Canvas API. There are still a number of things to do:

runtime/embedders/openglui/common/support.h

+// 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.
+
+#ifndef EMBEDDERS_OPENGLUI_COMMON_SUPPORT_H_
+#define EMBEDDERS_OPENGLUI_COMMON_SUPPORT_H_
+
+#include "embedders/openglui/common/opengl.h"
+
+#ifndef MAX
+#define MAX(a, b) (((a) > (b)) ? (a) : (b))
+#endif
+#ifndef MIN
+#define MIN(a, b) (((a) < (b)) ? (a) : (b))
+#endif
+
+// Colors as used by canvas.
+typedef struct ColorRGBA {
+  // We store Skia-compatible values. Skia uses
+  // the form AARRGGBB.
+  uint32_t v;
+
+  inline ColorRGBA(char rp, char gp, char bp, char ap = 255) {
+    v = ((static_cast<uint32_t>(rp) & 0xFF) << 16) |
+        ((static_cast<uint32_t>(gp) & 0xFF) << 8) |
+        ((static_cast<uint32_t>(bp) & 0xFF) << 0) |
+        ((static_cast<uint32_t>(ap) & 0xFF) << 24);
+  }
+  inline ColorRGBA(uint32_t vp)
+    : v(vp) {
+  }
+  inline uint8_t alpha() {
+    return (v >> 24) & 0xFF;
+  }
+} ColorRGBA;
+
+#endif  // EMBEDDERS_OPENGLUI_COMMON_SUPPORT_H_