From ffa367a3eb3d96745422c590caec885b12fe19ff Mon Sep 17 00:00:00 2001
From: jules <jules@rawmaterialsoftware.com>
Date: Fri, 20 Sep 2013 09:45:59 +0100
Subject: [PATCH] Added key signature detection to CoreAudioFormat.

---
 .../codecs/juce_CoreAudioFormat.cpp           | 36 +++++++++++++++++++
 .../codecs/juce_CoreAudioFormat.h             |  2 ++
 2 files changed, 38 insertions(+)

diff --git a/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.cpp b/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.cpp
index 89345b58da..8195242c54 100644
--- a/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.cpp
+++ b/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.cpp
@@ -53,6 +53,7 @@ namespace
 const char* const CoreAudioFormat::midiDataBase64   = "midiDataBase64";
 const char* const CoreAudioFormat::tempo            = "tempo";
 const char* const CoreAudioFormat::timeSig          = "time signature";
+const char* const CoreAudioFormat::keySig           = "key signature";
 
 //==============================================================================
 struct CoreAudioFormatMetatdata
@@ -143,6 +144,7 @@ struct CoreAudioFormatMetatdata
 
             findTempoEvents (midiFile, midiMetadata);
             findTimeSigEvents (midiFile, midiMetadata);
+            findKeySigEvents (midiFile, midiMetadata);
         }
 
         input.setPosition (originalPosition + size);
@@ -220,6 +222,40 @@ struct CoreAudioFormatMetatdata
             midiMetadata.set ("time signature sequence", timeSigSequence.toUTF8());
     }
 
+    static void findKeySigEvents (MidiFile& midiFile, StringPairArray& midiMetadata)
+    {
+        MidiMessageSequence keySigEvents;
+        midiFile.findAllKeySigEvents (keySigEvents);
+        const int numKeySigEvents = keySigEvents.getNumEvents();
+
+        MemoryOutputStream keySigSequence;
+
+        for (int i = 0; i < numKeySigEvents; ++i)
+        {
+            const MidiMessage& message (keySigEvents.getEventPointer (i)->message);
+            const int key = jlimit (0, 14, message.getKeySignatureNumberOfSharpsOrFlats() + 7);
+            const bool isMajor = message.isKeySignatureMajorKey();
+
+            static const char* majorKeys[] = { "Cb", "Gb", "Db", "Ab", "Eb", "Bb", "F", "C", "G", "D", "A", "E", "B", "F#", "C#" };
+            static const char* minorKeys[] = { "Ab", "Eb", "Bb", "F", "C", "G", "D", "A", "E", "B", "F#", "C#", "G#", "D#", "A#" };
+
+            String keySigString (isMajor ? majorKeys[key]
+                                         : minorKeys[key]);
+
+            if (! isMajor)
+                keySigString << 'm';
+
+            if (i == 0)
+                midiMetadata.set (CoreAudioFormat::keySig, keySigString);
+
+            if (numKeySigEvents > 1)
+                keySigSequence << keySigString << ',' << keySigEvents.getEventTime (i) << ';';
+        }
+
+        if (keySigSequence.getDataSize() > 0)
+            midiMetadata.set ("key signature sequence", keySigSequence.toUTF8());
+    }
+
     //==============================================================================
     static StringPairArray parseInformationChunk (InputStream& input)
     {
diff --git a/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.h b/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.h
index 2a439c61fc..60bace485d 100644
--- a/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.h
+++ b/modules/juce_audio_formats/codecs/juce_CoreAudioFormat.h
@@ -50,6 +50,8 @@ public:
     static const char* const tempo;
     /** Metadata property name used when reading a caf file time signature information. */
     static const char* const timeSig;
+    /** Metadata property name used when reading a caf file time signature information. */
+    static const char* const keySig;
 
     //==============================================================================
     Array<int> getPossibleSampleRates() override;