Refactor MIDI learning to support learning select knobs, jog wheels, etc.

* Learn mappings over multiple MIDI messages instead of just one.
* Allow the user to enable MIDI options from the GUI -- currently supports
  soft-takeover, invert, select-knob (two's complement), and switch mode.
* Add Undo option for reverting the most recently learned mapping.
* Introduce LearningUtils, a class that recognizes mappings from message
  streams.
* LearningUtils has a test suite for each mapping type we want to recognize.

If we don't recognize a mapping then we fall back on the 1.11.0 behavior of
mapping the first message in the stream.

This paves the way for learning 14-bit CC and pitch bend controls and
providing richer user feedback about what we thought the control was or why we
couldn't learn it.

1 files changed, 10 insertions, 0 deletions

diff --git a/src/controllers/midi/midicontroller.h b/src/controllers/midi/midicontroller.h
index 2338b7f93a..f2a14dd90f 100644
--- a/src/controllers/midi/midicontroller.h
+++ b/src/controllers/midi/midicontroller.h
@@ -55,6 +55,10 @@ class MidiController : public Controller {
 
     virtual bool matchPreset(const PresetInfo& preset);
 
+  signals:
+    void messageReceived(unsigned char status, unsigned char control,
+                         unsigned char value);
+
   protected:
     Q_INVOKABLE void sendShortMsg(unsigned char status, unsigned char byte1, unsigned char byte2);
     // Alias for send()
@@ -76,6 +80,11 @@ class MidiController : public Controller {
     // Initializes the engine and static output mappings.
     void applyPreset(QList<QString> scriptPaths);
 
+    void learnTemporaryInputMappings(const MixxxControl& control,
+                                     const MidiKeyAndOptionsList& mappings);
+    void clearTemporaryInputMappings();
+    void commitTemporaryInputMappings();
+
   private:
     virtual void sendWord(unsigned int word) = 0;
     double computeValue(MidiOptions options, double _prevmidivalue, double _newmidivalue);
@@ -89,6 +98,7 @@ class MidiController : public Controller {
         return &m_preset;
     }
 
+    QHash<uint16_t, QPair<MixxxControl, MidiOptions> > m_temporaryInputMappings;
     QList<MidiOutputHandler*> m_outputs;
     MidiControllerPreset m_preset;
     SoftTakeover m_st;