diff --git a/examples/custom_plugin/src/lib.rs b/examples/custom_plugin/src/lib.rs
index 860e0366a..0b21f3fc8 100644
--- a/examples/custom_plugin/src/lib.rs
+++ b/examples/custom_plugin/src/lib.rs
@@ -1,4 +1,4 @@
-use librustdesk::{api::RustDeskApiTable};
+use librustdesk::api::RustDeskApiTable;
 /// This file demonstrates how to write a custom plugin for RustDesk.
 use std::ffi::{c_char, c_int, CString};
 
@@ -9,8 +9,6 @@ lazy_static::lazy_static! {
     pub static ref API: RustDeskApiTable = RustDeskApiTable::default();
 }
 
-
-
 #[no_mangle]
 fn plugin_name() -> *const c_char {
     return PLUGIN_NAME.as_ptr();
diff --git a/src/api.rs b/src/api.rs
index 1c993a5ee..187c396d0 100644
--- a/src/api.rs
+++ b/src/api.rs
@@ -1,32 +1,87 @@
 use std::ffi::c_char;
 
-use crate::plugins::PLUGIN_REGISTRAR;
+use crate::{
+    flutter::{FlutterHandler, SESSIONS},
+    plugins::PLUGIN_REGISTRAR,
+    ui_session_interface::Session,
+};
 
 // API provided by RustDesk.
 pub type LoadPluginFunc = fn(*const c_char) -> i32;
 pub type UnloadPluginFunc = fn(*const c_char) -> i32;
+pub type AddSessionFunc = fn(session: Session<FlutterHandler>) -> bool;
+pub type RemoveSessionFunc = fn(session_id: &String) -> bool;
+pub type AddSessionHookFunc = fn(session_id: String, key: String, hook: SessionHook) -> bool;
+pub type RemoveSessionHookFunc = fn(session_id: String, key: &String) -> bool;
+
+/// Hooks for session.
+#[repr(usize)]
+#[derive(Clone)]
+pub enum SessionHook {
+    OnSessionRgba(fn(&Session<FlutterHandler>, Vec<i8>) -> Vec<i8>) = 1,
+}
 
 #[repr(C)]
 pub struct RustDeskApiTable {
-    pub(crate) register_plugin: LoadPluginFunc,
+    pub(crate) load_plugin: LoadPluginFunc,
     pub(crate) unload_plugin: UnloadPluginFunc,
+    pub add_session: AddSessionFunc,
+    pub remove_session: RemoveSessionFunc,
+    pub add_session_hook: AddSessionHookFunc,
+    pub remove_session_hook: RemoveSessionHookFunc,
 }
 
-#[no_mangle]
 fn load_plugin(path: *const c_char) -> i32 {
     PLUGIN_REGISTRAR.load_plugin(path)
 }
 
-#[no_mangle]
 fn unload_plugin(path: *const c_char) -> i32 {
     PLUGIN_REGISTRAR.unload_plugin(path)
 }
 
+fn add_session(session: Session<FlutterHandler>) -> bool {
+    let mut sessions = SESSIONS.write().unwrap();
+    if sessions.contains_key(&session.id) {
+        return false;
+    }
+    let _ = sessions.insert(session.id.to_owned(), session);
+    true
+}
+
+fn remove_session(session_id: &String) -> bool {
+    let mut sessions = SESSIONS.write().unwrap();
+    if !sessions.contains_key(session_id) {
+        return false;
+    }
+    let _ = sessions.remove(session_id);
+    true
+}
+
+fn add_session_hook(session_id: String, key: String, hook: SessionHook) -> bool {
+    let sessions = SESSIONS.read().unwrap();
+    if let Some(session) = sessions.get(&session_id) {
+        return session.add_session_hook(key, hook);
+    }
+    false
+}
+
+fn remove_session_hook(session_id: String, key: &String) -> bool {
+    let sessions = SESSIONS.read().unwrap();
+    if let Some(session) = sessions.get(&session_id) {
+        return session.remove_session_hook(key);
+    }
+    false
+}
+
 impl Default for RustDeskApiTable {
     fn default() -> Self {
         Self {
-            register_plugin: load_plugin,
-            unload_plugin: unload_plugin,
+            load_plugin,
+            unload_plugin,
+            add_session,
+            remove_session,
+            add_session_hook,
+            remove_session_hook,
         }
     }
 }
diff --git a/src/flutter.rs b/src/flutter.rs
index 8c4522e47..94c5e52e7 100644
--- a/src/flutter.rs
+++ b/src/flutter.rs
@@ -1,4 +1,5 @@
 use crate::{
+    api::SessionHook,
     client::*,
     flutter_ffi::EventToUI,
     ui_session_interface::{io_loop, InvokeUiSession, Session},
@@ -40,9 +41,9 @@ pub(super) const APP_TYPE_DESKTOP_FILE_TRANSFER: &str = "file transfer";
 pub(super) const APP_TYPE_DESKTOP_PORT_FORWARD: &str = "port forward";
 
