note expressions extension

include/clap/ext/draft/note-expressions.h

@@ -0,0 +1,53 @@
+#pragma once
+
+#include "../../plugin.h"
+
+// This extension reports which note expressions are supported by a plugin.
+// If this extension isn't present all note expressions are assumed to be supported.
+
+// TODO : is the clap_supported_note_expressions bitmask future-proof? Or should it be a "count / get-info" pattern?
+// TODO : does getNumMIDIChannels still make sense in a 'real' extension? It can probably removed if we go for a "count / get-info" pattern?
+
+static CLAP_CONSTEXPR const char CLAP_EXT_NOTE_EXPRESSIONS[] = "clap.note-expressions.draft/0";
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum clap_supported_note_expressions
+{
+  CLAP_NOTE_EXPRESSION_MASK_VOLUME = 1 << 0,
+  CLAP_NOTE_EXPRESSION_MASK_PAN = 1 << 1,
+  CLAP_NOTE_EXPRESSION_MASK_TUNING = 1 << 2,
+  CLAP_NOTE_EXPRESSION_MASK_VIBRATO = 1 << 3,
+  CLAP_NOTE_EXPRESSION_MASK_EXPRESSION = 1 << 4,
+  CLAP_NOTE_EXPRESSION_MASK_BRIGHTNESS = 1 << 5,
+  CLAP_NOTE_EXPRESSION_MASK_PRESSURE = 1 << 6,
+
+  CLAP_NOTE_EXPRESSION_MASK_ALL = (1<<7)-1 // just the and of the above
+};
+
+/*
+  retrieve additional information for the plugin itself, if note expressions are being supported and if there
+  is a limit in MIDI channels (to reduce the offered controllers etc. in the host)
+*/
+typedef struct clap_plugin_note_expressions
+{
+   // [main-thread]
+   uint32_t(CLAP_ABI* getNumMIDIChannels) (const clap_plugin* plugin, int16_t port_index); // return 1-16
+
+   // [main-thread]
+   uint32_t(CLAP_ABI* supportedNoteExpressions) (const clap_plugin* plugin, int16_t port_index, int16_t channel); // returns a bitmap of clap_supported_note_expressions
+} clap_plugin_note_expressions_t;
+
+
+typedef struct clap_host_note_expressions {
+   // port_index = -1 means 'all ports'
+   // [main-thread]
+   void(CLAP_ABI *changed)(const clap_host_t *host,
+                           int16_t            port_index);
+} clap_host_note_expressions_t;
+
+#ifdef __cplusplus
+}
+#endif