Add TIFF compression and corresponding tests

src/encoder/tiff_value.rs

@@ -1,4 +1,4 @@
-use std::io::Write;
+use std::{borrow::Cow, io::Write};
 
 use crate::{bytecast, tags::Type, TiffError, TiffFormatError, TiffResult};
 
@@ -12,7 +12,18 @@ pub trait TiffValue {
     fn bytes(&self) -> usize {
         self.count() * usize::from(Self::BYTE_LEN)
     }
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()>;
+
+    /// Access this value as an contiguous sequence of bytes.
+    /// If their is no trivial representation, allocate it on the heap.
+    fn data(&self) -> Cow<[u8]>;
+
+    /// Write this value to a TiffWriter.
+    /// While the default implementation will work in all cases, it may require unnecessary allocations.
+    /// The written bytes of any custom implementation MUST be the same as yielded by `self.data()`.
+    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
+        writer.write_bytes(&self.data())?;
+        Ok(())
+    }
 }
 
 impl TiffValue for [u8] {
@@ -23,9 +34,8 @@ impl TiffValue for [u8] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        writer.write_bytes(self)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(self)
     }
 }
 
@@ -37,10 +47,8 @@ impl TiffValue for [i8] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::i8_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::i8_as_ne_bytes(self))
     }
 }
 
@@ -52,10 +60,8 @@ impl TiffValue for [u16] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::u16_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::u16_as_ne_bytes(self))
     }
 }
 
@@ -67,10 +73,8 @@ impl TiffValue for [i16] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::i16_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::i16_as_ne_bytes(self))
     }
 }
 
@@ -82,10 +86,8 @@ impl TiffValue for [u32] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::u32_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::u32_as_ne_bytes(self))
     }
 }
 
@@ -97,10 +99,8 @@ impl TiffValue for [i32] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::i32_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::i32_as_ne_bytes(self))
     }
 }
 
@@ -112,10 +112,8 @@ impl TiffValue for [u64] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::u64_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::u64_as_ne_bytes(self))
     }
 }
 
@@ -127,10 +125,8 @@ impl TiffValue for [i64] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        let slice = bytecast::i64_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Borrowed(bytecast::i64_as_ne_bytes(self))
     }
 }
 
@@ -142,11 +138,9 @@ impl TiffValue for [f32] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        // We write using nativeedian so this sould be safe
-        let slice = bytecast::f32_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        // We write using native endian so this should be safe
+        Cow::Borrowed(bytecast::f32_as_ne_bytes(self))
     }
 }
 
@@ -158,75 +152,9 @@ impl TiffValue for [f64] {
         self.len()
     }
 
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        // We write using nativeedian so this sould be safe
-        let slice = bytecast::f64_as_ne_bytes(self);
-        writer.write_bytes(slice)?;
-        Ok(())
-    }
-}
-
-impl TiffValue for [Ifd] {
-    const BYTE_LEN: u8 = 4;
-    const FIELD_TYPE: Type = Type::IFD;
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        for x in self {
-            x.write(writer)?;
-        }
-        Ok(())
-    }
-}
-
-impl TiffValue for [Ifd8] {
-    const BYTE_LEN: u8 = 8;
-    const FIELD_TYPE: Type = Type::IFD8;
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        for x in self {
-            x.write(writer)?;
-        }
-        Ok(())
-    }
-}
-
-impl TiffValue for [Rational] {
-    const BYTE_LEN: u8 = 8;
-    const FIELD_TYPE: Type = Type::RATIONAL;
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        for x in self {
-            x.write(writer)?;
-        }
-        Ok(())
-    }
-}
-
-impl TiffValue for [SRational] {
-    const BYTE_LEN: u8 = 8;
-    const FIELD_TYPE: Type = Type::SRATIONAL;
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-
-    fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
-        for x in self {
-            x.write(writer)?;
-        }
-        Ok(())
+    fn data(&self) -> Cow<[u8]> {
+        // We write using native endian so this should be safe
+        Cow::Borrowed(bytecast::f64_as_ne_bytes(self))
     }
 }
 
