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-rw-r--r--plugins/eg-scope.lv2/examploscope_ui.c676
1 files changed, 676 insertions, 0 deletions
diff --git a/plugins/eg-scope.lv2/examploscope_ui.c b/plugins/eg-scope.lv2/examploscope_ui.c
new file mode 100644
index 0000000..ce0000c
--- /dev/null
+++ b/plugins/eg-scope.lv2/examploscope_ui.c
@@ -0,0 +1,676 @@
+/*
+ Copyright 2013 Robin Gareus <robin@gareus.org>
+
+ Permission to use, copy, modify, and/or distribute this software for any
+ purpose with or without fee is hereby granted, provided that the above
+ copyright notice and this permission notice appear in all copies.
+
+ THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "./uris.h"
+
+#include "lv2/atom/atom.h"
+#include "lv2/atom/forge.h"
+#include "lv2/atom/util.h"
+#include "lv2/core/lv2.h"
+#include "lv2/ui/ui.h"
+#include "lv2/urid/urid.h"
+
+#include <cairo.h>
+#include <gdk/gdk.h>
+#include <glib-object.h>
+#include <glib.h>
+#include <gobject/gclosure.h>
+#include <gtk/gtk.h>
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+// Drawing area size
+#define DAWIDTH (640)
+#define DAHEIGHT (200)
+
+/**
+ Max continuous points on path. Many short-path segments are
+ expensive|inefficient long paths are not supported by all surfaces (usually
+ its a miter - not point - limit, depending on used cairo backend)
+*/
+#define MAX_CAIRO_PATH (128)
+
+/**
+ Representation of the raw audio-data for display (min | max) values for a
+ given 'index' position.
+*/
+typedef struct {
+ float data_min[DAWIDTH];
+ float data_max[DAWIDTH];
+
+ uint32_t idx;
+ uint32_t sub;
+} ScoChan;
+
+typedef struct {
+ LV2_Atom_Forge forge;
+ LV2_URID_Map* map;
+ ScoLV2URIs uris;
+
+ LV2UI_Write_Function write;
+ LV2UI_Controller controller;
+
+ GtkWidget* hbox;
+ GtkWidget* vbox;
+ GtkWidget* sep[2];
+ GtkWidget* darea;
+ GtkWidget* btn_pause;
+ GtkWidget* lbl_speed;
+ GtkWidget* lbl_amp;
+ GtkWidget* spb_speed;
+ GtkWidget* spb_amp;
+ GtkAdjustment* spb_speed_adj;
+ GtkAdjustment* spb_amp_adj;
+
+ ScoChan chn[2];
+ uint32_t stride;
+ uint32_t n_channels;
+ bool paused;
+ float rate;
+ bool updating;
+} EgScopeUI;
+
+
+/** Send current UI settings to backend. */
+static void
+send_ui_state(LV2UI_Handle handle)
+{
+ EgScopeUI* ui = (EgScopeUI*)handle;
+ const float gain = gtk_spin_button_get_value(GTK_SPIN_BUTTON(ui->spb_amp));
+
+ // Use local buffer on the stack to build atom
+ uint8_t obj_buf[1024];
+ lv2_atom_forge_set_buffer(&ui->forge, obj_buf, sizeof(obj_buf));
+
+ // Start a ui:State object
+ LV2_Atom_Forge_Frame frame;
+ LV2_Atom* msg = (LV2_Atom*)lv2_atom_forge_object(
+ &ui->forge, &frame, 0, ui->uris.ui_State);
+
+ // msg[samples-per-pixel] = integer
+ lv2_atom_forge_key(&ui->forge, ui->uris.ui_spp);
+ lv2_atom_forge_int(&ui->forge, ui->stride);
+
+ // msg[amplitude] = float
+ lv2_atom_forge_key(&ui->forge, ui->uris.ui_amp);
+ lv2_atom_forge_float(&ui->forge, gain);
+
+ // Finish ui:State object
+ lv2_atom_forge_pop(&ui->forge, &frame);
+
+ // Send message to plugin port '0'
+ ui->write(ui->controller,
+ 0,
+ lv2_atom_total_size(msg),
+ ui->uris.atom_eventTransfer,
+ msg);
+}
+
+/** Notify backend that UI is closed. */
+static void
+send_ui_disable(LV2UI_Handle handle)
+{
+ EgScopeUI* ui = (EgScopeUI*)handle;
+ send_ui_state(handle);
+
+ uint8_t obj_buf[64];
+ lv2_atom_forge_set_buffer(&ui->forge, obj_buf, sizeof(obj_buf));
+
+ LV2_Atom_Forge_Frame frame;
+ LV2_Atom* msg = (LV2_Atom*)lv2_atom_forge_object(
+ &ui->forge, &frame, 0, ui->uris.ui_Off);
+ lv2_atom_forge_pop(&ui->forge, &frame);
+ ui->write(ui->controller,
+ 0,
+ lv2_atom_total_size(msg),
+ ui->uris.atom_eventTransfer,
+ msg);
+}
+
+/**
+ Notify backend that UI is active.
