more tests

24 files changed, 149 insertions, 17 deletions

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..04e126a
--- /dev/null
+++ b/README.md
@@ -0,0 +1,46 @@
+## tiny-png
+
+Tiny Rust PNG decoder.
+
+This decoder can be used without `std` or even `alloc` by disabling the `std` feature (enabled by default).
+
+## Goals
+
+- Correctly decode all non-interlaced PNG files (if a non-interlaced PNG is decoded incorrectly, please report it as a bug)
+- Small code size
+- No panics (if any function panics, please report it as a bug).
+- No unsafe code
+
+## Non-goals
+
+- Adam7 interlacing (interlaced PNGs are rare, and this would require additional code complexity
+  — but if you want to add it behind a feature gate, feel free to)
+- Sacrificing code size for speed (except maybe with a feature enabled)
+
+## Example usage
+
+Very basic usage:
+
+```rust
+let mut buffer = vec![0; 1 << 20]; // hope this is big enough!
+let mut png = &include_bytes!("image.png")[..];
+let image = tiny_png::read_png(&mut png, None, &mut buffer).expect("bad PNG");
+println!("{}x{} image", image.width(), image.height());
+let pixels = image.pixels();
+println!("top-left pixel is #{:02x}{:02x}{:02x}", pixels[0], pixels[1], pixels[2]);
+// (^ this only makes sense for RGB 8bpc images)
+```
+
+Allocate the right number of bytes:
+
+```rust
+let mut png = &include_bytes!("image.png")[..];
+let header = tiny_png::read_png_header(&mut png).expect("bad PNG");
+println!("need {} bytes of memory", header.required_bytes());
+let mut buffer = vec![0; header.required_bytes()];
+let image = tiny_png::read_png(&mut png, Some(&header), &mut buffer).expect("bad PNG");
+println!("{}x{} image", image.width(), image.height());
+let pixels = image.pixels();
+println!("top-left pixel is #{:02x}{:02x}{:02x}", pixels[0], pixels[1], pixels[2]);
+// (^ this only makes sense for RGB 8bpc images)
+```
diff --git a/examples/alloc_correct.rs b/examples/alloc_correct.rs
new file mode 100644
index 0000000..6711a1c
--- /dev/null
+++ b/examples/alloc_correct.rs
@@ -0,0 +1,14 @@
+fn main() {
+	let mut png = &include_bytes!("image.png")[..];
+	let header = tiny_png::read_png_header(&mut png).expect("bad PNG");
+	println!("need {} bytes of memory", header.required_bytes());
+	let mut buffer = vec![0; header.required_bytes()];
+	let image = tiny_png::read_png(&mut png, Some(&header), &mut buffer).expect("bad PNG");
+	println!("{}x{} image", image.width(), image.height());
+	let pixels = image.pixels();
+	println!(
+		"top-left pixel is #{:02x}{:02x}{:02x}",
+		pixels[0], pixels[1], pixels[2]
+	);
+	// (^ this only makes sense for RGB 8bpc images)
+}
diff --git a/examples/image.png b/examples/image.png
new file mode 100644
index 0000000..5452484
--- /dev/null
+++ b/examples/image.png
diff --git a/examples/small.rs b/examples/small.rs
deleted file mode 100644
index e6af172..0000000
--- a/examples/small.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-fn main() {
-	let mut data = &include_bytes!("small.png")[..];
-	let header = tiny_png::read_png_header(&mut data).unwrap();
-	let mut buf = vec![0; header.required_bytes()];
-	let result = tiny_png::read_png(&mut data, Some(&header), &mut buf);
-	println!("{result:?}");
-}
diff --git a/examples/very_basic.rs b/examples/very_basic.rs
new file mode 100644
index 0000000..33043b6
--- /dev/null
+++ b/examples/very_basic.rs
@@ -0,0 +1,12 @@
+fn main() {
+	let mut my_buffer = vec![0; 1 << 20]; // hope this is big enough!
+	let mut png = &include_bytes!("image.png")[..];
+	let image = tiny_png::read_png(&mut png, None, &mut my_buffer).expect("bad PNG");
+	println!("{}x{} image", image.width(), image.height());
+	let pixels = image.pixels();
+	println!(
+		"top-left pixel is #{:02x}{:02x}{:02x}",
+		pixels[0], pixels[1], pixels[2]
+	);
+	// (^ this only makes sense for RGB 8bpc images)
+}
diff --git a/src/lib.rs b/src/lib.rs
index 5869868..1602bca 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -786,13 +786,13 @@ fn apply_filters<I: IOError>(header: &ImageHeader, data: &mut [u8]) -> Result<()
 #[derive(Debug)]
 pub struct ImageData<'a> {
 	header: ImageHeader,
-	pixels: &'a [u8],
+	buffer: &'a mut [u8],
 	palette: [[u8; 4]; 256],
 }
 
