Add example listing a files directories

src/decoder/mod.rs

@@ -1538,7 +1538,7 @@ impl<R: Read + Seek> Decoder<R> {
     }
 
     /// Get the IFD decoder for our current image IFD.
-    fn image_ifd(&mut self) -> IfdDecoder<'_> {
+    pub fn image_ifd(&mut self) -> IfdDecoder<'_> {
         IfdDecoder {
             inner: tag_reader::TagReader {
                 decoder: &mut self.value_reader,
@@ -1885,6 +1885,11 @@ impl IfdDecoder<'_> {
     pub fn get_tag_ascii_string(&mut self, tag: Tag) -> TiffResult<String> {
         self.get_tag(tag)?.into_string()
     }
+
+    /// Inspect the raw underlying directory.
+    pub fn directory(&self) -> &Directory {
+        self.inner.ifd
+    }
 }
 
 impl<'l> IfdDecoder<'l> {

src/tags.rs

@@ -1,4 +1,5 @@
 use crate::encoder::TiffValue;
+use core::fmt;
 
 macro_rules! tags {
     {
@@ -169,6 +170,18 @@ pub enum Tag(u16) unknown(
 // practice it just returns garbage and the validity does not matter greatly to us).
 pub struct IfdPointer(pub u64);
 
+impl fmt::LowerHex for IfdPointer {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::LowerHex::fmt(&self.0, f)
+    }
+}
+
+impl core::fmt::UpperHex for IfdPointer {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::UpperHex::fmt(&self.0, f)
+    }
+}
+
 tags! {
 /// The type of an IFD entry (a 2 byte field).
 pub enum Type(u16) {