Support loading images from urls without extensions (#163)

* Support loading images from urls without extensions

* clippy fix

* update cargo-bundle-licenses

DEVELOP.md

@@ -57,7 +57,7 @@ Updating the CI build to use QEMU seems to have fixed the issue. Leaving this co
  > The Deno dependencies currently correspond to Deno 1.30.3. When updating to later versions, we've run into errors for packages cross compiled to Linux aarch64. See https://github.com/vega/vl-convert/issues/52. Be sure to test this scenario when updating Deno in the future.
 
 ## Debug Logging
-To enable logging, set the RUST_LOG environment variable to "vl_convert"
+To enable logging, set the RUST_LOG environment variable to info, warn, or error
 ```
-RUST_LOG=vl_convert
+RUST_LOG=info
 ```

vl-convert-pdf/src/lib.rs

@@ -424,10 +424,7 @@ fn node_has_zero_opacity(node: &Node) -> bool {
 }
 
 fn get_text_width(text: &Text, font_db: &Database) -> Option<f64> {
-    let Some(node) = text.convert(font_db, Default::default()) else {
-        return None;
-    };
-    get_text_width_from_path(node)
+    get_text_width_from_path(text.convert(font_db, Default::default())?)
 }
 
 fn get_text_width_from_path(node: Node) -> Option<f64> {

vl-convert-rs/src/image_loading.rs

@@ -1,5 +1,5 @@
 use http::StatusCode;
-use log::error;
+use log::{error, info};
 use reqwest::Client;
 use std::io::Write;
 use tokio::task;
@@ -29,21 +29,18 @@ pub type ImageHrefStringResolverFn = Box<dyn Fn(&str, &Options) -> Option<ImageK
 pub fn custom_string_resolver() -> ImageHrefStringResolverFn {
     let default_string_resolver = ImageHrefResolver::default_string_resolver();
     Box::new(move |href: &str, opts: &Options| {
+        info!("Resolving image: {href}");
         if href.starts_with("http://") || href.starts_with("https://") {
-            // parse as file to extract the extension
-            let href_path = std::path::Path::new(href);
-            let extension = href_path
-                .extension()
-                .and_then(|ext| ext.to_str().map(|ext| format!(".{}", ext)))
-                .unwrap_or("".to_string());
-
             // Download image to temporary file with reqwest
-            let bytes: Option<_> = task::block_in_place(move || {
+            let (bytes, content_type): (Option<_>, Option<_>) = task::block_in_place(move || {
                 IMAGE_TOKIO_RUNTIME.block_on(async {
                     if let Ok(response) = REQWEST_CLIENT.get(href).send().await {
+                        let content_type = response.headers().get("Content-Type")
+                            .and_then(|h| h.to_str().ok().map(|c| c.to_string()));
+
                         // Check status code.
                         match response.status() {
-                            StatusCode::OK => response.bytes().await.ok(),
+                            StatusCode::OK => (response.bytes().await.ok(), content_type),
                             status => {
                                 let msg = response
                                     .bytes()
@@ -60,15 +57,35 @@ pub fn custom_string_resolver() -> ImageHrefStringResolverFn {
                                         href, status
                                     );
                                 }
-                                None
+                                (None, None)
                             }
                         }
                     } else {
-                        None
+                        (None, None)
                     }
                 })
             });
 
+            // Compute file extension, which usvg uses to infer the image type
+            let href_path = std::path::Path::new(href);
+            let extension = href_path
+                .extension()
+                .and_then(|ext| ext.to_str().map(|ext| format!(".{}", ext)))
+                .unwrap_or_else(|| {
+                    // Fall back to extension based on content type
+                    if let Some(content_type) = &content_type {
+                        match content_type.as_str() {
+                            "image/jpeg" => ".jpg".to_string(),
+                            "image/png" => ".png".to_string(),
+                            "image/gif" => ".gif".to_string(),
+                            "image/svg+xml" => ".svg".to_string(),
+                            _ => String::new(),
+                        }
+                    } else {
+                        String::new()
+                    }
+                });
+
             if let Some(bytes) = bytes {
                 // Create the temporary file (maybe with an extension)
                 let mut builder = tempfile::Builder::new();

vl-convert-rs/tests/test_specs.rs

@@ -641,6 +641,7 @@ mod test_png_no_theme {
         case("line_with_log_scale", 2.0),
         case("remote_images", 1.0),
         case("maptile_background", 1.0),
+        case("maptile_background_2", 1.0),
         case("float_font_size", 1.0),
         case("no_text_in_font_metrics", 1.0),
         case("custom_projection", 1.0),