 lazy_static::lazy_static! {
-    pub static ref CUR_SESSION_ID: RwLock<String> = Default::default();
-    pub static ref SESSIONS: RwLock<HashMap<String, Session<FlutterHandler>>> = Default::default();
-    pub static ref GLOBAL_EVENT_STREAM: RwLock<HashMap<String, StreamSink<String>>> = Default::default(); // rust to dart event channel
+    pub(crate) static ref CUR_SESSION_ID: RwLock<String> = Default::default();
+    pub(crate) static ref SESSIONS: RwLock<HashMap<String, Session<FlutterHandler>>> = Default::default();
+    pub(crate) static ref GLOBAL_EVENT_STREAM: RwLock<HashMap<String, StreamSink<String>>> = Default::default(); // rust to dart event channel
 }
 
 #[cfg(all(target_os = "windows", feature = "flutter_texture_render"))]
@@ -146,6 +147,7 @@ pub struct FlutterHandler {
     notify_rendered: Arc<RwLock<bool>>,
     renderer: Arc<RwLock<VideoRenderer>>,
     peer_info: Arc<RwLock<PeerInfo>>,
+    hooks: Arc<RwLock<HashMap<String, SessionHook>>>,
 }
 
 #[cfg(not(feature = "flutter_texture_render"))]
@@ -157,6 +159,7 @@ pub struct FlutterHandler {
     pub rgba: Arc<RwLock<Vec<u8>>>,
     pub rgba_valid: Arc<AtomicBool>,
     peer_info: Arc<RwLock<PeerInfo>>,
+    hooks: Arc<RwLock<HashMap<String, SessionHook>>>,
 }
 
 #[cfg(feature = "flutter_texture_render")]
@@ -255,7 +258,7 @@ impl FlutterHandler {
         }
     }
 
-    pub fn close_event_stream(&mut self) {
+    pub(crate) fn close_event_stream(&mut self) {
         let mut stream_lock = self.event_stream.write().unwrap();
         if let Some(stream) = &*stream_lock {
             stream.add(EventToUI::Event("close".to_owned()));
@@ -277,6 +280,26 @@ impl FlutterHandler {
         serde_json::ser::to_string(&msg_vec).unwrap_or("".to_owned())
     }
 
+    pub(crate) fn add_session_hook(&self, key: String, hook: crate::api::SessionHook) -> bool {
+        let mut hooks = self.hooks.write().unwrap();
+        if hooks.contains_key(&key) {
+            // Already has the hook with this key.
+            return false;
+        }
+        let _ = hooks.insert(key, hook);
+        true
+    }
+
+    pub(crate) fn remove_session_hook(&self, key: &String) -> bool {
+        let mut hooks = self.hooks.write().unwrap();
+        if !hooks.contains_key(key) {
+            // The hook with this key does not found.
+            return false;
+        }
+        let _ = hooks.remove(key);
+        true
+    }
+
     #[inline]
     #[cfg(feature = "flutter_texture_render")]
     pub fn register_texture(&mut self, ptr: usize) {