Expand requested plane when reading chunk

src/decoder/image.rs

@@ -30,6 +30,23 @@ pub(crate) struct TileAttributes {
     pub tile_length: usize,
 }
 
+pub(crate) struct PlaneLayout {
+    /// Total chunks per plane.
+    pub plane_chunks: usize,
+    /// Buffer offset from one row of the image to its next, in bytes.
+    pub output_row_stride: usize,
+    /// Buffer offset from the start of one chunk to the next within a row.
+    pub chunk_row_stride: usize,
+    /// Buffer offset per strip of chunks.
+    pub chunks_stride: usize,
+    /// Number of chunks in one strip of chunks.
+    pub chunks_across: usize,
+    /// Number of bytes in a plane.
+    pub plane_stride: usize,
+    /// Buffer offset from one plane of output to the next.
+    pub plane_offsets: Vec<usize>,
+}
+
 impl TileAttributes {
     pub fn tiles_across(&self) -> usize {
         self.image_width.div_ceil(self.tile_width)
@@ -594,6 +611,77 @@ impl Image {
         }
     }
 
+    /// Get the layout for each output plane (i.e. one plane for non-planar tiff).
+    pub(crate) fn preferred_output_layout(&self) -> TiffResult<PlaneLayout> {
+        let Image { width, height, .. } = *self;
+
+        let chunk_dimensions = self.chunk_dimensions()?;
+
+        let chunk_dimensions = (
+            chunk_dimensions.0.min(width),
+            chunk_dimensions.1.min(height),
+        );
+
+        if chunk_dimensions.0 == 0 || chunk_dimensions.1 == 0 {
+            return Err(TiffError::FormatError(
+                TiffFormatError::InconsistentSizesEncountered,
+            ));
+        }
+
+        let color = self.colortype()?;
+        let samples = self.samples_per_out_texel(color);
+
+        let bits_per_sample = u64::from(self.bits_per_sample);
+
+        let output_row_bits = (u64::from(width) * bits_per_sample)
+            .checked_mul(samples as u64)
+            .ok_or(TiffError::LimitsExceeded)?;
+        let output_row_stride: usize = output_row_bits.div_ceil(8).try_into()?;
+
+        let chunk_row_bits = (chunk_dimensions.0 as u64 * bits_per_sample)
+            .checked_mul(samples as u64)
+            .ok_or(TiffError::LimitsExceeded)?;
+        let chunk_row_stride: usize = chunk_row_bits.div_ceil(8).try_into()?;
+
+        let chunks_stride = output_row_bits
+            .div_ceil(8)
+            .checked_mul(u64::from(chunk_dimensions.1))
+            .ok_or(TiffError::LimitsExceeded)?
+            .try_into()?;
+
+        let plane_stride = output_row_bits
+            .div_ceil(8)
+            .checked_mul(u64::from(height))
+            .ok_or(TiffError::LimitsExceeded)?
+            .try_into()?;
+
+        let plane_offsets = (0..=usize::MAX)
+            .step_by(plane_stride)
+            .take(usize::from(color.num_samples() / samples))
+            .collect();
+
+        let chunks_across: usize = ((width - 1) / chunk_dimensions.0 + 1).try_into()?;
+
+        // We would not get an offset in byte units, sorry, no bit interleaving.
+        if chunks_across > 1 && chunk_row_bits % 8 != 0 {
+            return Err(TiffError::UnsupportedError(
+                TiffUnsupportedError::MisalignedTileBoundaries,
+            ));
+        }
+
+        let plane_chunks = self.chunk_offsets.len() / self.strips_per_pixel();
+
+        Ok(PlaneLayout {
+            output_row_stride,
+            plane_chunks,
+            chunks_stride,
+            chunks_across,
+            chunk_row_stride,
+            plane_stride,
+            plane_offsets,
+        })
+    }
+
     pub(crate) fn chunk_data_dimensions(&self, chunk_index: u32) -> TiffResult<(u32, u32)> {
         let dims = self.chunk_dimensions()?;
 
