Track plugin input event latency

ppapi/examples/input/touch_event_latency_tracing.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.

[dmichael (off chromium), 2014/05/05 22:20:32]

nit: 2014
tinier nit: I've heard it's preferable to omit the "(c)" part now. (Here and
other new files)


Seeing as this is a private interface, do we really need an example? Maybe it
would be better to have an automated test?

+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <algorithm>
+
+#include "base/debug/trace_event.h"
+#include "ppapi/c/pp_input_event.h"
+#include "ppapi/cpp/graphics_2d.h"
+#include "ppapi/cpp/image_data.h"
+#include "ppapi/cpp/input_event.h"
+#include "ppapi/cpp/instance.h"
+#include "ppapi/cpp/logging.h"
+#include "ppapi/cpp/module.h"
+#include "ppapi/cpp/private/input_event_private.h"
+#include "ppapi/cpp/size.h"
+#include "ppapi/cpp/view.h"
+#include "ppapi/utility/graphics/paint_manager.h"
+
+pp::Rect SquareForTouchPoint(int x, int y, int radius) {
+  radius /= 2;
+  return PP_MakeRectFromXYWH(x - radius, y - radius,
+                             radius * 2 + 1, radius * 2 + 1);
+}
+
+static void FillRect(pp::ImageData* image,
+                     int left, int top, int width, int height,
+                     uint32_t color) {
+  for (int y = std::max(0, top);
+       y < std::min(image->size().height() - 1, top + height);
+       y++) {
+    for (int x = std::max(0, left);
+         x < std::min(image->size().width() - 1, left + width);
+         x++)
+      *image->GetAddr32(pp::Point(x, y)) = color;
+  }
+}
+
+class MyInstance : public pp::Instance, public pp::PaintManager::Client {
+ public:
+  MyInstance(PP_Instance instance)
+      : pp::Instance(instance),
+        paint_manager_() {
+    paint_manager_.Initialize(this, this, false);
+    RequestInputEvents(PP_INPUTEVENT_CLASS_TOUCH);
+  }
+
+  virtual bool HandleInputEvent(const pp::InputEvent& event) {
+    switch (event.GetType()) {
+      case PP_INPUTEVENT_TYPE_TOUCHSTART:
+      case PP_INPUTEVENT_TYPE_TOUCHEND:
+      case PP_INPUTEVENT_TYPE_TOUCHCANCEL: {
+        pp::InputEventPrivate private_event(event);
+        private_event.TraceInputLatency(false);
+        return true;
+      }
+
+      case PP_INPUTEVENT_TYPE_TOUCHMOVE: {
+        pp::TouchInputEvent touch(event);
+        uint32_t count = touch.GetTouchCount(PP_TOUCHLIST_TYPE_CHANGEDTOUCHES);
+        if (count > 0) {
+          pp::TouchPoint point = touch.GetTouchByIndex(
+              PP_TOUCHLIST_TYPE_CHANGEDTOUCHES, 0);
+          UpdateSquareTouch(static_cast<int>(point.position().x()),
+                            static_cast<int>(point.position().y()),
+                            static_cast<int>(point.radii().x()));
+          pp::InputEventPrivate private_event(event);
+          private_event.TraceInputLatency(true);
+        } else {
+          pp::InputEventPrivate private_event(event);
+          private_event.TraceInputLatency(false);
+        }
+        return true;
+      }
+      default:
+        return false;
+    }
+  }
+
+  virtual void DidChangeView(const pp::View& view) {
+    paint_manager_.SetSize(view.GetRect().size());
+  }
+
+  // PaintManager::Client implementation.
+  virtual bool OnPaint(pp::Graphics2D& graphics_2d,
+                       const std::vector<pp::Rect>& paint_rects,
+                       const pp::Rect& paint_bounds) {
+    // Make an image just large enough to hold all dirty rects. We won't
+    // actually paint all of these pixels below, but rather just the dirty
+    // ones. Since image allocation can be somewhat heavyweight, we wouldn't
+    // want to allocate separate images in the case of multiple dirty rects.
+    pp::ImageData updated_image(this, PP_IMAGEDATAFORMAT_BGRA_PREMUL,
+                                paint_bounds.size(), false);
+
+    for (size_t i = 0; i < paint_rects.size(); i++) {
+      // Since our image is just the invalid region, we need to offset the
+      // areas we paint by that much. This is just a light blue background.
+      FillRect(&updated_image,
+               paint_rects[i].x(),
+               paint_rects[i].y(),
+               paint_rects[i].width(),
+               paint_rects[i].height(),
+               0xFF000000);
+    }
+
+    graphics_2d.PaintImageData(updated_image, paint_bounds.point());
+    return true;
+  }
+
+ private:
+  void UpdateSquareTouch(int x, int y, int radius) {
+    paint_manager_.InvalidateRect(SquareForTouchPoint(x, y, radius));
+  }
+
+  pp::PaintManager paint_manager_;
+};
+
+class MyModule : public pp::Module {
+ public:
+  virtual pp::Instance* CreateInstance(PP_Instance instance) {
+    return new MyInstance(instance);
+  }
+};
+
+namespace pp {
+
+// Factory function for your specialization of the Module object.
+Module* CreateModule() {
+  return new MyModule();
+}
+
+}  // namespace pp