Refactored OpenGL embedder that works on Android, Mac or Linux.

runtime/embedders/openglui/common/timer.cc

Index: runtime/embedders/openglui/common/timer.cc
===================================================================
--- runtime/embedders/openglui/common/timer.cc	(revision 0)
+++ runtime/embedders/openglui/common/timer.cc	(revision 0)
@@ -0,0 +1,66 @@
+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "embedders/openglui/common/timer.h"
+
+#define NANO (+1.0E-9)
+
+#ifdef __MACH__
+#include <mach/mach.h>
+#include <mach/mach_time.h>
+#include <sys/time.h>
+
+#define GIGA UINT64_C(1000000000)
+
+#define CLOCK_REALTIME    0
+#define CLOCK_MONOTONIC   1
+
+double timebase = 0.0;
+uint64_t timestart = 0;
+
+void clock_gettime(int type, timespec* t) {
+  if (!timestart) {
+    mach_timebase_info_data_t tb = { 0, 1 };
+    mach_timebase_info(&tb);
+    timebase = tb.numer;
+    timebase /= tb.denom;
+    timestart = mach_absolute_time();
+  }
+  if (type == CLOCK_MONOTONIC) {
+    double diff = (mach_absolute_time() - timestart) * timebase;
+    t->tv_sec = diff * NANO;
+    t->tv_nsec = diff - (t->tv_sec * GIGA);
+  } else {  // type == CLOCK_REALTIME
+    struct timeval now;
+    gettimeofday(&now, NULL);
+    t->tv_sec  = now.tv_sec;
+    t->tv_nsec = now.tv_usec * 1000;
+  }
+}
+#endif
+
+Timer::Timer() : elapsed_(0.0f), last_time_(0.0) {
+}
+
+void Timer::reset() {
+  elapsed_ = 0.0f;
+  last_time_ = now();
+}
+
+void Timer::update() {
+  double current = now();
+  elapsed_ = (current - last_time_);
+  last_time_ = current;
+}
+
+double Timer::now() {
+  timespec timeval;
+  clock_gettime(CLOCK_MONOTONIC, &timeval);
+  return timeval.tv_sec + (timeval.tv_nsec * NANO);
+}
+
+float Timer::elapsed() {
+  return elapsed_;
+}
+