1 files changed, 204 insertions, 0 deletions
diff --git a/vendor/exr/src/image/read/layers.rs b/vendor/exr/src/image/read/layers.rs
new file mode 100644
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--- /dev/null
+++ b/vendor/exr/src/image/read/layers.rs
@@ -0,0 +1,204 @@
+//! How to read either a single or a list of layers.
+
+use crate::image::*;
+use crate::meta::header::{Header, LayerAttributes};
+use crate::error::{Result, UnitResult, Error};
+use crate::block::{UncompressedBlock, BlockIndex};
+use crate::math::Vec2;
+use crate::image::read::image::{ReadLayers, LayersReader};
+use crate::block::chunk::TileCoordinates;
+use crate::meta::MetaData;
+
+/// Specify to read all channels, aborting if any one is invalid.
+/// [`ReadRgbaChannels`] or [`ReadAnyChannels<ReadFlatSamples>`].
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct ReadAllLayers<ReadChannels> {
+
+    /// The channel reading specification
+    pub read_channels: ReadChannels,
+}
+
+/// Specify to read only the first layer which meets the previously specified requirements
+// FIXME do not throw error on deep data but just skip it!
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct ReadFirstValidLayer<ReadChannels> {
+
+    /// The channel reading specification
+    pub read_channels: ReadChannels,
+}
+
+/// A template that creates a [`ChannelsReader`] once for all channels per layer.
+pub trait ReadChannels<'s> {
+
+    /// The type of the temporary channels reader
+    type Reader: ChannelsReader;
+
+    /// Create a single reader for all channels of a specific layer
+    fn create_channels_reader(&'s self, header: &Header) -> Result<Self::Reader>;
+
+
+    /// Read only the first layer which meets the previously specified requirements
+    /// For example, skips layers with deep data, if specified earlier.
+    /// Aborts if the image contains no layers.
+    // TODO test if this filters non-deep layers while ignoring deep data layers!
+    fn first_valid_layer(self) -> ReadFirstValidLayer<Self> where Self:Sized { ReadFirstValidLayer { read_channels: self } }
+
+// FIXME do not throw error on deep data but just skip it!
+
+
+    /// Reads all layers, including an empty list. Aborts if any of the layers are invalid,
+    /// even if only one of the layers contains unexpected data.
+    fn all_layers(self) -> ReadAllLayers<Self> where Self:Sized { ReadAllLayers { read_channels: self } }
+
+    // TODO pub fn all_valid_layers(self) -> ReadAllValidLayers<Self> { ReadAllValidLayers { read_channels: self } }
+}
+
+
+/// Processes pixel blocks from a file and accumulates them into a list of layers.
+/// For example, `ChannelsReader` can be
+/// [`SpecificChannelsReader`] or [`AnyChannelsReader<FlatSamplesReader>`].
+#[derive(Debug, Clone, PartialEq)]
+pub struct AllLayersReader<ChannelsReader> {
+    layer_readers: SmallVec<[LayerReader<ChannelsReader>; 2]>, // TODO unpack struct?
+}
+
+/// Processes pixel blocks from a file and accumulates them into a single layers, using only the first.
+/// For example, `ChannelsReader` can be
+/// `SpecificChannelsReader` or `AnyChannelsReader<FlatSamplesReader>`.
+#[derive(Debug, Clone, PartialEq)]
+pub struct FirstValidLayerReader<ChannelsReader> {
+    layer_reader: LayerReader<ChannelsReader>,
+    layer_index: usize,
+}
+
+/// Processes pixel blocks from a file and accumulates them into a single layers.
+/// For example, `ChannelsReader` can be
+/// `SpecificChannelsReader` or `AnyChannelsReader<FlatSamplesReader>`.
+#[derive(Debug, Clone, PartialEq)]
+pub struct LayerReader<ChannelsReader> {
+    channels_reader: ChannelsReader,
+    attributes: LayerAttributes,
+    size: Vec2<usize>,
+    encoding: Encoding
+}
+
+/// Processes pixel blocks from a file and accumulates them into multiple channels per layer.