+
+ The plugin should send state and enable data transmission.
+*/
+static void
+send_ui_enable(LV2UI_Handle handle)
+{
+ EgScopeUI* ui = (EgScopeUI*)handle;
+
+ uint8_t obj_buf[64];
+ lv2_atom_forge_set_buffer(&ui->forge, obj_buf, sizeof(obj_buf));
+
+ LV2_Atom_Forge_Frame frame;
+ LV2_Atom* msg = (LV2_Atom*)lv2_atom_forge_object(
+ &ui->forge, &frame, 0, ui->uris.ui_On);
+ lv2_atom_forge_pop(&ui->forge, &frame);
+ ui->write(ui->controller,
+ 0,
+ lv2_atom_total_size(msg),
+ ui->uris.atom_eventTransfer,
+ msg);
+}
+
+/** Gtk widget callback. */
+static gboolean
+on_cfg_changed(GtkWidget* widget, gpointer data)
+{
+ EgScopeUI* ui = (EgScopeUI*)data;
+ if (!ui->updating) {
+ // Only send UI state if the change is from user interaction
+ send_ui_state(data);
+ }
+ return TRUE;
+}
+
+/**
+ Gdk drawing area draw callback.
+
+ Called in Gtk's main thread and uses Cairo to draw the data.
+*/
+static gboolean
+on_expose_event(GtkWidget* widget, GdkEventExpose* ev, gpointer data)
+{
+ EgScopeUI* ui = (EgScopeUI*)data;
+ const float gain = gtk_spin_button_get_value(GTK_SPIN_BUTTON(ui->spb_amp));
+
+ // Get cairo type for the gtk window
+ cairo_t* cr;
+ cr = gdk_cairo_create(ui->darea->window);
+
+ // Limit cairo-drawing to exposed area
+ cairo_rectangle(cr, ev->area.x, ev->area.y, ev->area.width, ev->area.height);
+ cairo_clip(cr);
+
+ // Clear background
+ cairo_set_source_rgba(cr, 0.0, 0.0, 0.0, 1.0);
+ cairo_rectangle(cr, 0, 0, DAWIDTH, DAHEIGHT * ui->n_channels);
+ cairo_fill(cr);
+
+ cairo_set_line_width(cr, 1.0);
+
+ const uint32_t start = ev->area.x;
+ const uint32_t end = ev->area.x + ev->area.width;
+
+ assert(start < DAWIDTH);
+ assert(end <= DAWIDTH);
+ assert(start < end);
+
+ for (uint32_t c = 0; c < ui->n_channels; ++c) {
+ ScoChan* chn = &ui->chn[c];
+
+ /* Drawing area Y-position of given sample-value.