@@ -242,6 +170,10 @@ impl TiffValue for u8 {
         writer.write_u8(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(vec![*self])
+    }
 }
 
 impl TiffValue for i8 {
@@ -256,6 +188,10 @@ impl TiffValue for i8 {
         writer.write_i8(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for u16 {
@@ -270,6 +206,10 @@ impl TiffValue for u16 {
         writer.write_u16(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for i16 {
@@ -284,6 +224,10 @@ impl TiffValue for i16 {
         writer.write_i16(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for u32 {
@@ -298,6 +242,10 @@ impl TiffValue for u32 {
         writer.write_u32(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for i32 {
@@ -312,6 +260,10 @@ impl TiffValue for i32 {
         writer.write_i32(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for u64 {
@@ -326,6 +278,10 @@ impl TiffValue for u64 {
         writer.write_u64(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for i64 {
@@ -340,6 +296,10 @@ impl TiffValue for i64 {
         writer.write_i64(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for f32 {
@@ -354,6 +314,10 @@ impl TiffValue for f32 {
         writer.write_f32(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for f64 {
@@ -368,6 +332,10 @@ impl TiffValue for f64 {
         writer.write_f64(*self)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned(self.to_ne_bytes().to_vec())
+    }
 }
 
 impl TiffValue for Ifd {
@@ -382,6 +350,13 @@ impl TiffValue for Ifd {
         writer.write_u32(self.0)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            let dword: [u8; 4] = self.0.to_ne_bytes();
+            dword.to_vec()
+        })
+    }
 }
 
 impl TiffValue for Ifd8 {
@@ -396,6 +371,13 @@ impl TiffValue for Ifd8 {
         writer.write_u64(self.0)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            let qword: [u8; 8] = self.0.to_ne_bytes();
+            qword.to_vec()
+        })
+    }
 }
 
 impl TiffValue for Rational {
@@ -411,6 +393,14 @@ impl TiffValue for Rational {
         writer.write_u32(self.d)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            let first_dword: [u8; 4] = self.n.to_ne_bytes();
+            let second_dword: [u8; 4] = self.d.to_ne_bytes();
+            [first_dword, second_dword].concat()
+        })
+    }
 }
 
 impl TiffValue for SRational {
@@ -426,6 +416,14 @@ impl TiffValue for SRational {
         writer.write_i32(self.d)?;
         Ok(())
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            let first_dword: [u8; 4] = self.n.to_ne_bytes();
+            let second_dword: [u8; 4] = self.d.to_ne_bytes();
+            [first_dword, second_dword].concat()
+        })
+    }
 }
 
 impl TiffValue for str {
@@ -445,6 +443,17 @@ impl TiffValue for str {
             Err(TiffError::FormatError(TiffFormatError::InvalidTag))
         }
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        Cow::Owned({
+            if self.is_ascii() && !self.bytes().any(|b| b == 0) {
+                let bytes: &[u8] = self.as_bytes();
+                [bytes, &[0]].concat()
+            } else {
+                vec![]
+            }
+        })
+    }
 }
 
 impl<'a, T: TiffValue + ?Sized> TiffValue for &'a T {
@@ -458,8 +467,45 @@ impl<'a, T: TiffValue + ?Sized> TiffValue for &'a T {
     fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
         (*self).write(writer)
     }
+
+    fn data(&self) -> Cow<[u8]> {
+        T::data(self)
+    }
 }
 
+macro_rules! impl_tiff_value_for_contiguous_sequence {
+    ($inner_type:ty; $bytes:expr; $field_type:expr) => {
+        impl $crate::encoder::TiffValue for [$inner_type] {
+            const BYTE_LEN: u8 = $bytes;
+            const FIELD_TYPE: Type = $field_type;
+
+            fn count(&self) -> usize {
+                self.len()
+            }
+
+            fn write<W: Write>(&self, writer: &mut TiffWriter<W>) -> TiffResult<()> {
+                for x in self {
+                    x.write(writer)?;
+                }
+                Ok(())
+            }
+
+            fn data(&self) -> Cow<[u8]> {
+                let mut buf: Vec<u8> = Vec::with_capacity(Self::BYTE_LEN as usize * self.len());
+                for x in self {
+                    buf.extend_from_slice(&x.data());
+                }
+                Cow::Owned(buf)
+            }
+        }
+    };
+}
+
+impl_tiff_value_for_contiguous_sequence!(Ifd; 4; Type::IFD);
+impl_tiff_value_for_contiguous_sequence!(Ifd8; 8; Type::IFD8);
+impl_tiff_value_for_contiguous_sequence!(Rational; 8; Type::RATIONAL);
+impl_tiff_value_for_contiguous_sequence!(SRational; 8; Type::SRATIONAL);
+
 /// Type to represent tiff values of type `IFD`
 #[derive(Clone)]
 pub struct Ifd(pub u32);