+pub trait ChannelsReader {
+
+    /// The type of the resulting channel collection
+    type Channels;
+
+    /// Specify whether a single block of pixels should be loaded from the file
+    fn filter_block(&self, tile: TileCoordinates) -> bool;
+
+    /// Load a single pixel block, which has not been filtered, into the reader, accumulating the channel data
+    fn read_block(&mut self, header: &Header, block: UncompressedBlock) -> UnitResult;
+
+    /// Deliver the final accumulated channel collection for the image
+    fn into_channels(self) -> Self::Channels;
+}
+
+
+impl<C> LayerReader<C> {
+    fn new(header: &Header, channels_reader: C) -> Result<Self> {
+        Ok(LayerReader {
+            channels_reader,
+            attributes: header.own_attributes.clone(),
+            size: header.layer_size,
+            encoding: Encoding {
+                compression: header.compression,
+                line_order: header.line_order,
+                blocks: match header.blocks {
+                    crate::meta::BlockDescription::ScanLines => Blocks::ScanLines,
+                    crate::meta::BlockDescription::Tiles(TileDescription { tile_size, .. }) => Blocks::Tiles(tile_size)
+                },
+            },
+        })
+    }
+}
+
+impl<'s, C> ReadLayers<'s> for ReadAllLayers<C> where C: ReadChannels<'s> {
+    type Layers = Layers<<C::Reader as ChannelsReader>::Channels>;
+    type Reader = AllLayersReader<C::Reader>;
+
+    fn create_layers_reader(&'s self, headers: &[Header]) -> Result<Self::Reader> {
+        let readers: Result<_> = headers.iter()
+            .map(|header| LayerReader::new(header, self.read_channels.create_channels_reader(header)?))
+            .collect();
+
+        Ok(AllLayersReader {
+            layer_readers: readers?
+        })
+    }
+}
+
+impl<C> LayersReader for AllLayersReader<C> where C: ChannelsReader {
+    type Layers = Layers<C::Channels>;
+
+    fn filter_block(&self, _: &MetaData, tile: TileCoordinates, block: BlockIndex) -> bool {
+        let layer = self.layer_readers.get(block.layer).expect("invalid layer index argument");
+        layer.channels_reader.filter_block(tile)
+    }
+
+    fn read_block(&mut self, headers: &[Header], block: UncompressedBlock) -> UnitResult {
+        self.layer_readers
+            .get_mut(block.index.layer).expect("invalid layer index argument")
+            .channels_reader.read_block(headers.get(block.index.layer).expect("invalid header index in block"), block)
+    }
+
+    fn into_layers(self) -> Self::Layers {
+        self.layer_readers
+            .into_iter()
+            .map(|layer| Layer {
+                channel_data: layer.channels_reader.into_channels(),
+                attributes: layer.attributes,
+                size: layer.size,
+                encoding: layer.encoding
+            })
+            .collect()
+    }
+}
+
+
+impl<'s, C> ReadLayers<'s> for ReadFirstValidLayer<C> where C: ReadChannels<'s> {
+    type Layers = Layer<<C::Reader as ChannelsReader>::Channels>;
+    type Reader = FirstValidLayerReader<C::Reader>;
+
+    fn create_layers_reader(&'s self, headers: &[Header]) -> Result<Self::Reader> {
+        headers.iter().enumerate()
+            .flat_map(|(index, header)|
+                self.read_channels.create_channels_reader(header)
+                    .and_then(|reader| Ok(FirstValidLayerReader {
+                        layer_reader: LayerReader::new(header, reader)?,
+                        layer_index: index
+                    }))
+                    .ok()
+            )
+            .next()
+            .ok_or(Error::invalid("no layer in the image matched your specified requirements"))
+    }
+}
+
+
+impl<C> LayersReader for FirstValidLayerReader<C> where C: ChannelsReader {
+    type Layers = Layer<C::Channels>;
+
+    fn filter_block(&self, _: &MetaData, tile: TileCoordinates, block: BlockIndex) -> bool {
+        block.layer == self.layer_index && self.layer_reader.channels_reader.filter_block(tile)
+    }
+
+    fn read_block(&mut self, headers: &[Header], block: UncompressedBlock) -> UnitResult {
+        debug_assert_eq!(block.index.layer, self.layer_index, "block should have been filtered out");
+        self.layer_reader.channels_reader.read_block(&headers[self.layer_index], block)
+    }
+
+    fn into_layers(self) -> Self::Layers {
+        Layer {
+            channel_data: self.layer_reader.channels_reader.into_channels(),
+            attributes: self.layer_reader.attributes,
+            size: self.layer_reader.size,
+            encoding: self.layer_reader.encoding
+        }
+    }
+}
+