 impl ImageData<'_> {
 	pub fn pixels(&self) -> &[u8] {
-		self.pixels
+		&self.buffer[..self.header.data_size()]
 	}
 	pub fn palette(&self) -> &[[u8; 4]] {
 		&self.palette[..]
@@ -832,6 +832,7 @@ fn read_non_idat_chunks<R: Read>(
 			chunk_header[7],
 		];
 		if &chunk_type == b"IEND" {
+			reader.skip_bytes(4)?; // CRC
 			break;
 		} else if &chunk_type == b"IDAT" {
 			return Ok(Some(chunk_len));
@@ -895,7 +896,7 @@ pub fn read_png<'a, R: Read>(
 	let buf = writer.slice;
 	apply_filters(&header, buf)?;
 	Ok(ImageData {
-		pixels: &buf[..header.data_size()],
+		buffer: buf,
 		header,
 		palette,
 	})
@@ -917,9 +918,8 @@ mod tests {
 		let mut r = std::io::BufReader::new(File::open(path).expect("file not found"));
 		let tiny_header = read_png_header(&mut r).unwrap();
 		let mut tiny_buf = vec![0; tiny_header.required_bytes()];
-		let tiny_bytes = read_png(&mut r, Some(&tiny_header), &mut tiny_buf)
-			.unwrap()
-			.pixels;
+		let image = read_png(&mut r, Some(&tiny_header), &mut tiny_buf).unwrap();
+		let tiny_bytes = image.pixels();
 
 		assert_eq!(png_bytes.len(), tiny_bytes.len());
 		assert_eq!(png_bytes, tiny_bytes);
@@ -935,9 +935,8 @@ mod tests {
 
 		let tiny_header = read_png_header(&mut bytes).unwrap();
 		let mut tiny_buf = vec![0; tiny_header.required_bytes()];
-		let tiny_bytes = read_png(&mut bytes, Some(&tiny_header), &mut tiny_buf)
-			.unwrap()
-			.pixels;
+		let image = read_png(&mut bytes, Some(&tiny_header), &mut tiny_buf).unwrap();
+		let tiny_bytes = image.pixels();
 
 		assert_eq!(png_bytes.len(), tiny_bytes.len());
 		assert_eq!(png_bytes, tiny_bytes);
@@ -952,7 +951,7 @@ mod tests {
 