@@ -640,7 +728,6 @@ impl Image {
         } = reader;
 
         let byte_order = reader.byte_order;
-        let reader = reader.inner();
 
         // Validate that the color type is supported.
         let color_type = self.colortype()?;
@@ -740,17 +827,17 @@ impl Image {
         assert!(output_row_stride >= data_row_bytes);
         assert!(buf.len() >= output_row_stride * (data_dims.1 as usize - 1) + data_row_bytes);
 
+        let is_all_bits = samples == usize::from(data_samples);
+        let is_output_chunk_rows = output_row_stride == chunk_row_bytes;
+
         let mut reader = Self::create_reader(
-            reader,
+            reader.inner(),
             compression_method,
             *compressed_bytes,
             self.jpeg_tables.as_deref().map(|a| &**a),
             chunk_dims,
         )?;
 
-        let is_all_bits = samples == usize::from(data_samples);
-        let is_output_chunk_rows = output_row_stride == chunk_row_bytes;
-
         if is_output_chunk_rows && is_all_bits {
             // Here we can read directly into the output buffer itself.
             let tile = &mut buf[..chunk_row_bytes * data_dims.1 as usize];

src/decoder/mod.rs

@@ -210,6 +210,10 @@ pub struct BufferLayoutPreference {
     pub len: usize,
     /// Minimum number of bytes to represent a row of image data of the requested content.
     pub row_stride: Option<NonZeroUsize>,
+    /// Number of planes in the image.
+    pub planes: usize,
+    /// Number of bytes used to represent one plane.
+    pub plane_stride: Option<NonZeroUsize>,
 }
 
 /// The count and matching discriminant for a `DecodingBuffer`.
@@ -1101,15 +1105,22 @@ impl<R: Read + Seek> Decoder<R> {
         chunk_index: u32,
     ) -> TiffResult<BufferLayoutPreference> {
         let data_dims = self.image().chunk_data_dimensions(chunk_index)?;
+
         let layout = self
             .result_extent(data_dims.0 as usize, data_dims.1 as usize)?
             .preferred_layout()?;
 
         let row_stride = self.image.minimum_row_stride(data_dims);
 
+        let plane_stride = row_stride
+            .and_then(|v| v.get().checked_mul(data_dims.1 as usize))
+            .and_then(core::num::NonZeroUsize::new);
+
         Ok(BufferLayoutPreference {
             len: layout.size(),
             row_stride,
+            planes: 1,
+            plane_stride,
         })
     }
 
@@ -1183,17 +1194,13 @@ impl<R: Read + Seek> Decoder<R> {
     /// indicate the layout needed to read the first data plane. This will be fixed in a future
     /// major version of `tiff`.
     pub fn image_buffer_layout(&mut self) -> TiffResult<BufferLayoutPreference> {
-        let data_dims @ (width, height) = (self.image.width, self.image.height);
-
-        let layout = self
-            .result_extent(width as usize, height as usize)?
-            .preferred_layout()?;
-
-        let row_stride = self.image.minimum_row_stride(data_dims);
+        let layout = self.image().preferred_output_layout()?;
 
         Ok(BufferLayoutPreference {
-            len: layout.size(),
-            row_stride,
+            len: layout.plane_stride,
+            row_stride: core::num::NonZeroUsize::new(layout.output_row_stride),
+            planes: layout.plane_offsets.len(),
+            plane_stride: core::num::NonZeroUsize::new(layout.plane_stride),
         })
     }
 
@@ -1224,73 +1231,46 @@ impl<R: Read + Seek> Decoder<R> {
     /// When the image is stored as a planar configuration, this method will currently only read
     /// the first sample's plane. This will be fixed in a future major version of `tiff`.
     pub fn read_image_bytes(&mut self, buffer: &mut [u8]) -> TiffResult<()> {
-        let width = self.image().width;
-        let height = self.image().height;
+        let image::PlaneLayout {
+            plane_chunks,
+            output_row_stride,
+            chunk_row_stride,
+            chunks_stride,
+            chunks_across,
+            plane_stride,
+            plane_offsets,
+        } = self.image().preferred_output_layout()?;
 
