Initial revision

src/widget-gain.c

@@ -0,0 +1,56 @@
+// SPDX-FileCopyrightText: 2022 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "gtkdial.h"
+#include "widget-gain.h"
+
+// gain controls -80dB - +6dB, 0.5dB steps
+#define DIAL_MIN_VALUE 0
+#define DIAL_MAX_VALUE 172
+#define DIAL_ZERO_DB_VALUE 160
+
+static void gain_changed(GtkWidget *widget, struct alsa_elem *elem) {
+  int value = gtk_dial_get_value(GTK_DIAL(widget));
+
+  alsa_set_elem_value(elem, value);
+}
+
+static void gain_updated(struct alsa_elem *elem) {
+  int is_writable = alsa_get_elem_writable(elem);
+  gtk_widget_set_sensitive(elem->widget, is_writable);
+
+  int value = alsa_get_elem_value(elem);
+  gtk_dial_set_value(GTK_DIAL(elem->widget), value);
+
+  char s[20];
+  snprintf(s, 20, "%.1f", (value / 2.0) - 80);
+  gtk_label_set_text(GTK_LABEL(elem->widget2), s);
+}
+
+GtkWidget *make_gain_alsa_elem(struct alsa_elem *elem) {
+  GtkWidget *vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
+  gtk_widget_set_hexpand(vbox, TRUE);
+
+  GtkWidget *dial = gtk_dial_new_with_range(
+    DIAL_MIN_VALUE, DIAL_MAX_VALUE, 1
+  );
+  gtk_dial_set_zero_db(GTK_DIAL(dial), DIAL_ZERO_DB_VALUE);
+
+  gtk_widget_set_vexpand(dial, TRUE);
+
+  g_signal_connect(
+    dial, "value-changed", G_CALLBACK(gain_changed), elem
+  );
+  elem->widget = dial;
+  elem->widget_callback = gain_updated;
+
+  GtkWidget *label = gtk_label_new(NULL);
+  elem->widget2 = label;
+
+  gain_updated(elem);
+
+  gtk_box_append(GTK_BOX(vbox), dial);
+  gtk_box_append(GTK_BOX(vbox), label);
+
+  return vbox;
+}