Fix 1bpp image decoding and add a test image (#252)

src/decoder/image.rs

@@ -687,8 +687,6 @@ impl Image {
                 let row = &mut row[..data_row_bytes];
                 reader.read_exact(row)?;
 
-                println!("chunk={chunk_index}, index={i}");
-
                 // Skip horizontal padding
                 if chunk_row_bytes > data_row_bytes {
                     let len = u64::try_from(chunk_row_bytes - data_row_bytes)?;

src/decoder/mod.rs

@@ -969,13 +969,20 @@ impl<R: Read + Seek> Decoder<R> {
     }
 
     fn result_buffer(&self, width: usize, height: usize) -> TiffResult<DecodingResult> {
-        let buffer_size = match width
+        let bits_per_sample = self.image().bits_per_sample;
+
+        let row_samples = if bits_per_sample >= 8 {
+            width
+        } else {
+            ((((width as u64) * bits_per_sample as u64) + 7) / 8)
+                .try_into()
+                .map_err(|_| TiffError::LimitsExceeded)?
+        };
+
+        let buffer_size = row_samples
             .checked_mul(height)
             .and_then(|x| x.checked_mul(self.image().samples_per_pixel()))
-        {
-            Some(s) => s,
-            None => return Err(TiffError::LimitsExceeded),
-        };
+            .ok_or(TiffError::LimitsExceeded)?;
 
         let max_sample_bits = self.image().bits_per_sample;
         match self.image().sample_format {

tests/decode_images.rs

@@ -216,6 +216,11 @@ fn issue_69() {
 //assert!(img_res.is_ok());
 //}
 
+#[test]
+fn test_tiled_gray_i1() {
+    test_image_sum_u8("tiled-gray-i1.tif", ColorType::Gray(1), 30531);
+}
+
 #[test]
 fn test_tiled_rgb_u8() {
     test_image_sum_u8("tiled-rgb-u8.tif", ColorType::RGB(8), 39528948);