Add stdin and stdout support

Cargo.lock

@@ -63,9 +63,9 @@ checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
 [[package]]
 name = "clap"
-version = "3.0.0-beta.4"
+version = "3.0.0-beta.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fcd70aa5597dbc42f7217a543f9ef2768b2ef823ba29036072d30e1d88e98406"
+checksum = "feff3878564edb93745d58cf63e17b63f24142506e7a20c87a5521ed7bfb1d63"
 dependencies = [
  "atty",
  "bitflags",
@@ -76,14 +76,14 @@ dependencies = [
  "strsim",
  "termcolor",
  "textwrap",
- "vec_map",
+ "unicase",
 ]
 
 [[package]]
 name = "clap_derive"
-version = "3.0.0-beta.4"
+version = "3.0.0-beta.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0b5bb0d655624a0b8770d1c178fb8ffcb1f91cc722cb08f451e3dc72465421ac"
+checksum = "8b15c6b4f786ffb6192ffe65a36855bc1fc2444bcd0945ae16748dcd6ed7d0d3"
 dependencies = [
  "heck",
  "proc-macro-error",
@@ -169,9 +169,9 @@ checksum = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
 
 [[package]]
 name = "gif"
-version = "0.11.2"
+version = "0.11.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5a668f699973d0f573d15749b7002a9ac9e1f9c6b220e7b165601334c173d8de"
+checksum = "c3a7187e78088aead22ceedeee99779455b23fc231fe13ec443f99bb71694e5b"
 dependencies = [
  "color_quant",
  "weezl",
@@ -247,9 +247,9 @@ checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
 [[package]]
 name = "libc"
-version = "0.2.103"
+version = "0.2.105"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dd8f7255a17a627354f321ef0055d63b898c6fb27eff628af4d1b66b7331edf6"
+checksum = "869d572136620d55835903746bcb5cdc54cb2851fd0aeec53220b4bb65ef3013"
 
 [[package]]
 name = "lockscreen-blur"
@@ -260,6 +260,12 @@ dependencies = [
  "image",
 ]
 
+[[package]]
+name = "memchr"
+version = "2.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "308cc39be01b73d0d18f82a0e7b2a3df85245f84af96fdddc5d202d27e47b86a"
+
 [[package]]
 name = "memoffset"
 version = "0.6.4"
@@ -341,9 +347,12 @@ dependencies = [
 
 [[package]]
 name = "os_str_bytes"
-version = "3.1.0"
+version = "4.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6acbef58a60fe69ab50510a55bc8cdd4d6cf2283d27ad338f54cb52747a9cf2d"
+checksum = "addaa943333a514159c80c97ff4a93306530d965d27e139188283cd13e06a799"
+dependencies = [
+ "memchr",
+]
 
 [[package]]
 name = "png"
@@ -383,18 +392,18 @@ dependencies = [
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.29"
+version = "1.0.32"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b9f5105d4fdaab20335ca9565e106a5d9b82b6219b5ba735731124ac6711d23d"
+checksum = "ba508cc11742c0dc5c1659771673afbab7a0efab23aa17e854cbab0837ed0b43"
 dependencies = [
  "unicode-xid",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.9"
+version = "1.0.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c3d0b9745dc2debf507c8422de05d7226cc1f0644216dfdfead988f9b1ab32a7"
+checksum = "38bc8cc6a5f2e3655e0899c1b848643b2562f853f114bfec7be120678e3ace05"
 dependencies = [
  "proc-macro2",
 ]
@@ -444,9 +453,9 @@ checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
 
 [[package]]
 name = "syn"
-version = "1.0.77"
+version = "1.0.81"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5239bc68e0fef57495900cfea4e8dc75596d9a319d7e16b1e0a440d24e6fe0a0"
+checksum = "f2afee18b8beb5a596ecb4a2dce128c719b4ba399d34126b9e4396e3f9860966"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -482,6 +491,15 @@ dependencies = [
  "weezl",
 ]
 
+[[package]]
+name = "unicase"
+version = "2.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "50f37be617794602aabbeee0be4f259dc1778fabe05e2d67ee8f79326d5cb4f6"
+dependencies = [
+ "version_check",
+]
+
 [[package]]
 name = "unicode-segmentation"
 version = "1.8.0"
@@ -500,12 +518,6 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
 
-[[package]]
-name = "vec_map"
-version = "0.8.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f1bddf1187be692e79c5ffeab891132dfb0f236ed36a43c7ed39f1165ee20191"
-
 [[package]]
 name = "version_check"
 version = "0.9.3"

src/main.rs

@@ -1,18 +1,22 @@
-use clap::Clap;
+use clap::Parser;
 use image::imageops::overlay;
 use image::imageops::FilterType;
 use image::io::Reader as ImageReader;
 use image::{DynamicImage, ImageOutputFormat};
+use std::io::{self, Cursor, Read};
 use std::path::PathBuf;
 
-#[derive(Clap)]
+#[derive(Parser)]
 struct Opt {
+    /// The path to the input image, if not specified will read from stdin
     #[clap(short, long)]
-    input: PathBuf,
+    input: Option<PathBuf>,
 
+    /// The path to the output image, if not specified will write to stdout
     #[clap(short, long)]
-    output: PathBuf,
+    output: Option<PathBuf>,
 
+    /// An optional path to an additional image to overlay on top of the output image
     #[clap(short, long)]
     stamp: Option<PathBuf>,
 
@@ -22,7 +26,19 @@ struct Opt {
 
 fn main() -> anyhow::Result<()> {
     let opt = Opt::parse();
-    let img = ImageReader::open(&opt.input)?.decode()?;
+
+    let img = match &opt.input {
+        Some(path) => ImageReader::open(path)?.decode()?,
+        None => {
+            let mut data = vec![];
+            let stdin = io::stdin();
+            stdin.lock().read_to_end(&mut data)?;
+            ImageReader::new(Cursor::new(&data))
+                .with_guessed_format()?
+                .decode()?
+        }
+    };
+
     let (w, h) = dimensions(&img);
     let img = img.resize(w / opt.blur, h / opt.blur, FilterType::Triangle);
     let mut img = img.resize(w, h, FilterType::Nearest);
@@ -33,8 +49,16 @@ fn main() -> anyhow::Result<()> {
         overlay(&mut img, &stamp, (w - sw) / 2, (h - sh) / 2);
     }
 
-    let mut output = std::fs::File::create(opt.output)?;
+    match &opt.output {
+        Some(path) => {
+            let mut output = std::fs::File::create(path)?;
             img.write_to(&mut output, ImageOutputFormat::Png)?;
+        }
+        None => {
+            let stdout = io::stdout();
+            img.write_to(&mut stdout.lock(), ImageOutputFormat::Png)?;
+        }
+    }
 
     Ok(())
 }