sysprof: add colorization to time span layers

We might need to back this off or find some tweaks if it's too slow, but
for now it seems reasonably fast to just do it.

src/sysprof/sysprof-time-span-layer.c

@@ -22,6 +22,7 @@
 #include "config.h"
 
 #include "sysprof-chart-layer-private.h"
+#include "sysprof-color-iter-private.h"
 #include "sysprof-normalized-series.h"
 #include "sysprof-time-series-item.h"
 #include "sysprof-time-span-layer.h"
@@ -38,9 +39,14 @@ struct _SysprofTimeSpanLayer
 
   GBindingGroup *series_bindings;
 
+  GHashTable *colors_hash;
+
+  SysprofColorIter colors;
+
   GdkRGBA color;
   GdkRGBA event_color;
 
+  guint auto_color : 1;
   guint color_set : 1;
   guint event_color_set : 1;
 };
@@ -49,6 +55,7 @@ G_DEFINE_FINAL_TYPE (SysprofTimeSpanLayer, sysprof_time_span_layer, SYSPROF_TYPE
 
 enum {
   PROP_0,
+  PROP_AUTO_COLOR,
   PROP_AXIS,
   PROP_COLOR,
   PROP_EVENT_COLOR,
@@ -170,6 +177,7 @@ sysprof_time_span_layer_snapshot (GtkWidget   *widget,
 
           if (begin != end)
             {
+              g_autofree char *label = sysprof_time_series_dup_label (self->series, i);
               graphene_rect_t rect;
 
               rect = GRAPHENE_RECT_INIT (floor (begin * width),
@@ -190,11 +198,26 @@ sysprof_time_span_layer_snapshot (GtkWidget   *widget,
               if (rect.origin.x + rect.size.width > width)
                 rect.size.width = width - rect.origin.x;
 
-              gtk_snapshot_append_color (snapshot, color, &rect);
+              if (self->auto_color && label)
+                {
+                  const GdkRGBA *this_color = g_hash_table_lookup (self->colors_hash, label);
+
+                  if (this_color == NULL)
+                    {
+                      const GdkRGBA *next_color = sysprof_color_iter_next (&self->colors);
+                      g_hash_table_insert (self->colors_hash, g_strdup (label), (GdkRGBA *)next_color);
+                      this_color = next_color;
+                    }
+
+                  gtk_snapshot_append_color (snapshot, this_color, &rect);
+                }
+              else
+                {
+                  gtk_snapshot_append_color (snapshot, color, &rect);
+                }
 
               if (rect.size.width > 20)
                 {
-                  g_autofree char *label = sysprof_time_series_dup_label (self->series, i);
 
                   if (label != NULL)
                     {
@@ -315,6 +338,7 @@ sysprof_time_span_layer_finalize (GObject *object)
   g_clear_object (&self->series);
   g_clear_object (&self->normal_x);
   g_clear_object (&self->normal_x2);
+  g_clear_pointer (&self->colors_hash, g_hash_table_unref);
 
   G_OBJECT_CLASS (sysprof_time_span_layer_parent_class)->finalize (object);
 }
@@ -329,6 +353,10 @@ sysprof_time_span_layer_get_property (GObject    *object,
 
   switch (prop_id)
     {
+    case PROP_AUTO_COLOR:
+      g_value_set_boolean (value, self->auto_color);
+      break;
+
     case PROP_AXIS:
       g_value_set_object (value, sysprof_time_span_layer_get_axis (self));
       break;
@@ -368,6 +396,10 @@ sysprof_time_span_layer_set_property (GObject      *object,
 
   switch (prop_id)
     {
+    case PROP_AUTO_COLOR:
+      self->auto_color = g_value_get_boolean (value);
+      break;
+
     case PROP_AXIS:
       sysprof_time_span_layer_set_axis (self, g_value_get_object (value));
       break;
@@ -404,6 +436,11 @@ sysprof_time_span_layer_class_init (SysprofTimeSpanLayerClass *klass)
 
   chart_layer_class->lookup_item = sysprof_time_span_layer_lookup_item;
 
+  properties[PROP_AUTO_COLOR] =
+    g_param_spec_boolean ("auto-color", NULL, NULL,
+                          TRUE,
+                          (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS));
+
   properties[PROP_AXIS] =
     g_param_spec_object ("axis", NULL, NULL,
                          SYSPROF_TYPE_AXIS,
@@ -443,6 +480,10 @@ sysprof_time_span_layer_init (SysprofTimeSpanLayer *self)
   self->normal_x = g_object_new (SYSPROF_TYPE_NORMALIZED_SERIES, NULL);
   self->normal_x2 = g_object_new (SYSPROF_TYPE_NORMALIZED_SERIES, NULL);
 
+  self->colors_hash = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, NULL);
+  sysprof_color_iter_init (&self->colors);
+  self->auto_color = TRUE;
+
   g_signal_connect_object (self->normal_x,
                            "items-changed",
                            G_CALLBACK (gtk_widget_queue_draw),