Use tiff tag types from tiff crate (#11)

* Add tiff

TIFF decoding and encoding library in pure Rust! Repo at https://github.com/image-rs/image-tiff

* Rename src/tiff.rs to src/geotiff.rs

Reduce confusion when using the `tiff` crate later.

* Use tiff tag type enums from upstream tiff crate

Remove the TagType enum in src/lowlevel.rs, use tiff:tags:Type instead (https://docs.rs/tiff/0.9.1/tiff/tags/enum.Type.html). Added support for IFD, LONG8, SLONG8 and IFD8 types.

* Fix clippy lint error on match_ref_pats

Remove the & from the match statements. Xref https://rust-lang.github.io/rust-clippy/master/index.html#/match_ref_pats

* Add note to main README.md on refactoring process to rely on tiff crate

Also bumped up version in badge from v0.0.1 to v0.0.2 to match that in crates.io.

Cargo.toml

@@ -9,3 +9,4 @@ repository = "https://github.com/georust/geotiff"
 byteorder = "*"
 enum_primitive = "*"
 num = "*"
+tiff = "0.9"

README.md

@@ -1,6 +1,14 @@
 # A TIFF Library for Rust
 
-![Version](https://img.shields.io/badge/version-v0.0.1-red.svg)
+![Version](https://img.shields.io/badge/version-v0.0.2-red.svg)
+
+> [!IMPORTANT]
+> This crate is currently undergoing a significant refactoring process to be built on
+> top of the [`tiff`](https://crates.io/crates/tiff) crate, so expect breaking changes
+> as we work towards a v0.1.0 release sometime in 2024 (contributions are welcome!). See
+> the thread at https://github.com/georust/geotiff/issues/7 for more details.
+
+## Motivation (pre-2020)
 
 I needed this library to import elevation models for a routing library. As elevation models usually come in GeoTIFF format, but no such library was available for Rust, I created this library, taking other libraries as inspiration:
 
@@ -46,4 +54,3 @@ Several documents describe the structure of a (Geo)TIFF:
 * The official TIFF specification: http://download.osgeo.org/geotiff/spec/tiff6.pdf.
 * The official GeoTIFF specitication: http://download.osgeo.org/geotiff/spec/geotiff.rtf
 * The article "GeoTIFF – A standard image file format for GIS applications" by Mahammad and Ramakrishnan: https://www.geospatialworld.net/article/geotiff-a-standard-image-file-format-for-gis-applications/
-

src/tiff.rs → src/geotiff.rs

@@ -1,6 +1,7 @@
 use std::collections::HashSet;
 
 use enum_primitive::FromPrimitive;
+use tiff::tags::Type;
 
 use crate::lowlevel::*;
 
@@ -35,11 +36,11 @@ pub struct IFD {
 /// tag values.
 #[derive(Debug)]
 pub struct IFDEntry {
-    pub tag:          TIFFTag,
-    pub tpe:          TagType,
-    pub count:        LONG,
+    pub tag: TIFFTag,
+    pub tpe: Type,
+    pub count: LONG,
     pub value_offset: LONG,
-    pub value:        Vec<TagValue>,
+    pub value: Vec<TagValue>,
 }
 
 /// Implementations for the IFD struct.
@@ -62,11 +63,6 @@ pub fn decode_tag(value: u16) -> Option<TIFFTag> {
     TIFFTag::from_u16(value)
 }
 
-/// Decodes an u16 value into a TagType.
-pub fn decode_tag_type(tpe: u16) -> Option<TagType> {
-    TagType::from_u16(tpe)
-}
-
 /// Validation functions to make sure all the required tags are existing for a certain GeoTiff
 /// image type (e.g., grayscale or RGB image).
 pub fn validate_required_tags_for(typ: &ImageType) -> Option<HashSet<TIFFTag>> {

src/lib.rs

@@ -6,12 +6,12 @@ extern crate num;
 use std::fmt;
 use std::io::Result;
 
+pub mod geotiff;
 mod lowlevel;
 mod reader;
-pub mod tiff;
 
+pub use geotiff::TIFF;
 use reader::*;
-pub use tiff::TIFF;
 
 /// The GeoTIFF library reads `.tiff` files.
 ///

src/lowlevel.rs

@@ -1,4 +1,4 @@
-#![allow(dead_code)]
+use tiff::tags::Type;
 
 // Base types of the TIFF format.
 pub type BYTE      = u8;
@@ -23,40 +23,26 @@ enum_from_primitive! {
     }
 }
 
-enum_from_primitive! {
-    #[repr(u16)]
-    #[derive(Debug,PartialEq)]
-    pub enum TagType {
-        ByteTag           = 1,
-        ASCIITag          = 2,
-        ShortTag          = 3,
-        LongTag           = 4,
-        RationalTag       = 5,
-        SignedByteTag     = 6,
-        UndefinedTag      = 7,
-        SignedShortTag    = 8,
-        SignedLongTag     = 9,
-        SignedRationalTag = 10,
-        FloatTag          = 11,
-        DoubleTag         = 12,
-    }
-}
-
 /// Helper function that returns the size of a certain tag.
-pub fn tag_size(t: &TagType) -> u32 {
+pub fn tag_size(t: &Type) -> u32 {
     match *t {
-        TagType::ByteTag           => 1,
-        TagType::ASCIITag          => 1,
-        TagType::ShortTag          => 2,
-        TagType::LongTag           => 4,
-        TagType::RationalTag       => 8,
-        TagType::SignedByteTag     => 1,
-        TagType::UndefinedTag      => 1,
-        TagType::SignedShortTag    => 2,
-        TagType::SignedLongTag     => 2,
-        TagType::SignedRationalTag => 8,
-        TagType::FloatTag          => 4,
-        TagType::DoubleTag         => 8,
+        Type::BYTE => 1,
+        Type::ASCII => 1,
+        Type::SHORT => 2,
+        Type::LONG => 4,
+        Type::RATIONAL => 8,
+        Type::SBYTE => 1,
+        Type::UNDEFINED => 1,
+        Type::SSHORT => 2,
+        Type::SLONG => 2,
+        Type::SRATIONAL => 8,
+        Type::FLOAT => 4,
+        Type::DOUBLE => 8,
+        Type::IFD => 4,
+        Type::LONG8 => 8,
+        Type::SLONG8 => 8,
+        Type::IFD8 => 8,
+        _ => unimplemented!(),
     }
 }