Medium-level API: Add calc_media_src_loudness

It requires user to use `get_set_project_info_string_get` from the helgoboss#68.

main/medium/src/reaper.rs

@@ -1064,6 +1064,29 @@ impl<UsageScope> Reaper<UsageScope> {
         self.low().BypassFxAllTracks(byp);
     }
 
+    /// Calculates loudness statistics of media via dry run render.
+    ///
+    /// Statistics will be displayed to the user.
+    ///
+    /// call GetSetProjectInfo_String("RENDER_STATS") to retrieve via API.
+    ///
+    /// Returns Ok(()) if loudness was calculated successfully,
+    /// Err("User aborted render") if user canceled the dry run render,
+    /// Err("Unexpected result") if something went wrong.
+    pub unsafe fn calc_media_src_loudness(
+        &self,
+        media_source: PcmSource,
+    ) -> ReaperFunctionResult<()>
+    where
+        UsageScope: MainThreadOnly,
+    {
+        match self.low().CalcMediaSrcLoudness(media_source.as_ptr()) {
+            1 => Ok(()),
+            -1 => Err(ReaperFunctionError::new("User aborted render.")),
+            _ => Err(ReaperFunctionError::new("Unexpected result.")),
+        }
+    }
+
     /// Starts playing.
     pub fn csurf_on_play(&self)
     where
@@ -1161,11 +1184,11 @@ impl<UsageScope> Reaper<UsageScope> {
     }
 
     /// True if function name exists in the REAPER API
-    pub fn api_exists(&self, function_name: ReaperStringArg) -> bool
+    pub fn api_exists<'a, I: Into<ReaperStringArg<'a>>>(&self, function_name: I) -> bool
     where
         UsageScope: MainThreadOnly,
     {
-        unsafe { self.low().APIExists(function_name.as_ptr()) }
+        unsafe { self.low().APIExists(function_name.into().as_ptr()) }
     }
 
     /// Displays a message window if the API was successfully called.
@@ -5808,6 +5831,106 @@ impl<UsageScope> Reaper<UsageScope> {
         NonNull::new(ptr)
     }
 
+    /// Save project with given filename and options.
+    ///
+    /// # Safety
+    ///
+    /// REAPER can crash if you pass an invalid project.
+    pub unsafe fn save_project(&self, project: ProjectContext, force_save_as: bool)
+    where
+        UsageScope: MainThreadOnly,
+    {
+        self.low().Main_SaveProject(project.to_raw(), force_save_as);
+    }
+
+    /// Save project with given filename and options.
+    ///
+    /// # Safety
+    ///
+    /// REAPER can crash if you pass an invalid project.
+    pub unsafe fn save_project_ex<'a, I: Into<ReaperStringArg<'a>>>(
+        &self,
+        project: ProjectContext,
+        file_name: I,
+        options: BitFlags<SaveProjectFlags>,
+    ) where
+        UsageScope: MainThreadOnly,
+    {
+        self.low().Main_SaveProjectEx(
+            project.to_raw(),
+            file_name.into().as_ptr(),
+            options.bits_c() as i32,
+        );
+    }
+
+    /// Set project information.
+    ///
+    /// For more information of possible values see `ProjectInfoStringCategory`
+    /// documentation.
+    ///
+    /// # Known bugs
+    ///
+    /// This function constantly returns false, but sometimes it works.
+    ///
+    /// # Safety
+    ///
+    /// REAPER can crash if you pass an invalid project.
+    pub unsafe fn get_set_project_info_string_set<'a, I: Into<ReaperStringArg<'a>>>(
+        &self,
+        project: ProjectContext,
+        category: ProjectInfoStringCategory,
+        value: I,
+    ) -> bool
+    where
+        UsageScope: MainThreadOnly,
+    {
+        let val: ReaperStringArg = value.into();
+        let val: CString = CString::from(val.as_reaper_str().as_c_str());
+        self.low().GetSetProjectInfo_String(
+            project.to_raw(),
+            category.to_raw().as_ptr(),
+            val.into_raw(),
+            true,
+        )
+    }
+
+    /// Get project information.
+    ///
+    /// For more information of possible values see `ProjectInfoStringCategory`
+    /// documentation.
+    ///
+    /// # Known bugs
+    ///
+    /// There are problems with several categories. At least, with
+    /// TrackGroupName(x), which makes definitely right string for category,
+    /// but doesn't work with reaper-rs.
+    ///
+    /// # Safety
+    ///
+    /// REAPER can crash if you pass an invalid project.
+    pub unsafe fn get_set_project_info_string_get(
+        &self,
+        project: ProjectContext,
+        category: ProjectInfoStringCategory,
+    ) -> ReaperFunctionResult<String>
+    where
+        UsageScope: MainThreadOnly,
+    {
+        let max_size = 1024 * 10;
+        let (result, status) = with_string_buffer(max_size, |buf, _| -> bool {
+            self.low().GetSetProjectInfo_String(
+                project.to_raw(),
+                category.to_raw().as_ptr(),
+                buf,
+                false,
+            )
+        });
+        match status {
+            true => Ok(result.into_string()),
+            false => Err(ReaperFunctionError::new("Can not get project info.")),
+        }
+    }
+
     /// Returns the take that is currently being edited in the given MIDI editor.
     ///
     /// # Safety