    dynamic_image
+}

emulator/screenshot-generator/src/main.rs

@@ -0,0 +1,96 @@
+use std::{
+    error::Error,
+    fs::File,
+    io::{BufWriter, Read},
+    path::{Path, PathBuf},
+};
+
+use anyhow::anyhow;
+use clap::Parser;
+use image::DynamicImage;
+use image_generate::generate_image;
+use mgba::{LogLevel, Logger, MCore, MemoryBacked, VFile};
+
+mod image_generate;
+
+static LOGGER: Logger = Logger::new(my_logger);
+
+fn my_logger(_category: &str, _level: LogLevel, _s: String) {}
+
+#[derive(Parser)]
+struct CliArguments {
+    #[arg(long)]
+    rom: PathBuf,
+    #[arg(long)]
+    frames: usize,
+    #[arg(long)]
+    output: PathBuf,
+}
+
+struct ScreenshotGenerator {
+    mgba: MCore,
+}
+
+impl ScreenshotGenerator {
+    fn new<V: VFile>(rom: V) -> Result<Self, Box<dyn Error>> {
+        let mut mgba = MCore::new().ok_or(anyhow!("cannot create core"))?;
+
+        mgba::set_global_default_logger(&LOGGER);
+
+        mgba.load_rom(rom);
+
+        Ok(Self { mgba })
+    }
+
+    fn run(mut self, frames: usize) -> DynamicImage {
+        for _ in 0..frames {
+            self.mgba.frame();
+        }
+
+        generate_image(self.mgba.video_buffer())
+    }
+}
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let args = CliArguments::parse();
+
+    let rom = load_rom(args.rom)?;
+    let rom = MemoryBacked::new(rom);
+
+    let image = ScreenshotGenerator::new(rom)?.run(args.frames);
+
+    let mut output = BufWriter::new(
+        File::options()
+            .write(true)
+            .create(true)
+            .truncate(true)
+            .open(args.output)?,
+    );
+    image.write_to(&mut output, image::ImageOutputFormat::Png)?;
+
+    Ok(())
+}
+
+fn load_rom<P: AsRef<Path>>(path: P) -> anyhow::Result<Vec<u8>> {
+    let mut input_file = File::open(path)?;
+    let mut input_file_buffer = Vec::new();
+
+    input_file.read_to_end(&mut input_file_buffer)?;
+
+    let mut elf_buffer = Vec::new();
+
+    let inculde_debug_info = false;
+    if agb_gbafix::write_gba_file(
+        &input_file_buffer,
+        Default::default(),
+        agb_gbafix::PaddingBehaviour::DoNotPad,
+        inculde_debug_info,
+        &mut elf_buffer,
+    )
+    .is_ok()
+    {
+        Ok(elf_buffer)
+    } else {
+        Ok(input_file_buffer)
+    }
+}