Add the special win32-dpi-aware feature on Windows

src/plugin.rs

@@ -137,9 +137,8 @@ pub trait ClapPlugin: Plugin {
     const CLAP_DESCRIPTION: &'static str;
     /// Arbitrary keywords describing the plugin. See the CLAP specification for examples:
     /// <https://github.com/free-audio/clap/blob/main/include/clap/plugin.h>.
-    //
+    ///
-    // TODO: CLAP mentions that `win32-dpi-aware` is a special keyword that informs the host that
+    /// On windows `win32-dpi-aware` is automatically added.
-    //       the plugin is DPI aware, can and should we have special handling for this?
     const CLAP_FEATURES: &'static [&'static str];
     /// A URL to the plugin's manual, CLAP does not specify what to do when there is none.
     //

src/wrapper/clap/descriptor.rs

@@ -60,7 +60,16 @@ impl<P: ClapPlugin> Default for PluginDescriptor<P> {
             _phantom: PhantomData,
         };
 
-        // The keyword list is an environ-like list of char pointers terminated by a null pointer
+        // The keyword list is an environ-like list of char pointers terminated by a null pointer.
+        // On Windows `win32-dpi-aware` is a special value informing the host that the plugin is
+        // DPI-aware.
+        // TODO: Is this actually what we want? What happens if we don't add it? If this means that
+        //       we need to do our own DPI handling instead of the host passing a scale then we
+        //       don't want that of course.
+        #[cfg(target_os = "windows")]
+        descriptor
+            .clap_features
+            .push(CString::new("win32-dpi-aware").unwrap());
         let mut clap_features_ptrs: Vec<*const c_char> = descriptor
             .clap_features
             .iter()