 	#[test]
 	fn test_small() {
-		test_both!("examples/small.png");
+		test_both!("test/small.png");
 	}
 	#[test]
 	fn test_small_rgb() {
@@ -963,6 +962,10 @@ mod tests {
 		test_both!("test/small_rgba.png");
 	}
 	#[test]
+	fn test_gray_alpha() {
+		test_both!("test/gray_alpha.png");
+	}
+	#[test]
 	fn test_earth0() {
 		test_both!("test/earth0.png");
 	}
@@ -971,7 +974,71 @@ mod tests {
 		test_both!("test/earth9.png");
 	}
 	#[test]
+	fn test_photograph() {
+		test_both!("test/photograph.png");
+	}
+	#[test]
 	fn test_earth_palette() {
 		test_both!("test/earth_palette.png");
 	}
+	#[test]
+	fn test_württemberg() {
+		test_both!("test/württemberg.png");
+	}
+	#[test]
+	fn test_endsleigh() {
+		test_both!("test/endsleigh.png");
+	}
+	#[test]
+	fn test_1qps() {
+		test_both!("test/1QPS.png");
+	}
+	#[test]
+	fn test_rabbit() {
+		test_both!("test/rabbit.png");
+	}
+	#[test]
+	fn test_basketball() {
+		test_both!("test/basketball.png");
+	}
+	#[test]
+	fn test_triangle() {
+		test_both!("test/triangle.png");
+	}
+	#[test]
+	fn test_iroquois() {
+		test_both!("test/iroquois.png");
+	}
+	#[test]
+	fn test_canada() {
+		test_both!("test/canada.png");
+	}
+	#[test]
+	fn test_berry() {
+		test_both!("test/berry.png");
+	}
+	#[test]
+	fn test_adam() {
+		test_both!("test/adam.png");
+	}
+	#[test]
+	fn test_nightingale() {
+		test_both!("test/nightingale.png");
+	}
+	#[test]
+	fn test_ratatoskr() {
+		test_both!("test/ratatoskr.png");
+	}
+	#[test]
+	fn test_cheerios() {
+		test_both!("test/cheerios.png");
+	}
+	#[test]
+	fn test_cavendish() {
+		test_both!("test/cavendish.png");
+	}
+	#[test]
+	fn test_ouroboros() {
+		test_both!("test/ouroboros.png");
+	}
 }
diff --git a/test/1QPS.png b/test/1QPS.png
new file mode 100644
index 0000000..50836ca
--- /dev/null
+++ b/test/1QPS.png
diff --git a/test/adam.png b/test/adam.png
new file mode 100644
index 0000000..8661a2e
--- /dev/null
+++ b/test/adam.png
diff --git a/test/basketball.png b/test/basketball.png
new file mode 100644
index 0000000..bbcf32f
--- /dev/null
+++ b/test/basketball.png
diff --git a/test/berry.png b/test/berry.png
new file mode 100644
index 0000000..341564a
--- /dev/null
+++ b/test/berry.png
diff --git a/test/canada.png b/test/canada.png
new file mode 100644
index 0000000..41ea0db
--- /dev/null
+++ b/test/canada.png
diff --git a/test/cavendish.png b/test/cavendish.png
new file mode 100644
index 0000000..5bf99ff
--- /dev/null
+++ b/test/cavendish.png
diff --git a/test/cheerios.png b/test/cheerios.png
new file mode 100644
index 0000000..a53fd2c
--- /dev/null
+++ b/test/cheerios.png
diff --git a/test/endsleigh.png b/test/endsleigh.png
new file mode 100644
index 0000000..2dc6e65
--- /dev/null
+++ b/test/endsleigh.png
diff --git a/test/gray_alpha.png b/test/gray_alpha.png
new file mode 100644
index 0000000..2857715
--- /dev/null
+++ b/test/gray_alpha.png
diff --git a/test/iroquois.png b/test/iroquois.png
new file mode 100644
index 0000000..069cd4c
--- /dev/null
+++ b/test/iroquois.png
diff --git a/test/nightingale.png b/test/nightingale.png
new file mode 100644
index 0000000..617a7fc
--- /dev/null
+++ b/test/nightingale.png
diff --git a/test/ouroboros.png b/test/ouroboros.png
new file mode 100644
index 0000000..fd22ae8
--- /dev/null
+++ b/test/ouroboros.png
diff --git a/test/photograph.png b/test/photograph.png
new file mode 100644
index 0000000..09a62b9
--- /dev/null
+++ b/test/photograph.png
diff --git a/test/rabbit.png b/test/rabbit.png
new file mode 100644
index 0000000..c1f4928
--- /dev/null
+++ b/test/rabbit.png
diff --git a/test/ratatoskr.png b/test/ratatoskr.png
new file mode 100644
index 0000000..5452484
--- /dev/null
+++ b/test/ratatoskr.png
diff --git a/examples/small.png b/test/small.png
index 47226a2..47226a2 100644
--- a/examples/small.png
+++ b/test/small.png
diff --git a/test/triangle.png b/test/triangle.png
new file mode 100644
index 0000000..893b4dd
--- /dev/null
+++ b/test/triangle.png
diff --git a/test/württemberg.png b/test/württemberg.png
new file mode 100644
index 0000000..1c02a68
--- /dev/null
+++ b/test/württemberg.png