tests: Add performance tracking framework

This adds a performance tracking framework that can run a set of tests over
specified git revisions. The ruby script for generating the reports comes from
similar performance tracking in GEGL. The framework permits evaluating new
tests against older version of clutter.

The tests themselves go through a few hoops for disabling framerate limiting in
both mesa and clutter.

When running make check the tests will be run and lines of the form:

@ test-state: 40.51 fps

will be left in the output, a script can scrape these lines out of a build log
on a buildbot to in other ways track performance.

tests/performance/test-text-perf.c

@@ -0,0 +1,164 @@
+#include <clutter/clutter.h>
+
+#include <stdlib.h>
+#include <string.h>
+#include "test-common.h"
+
+#define STAGE_WIDTH  800
+#define STAGE_HEIGHT 600
+
+static int font_size;
+static int n_chars;
+static int rows, cols;
+
+static gboolean
+queue_redraw (gpointer stage)
+{
+  clutter_actor_queue_redraw (CLUTTER_ACTOR (stage));
+  return TRUE;
+}
+
+static gunichar
+get_character (int ch)
+{
+  int total_letters = 0;
+  int i;
+
+  static const struct
+  {
+    gunichar first_letter;
+    int n_letters;
+  }
+  ranges[] =
+    {
+      { 'a', 26 }, /* lower case letters */
+      { 'A', 26 }, /* upper case letters */
+      { '0', 10 }, /* digits */
+      { 0x410, 0x40 }, /* cyrillic alphabet */
+      { 0x3b1, 18 } /* greek alphabet */
+    };
+
+  for (i = 0; i < G_N_ELEMENTS (ranges); i++)
+    total_letters += ranges[i].n_letters;
+
+  ch %= total_letters;
+
+  for (i = 0; i < G_N_ELEMENTS (ranges) - 1; i++)
+    if (ch < ranges[i].n_letters)
+      return ch + ranges[i].first_letter;
+    else
+      ch -= ranges[i].n_letters;
+
+  return ch + ranges[i].first_letter;
+}
+
+static ClutterActor *
+create_label (void)
+{
+  ClutterColor label_color = { 0xff, 0xff, 0xff, 0xff };
+  ClutterActor *label;
+  char         *font_name;
+  GString      *str;
+  int           i;
+
+  font_name = g_strdup_printf ("Monospace %dpx", font_size);
+
+  str = g_string_new (NULL);
+  for (i = 0; i < n_chars; i++)
+    g_string_append_unichar (str, get_character (i));
+
+  label = clutter_text_new_with_text (font_name, str->str);
+  clutter_text_set_color (CLUTTER_TEXT (label), &label_color);
+
+  g_free (font_name);
+  g_string_free (str, TRUE);
+
+  return label;
+}
+
+int
+main (int argc, char *argv[])
+{
+  ClutterActor    *stage;
+  ClutterColor     stage_color = { 0x00, 0x00, 0x00, 0xff };
+  ClutterActor    *label;
+  int              w, h;
+  int              row, col;
+  float            scale = 1.0f;
+
+  clutter_perf_fps_init ();
+
+  if (CLUTTER_INIT_SUCCESS != clutter_init (&argc, &argv))
+    g_error ("Failed to initialize Clutter");
+
+  if (argc != 3)
+    {
+      //g_printerr ("Usage test-text-perf FONT_SIZE N_CHARS\n");
+      //exit (1);
+      font_size = 30;
+      n_chars = 400;
+    }
+  else
+    {
+      font_size = atoi (argv[1]);
+      n_chars = atoi (argv[2]);
+    }
+
+  g_print ("Monospace %dpx, string length = %d\n", font_size, n_chars);
+
+  stage = clutter_stage_get_default ();
+  clutter_actor_set_size (stage, STAGE_WIDTH, STAGE_HEIGHT);
+  clutter_stage_set_color (CLUTTER_STAGE (stage), &stage_color);
+
+  label = create_label ();
+  w = clutter_actor_get_width (label);
+  h = clutter_actor_get_height (label);
+
+  /* If the label is too big to fit on the stage then scale it so that
+     it will fit */
+  if (w > STAGE_WIDTH || h > STAGE_HEIGHT)
+    {
+      float x_scale = STAGE_WIDTH / (float) w;
+      float y_scale = STAGE_HEIGHT / (float) h;
+
+      if (x_scale < y_scale)
+        {
+          scale = x_scale;
+          cols = 1;
+          rows = STAGE_HEIGHT / (h * scale);
+        }
+      else
+        {
+          scale = y_scale;
+          cols = STAGE_WIDTH / (w * scale);
+          rows = 1;
+        }
+
+      g_print ("Text scaled by %f to fit on the stage\n", scale);
+    }
+  else
+    {
+      cols = STAGE_WIDTH / w;
+      rows = STAGE_HEIGHT / h;
+    }
+
+  clutter_actor_destroy (label);
+
+  for (row=0; row<rows; row++)
+    for (col=0; col<cols; col++)
+      {
+	label = create_label();
+        clutter_actor_set_scale (label, scale, scale);
+	clutter_actor_set_position (label, w * col * scale, h * row * scale);
+	clutter_container_add_actor (CLUTTER_CONTAINER (stage), label);
+      }
+
+  clutter_actor_show_all (stage);
+
+  clutter_perf_fps_start (CLUTTER_STAGE (stage));
+  g_idle_add (queue_redraw, stage);
+  clutter_main ();
+  clutter_perf_fps_report ("test-text-perf");
+
+  return 0;
+}