-        let extent = self.result_extent(width as usize, height as usize)?;
-        extent.assert_layout(buffer.len())?;
+        // Find how many planes fit into the output buffer.
+        let used_plane_offsets = plane_offsets
+            .iter()
+            .enumerate()
+            // Find the first plane that would not fit completely at its offset.
+            .skip_while(|(_, &offset)| buffer.len().checked_sub(plane_stride) >= Some(offset))
+            .nth(0)
+            // If all planes fit, use all of them.
+            .map_or(plane_offsets.len(), |(idx, _)| idx);
 
-        if width == 0 || height == 0 {
-            return Ok(());
-        }
-
-        let chunk_dimensions = self.image().chunk_dimensions()?;
-        let chunk_dimensions = (
-            chunk_dimensions.0.min(width),
-            chunk_dimensions.1.min(height),
-        );
-
-        if chunk_dimensions.0 == 0 || chunk_dimensions.1 == 0 {
-            return Err(TiffError::FormatError(
-                TiffFormatError::InconsistentSizesEncountered,
-            ));
-        }
-
-        let color = self.image().colortype()?;
-        let samples = self.image().samples_per_out_texel(color);
-
-        if samples == 0 {
-            return Err(TiffError::FormatError(
-                TiffFormatError::InconsistentSizesEncountered,
-            ));
-        }
-
-        let output_row_bits = (width as u64 * self.image.bits_per_sample as u64)
-            .checked_mul(samples as u64)
-            .ok_or(TiffError::LimitsExceeded)?;
-        let output_row_stride: usize = output_row_bits.div_ceil(8).try_into()?;
-
-        let chunk_row_bits = (chunk_dimensions.0 as u64 * self.image.bits_per_sample as u64)
-            .checked_mul(samples as u64)
-            .ok_or(TiffError::LimitsExceeded)?;
-        let chunk_row_bytes: usize = chunk_row_bits.div_ceil(8).try_into()?;
-
-        let chunks_across = ((width - 1) / chunk_dimensions.0 + 1) as usize;
-
-        if chunks_across > 1 && chunk_row_bits % 8 != 0 {
-            return Err(TiffError::UnsupportedError(
-                TiffUnsupportedError::MisalignedTileBoundaries,
-            ));
-        }
-
-        let image_chunks = self.image().chunk_offsets.len() / self.image().strips_per_pixel();
         // For multi-band images, only the first band is read.
         // Possible improvements:
         // * pass requested band as parameter
         // * collect bands to a RGB encoding result in case of RGB bands
-        for chunk in 0..image_chunks {
-            self.goto_offset_u64(self.image().chunk_offsets[chunk])?;
-
+        for chunk in 0..plane_chunks {
             let x = chunk % chunks_across;
             let y = chunk / chunks_across;
-            let buffer_offset =
-                y * output_row_stride * chunk_dimensions.1 as usize + x * chunk_row_bytes;
-            self.image.expand_chunk(
-                &mut self.value_reader,
-                &mut buffer[buffer_offset..],
-                output_row_stride,
-                chunk as u32,
-            )?;
+            let buffer_offset = y * chunks_stride + x * chunk_row_stride;
+
+            for (idx, &plane_offset) in plane_offsets[..used_plane_offsets].iter().enumerate() {
+                let chunk = chunk + idx * plane_chunks;
+                self.goto_offset_u64(self.image().chunk_offsets[chunk])?;
+
+                self.image.expand_chunk(
+                    &mut self.value_reader,
+                    &mut buffer[plane_offset..][buffer_offset..],
+                    output_row_stride,
+                    chunk as u32,
+                )?;
+            }
         }
 
         Ok(())