1 files changed, 152 insertions, 0 deletions
diff --git a/gfx/layers/composite/FrameUniformityData.cpp b/gfx/layers/composite/FrameUniformityData.cpp
new file mode 100644
index 000000000..e8bab6adb
--- /dev/null
+++ b/gfx/layers/composite/FrameUniformityData.cpp
@@ -0,0 +1,152 @@
+/* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "FrameUniformityData.h"
+
+#include <map>
+
+#include "Units.h"
+#include "gfxPoint.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/dom/APZTestDataBinding.h"
+#include "mozilla/dom/ToJSValue.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace layers {
+
+using namespace gfx;
+
+Point
+LayerTransforms::GetAverage()
+{
+  MOZ_ASSERT(!mTransforms.IsEmpty());
+
+  Point current = mTransforms[0];
+  Point average;
+  size_t length = mTransforms.Length();
+
+  for (size_t i = 1; i < length; i++) {
+    Point nextTransform = mTransforms[i];
+    Point movement = nextTransform - current;
+    average += Point(std::fabs(movement.x), std::fabs(movement.y));
+    current = nextTransform;
+  }
+
+  average = average / (float) length;
+  return average;
+}
+
+Point
+LayerTransforms::GetStdDev()
+{
+  Point average = GetAverage();
+  Point stdDev;
+  Point current = mTransforms[0];
+
+  for (size_t i = 1; i < mTransforms.Length(); i++) {
+    Point next = mTransforms[i];
+    Point move = next - current;
+    move.x = fabs(move.x);
+    move.y = fabs(move.y);
+
+    Point diff = move - average;
+    diff.x = diff.x * diff.x;
+    diff.y = diff.y * diff.y;
+    stdDev += diff;
+
+    current = next;
+  }
+
+  stdDev = stdDev / mTransforms.Length();
+  stdDev.x = sqrt(stdDev.x);
+  stdDev.y = sqrt(stdDev.y);
+  return stdDev;
+}
+
+LayerTransformRecorder::~LayerTransformRecorder()
+{
+  Reset();
+}
+
+void
+LayerTransformRecorder::RecordTransform(Layer* aLayer, const Point& aTransform)
+{
+  LayerTransforms* layerTransforms = GetLayerTransforms((uintptr_t) aLayer);
+  layerTransforms->mTransforms.AppendElement(aTransform);
+}
+
+void
+LayerTransformRecorder::EndTest(FrameUniformityData* aOutData)
+{
+  for (auto iter = mFrameTransforms.begin(); iter != mFrameTransforms.end(); ++iter) {
+    uintptr_t layer = iter->first;
+    float uniformity = CalculateFrameUniformity(layer);
+
+    std::pair<uintptr_t,float> result(layer, uniformity);
+    aOutData->mUniformities.insert(result);
+  }
+
+  Reset();
+}
+
+LayerTransforms*
+LayerTransformRecorder::GetLayerTransforms(uintptr_t aLayer)
+{
+  if (!mFrameTransforms.count(aLayer)) {
+    LayerTransforms* newTransform = new LayerTransforms();
+    std::pair<uintptr_t, LayerTransforms*> newLayer(aLayer, newTransform);
+    mFrameTransforms.insert(newLayer);
+  }
+
+  return mFrameTransforms.find(aLayer)->second;
+}
+
+void
+LayerTransformRecorder::Reset()
+{
+  for (auto iter = mFrameTransforms.begin(); iter != mFrameTransforms.end(); ++iter) {
+    LayerTransforms* layerTransforms = iter->second;
+    delete layerTransforms;
+  }
+
+  mFrameTransforms.clear();
+}
+
+float
+LayerTransformRecorder::CalculateFrameUniformity(uintptr_t aLayer)
+{
+  LayerTransforms* layerTransform = GetLayerTransforms(aLayer);
+  float yUniformity = -1;
+  if (!layerTransform->mTransforms.IsEmpty()) {
+    Point stdDev = layerTransform->GetStdDev();
+    yUniformity = stdDev.y;
+  }
+  return yUniformity;
+}
+
+bool
+FrameUniformityData::ToJS(JS::MutableHandleValue aOutValue, JSContext* aContext)
+{
+  dom::FrameUniformityResults results;
+  dom::Sequence<dom::FrameUniformity>& layers = results.mLayerUniformities.Construct();
+
+  for (auto iter = mUniformities.begin(); iter != mUniformities.end(); ++iter) {
+    uintptr_t layerAddr = iter->first;
+    float uniformity = iter->second;
+
+    // FIXME: Make this infallible after bug 968520 is done.
+    MOZ_ALWAYS_TRUE(layers.AppendElement(fallible));
+    dom::FrameUniformity& entry = layers.LastElement();
+
+    entry.mLayerAddress.Construct() = layerAddr;
+    entry.mFrameUniformity.Construct() = uniformity;
+  }
+
+  return dom::ToJSValue(aContext, results, aOutValue);
+}
+
+} // namespace layers
+} // namespace mozilla