Add SignedByte and SignedShort enum variants (#234)

src/decoder/ifd.rs

@@ -11,7 +11,7 @@ use crate::{TiffError, TiffFormatError, TiffResult};
 
 use self::Value::{
     Ascii, Byte, Double, Float, Ifd, IfdBig, List, Rational, RationalBig, SRational, SRationalBig,
-    Short, Signed, SignedBig, Unsigned, UnsignedBig,
+    Short, Signed, SignedBig, SignedByte, SignedShort, Unsigned, UnsignedBig,
 };
 
 #[allow(unused_qualifications)]
@@ -20,6 +20,8 @@ use self::Value::{
 pub enum Value {
     Byte(u8),
     Short(u16),
+    SignedByte(i8),
+    SignedShort(i16),
     Signed(i32),
     SignedBig(i64),
     Unsigned(u32),
@@ -43,6 +45,14 @@ impl Value {
             val => Err(TiffError::FormatError(TiffFormatError::ByteExpected(val))),
         }
     }
+    pub fn into_i8(self) -> TiffResult<i8> {
+        match self {
+            SignedByte(val) => Ok(val),
+            val => Err(TiffError::FormatError(TiffFormatError::SignedByteExpected(
+                val,
+            ))),
+        }
+    }
 
     pub fn into_u16(self) -> TiffResult<u16> {
         match self {
@@ -55,6 +65,18 @@ impl Value {
         }
     }
 
+    pub fn into_i16(self) -> TiffResult<i16> {
+        match self {
+            SignedByte(val) => Ok(val.into()),
+            SignedShort(val) => Ok(val),
+            Signed(val) => Ok(i16::try_from(val)?),
+            SignedBig(val) => Ok(i16::try_from(val)?),
+            val => Err(TiffError::FormatError(
+                TiffFormatError::SignedShortExpected(val),
+            )),
+        }
+    }
+
     pub fn into_u32(self) -> TiffResult<u32> {
         match self {
             Short(val) => Ok(val.into()),
@@ -70,6 +92,8 @@ impl Value {
 
     pub fn into_i32(self) -> TiffResult<i32> {
         match self {
+            SignedByte(val) => Ok(val.into()),
+            SignedShort(val) => Ok(val.into()),
             Signed(val) => Ok(val),
             SignedBig(val) => Ok(i32::try_from(val)?),
             val => Err(TiffError::FormatError(
@@ -93,6 +117,8 @@ impl Value {
 
     pub fn into_i64(self) -> TiffResult<i64> {
         match self {
+            SignedByte(val) => Ok(val.into()),
+            SignedShort(val) => Ok(val.into()),
             Signed(val) => Ok(val.into()),
             SignedBig(val) => Ok(val),
             val => Err(TiffError::FormatError(
@@ -204,6 +230,8 @@ impl Value {
                 }
                 Ok(new_vec)
             }
+            SignedByte(val) => Ok(vec![val.into()]),
+            SignedShort(val) => Ok(vec![val.into()]),
             Signed(val) => Ok(vec![val]),
             SignedBig(val) => Ok(vec![i32::try_from(val)?]),
             SRational(numerator, denominator) => Ok(vec![numerator, denominator]),
@@ -289,6 +317,8 @@ impl Value {
                 }
                 Ok(new_vec)
             }
+            SignedByte(val) => Ok(vec![val.into()]),
+            SignedShort(val) => Ok(vec![val.into()]),
             Signed(val) => Ok(vec![val.into()]),
             SignedBig(val) => Ok(vec![val]),
             SRational(numerator, denominator) => Ok(vec![numerator.into(), denominator.into()]),