1 files changed, 79 insertions, 0 deletions
diff --git a/src/sprite_loader.rs b/src/sprite_loader.rs
new file mode 100644
index 0000000..eccf066
--- /dev/null
+++ b/src/sprite_loader.rs
@@ -0,0 +1,79 @@
+use serde::Deserialize;
+use std::{collections::HashMap, error::Error, fs::File, io::BufReader, path::Path};
+
+use crate::{content::materials::MaterialId, sim::cell::Cell};
+
+fn load_img(path: &Path) -> Result<(Vec<u8>, u32, u32), Box<dyn Error>> {
+    let mut decoder = png::Decoder::new(BufReader::new(File::open(path)?));
+    decoder.set_transformations(png::Transformations::IDENTITY);
+
+    let mut reader = decoder.read_info()?;
+    // only None if it's too big for memory
+    let mut buf = vec![0; reader.output_buffer_size().unwrap()];
+    let info = reader.next_frame(&mut buf)?;
+
+    if info.color_type != png::ColorType::Indexed {
+        return Err(format!("{:#?}: not indexed", path.to_str()).into());
+    }
+    if info.bit_depth != png::BitDepth::Eight {
+        return Err(format!(
+            "{:#?}: expected 8-bit, got {:?}",
+            path.to_str(),
+            info.bit_depth
+        )
+        .into());
+    }
+
+    buf.truncate(info.buffer_size());
+    Ok((buf, info.width, info.height))
+}
+
+#[derive(Deserialize)]
+struct PaletteEntry {
+    material: MaterialId,
+}
+
+#[derive(Deserialize)]
+struct SpriteManifest {
+    palette: HashMap<u8, PaletteEntry>,
+}
+
+fn load_manifest(path: &Path) -> Result<SpriteManifest, Box<dyn Error>> {
+    Ok(toml::from_str(&std::fs::read_to_string(path)?)?)
+}
+
+pub struct SpriteCells {
+    pub cells: Vec<Cell>,
+    pub width: u32,
+    pub height: u32,
+}
+
+pub fn load_sprite_to_cells(path: &str) -> SpriteCells {
+    let img_result = load_img(&Path::join(Path::new(path), Path::new("img.png")));
+    match img_result {
+        Ok((indices, width, height)) => {
+            let manifest_result =
+                load_manifest(&Path::join(Path::new(path), Path::new("manifest.toml")));
+            match manifest_result {
+                Ok(SpriteManifest { palette }) => {
+                    let cells: Vec<Cell> = indices
+                        .iter()
+                        .map(|i| Cell::from_material(palette.get(i).unwrap().material))
+                        .collect();
+
+                    SpriteCells {
+                        cells,
+                        width,
+                        height,
+                    }
+                }
+                Err(e) => {
+                    panic!("Couldn't load sprite: {}", e)
+                }
+            }
+        }
+        Err(e) => {
+            panic!("Couldn't load sprite: {}", e)
+        }
+    }
+}