Add configurable taper to GtkDial

The taper was previously set to a log function which matched the
Clarett volume knob. Add linear option to match the Scarlett 4th Gen
input gain knobs and hardware level meters.

src/gtkdial.c

@@ -84,6 +84,7 @@ enum {
   PROP_ADJUSTMENT,
   PROP_ROUND_DIGITS,
   PROP_ZERO_DB,
+  PROP_TAPER,
   LAST_PROP
 };
 
@@ -117,6 +118,7 @@ struct _GtkDial {
 
   int round_digits;
   double zero_db;
+  int taper;
 };
 
 G_DEFINE_TYPE(GtkDial, gtk_dial, GTK_TYPE_WIDGET)
@@ -166,6 +168,18 @@ static double taper_log(double val) {
   return (val - 0.1) / 0.9;
 }
 
+static double calc_taper(GtkDial *dial, double val) {
+  if (dial->taper == GTK_DIAL_TAPER_LINEAR)
+    return val;
+
+  if (dial->taper == GTK_DIAL_TAPER_LOG)
+    return taper_log(val);
+
+  g_warning("Invalid taper value: %d", dial->taper);
+
+  return val;
+}
+
 static double calc_val(double valp, double mn, double mx) {
   return (mx - mn) * valp + mn;
 }
@@ -201,7 +215,7 @@ static void get_dial_properties(
   double mn = dial->adj ? gtk_adjustment_get_lower(dial->adj) : 0;
   double mx = dial->adj ? gtk_adjustment_get_upper(dial->adj) : 1;
   double value = dial->adj ? gtk_adjustment_get_value(dial->adj) : 0.25;
-  props->valp = taper_log(calc_valp(value, mn, mx));
+  props->valp = calc_taper(dial, calc_valp(value, mn, mx));
 
   props->angle = calc_val(props->valp, ANGLE_START, ANGLE_END);
   double radius = props->radius - props->thickness / 2;
@@ -287,6 +301,20 @@ static void gtk_dial_class_init(GtkDialClass *klass) {
     G_PARAM_READWRITE | G_PARAM_CONSTRUCT
   );
 
+  /**
+   * GtkDial:taper: (attributes org.gtk.Method.get=gtk_dial_get_taper org.gtk.Method.set=gtk_dial_set_taper)
+   *
+   * The taper of the dial.
+   */
+  properties[PROP_TAPER] = g_param_spec_int(
+    "taper",
+    "Taper",
+    "The taper of the dial",
+    GTK_DIAL_TAPER_LINEAR, GTK_DIAL_TAPER_LOG,
+    GTK_DIAL_TAPER_LINEAR,
+    G_PARAM_READWRITE | G_PARAM_CONSTRUCT
+  );
+
   g_object_class_install_properties(g_class, LAST_PROP, properties);
 
   /**
@@ -525,6 +553,9 @@ static void gtk_dial_set_property(
     case PROP_ZERO_DB:
       gtk_dial_set_zero_db(dial, g_value_get_double(value));
       break;
+    case PROP_TAPER:
+      gtk_dial_set_taper(dial, g_value_get_int(value));
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
       break;
@@ -549,6 +580,9 @@ static void gtk_dial_get_property(
     case PROP_ZERO_DB:
       g_value_set_double(value, dial->zero_db);
       break;
+    case PROP_TAPER:
+      g_value_set_int(value, dial->taper);
+      break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
       break;
@@ -581,6 +615,14 @@ double gtk_dial_get_zero_db(GtkDial *dial) {
   return dial->zero_db;
 }
 
+void gtk_dial_set_taper(GtkDial *dial, int taper) {
+  dial->taper = taper;
+}
+
+int gtk_dial_get_taper(GtkDial *dial) {
+  return dial->taper;
+}
+
 gboolean gtk_dial_set_style(
   GtkDial    *dial,
   const char *trough_border,

src/gtkdial.h

@@ -65,6 +65,15 @@ int gtk_dial_get_round_digits(GtkDial *dial);
 void gtk_dial_set_zero_db(GtkDial *dial, double zero_db);
 double gtk_dial_get_zero_db(GtkDial *dial);
 
+// taper functions
+enum {
+  GTK_DIAL_TAPER_LINEAR,
+  GTK_DIAL_TAPER_LOG
+};
+
+void gtk_dial_set_taper(GtkDial *dial, int taper);
+int gtk_dial_get_taper(GtkDial *dial);
+
 /**
  * @brief Set the colors which this dial uses. String codes can be one of the following:
  *     A standard name (Taken from the X11 rgb.txt file)

src/iface-mixer.c

@@ -174,7 +174,7 @@ static void create_input_gain_control(
   int               current_row,
   int               line_num
 ) {
-  GtkWidget *w = make_gain_alsa_elem(elem, 0);
+  GtkWidget *w = make_gain_alsa_elem(elem, 0, WIDGET_GAIN_TAPER_LINEAR);
 
   gtk_grid_attach(GTK_GRID(grid), w, line_num, current_row, 1, 1);
 }
@@ -466,7 +466,7 @@ static void create_output_controls(
     // output controls
     if (strncmp(elem->name, "Line", 4) == 0) {
       if (strstr(elem->name, "Playback Volume")) {
-        w = make_gain_alsa_elem(elem, 1);
+        w = make_gain_alsa_elem(elem, 1, WIDGET_GAIN_TAPER_LOG);
         gtk_grid_attach(
           GTK_GRID(output_grid), w, line_num - 1 + line_1_col, 1, 1, 1
         );
@@ -503,7 +503,7 @@ static void create_output_controls(
 