+ * Note: cairo-pixel at 0 spans -0.5 .. +0.5, hence (DAHEIGHT / 2.0 -0.5)
+ * also the cairo Y-axis points upwards (hence 'minus value')
+ *
+ * == ( DAHEIGHT * (CHN) // channel offset
+ * + (DAHEIGHT / 2) - 0.5 // vertical center -- '0'
+ * - (DAHEIGHT / 2) * (VAL) * (GAIN)
+ * )
+ */
+ const float chn_y_offset = DAHEIGHT * c + DAHEIGHT * 0.5f - 0.5f;
+ const float chn_y_scale = DAHEIGHT * 0.5f * gain;
+
+#define CYPOS(VAL) (chn_y_offset - (VAL) * chn_y_scale)
+
+ cairo_save(cr);
+
+ /* Restrict drawing to current channel area, don't bleed drawing into
+ neighboring channels. */
+ cairo_rectangle(cr, 0, DAHEIGHT * c, DAWIDTH, DAHEIGHT);
+ cairo_clip(cr);
+
+ // Set color of wave-form
+ cairo_set_source_rgba(cr, 0.0, 1.0, 0.0, 1.0);
+
+ /* This is a somewhat 'smart' mechanism to plot audio data using
+ alternating up/down line-directions. It works well for both cases:
+ 1 pixel <= 1 sample and 1 pixel represents more than 1 sample, but
+ is not ideal for either. */
+ if (start == chn->idx) {
+ cairo_move_to(cr, start - 0.5, CYPOS(0));
+ } else {
+ cairo_move_to(cr, start - 0.5, CYPOS(chn->data_max[start]));
+ }
+
+ uint32_t pathlength = 0;
+ for (uint32_t i = start; i < end; ++i) {
+ if (i == chn->idx) {
+ continue;
+ } else if (i % 2) {
+ cairo_line_to(cr, i - .5, CYPOS(chn->data_min[i]));
+ cairo_line_to(cr, i - .5, CYPOS(chn->data_max[i]));
+ ++pathlength;
+ } else {
+ cairo_line_to(cr, i - .5, CYPOS(chn->data_max[i]));
+ cairo_line_to(cr, i - .5, CYPOS(chn->data_min[i]));
+ ++pathlength;
+ }
+
+ /** Limit the max cairo path length. This is an optimization trade
+ off: too short path: high load CPU/GPU load. too-long path:
+ bad anti-aliasing, or possibly lost points */
+ if (pathlength > MAX_CAIRO_PATH) {
+ pathlength = 0;
+ cairo_stroke(cr);
+ if (i % 2) {
+ cairo_move_to(cr, i - .5, CYPOS(chn->data_max[i]));
+ } else {
+ cairo_move_to(cr, i - .5, CYPOS(chn->data_min[i]));
+ }
+ }
+ }
+
+ if (pathlength > 0) {
+ cairo_stroke(cr);
+ }
+
+ // Draw current position vertical line if display is slow
+ if (ui->stride >= ui->rate / 4800.0f || ui->paused) {
+ cairo_set_source_rgba(cr, .9, .2, .2, .6);
+ cairo_move_to(cr, chn->idx - .5, DAHEIGHT * c);
+ cairo_line_to(cr, chn->idx - .5, DAHEIGHT * (c + 1));
+ cairo_stroke(cr);
+ }
+
+ // Undo the 'clipping' restriction
+ cairo_restore(cr);
+
+ // Channel separator
+ if (c > 0) {
+ cairo_set_source_rgba(cr, .5, .5, .5, 1.0);
+ cairo_move_to(cr, 0, DAHEIGHT * c - .5);
+ cairo_line_to(cr, DAWIDTH, DAHEIGHT * c - .5);
+ cairo_stroke(cr);
+ }
+
+ // Zero scale line
+ cairo_set_source_rgba(cr, .3, .3, .7, .5);
+ cairo_move_to(cr, 0, DAHEIGHT * (c + .5) - .5);
+ cairo_line_to(cr, DAWIDTH, DAHEIGHT * (c + .5) - .5);
+ cairo_stroke(cr);
+ }
+
+ cairo_destroy(cr);
+ return TRUE;
+}
+
+/**
+ Parse raw audio data and prepare for later drawing.
+
+ Note this is a toy example, which is really a waveform display, not an
+ oscilloscope. A serious scope would not display samples as is.
+
+ Signals above ~ 1/10 of the sampling-rate will not yield a useful visual
+ display and result in a rather unintuitive representation of the actual
+ waveform.
+
+ Ideally the audio-data would be buffered and upsampled here and after that
+ written in a display buffer for later use.
+
+ For more information, see
+ https://wiki.xiph.org/Videos/Digital_Show_and_Tell
+ http://lac.linuxaudio.org/2013/papers/36.pdf
+ and https://github.com/x42/sisco.lv2
+*/
+static int
+process_channel(EgScopeUI* ui,
+ ScoChan* chn,
+ const size_t n_elem,
+ float const* data,
+ uint32_t* idx_start,
+ uint32_t* idx_end)
+{
+ int overflow = 0;
+ *idx_start = chn->idx;
+ for (size_t i = 0; i < n_elem; ++i) {
+ if (data[i] < chn->data_min[chn->idx]) {
+ chn->data_min[chn->idx] = data[i];
+ }
+ if (data[i] > chn->data_max[chn->idx]) {
+ chn->data_max[chn->idx] = data[i];
+ }
+ if (++chn->sub >= ui->stride) {
+ chn->sub = 0;
+ chn->idx = (chn->idx + 1) % DAWIDTH;
+ if (chn->idx == 0) {
+ ++overflow;
+ }
+ chn->data_min[chn->idx] = 1.0;
+ chn->data_max[chn->idx] = -1.0;
+ }
+ }
+ *idx_end = chn->idx;
+ return overflow;
+}
+
+/**
+ Called via port_event() which is called by the host, typically at a rate of
+ around 25 FPS.
