sns: filter resize should reset internal state

code/espurna/filters/LastFilter.h

@@ -18,7 +18,11 @@ public:
     }
 
     void reset() override {
-        _value = 0;
+        _reset();
+    }
+
+    void resize(size_t) override {
+        _reset();
     }
 
     double value() const override {
@@ -26,6 +30,10 @@ public:
     }
 
 private:
+    void _reset() {
+        _value = 0;
+    }
+
     double _value = 0;
     bool _status = false;
 };

code/espurna/filters/MaxFilter.h

@@ -19,8 +19,12 @@ public:
         return 1;
     }
 
+    void resize(size_t) override {
+        _reset();
+    }
+
     void reset() override {
-        _value = 0;
+        _reset();
     }
 
     double value() const {
@@ -28,5 +32,9 @@ public:
     }
 
 private:
+    void _reset() {
+        _value = 0;
+    }
+
     double _value = 0;
 };

code/espurna/filters/MedianFilter.h

@@ -19,12 +19,7 @@ public:
     }
 
     void reset() override {
-        if (_values.size() > 2) {
-            _values[0] = _values.back();
-            _values.resize(1);
-        } else {
-            _values.clear();
-        }
+        _reset();
     }
 
     double value() const override {
@@ -66,14 +61,20 @@ public:
     }
 
     void resize(size_t capacity) override {
-        if (_capacity != capacity) {
-            _capacity = capacity;
-            _values.clear();
-            _values.reserve(_capacity + 1);
-        }
+        _values.reserve(capacity + 1);
+        _reset();
     }
 
 private:
+    void _reset() {
+        auto previous = _values.size()
+            ? _values.back()
+            : 0.0;
+        _values.clear();
+        _values.push_back(previous);
+
+    }
+
     std::vector<double> _values;
     size_t _capacity = 0;
 };

code/espurna/filters/MovingAverageFilter.h

@@ -36,14 +36,22 @@ public:
     }
 
     void resize(size_t size) override {
-        _values.clear();
         _values.reserve(size);
+        _reset();
     }
 
     void reset() override {
-        _values.clear();
+        _reset();
     }
 
 private:
+    void _reset() {
+        if (_values.size()) {
+            _values.erase(_values.begin(), _values.end() - 1);
+        } else {
+            _values.clear();
+        }
+    }
+
     std::vector<double> _values{};
 };

code/espurna/filters/SumFilter.h

@@ -17,8 +17,12 @@ public:
         return 1;
     }
 
+    void resize(size_t) override {
+        _reset();
+    }
+
     void reset() override {
-        _value = 0.0;
+        _reset();
     }
 
     double value() const override {
@@ -26,5 +30,9 @@ public:
     }
 
 private:
+    void _reset() {
+        _value = 0.0;
+    }
+
     double _value = 0.0;
 };