       GtkWidget *l = gtk_label_new(gen4 ? "Line 1–2" : "HW");
       gtk_grid_attach(GTK_GRID(output_grid), l, 0, 0, 1, 1);
-      w = make_gain_alsa_elem(elem, 1);
+      w = make_gain_alsa_elem(elem, 1, WIDGET_GAIN_TAPER_LOG);
       gtk_widget_set_tooltip_text(
         w,
         gen4
@@ -522,7 +522,7 @@ static void create_output_controls(
         "This control shows the setting of the headphone volume knob."
       );
       gtk_grid_attach(GTK_GRID(output_grid), l, 1, 0, 1, 1);
-      w = make_gain_alsa_elem(elem, 1);
+      w = make_gain_alsa_elem(elem, 1, WIDGET_GAIN_TAPER_LOG);
       gtk_grid_attach(GTK_GRID(output_grid), w, 1, 1, 1, 1);
     } else if (strcmp(elem->name, "Mute Playback Switch") == 0) {
       w = make_boolean_alsa_elem(

src/widget-gain.c

@@ -57,7 +57,11 @@ static void gain_updated(
 }
 
 //GList *make_gain_alsa_elem(struct alsa_elem *elem) {
-GtkWidget *make_gain_alsa_elem(struct alsa_elem *elem, int zero_is_off) {
+GtkWidget *make_gain_alsa_elem(
+  struct alsa_elem *elem,
+  int               zero_is_off,
+  int               widget_taper
+) {
   struct gain *data = g_malloc(sizeof(struct gain));
   data->elem = elem;
   data->vbox = gtk_box_new(GTK_ORIENTATION_VERTICAL, 0);
@@ -78,6 +82,16 @@ GtkWidget *make_gain_alsa_elem(struct alsa_elem *elem, int zero_is_off) {
 
   gtk_dial_set_zero_db(GTK_DIAL(data->dial), zero_db_value);
 
+  // convert from widget_taper to gtk_dial_taper
+  int gtk_dial_taper;
+  if (widget_taper == WIDGET_GAIN_TAPER_LINEAR)
+    gtk_dial_taper = GTK_DIAL_TAPER_LINEAR;
+  else if (widget_taper == WIDGET_GAIN_TAPER_LOG)
+    gtk_dial_taper = GTK_DIAL_TAPER_LOG;
+  else
+    gtk_dial_taper = GTK_DIAL_TAPER_LINEAR;
+  gtk_dial_set_taper(GTK_DIAL(data->dial), gtk_dial_taper);
+
   data->label = gtk_label_new(NULL);
   gtk_widget_set_vexpand(data->dial, TRUE);
 

src/widget-gain.h

@@ -7,4 +7,13 @@
 
 #include "alsa.h"
 
-GtkWidget *make_gain_alsa_elem(struct alsa_elem *alsa_elem, int zero_is_off);
+enum {
+  WIDGET_GAIN_TAPER_LINEAR,
+  WIDGET_GAIN_TAPER_LOG
+};
+
+GtkWidget *make_gain_alsa_elem(
+  struct alsa_elem *elem,
+  int               zero_is_off,
+  int               taper_type
+);

src/window-levels.c

@@ -96,6 +96,7 @@ GtkWidget *create_levels_controls(struct alsa_card *card) {
 
       // create the meter widget and attach to the grid
       GtkWidget *meter = gtk_dial_new_with_range(-80, 0, 0, 0);
+      gtk_dial_set_taper(GTK_DIAL(meter), GTK_DIAL_TAPER_LINEAR);
       gtk_widget_set_sensitive(meter, FALSE);
       card->meters[meter_num++] = meter;
       gtk_grid_attach(GTK_GRID(grid), meter, j + 1, i + 1, 1, 1);

src/window-mixer.c

@@ -76,7 +76,7 @@ GtkWidget *create_mixer_controls(struct alsa_card *card) {
     }
 
     // create the gain control and attach to the grid
-    GtkWidget *w = make_gain_alsa_elem(elem, 1);
+    GtkWidget *w = make_gain_alsa_elem(elem, 1, WIDGET_GAIN_TAPER_LOG);
     gtk_grid_attach(GTK_GRID(mixer_top), w, input_num + 1, mix_num + 2, 1, 1);
 
     // look up the r_snk entry for the mixer input number