threaded brush preview rendering

src/util.h

@@ -151,18 +151,18 @@ template<typename T> struct cbuffer
 template<typename T, int Max = 0>
 class BlockingQueue
 {
+public:
     std::deque<T> q;
     std::condition_variable post_cv;
     std::condition_variable get_cv;
     mutable std::mutex mutex;
-public:
     volatile bool unlocked = false;
     BlockingQueue() = default;
     BlockingQueue(const BlockingQueue& other) = delete;
     BlockingQueue& operator=(const BlockingQueue& other) = delete;
     BlockingQueue(BlockingQueue&& other) : q(std::move(q)) { }
     BlockingQueue& operator=(BlockingQueue&& other) { q = std::move(q); return *this; }
-    void Post(T&& pkt)
+    void Post(T pkt)
     {
         std::unique_lock<std::mutex> lock(mutex);
         if (Max > 0)
@@ -170,7 +170,19 @@ public:
             post_cv.wait(lock, [&]() { return unlocked | (q.size() < Max); });
             if (q.size() >= Max) return;
         }
-        q.push_back(std::forward<T>(pkt));
+        q.push_back(pkt);
+        get_cv.notify_one();
+    }
+    void PostUnique(T pkt)
+    {
+        std::unique_lock<std::mutex> lock(mutex);
+        if (Max > 0)
+        {
+            post_cv.wait(lock, [&]() { return unlocked | (q.size() < Max); });
+            if (q.size() >= Max) return;
+        }
+        if (std::find(q.begin(), q.end(), pkt) == q.end());
+            q.push_back(pkt);
         get_cv.notify_one();
     }
     T Get()