MIDI: Allow MidiMessageCollector to preallocate storage

modules/juce_audio_devices/midi_io/juce_MidiMessageCollector.cpp

@@ -128,6 +128,11 @@ void MidiMessageCollector::removeNextBlockOfMessages (MidiBuffer& destBuffer,
     }
 }
 
+void MidiMessageCollector::ensureStorageAllocated (size_t bytes)
+{
+    incomingMessages.ensureSize (bytes);
+}
+
 //==============================================================================
 void MidiMessageCollector::handleNoteOn (MidiKeyboardState*, int midiChannel, int midiNoteNumber, float velocity)
 {

modules/juce_audio_devices/midi_io/juce_MidiMessageCollector.h

@@ -80,6 +80,14 @@ public:
     */
     void removeNextBlockOfMessages (MidiBuffer& destBuffer, int numSamples);
 
+    /** Preallocates storage for collected messages.
+
+        This can be called before audio processing begins to ensure that there
+        is sufficient space for the expected MIDI messages, in order to avoid
+        allocations within the audio callback.
+    */
+    void ensureStorageAllocated (size_t bytes);
+
 
     //==============================================================================
     /** @internal */