+*/
+static void
+update_scope(EgScopeUI* ui,
+ const int32_t channel,
+ const size_t n_elem,
+ float const* data)
+{
+ // Never trust input data which could lead to application failure.
+ if (channel < 0 || (uint32_t)channel > ui->n_channels) {
+ return;
+ }
+
+ // Update state in sync with 1st channel
+ if (channel == 0) {
+ ui->stride = gtk_spin_button_get_value(GTK_SPIN_BUTTON(ui->spb_speed));
+ const bool paused = gtk_toggle_button_get_active(
+ GTK_TOGGLE_BUTTON(ui->btn_pause));
+
+ if (paused != ui->paused) {
+ ui->paused = paused;
+ gtk_widget_queue_draw(ui->darea);
+ }
+ }
+ if (ui->paused) {
+ return;
+ }
+
+ uint32_t idx_start; // Display pixel start
+ uint32_t idx_end; // Display pixel end
+ int overflow; // Received more audio-data than display-pixel
+
+ // Process this channel's audio-data for display
+ ScoChan* chn = &ui->chn[channel];
+ overflow = process_channel(ui, chn, n_elem, data, &idx_start, &idx_end);
+
+ // Signal gtk's main thread to redraw the widget after the last channel
+ if ((uint32_t)channel + 1 == ui->n_channels) {
+ if (overflow > 1) {
+ // Redraw complete widget
+ gtk_widget_queue_draw(ui->darea);
+ } else if (idx_end > idx_start) {
+ // Redraw area between start -> end pixel
+ gtk_widget_queue_draw_area(ui->darea, idx_start - 2, 0, 3
+ + idx_end - idx_start,
+ DAHEIGHT * ui->n_channels);
+ } else if (idx_end < idx_start) {
+ // Wrap-around: redraw area between 0->start AND end->right-end
+ gtk_widget_queue_draw_area(
+ ui->darea,
+ idx_start - 2, 0,
+ 3 + DAWIDTH - idx_start, DAHEIGHT * ui->n_channels);
+ gtk_widget_queue_draw_area(
+ ui->darea,
+ 0, 0,
+ idx_end + 1, DAHEIGHT * ui->n_channels);
+ }
+ }
+}
+
+static LV2UI_Handle
+instantiate(const LV2UI_Descriptor* descriptor,
+ const char* plugin_uri,
+ const char* bundle_path,
+ LV2UI_Write_Function write_function,
+ LV2UI_Controller controller,
+ LV2UI_Widget* widget,
+ const LV2_Feature* const* features)
+{
+ EgScopeUI* ui = (EgScopeUI*)calloc(1, sizeof(EgScopeUI));
+
+ if (!ui) {
+ fprintf(stderr, "EgScope.lv2 UI: out of memory\n");
+ return NULL;
+ }
+
+ ui->map = NULL;
+ *widget = NULL;
+
+ if (!strcmp(plugin_uri, SCO_URI "#Mono")) {
+ ui->n_channels = 1;
+ } else if (!strcmp(plugin_uri, SCO_URI "#Stereo")) {
+ ui->n_channels = 2;
+ } else {
+ free(ui);
+ return NULL;
+ }
+
+ for (int i = 0; features[i]; ++i) {
+ if (!strcmp(features[i]->URI, LV2_URID_URI "#map")) {
+ ui->map = (LV2_URID_Map*)features[i]->data;
+ }
+ }
+
+ if (!ui->map) {
+ fprintf(stderr, "EgScope.lv2 UI: Host does not support urid:map\n");
+ free(ui);
+ return NULL;
+ }
+
+ // Initialize private data structure
+ ui->write = write_function;
+ ui->controller = controller;
+
+ ui->vbox = NULL;
+ ui->hbox = NULL;
+ ui->darea = NULL;
+ ui->stride = 25;
+ ui->paused = false;
+ ui->rate = 48000;
+
+ ui->chn[0].idx = 0;
+ ui->chn[0].sub = 0;
+ ui->chn[1].idx = 0;
+ ui->chn[1].sub = 0;
+ memset(ui->chn[0].data_min, 0, sizeof(float) * DAWIDTH);
