Added Flatpak PDFium library lookup (#834)

runtime/src/pdfium.rs

@@ -2,7 +2,7 @@ use std::error::Error;
 use std::sync::Mutex;
 use once_cell::sync::Lazy;
 use pdfium_render::prelude::Pdfium;
-use log::{error, warn};
+use log::{error, info, warn};
 
 pub static PDFIUM_LIB_PATH: Lazy<Mutex<Option<String>>> = Lazy::new(|| Mutex::new(None));
 static PDFIUM: Lazy<Mutex<Option<Pdfium>>> = Lazy::new(|| Mutex::new(None));
@@ -32,11 +32,22 @@ impl PdfiumInit for Pdfium {
 fn load_pdfium() -> Result<Pdfium, String> {
     let lib_path = PDFIUM_LIB_PATH.lock().unwrap().clone();
     if let Some(path) = lib_path.as_ref() {
-        return match Pdfium::bind_to_library(Pdfium::pdfium_platform_library_name_at_path(path)) {
-            Ok(binding) => Ok(Pdfium::new(binding)),
+        let pdfium_library_path = Pdfium::pdfium_platform_library_name_at_path(path);
+
+        return match Pdfium::bind_to_library(&pdfium_library_path) {
+            Ok(binding) => {
+                info!("Loaded PDFium from '{path}'.", path = pdfium_library_path.to_string_lossy());
+                Ok(Pdfium::new(binding))
+            },
             Err(library_error) => {
                 match Pdfium::bind_to_system_library() {
-                    Ok(binding) => Ok(Pdfium::new(binding)),
+                    Ok(binding) => {
+                        info!(
+                            "Loaded PDFium from the system library after failing to load '{path}'.",
+                            path = pdfium_library_path.to_string_lossy(),
+                        );
+                        Ok(Pdfium::new(binding))
+                    },
                     Err(system_error) => {
                         let error_message = format!(
                             "Failed to load PDFium from '{path}' and the system library. Developer action (from repo root): run the build script once to download the required PDFium version: `cd app/Build` and `dotnet run build`. Details: library error: '{library_error}'; system error: '{system_error}'."
@@ -52,7 +63,10 @@ fn load_pdfium() -> Result<Pdfium, String> {
 
     warn!("No custom PDFium library path set; trying to load PDFium from the system library.");
     match Pdfium::bind_to_system_library() {
-        Ok(binding) => Ok(Pdfium::new(binding)),
+        Ok(binding) => {
+            info!("Loaded PDFium from the system library.");
+            Ok(Pdfium::new(binding))
+        },
         Err(system_error) => {
             let error_message = format!(
                 "Failed to load PDFium from the system library. Developer action (from repo root): run the build script once to download the required PDFium version: `cd app/Build` and `dotnet run build`. Details: '{system_error}'."