virtual slider mouse input mode, minor refactoring, minor bug fixes

mouseinput.h

@@ -12,6 +12,36 @@ http://mozilla.org/MPL/2.0/.
 #include <unordered_map>
 #include "command.h"
 
+// virtual slider; value determined by position of the mouse
+class mouse_slider {
+
+public:
+// constructors
+    mouse_slider() = default;
+// methods
+    void
+        bind( user_command const &Command );
+    void
+        release();
+    void
+        on_move( double const Mousex, double const Mousey );
+    inline
+    user_command
+        command() const {
+            return m_command; }
+    double
+        value() const {
+            return m_value; }
+
+private:
+// members
+    user_command m_command { user_command::none };
+    double m_value { 0.0 };
+    double m_valuerange { 0.0 };
+    bool m_analogue { false };
+    glm::dvec2 m_cursorposition { 0.0 };
+};
+
 class mouse_input {
 
 public:
@@ -27,6 +57,8 @@ public:
         move( double const Mousex, double const Mousey );
     void
         poll();
+    user_command
+        command() const;
 
 private:
 // types
@@ -44,6 +76,7 @@ private:
 
 // members
     command_relay m_relay;
+    mouse_slider m_slider; // virtual control, when active translates intercepted mouse position to a value
     controlcommands_map m_mousecommands;
     user_command m_mousecommandleft { user_command::none }; // last if any command issued with left mouse button
     user_command m_mousecommandright { user_command::none }; // last if any command issued with right mouse button