Add support for SVG files to `get_image_metadata` (Fixes #769) (#1063)

* Add support for SVG files to `get_image_metadata`

* Add support for SVG files to `get_image_metadata`

* Update documentation after adding SVG support

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - Add 2 syntax highlighting themes: `green` and `railsbase16-green-screen-dark`
 - Enable task lists in Markdown
+- Add support for SVG in `get_image_metadata`
 
 ## 0.11.0 (2020-05-25)
 

Cargo.lock

@@ -369,6 +369,12 @@ dependencies = [
  "generic-array",
 ]
 
+[[package]]
+name = "doc-comment"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
+
 [[package]]
 name = "dtoa"
 version = "0.4.5"
@@ -1756,6 +1762,15 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "roxmltree"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d5001f134077069d87f77c8b9452b690df2445f7a43f1c7ca4a1af8dd505789d"
+dependencies = [
+ "xmlparser",
+]
+
 [[package]]
 name = "rust-stemmers"
 version = "1.2.0"
@@ -2042,6 +2057,18 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "svg_metadata"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5fe5b1fbd62339f055704951dcaf2e757c460b9f6abe17f6de0d2563da821c57"
+dependencies = [
+ "doc-comment",
+ "lazy_static",
+ "regex",
+ "roxmltree",
+]
+
 [[package]]
 name = "syn"
 version = "1.0.31"
@@ -2117,6 +2144,7 @@ dependencies = [
  "reqwest",
  "serde_json",
  "sha2",
+ "svg_metadata",
  "tera",
  "toml",
  "url",
@@ -2668,6 +2696,12 @@ dependencies = [
  "time",
 ]
 
+[[package]]
+name = "xmlparser"
+version = "0.13.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ccb4240203dadf40be2de9369e5c6dec1bf427528115b030baca3334c18362d7"
+
 [[package]]
 name = "yaml-rust"
 version = "0.4.4"

components/templates/Cargo.toml

@@ -21,6 +21,7 @@ utils = { path = "../utils" }
 library = { path = "../library" }
 config = { path = "../config" }
 imageproc = { path = "../imageproc" }
+svg_metadata = "0.4.1"
 
 [dependencies.reqwest]
 version = "0.10"

components/templates/src/global_fns/mod.rs

@@ -2,9 +2,11 @@ use std::collections::HashMap;
 use std::path::PathBuf;
 use std::sync::{Arc, Mutex, RwLock};
 use std::{fs, io, result};
+use std::ffi::OsStr; 
 
 use sha2::{Digest, Sha256, Sha384, Sha512};
 use tera::{from_value, to_value, Error, Function as TeraFn, Result, Value};
+use svg_metadata as svg;
 
 use config::Config;
 use image;
@@ -279,15 +281,31 @@ impl TeraFn for GetImageMeta {
         if !src_path.exists() {
             return Err(format!("`get_image_metadata`: Cannot find path: {}", path).into());
         }
-        let img = image::open(&src_path)
-            .map_err(|e| Error::chain(format!("Failed to process image: {}", path), e))?;
+        let (height, width) = image_dimensions(&src_path)?;
         let mut map = tera::Map::new();
-        map.insert(String::from("height"), Value::Number(tera::Number::from(img.height())));
-        map.insert(String::from("width"), Value::Number(tera::Number::from(img.width())));
+        map.insert(String::from("height"), Value::Number(tera::Number::from(height)));
+        map.insert(String::from("width"), Value::Number(tera::Number::from(width)));
         Ok(Value::Object(map))
     }
 }
 
+// Try to read the image dimensions for a given image
+fn image_dimensions(path: &PathBuf) -> Result<(u32, u32)> {
+    if let Some("svg") = path.extension().and_then(OsStr::to_str) {
+        let img = svg::Metadata::parse_file(&path)
+            .map_err(|e| Error::chain(format!("Failed to process SVG: {}", path.display()), e))?;
+        match (img.height(), img.width(), img.view_box()) {
+            (Some(h), Some(w), _) => Ok((h as u32, w as u32)),
+            (_, _, Some(view_box)) => Ok((view_box.height as u32, view_box.width as u32)),
+            _ => Err("Invalid dimensions: SVG width/height and viewbox not set.".into())
+        }
+    } else {
+        let img = image::open(&path)
+            .map_err(|e| Error::chain(format!("Failed to process image: {}", path.display()), e))?;
+        Ok((img.height(), img.width()))
+    }
+}
+
 #[derive(Debug)]
 pub struct GetTaxonomyUrl {
     taxonomies: HashMap<String, HashMap<String, String>>,

docs/content/documentation/templates/overview.md

@@ -165,7 +165,8 @@ Whenever hashing files, whether using `get_file_hash` or `get_url(..., cachebust
 
 
 ### `get_image_metadata`
-Gets metadata for an image.  Currently, the only supported keys are `width` and `height`.
+Gets metadata for an image. This supports common formats like JPEG, PNG, as well as SVG.  
+Currently, the only supported keys are `width` and `height`.
 
 ```jinja2
   {% set meta = get_image_metadata(path="...") %}