Initial commit

.gitignore

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+/target
+/Cargo.lock

Cargo.toml

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+[package]
+name = "image-c"
+version = "0.1.0"
+edition = "2021"
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+image = { version = "0.25.1", default-features = false, features = ["png", "rayon"] }

src/lib.rs

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+use std::{io::Cursor, mem::MaybeUninit};
+
+use image::{codecs::png::PngDecoder, ImageDecoder};
+
+#[repr(C)]
+pub struct ImageInfo {
+    width: u32,
+    height: u32,
+    byte_count: u64,
+    color_type: ColorType,
+}
+
+#[repr(u8)]
+pub enum ColorType {
+    L8,
+    La8,
+    Rgb8,
+    Rgba8,
+    L16,
+    La16,
+    Rgb16,
+    Rgba16,
+    Rgb32F,
+    Rgba32F,
+}
+
+impl ColorType {
+    fn from(value: image::ColorType) -> Option<Self> {
+        Some(match value {
+            image::ColorType::L8 => Self::L8,
+            image::ColorType::La8 => Self::La8,
+            image::ColorType::Rgb8 => Self::Rgb8,
+            image::ColorType::Rgba8 => Self::Rgba8,
+            image::ColorType::L16 => Self::L16,
+            image::ColorType::La16 => Self::La16,
+            image::ColorType::Rgb16 => Self::Rgb16,
+            image::ColorType::Rgba16 => Self::Rgba16,
+            image::ColorType::Rgb32F => Self::Rgb32F,
+            image::ColorType::Rgba32F => Self::Rgba32F,
+            _ => return None,
+        })
+    }
+}
+
+/// Returns `true` to indicate failure.
+#[no_mangle]
+pub extern "system" fn load_png_info(input: *const u8, input_len: usize, result: &mut MaybeUninit<ImageInfo>) -> bool {
+    let input = unsafe { std::slice::from_raw_parts(input, input_len) };
+    let Ok(dec) = PngDecoder::new(Cursor::new(input)) else {
+        return true;
+    };
+    let (width, height) = dec.dimensions();
+    let Some(color_type) = ColorType::from(dec.color_type()) else {
+        return true;
+    };
+    result.write(ImageInfo {
+        width,
+        height,
+        byte_count: dec.total_bytes(),
+        color_type,
+    });
+    false
+}
+
+/// Returns `true` to indicate failure.
+#[no_mangle]
+pub extern "system" fn load_png(input: *const u8, input_len: usize, output: *mut u8, output_len: usize) -> bool {
+    let input = unsafe { std::slice::from_raw_parts(input, input_len) };
+    let output = unsafe { std::slice::from_raw_parts_mut(output, output_len) };
+    let Ok(dec) = PngDecoder::new(Cursor::new(input)) else {
+        return true;
+    };
+    let Ok(byte_count) = usize::try_from(dec.total_bytes()) else {
+        return true;
+    };
+    if byte_count != output.len() {
+        return true;
+    }
+    if let Err(_) = dec.read_image(output) {
+        return true;
+    }
+    false
+}