+ memset(ui->chn[0].data_max, 0, sizeof(float) * DAWIDTH);
+ memset(ui->chn[1].data_min, 0, sizeof(float) * DAWIDTH);
+ memset(ui->chn[1].data_max, 0, sizeof(float) * DAWIDTH);
+
+ map_sco_uris(ui->map, &ui->uris);
+ lv2_atom_forge_init(&ui->forge, ui->map);
+
+ // Setup UI
+ ui->hbox = gtk_hbox_new(FALSE, 0);
+ ui->vbox = gtk_vbox_new(FALSE, 0);
+
+ ui->darea = gtk_drawing_area_new();
+ gtk_widget_set_size_request(ui->darea, DAWIDTH, DAHEIGHT * ui->n_channels);
+
+ ui->lbl_speed = gtk_label_new("Samples/Pixel");
+ ui->lbl_amp = gtk_label_new("Amplitude");
+
+ ui->sep[0] = gtk_hseparator_new();
+ ui->sep[1] = gtk_label_new("");
+ ui->btn_pause = gtk_toggle_button_new_with_label("Pause");
+
+ ui->spb_speed_adj = (GtkAdjustment*)gtk_adjustment_new(
+ 25.0, 1.0, 1000.0, 1.0, 5.0, 0.0);
+ ui->spb_speed = gtk_spin_button_new(ui->spb_speed_adj, 1.0, 0);
+
+ ui->spb_amp_adj = (GtkAdjustment*)gtk_adjustment_new(
+ 1.0, 0.1, 6.0, 0.1, 1.0, 0.0);
+ ui->spb_amp = gtk_spin_button_new(ui->spb_amp_adj, 0.1, 1);
+
+ gtk_box_pack_start(GTK_BOX(ui->hbox), ui->darea, FALSE, FALSE, 0);
+ gtk_box_pack_start(GTK_BOX(ui->hbox), ui->vbox, FALSE, FALSE, 4);
+
+ gtk_box_pack_start(GTK_BOX(ui->vbox), ui->lbl_speed, FALSE, FALSE, 2);
+ gtk_box_pack_start(GTK_BOX(ui->vbox), ui->spb_speed, FALSE, FALSE, 2);
+ gtk_box_pack_start(GTK_BOX(ui->vbox), ui->sep[0], FALSE, FALSE, 8);
+ gtk_box_pack_start(GTK_BOX(ui->vbox), ui->lbl_amp, FALSE, FALSE, 2);
+ gtk_box_pack_start(GTK_BOX(ui->vbox), ui->spb_amp, FALSE, FALSE, 2);
+ gtk_box_pack_start(GTK_BOX(ui->vbox), ui->sep[1], TRUE, FALSE, 8);
+ gtk_box_pack_start(GTK_BOX(ui->vbox), ui->btn_pause, FALSE, FALSE, 2);
+
+ g_signal_connect(G_OBJECT(ui->darea), "expose_event",
+ G_CALLBACK(on_expose_event), ui);
+ g_signal_connect(G_OBJECT(ui->spb_amp), "value-changed",
+ G_CALLBACK(on_cfg_changed), ui);
+ g_signal_connect(G_OBJECT(ui->spb_speed), "value-changed",
+ G_CALLBACK(on_cfg_changed), ui);
+
+ *widget = ui->hbox;
+
+ /* Send UIOn message to plugin, which will request state and enable message
+ transmission. */
+ send_ui_enable(ui);
+
+ return ui;
+}
+
+static void
+cleanup(LV2UI_Handle handle)
+{
+ EgScopeUI* ui = (EgScopeUI*)handle;
+ /* Send UIOff message to plugin, which will save state and disable message
+ * transmission. */
+ send_ui_disable(ui);
+ gtk_widget_destroy(ui->darea);
+ free(ui);
+}
+
+static int
+recv_raw_audio(EgScopeUI* ui, const LV2_Atom_Object* obj)
+{
+ const LV2_Atom* chan_val = NULL;
+ const LV2_Atom* data_val = NULL;
+ const int n_props = lv2_atom_object_get(
+ obj,
+ ui->uris.channelID, &chan_val,
+ ui->uris.audioData, &data_val,
+ NULL);
+
+ if (n_props != 2 ||
+ chan_val->type != ui->uris.atom_Int ||
+ data_val->type != ui->uris.atom_Vector) {
+ // Object does not have the required properties with correct types
+ fprintf(stderr, "eg-scope.lv2 UI error: Corrupt audio message\n");
+ return 1;
+ }
+
+ // Get the values we need from the body of the property value atoms
