Add standalone target for the gain example

Author: emuell

examples/gain-plugin/Cargo.toml

@@ -9,6 +9,11 @@ standalone = ["plinth-plugin/standalone"]
 [lib]
 crate-type = ["cdylib", "lib", "staticlib"]
 
+[[bin]]
+name = "gain-standalone"
+path = "src/main.rs"
+required-features = ["standalone"]
+
 [dependencies]
 plinth-derive.workspace = true
 plinth-plugin.workspace = true

examples/gain-plugin/src/main.rs

@@ -0,0 +1,3 @@
+use gain_plugin::GainPlugin;
+
+plinth_plugin::export_standalone!(GainPlugin);

examples/gain-plugin/src/plugin.rs

@@ -12,7 +12,7 @@ use crate::editor::{EditorSettings, GainPluginEditor};
 use crate::{parameters::GainParameters, processor::GainPluginProcessor};
 
 #[derive(Default)]
-struct GainPlugin {
+pub struct GainPlugin {
     parameters: Rc<GainParameters>,
     editor_settings: Rc<RefCell<EditorSettings>>,
 }
@@ -88,3 +88,6 @@ impl Vst3Plugin for GainPlugin {
 
 export_clap!(GainPlugin);
 export_vst3!(GainPlugin);
+
+#[cfg(feature = "standalone")]
+impl plinth_plugin::standalone::StandalonePlugin for GainPlugin {}