Construct ValueBuffer from TiffValue

Author: 197g

src/encoder/mod.rs

@@ -294,7 +294,7 @@ impl<'a, W: 'a + Write + Seek, K: TiffKind> DirectoryEncoder<'a, W, K> {
     /// Write a tag-value pair with prepared byte data.
     ///
     /// Note that the library will _not_ attempt to verify that the data type or the count of the
-    /// opaque value is permissible for the given tag. The data will be associated with the tag
+    /// buffered value is permissible for the given tag. The data will be associated with the tag
     /// exactly as-is.
     ///
     /// An error is returned if the byte order of the presented value does not match the byte order

src/tags.rs

@@ -1,4 +1,4 @@
-use crate::decoder::ifd;
+use crate::{decoder::ifd, encoder::TiffValue};
 
 macro_rules! tags {
     {
@@ -362,6 +362,15 @@ impl ValueBuffer {
         }
     }
 
+    /// Create a value with native byte order from in-memory data.
+    pub fn from_value<T: TiffValue>(value: &T) -> Self {
+        ValueBuffer {
+            bytes: value.data().into_owned(),
+            ty: <T as TiffValue>::FIELD_TYPE,
+            byte_order: ByteOrder::native(),
+        }
+    }
+
     pub fn byte_order(&self) -> ByteOrder {
         self.byte_order
     }