+ const int32_t chn = ((const LV2_Atom_Int*)chan_val)->body;
+ const LV2_Atom_Vector* vec = (const LV2_Atom_Vector*)data_val;
+ if (vec->body.child_type != ui->uris.atom_Float) {
+ return 1; // Vector has incorrect element type
+ }
+
+ // Number of elements = (total size - header size) / element size
+ const size_t n_elem = ((data_val->size - sizeof(LV2_Atom_Vector_Body))
+ / sizeof(float));
+
+ // Float elements immediately follow the vector body header
+ const float* data = (const float*)(&vec->body + 1);
+
+ // Update display
+ update_scope(ui, chn, n_elem, data);
+ return 0;
+}
+
+static int
+recv_ui_state(EgScopeUI* ui, const LV2_Atom_Object* obj)
+{
+ const LV2_Atom* spp_val = NULL;
+ const LV2_Atom* amp_val = NULL;
+ const LV2_Atom* rate_val = NULL;
+ const int n_props = lv2_atom_object_get(
+ obj,
+ ui->uris.ui_spp, &spp_val,
+ ui->uris.ui_amp, &amp_val,
+ ui->uris.param_sampleRate, &rate_val,
+ NULL);
+
+ if (n_props != 3 ||
+ spp_val->type != ui->uris.atom_Int ||
+ amp_val->type != ui->uris.atom_Float ||
+ rate_val->type != ui->uris.atom_Float) {
+ // Object does not have the required properties with correct types
+ fprintf(stderr, "eg-scope.lv2 UI error: Corrupt state message\n");
+ return 1;
+ }
+
+ // Get the values we need from the body of the property value atoms
+ const int32_t spp = ((const LV2_Atom_Int*)spp_val)->body;
+ const float amp = ((const LV2_Atom_Float*)amp_val)->body;
+ const float rate = ((const LV2_Atom_Float*)rate_val)->body;
+
+ // Disable transmission and update UI
+ ui->updating = true;
+ gtk_spin_button_set_value(GTK_SPIN_BUTTON(ui->spb_speed), spp);
+ gtk_spin_button_set_value(GTK_SPIN_BUTTON(ui->spb_amp), amp);
+ ui->updating = false;
+ ui->rate = rate;
+
+ return 0;
+}
+
+/**
+ Receive data from the DSP-backend.
+
+ This is called by the host, typically at a rate of around 25 FPS.
+
+ Ideally this happens regularly and with relatively low latency, but there
+ are no hard guarantees about message delivery.
+*/
+static void
+port_event(LV2UI_Handle handle,
+ uint32_t port_index,
+ uint32_t buffer_size,
+ uint32_t format,
+ const void* buffer)
+{
+ EgScopeUI* ui = (EgScopeUI*)handle;
+ const LV2_Atom* atom = (const LV2_Atom*)buffer;
+
+ /* Check type of data received
+ * - format == 0: Control port event (float)
+ * - format > 0: Message (atom)
+ */
+ if (format == ui->uris.atom_eventTransfer &&
+ lv2_atom_forge_is_object_type(&ui->forge, atom->type)) {
+ const LV2_Atom_Object* obj = (const LV2_Atom_Object*)atom;
+ if (obj->body.otype == ui->uris.RawAudio) {
+ recv_raw_audio(ui, obj);
+ } else if (obj->body.otype == ui->uris.ui_State) {
+ recv_ui_state(ui, obj);
+ }
+ }
+}
+
+static const LV2UI_Descriptor descriptor = {
+ SCO_URI "#ui",
+ instantiate,
+ cleanup,
+ port_event,
+ NULL
+};
+
+LV2_SYMBOL_EXPORT
+const LV2UI_Descriptor*
+lv2ui_descriptor(uint32_t index)
+{
+ switch (index) {
+ case 0:
+ return &descriptor;
+ default:
+ return NULL;
+ }
+}