Make MIDI CC events apply in log scale if needed

This helps #387, but rule is defined by the plugin.
Later on the user must be able to choose the scale mode
(among other things)

source/backend/CarlaBackend.h

@@ -20,6 +20,8 @@
 
 #include "CarlaDefines.h"
 
+#include <cmath>
+
 #ifdef CARLA_PROPER_CPP11_SUPPORT
 # include <cstdint>
 #else
@@ -1384,6 +1386,19 @@ typedef struct {
 
         return value * (max - min) + min;
     }
+
+    /*!
+     * Get a logarithmic value previously normalized to 0.0<->1.0.
+     */
+    float getUnnormalizedLogValue(const float& value) const noexcept
+    {
+        if (value <= 0.0f)
+            return min;
+        if (value >= 1.0f)
+            return max;
+
+        return min * std::pow(max/min, value);
+    }
 #endif /* __cplusplus */
 
 } ParameterRanges;

source/backend/plugin/CarlaPluginDSSI.cpp

@@ -1533,7 +1533,10 @@ public:
                             }
                             else
                             {
-                                value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
+                                if (pData->param.data[k].hints & PARAMETER_IS_LOGARITHMIC)
+                                    value = pData->param.ranges[k].getUnnormalizedLogValue(ctrlEvent.value);
+                                else
+                                    value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
 
                                 if (pData->param.data[k].hints & PARAMETER_IS_INTEGER)
                                     value = std::rint(value);

source/backend/plugin/CarlaPluginFluidSynth.cpp

@@ -1192,7 +1192,10 @@ public:
                             }
                             else
                             {
-                                value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
+                                if (pData->param.data[k].hints & PARAMETER_IS_LOGARITHMIC)
+                                    value = pData->param.ranges[k].getUnnormalizedLogValue(ctrlEvent.value);
+                                else
+                                    value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
 
                                 if (pData->param.data[k].hints & PARAMETER_IS_INTEGER)
                                     value = std::rint(value);

source/backend/plugin/CarlaPluginJuce.cpp

@@ -824,7 +824,10 @@ public:
                             }
                             else
                             {
-                                value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
+                                if (pData->param.data[k].hints & PARAMETER_IS_LOGARITHMIC)
+                                    value = pData->param.ranges[k].getUnnormalizedLogValue(ctrlEvent.value);
+                                else
+                                    value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
 
                                 if (pData->param.data[k].hints & PARAMETER_IS_INTEGER)
                                     value = std::rint(value);

source/backend/plugin/CarlaPluginLADSPA.cpp

@@ -1026,7 +1026,10 @@ public:
                             }
                             else
                             {
-                                value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
+                                if (pData->param.data[k].hints & PARAMETER_IS_LOGARITHMIC)
+                                    value = pData->param.ranges[k].getUnnormalizedLogValue(ctrlEvent.value);
+                                else
+                                    value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
 
                                 if (pData->param.data[k].hints & PARAMETER_IS_INTEGER)
                                     value = std::rint(value);

source/backend/plugin/CarlaPluginLV2.cpp

@@ -3168,7 +3168,10 @@ public:
                             }
                             else
                             {
-                                value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
+                                if (pData->param.data[k].hints & PARAMETER_IS_LOGARITHMIC)
+                                    value = pData->param.ranges[k].getUnnormalizedLogValue(ctrlEvent.value);
+                                else
+                                    value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
 
                                 if (pData->param.data[k].hints & PARAMETER_IS_INTEGER)
                                     value = std::rint(value);

source/backend/plugin/CarlaPluginNative.cpp

@@ -1560,7 +1560,10 @@ public:
                             }
                             else
                             {
-                                value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
+                                if (pData->param.data[k].hints & PARAMETER_IS_LOGARITHMIC)
+                                    value = pData->param.ranges[k].getUnnormalizedLogValue(ctrlEvent.value);
+                                else
+                                    value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
 
                                 if (pData->param.data[k].hints & PARAMETER_IS_INTEGER)
                                     value = std::rint(value);

source/backend/plugin/CarlaPluginVST2.cpp

@@ -1279,7 +1279,10 @@ public:
                             }
                             else
                             {
-                                value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
+                                if (pData->param.data[k].hints & PARAMETER_IS_LOGARITHMIC)
+                                    value = pData->param.ranges[k].getUnnormalizedLogValue(ctrlEvent.value);
+                                else
+                                    value = pData->param.ranges[k].getUnnormalizedValue(ctrlEvent.value);
 
                                 if (pData->param.data[k].hints & PARAMETER_IS_INTEGER)
                                     value = std::rint(value);