Use Flate2 for encoding

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "png"
-version = "0.17.5"
+version = "0.17.6"
 license = "MIT OR Apache-2.0"
 
 description = "PNG decoding and encoding library in pure Rust"
@@ -22,8 +22,8 @@ include = [
 [dependencies]
 bitflags = "1.0"
 crc32fast = "1.2.0"
-deflate = "1.0"
-miniz_oxide = "0.5.1"
+flate2 = "1.0"
+miniz_oxide = "0.5.0"
 
 [dev-dependencies]
 criterion = "0.3.1"

src/common.rs

@@ -315,7 +315,15 @@ pub enum Compression {
     /// the encoder can do, but is meant to emulate the `Best` setting in the `Flate2`
     /// library.
     Best,
+    #[deprecated(
+        since = "0.17.6",
+        note = "use one of the other compression levels instead, such as 'fast'"
+    )]
     Huffman,
+    #[deprecated(
+        since = "0.17.6",
+        note = "use one of the other compression levels instead, such as 'fast'"
+    )]
     Rle,
 }
 

src/encoder.rs

@@ -4,7 +4,7 @@ use ops::{Deref, DerefMut};
 use std::{borrow, error, fmt, io, mem, ops, result};
 
 use crc32fast::Hasher as Crc32;
-use deflate::write::ZlibEncoder;
+use flate2::write::ZlibEncoder;
 
 use crate::chunk::{self, ChunkType};
 use crate::common::{
@@ -670,8 +670,7 @@ impl<W: Write> Writer<W> {
         let mut prev = prev.as_slice();
         let mut current = vec![0; in_len];
 
-        let mut zlib =
-            deflate::write::ZlibEncoder::new(Vec::new(), self.info.compression.to_options());
+        let mut zlib = ZlibEncoder::new(Vec::new(), self.info.compression.to_options());
         let bpp = self.info.bpp_in_prediction();
         let filter_method = self.options.filter;
         let adaptive_method = self.options.adaptive_filter;
@@ -2289,13 +2288,13 @@ mod tests {
 /// Since this only contains trait impls, there is no need to make this public, they are simply
 /// available when the mod is compiled as well.
 impl Compression {
-    fn to_options(self) -> deflate::CompressionOptions {
+    fn to_options(self) -> flate2::Compression {
         match self {
-            Compression::Default => deflate::CompressionOptions::default(),
-            Compression::Fast => deflate::CompressionOptions::fast(),
-            Compression::Best => deflate::CompressionOptions::high(),
-            Compression::Huffman => deflate::CompressionOptions::huffman_only(),
-            Compression::Rle => deflate::CompressionOptions::rle(),
+            Compression::Default => flate2::Compression::default(),
+            Compression::Fast => flate2::Compression::fast(),
+            Compression::Best => flate2::Compression::best(),
+            Compression::Huffman => flate2::Compression::none(),
+            Compression::Rle => flate2::Compression::none(),
         }
     }
 }

src/text_metadata.rs

@@ -103,7 +103,8 @@
 #![warn(missing_docs)]
 
 use crate::{chunk, encoder, DecodingError, EncodingError};
-use deflate::{write::ZlibEncoder, Compression};
+use flate2::write::ZlibEncoder;
+use flate2::Compression;
 use miniz_oxide::inflate::{decompress_to_vec_zlib, decompress_to_vec_zlib_with_limit};
 use std::{convert::TryFrom, io::Write};
 
@@ -322,7 +323,7 @@ impl ZTXtChunk {
         match &self.text {
             OptCompressed::Uncompressed(s) => {
                 let uncompressed_raw = encode_iso_8859_1(s)?;
-                let mut encoder = ZlibEncoder::new(Vec::new(), Compression::Fast);
+                let mut encoder = ZlibEncoder::new(Vec::new(), Compression::fast());
                 encoder
                     .write_all(&uncompressed_raw)
                     .map_err(|_| EncodingError::from(TextEncodingError::CompressionError))?;
@@ -360,7 +361,7 @@ impl EncodableTextChunk for ZTXtChunk {
             OptCompressed::Uncompressed(s) => {
                 // This code may have a bug. Check for correctness.
                 let uncompressed_raw = encode_iso_8859_1(s)?;
-                let mut encoder = ZlibEncoder::new(data, Compression::Fast);
+                let mut encoder = ZlibEncoder::new(data, Compression::fast());
                 encoder
                     .write_all(&uncompressed_raw)
                     .map_err(|_| EncodingError::from(TextEncodingError::CompressionError))?;
@@ -496,7 +497,7 @@ impl ITXtChunk {
         match &self.text {
             OptCompressed::Uncompressed(s) => {
                 let uncompressed_raw = s.as_bytes();
-                let mut encoder = ZlibEncoder::new(Vec::new(), Compression::Fast);
+                let mut encoder = ZlibEncoder::new(Vec::new(), Compression::fast());
                 encoder
                     .write_all(uncompressed_raw)
                     .map_err(|_| EncodingError::from(TextEncodingError::CompressionError))?;
@@ -558,7 +559,7 @@ impl EncodableTextChunk for ITXtChunk {
                 }
                 OptCompressed::Uncompressed(s) => {
                     let uncompressed_raw = s.as_bytes();
-                    let mut encoder = ZlibEncoder::new(data, Compression::Fast);
+                    let mut encoder = ZlibEncoder::new(data, Compression::fast());
                     encoder
                         .write_all(uncompressed_raw)
                         .map_err(|_| EncodingError::from(TextEncodingError::CompressionError))?;