1 files changed, 107 insertions, 5 deletions

diff --git a/desktop/inc/lib/init.hxx b/desktop/inc/lib/init.hxx
index 5b386e4820d7..5c987bec57ab 100644
--- a/desktop/inc/lib/init.hxx
+++ b/desktop/inc/lib/init.hxx
@@ -10,24 +10,126 @@
 #ifndef INCLUDED_DESKTOP_INC_LIB_INIT_HXX
 #define INCLUDED_DESKTOP_INC_LIB_INIT_HXX
 
+#include <map>
+#include <memory>
+#include <mutex>
+
+#include <osl/thread.h>
+#include <vcl/idle.hxx>
 #include <LibreOfficeKit/LibreOfficeKit.h>
 #include <LibreOfficeKit/LibreOfficeKitEnums.h>
 #include <com/sun/star/frame/XStorable.hpp>
 #include <com/sun/star/lang/XComponent.hpp>
-#include <memory>
-#include <map>
+
 #include <desktop/dllapi.h>
-#include <osl/thread.h>
 
 class LOKInteractionHandler;
 
 namespace desktop {
+
+    class CallbackFlushHandler : public Idle
+    {
+    public:
+        explicit CallbackFlushHandler(LibreOfficeKitCallback pCallback, void* pData)
+            : Idle( "lokit timer callback" ),
+              m_pCallback(pCallback),
+              m_pData(pData)
+        {
+            SetPriority(SchedulerPriority::POST_PAINT);
+
+            // Add the states that are safe to skip duplicates on,
+            // even when not consequent.
+            m_states.emplace(LOK_CALLBACK_TEXT_SELECTION, "NIL");
+            m_states.emplace(LOK_CALLBACK_INVALIDATE_VISIBLE_CURSOR, "NIL");
+            m_states.emplace(LOK_CALLBACK_STATE_CHANGED, "NIL");
+
+            Start();
+        }
+
+        virtual ~CallbackFlushHandler()
+        {
+            Stop();
+
+            // We might have important notification (.uno:save?).
+            flush();
+        }
+
+        virtual void Invoke() override
+        {
+            flush();
+        }
+
+        static
+        void callback(const int type, const char* payload, void* data)
+        {
+            CallbackFlushHandler* self = reinterpret_cast<CallbackFlushHandler*>(data);
+            if (self)
+            {
+                self->queue(type, payload);
+            }
+        }
+
+        void queue(const int type, const char* data)
+        {
+            const std::string payload(data ? data : "(nil)");
+            std::unique_lock<std::mutex> lock(m_mutex);
+
+            const auto stateIt = m_states.find(type);
+            if (stateIt != m_states.end())
+            {
+                // If the state didn't change, it's safe to ignore.
+                if (stateIt->second == payload)
+                {
+                    return;
+                }
+
+                stateIt->second = payload;
+            }
+
+            if (type == LOK_CALLBACK_INVALIDATE_TILES &&
+                !m_queue.empty() && std::get<0>(m_queue.back()) == type && std::get<1>(m_queue.back()) == payload)
+            {
+                // Supress duplicate invalidation only when they are in sequence.
+                return;
+            }
+
+            m_queue.emplace_back(type, payload);
+
+            lock.unlock();
+            if (!IsActive())
+            {
+                Start();
+            }
+        }
+
+    private:
+        void flush()
+        {
+            if (m_pCallback)
+            {
+                std::unique_lock<std::mutex> lock(m_mutex);
+                for (auto& pair : m_queue)
+                {
+                    m_pCallback(std::get<0>(pair), std::get<1>(pair).c_str(), m_pData);
+                }
+
+                m_queue.clear();
+            }
+        }
+
+    private:
+        std::vector<std::tuple<int, std::string>> m_queue;
+        std::map<int, std::string> m_states;
+        LibreOfficeKitCallback m_pCallback;
+        void *m_pData;
+        std::mutex m_mutex;
+    };
+
     struct DESKTOP_DLLPUBLIC LibLODocument_Impl : public _LibreOfficeKitDocument
     {
         css::uno::Reference<css::lang::XComponent> mxComponent;
         std::shared_ptr< LibreOfficeKitDocumentClass > m_pDocumentClass;
-        LibreOfficeKitCallback mpCallback;
-        void *mpCallbackData;
+        std::shared_ptr<CallbackFlushHandler> mpCallbackFlushHandler;
 
         explicit LibLODocument_Impl(const css::uno::Reference <css::lang::XComponent> &xComponent);
         ~LibLODocument_Impl();