3 files changed, 42 insertions, 6 deletions

diff --git a/plugins/eg-sampler.lv2/sampler.c b/plugins/eg-sampler.lv2/sampler.c
index 0471a90..3be9730 100644
--- a/plugins/eg-sampler.lv2/sampler.c
+++ b/plugins/eg-sampler.lv2/sampler.c
@@ -84,6 +84,7 @@ typedef struct {
 	uint32_t frame_offset;
 
 	// Playback state
+	float      gain;
 	sf_count_t frame;
 	bool       play;
 } Sampler;
@@ -309,6 +310,9 @@ cleanup(LV2_Handle instance)
 	free(self);
 }
 
+/** Define a macro for converting a gain in dB to a coefficient. */
+#define DB_CO(g) ((g) > -90.0f ? powf(10.0f, (g) * 0.05f) : 0.0f)
+
 static void
 run(LV2_Handle instance,
     uint32_t   sample_count)
@@ -345,11 +349,36 @@ run(LV2_Handle instance,
 		} else if (lv2_atom_forge_is_object_type(&self->forge, ev->body.type)) {
 			const LV2_Atom_Object* obj = (const LV2_Atom_Object*)&ev->body;
 			if (obj->body.otype == uris->patch_Set) {
-				// Received a set message, send it to the worker.
-				lv2_log_trace(&self->logger, "Queueing set message\n");
-				self->schedule->schedule_work(self->schedule->handle,
-				                              lv2_atom_total_size(&ev->body),
-				                              &ev->body);
+				// Get the property and value of the set message
+				const LV2_Atom* property = NULL;
+				const LV2_Atom* value    = NULL;
+				lv2_atom_object_get(obj,
+				                    uris->patch_property, &property,
+				                    uris->patch_value,    &value,
+				                    0);
+				if (!property) {
+					lv2_log_error(&self->logger,
+					              "patch:Set message with no property\n");
+					continue;
+				} else if (property->type != uris->atom_URID) {
+					lv2_log_error(&self->logger,
+					              "patch:Set property is not a URID\n");
+					continue;
+				}
+
+				const uint32_t key = ((const LV2_Atom_URID*)property)->body;
+				if (key == uris->eg_sample) {
+					// Sample change, send it to the worker.
+					lv2_log_trace(&self->logger, "Queueing set message\n");
+					self->schedule->schedule_work(self->schedule->handle,
+					                              lv2_atom_total_size(&ev->body),
+					                              &ev->body);
+				} else if (key == uris->param_gain) {
+					// Gain change
+					if (value->type == uris->atom_Float) {
+						self->gain = DB_CO(((LV2_Atom_Float*)value)->body);
+					}
+				}
 			} else if (obj->body.otype == uris->patch_Get) {
 				// Received a get message, emit our state (probably to UI)
 				lv2_log_trace(&self->logger, "Responding to get request\n");
@@ -377,7 +406,7 @@ run(LV2_Handle instance,
 		}
 
 		for (; pos < sample_count && f < lf; ++pos, ++f) {
-			output[pos] = self->sample->data[f];
+			output[pos] = self->sample->data[f] * self->gain;
 		}
 
 		self->frame = f;
diff --git a/plugins/eg-sampler.lv2/sampler.ttl b/plugins/eg-sampler.lv2/sampler.ttl
index 2a89dd2..197a735 100644
--- a/plugins/eg-sampler.lv2/sampler.ttl
+++ b/plugins/eg-sampler.lv2/sampler.ttl
@@ -7,6 +7,7 @@
 @prefix ui:    <http://lv2plug.in/ns/extensions/ui#> .
 @prefix urid:  <http://lv2plug.in/ns/ext/urid#> .
 @prefix work:  <http://lv2plug.in/ns/ext/worker#> .
+@prefix param: <http://lv2plug.in/ns/ext/parameters#> .
 
 <http://lv2plug.in/plugins/eg-sampler#sample>
 	a lv2:Parameter ;
@@ -26,6 +27,7 @@
 		work:interface ;
 	ui:ui <http://lv2plug.in/plugins/eg-sampler#ui> ;
 	patch:writable <http://lv2plug.in/plugins/eg-sampler#sample> ;
+	patch:writable param:gain ;
 	lv2:port [
 		a lv2:InputPort ,
 			atom:AtomPort ;
diff --git a/plugins/eg-sampler.lv2/uris.h b/plugins/eg-sampler.lv2/uris.h
index c21c6c8..e7c4dcd 100644
--- a/plugins/eg-sampler.lv2/uris.h
+++ b/plugins/eg-sampler.lv2/uris.h
@@ -21,6 +21,7 @@
 #include "lv2/lv2plug.in/ns/ext/log/log.h"
 #include "lv2/lv2plug.in/ns/ext/midi/midi.h"
 #include "lv2/lv2plug.in/ns/ext/state/state.h"
+#include "lv2/lv2plug.in/ns/ext/parameters/parameters.h"
 
 #define EG_SAMPLER_URI          "http://lv2plug.in/plugins/eg-sampler"
 #define EG_SAMPLER__sample      EG_SAMPLER_URI "#sample"
@@ -28,6 +29,7 @@
 #define EG_SAMPLER__freeSample  EG_SAMPLER_URI "#freeSample"
 
 typedef struct {
+	LV2_URID atom_Float;
 	LV2_URID atom_Path;
 	LV2_URID atom_Resource;
 	LV2_URID atom_Sequence;
@@ -37,6 +39,7 @@ typedef struct {
 	LV2_URID eg_sample;
 	LV2_URID eg_freeSample;
 	LV2_URID midi_Event;
+	LV2_URID param_gain;
 	LV2_URID patch_Get;
 	LV2_URID patch_Set;
 	LV2_URID patch_property;
@@ -46,6 +49,7 @@ typedef struct {
 static inline void
 map_sampler_uris(LV2_URID_Map* map, SamplerURIs* uris)
 {
+	uris->atom_Float         = map->map(map->handle, LV2_ATOM__Float);
 	uris->atom_Path          = map->map(map->handle, LV2_ATOM__Path);
 	uris->atom_Resource      = map->map(map->handle, LV2_ATOM__Resource);
 	uris->atom_Sequence      = map->map(map->handle, LV2_ATOM__Sequence);
@@ -55,6 +59,7 @@ map_sampler_uris(LV2_URID_Map* map, SamplerURIs* uris)
 	uris->eg_freeSample      = map->map(map->handle, EG_SAMPLER__freeSample);
 	uris->eg_sample          = map->map(map->handle, EG_SAMPLER__sample);
 	uris->midi_Event         = map->map(map->handle, LV2_MIDI__MidiEvent);
+	uris->param_gain         = map->map(map->handle, LV2_PARAMETERS__gain);
 	uris->patch_Get          = map->map(map->handle, LV2_PATCH__Get);
 	uris->patch_Set          = map->map(map->handle, LV2_PATCH__Set);
 	uris->patch_property     = map->map(map->handle, LV2_PATCH__property);