Adding java TouchPoint class for android

content/browser/android/touch_point.cc

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/browser/android/touch_point.h"
+
+#include "base/debug/debugger.h"
+#include "base/time.h"
+#include "base/logging.h"
+
+#include "jni/touch_point_jni.h"
+
+using WebKit::WebTouchEvent;
+using WebKit::WebTouchPoint;
+
+namespace {
+
+void MaybeAddTouchPoint(JNIEnv* env, jobject pt, WebKit::WebTouchEvent& event) {
+  WebTouchPoint::State state = static_cast<WebTouchPoint::State>(
+      Java_TouchPoint_getState(env, pt));
+  if (state == WebTouchPoint::StateUndefined)
+    return;
+
+  // When generating a cancel event from an event of a different type, the
+  // touch points are out of sync, so we ensure the points are marked as
+  // canceled as well.
+  if (event.type == WebTouchEvent::TouchCancel)
+    state = WebTouchPoint::StateCancelled;
+
+  // Record the current number of points in the WebTouchEvent
+  const int idx = event.touchesLength;
+  DCHECK_LT(idx, WebKit::WebTouchEvent::touchesLengthCap);
+
+  WebTouchPoint wtp;
+  wtp.id = Java_TouchPoint_getId(env, pt);
+  wtp.state = state;
+  wtp.position.x = Java_TouchPoint_getX(env, pt);
+  wtp.position.y = Java_TouchPoint_getY(env, pt);
+  // TODO(joth): Raw event co-ordinates.
+  wtp.screenPosition = wtp.position;
+  wtp.force = Java_TouchPoint_getPressure(env, pt);
+
+  // TODO(djsollen): WebKit stores touch point size as a pair of radii, which
+  // are integers.  We receive touch point size from Android as a float
+  // between 0 and 1 and interpret 'size' as an elliptical area.  We convert
+  // size to a radius and then scale up to avoid truncating away all of the
+  // data. W3C spec is for the radii to be in units of screen pixels. Need to
+  // change.
+  const static double PI = 3.1415926;
+  const static double SCALE_FACTOR = 1024.0;
+  const int radius = static_cast<int>(
+      (sqrt(Java_TouchPoint_getSize(env, pt)) / PI) * SCALE_FACTOR);
+  wtp.radiusX = radius;
+  wtp.radiusY = radius;
+  // Since our radii are equal, a rotation angle doesn't mean anything.
+  wtp.rotationAngle = 0.0;
+
+  // Add the newly created WebTouchPoint to the event
+  event.touches[idx] = wtp;
+  ++(event.touchesLength);
+}
+
+}  // namespace
+
+namespace content {
+
+void TouchPoint::BuildWebTouchEvent(JNIEnv* env, jint type, jlong time_ms,
+    jobjectArray pts, WebKit::WebTouchEvent& event) {
+  event.type = static_cast<WebTouchEvent::Type>(type);
+  event.timeStampSeconds =
+      static_cast<double>(time_ms) / base::Time::kMillisecondsPerSecond;
+  int arrayLength = env->GetArrayLength(pts);
+  // Loop until either all of the input points have been consumed or the output
+  // array has been filled
+  for (int i = 0; i < arrayLength; i++) {
+    jobject pt = env->GetObjectArrayElement(pts, i);
+    MaybeAddTouchPoint(env, pt, event);
+    if (event.touchesLength >= event.touchesLengthCap)
+      break;
+  }
+  DCHECK_GT(event.touchesLength, 0U);
+}
+
+static void RegisterConstants(JNIEnv* env) {
+   Java_TouchPoint_initializeConstants(
+       env,
+       WebKit::WebTouchEvent::TouchStart,
+       WebKit::WebTouchEvent::TouchMove,
+       WebKit::WebTouchEvent::TouchEnd,
+       WebKit::WebTouchEvent::TouchCancel,
+       WebKit::WebTouchPoint::StateUndefined,
+       WebKit::WebTouchPoint::StateReleased,
+       WebKit::WebTouchPoint::StatePressed,
+       WebKit::WebTouchPoint::StateMoved,
+       WebKit::WebTouchPoint::StateStationary,
+       WebKit::WebTouchPoint::StateCancelled);
+}
+
+bool RegisterTouchPoint(JNIEnv* env) {
+  if (!RegisterNativesImpl(env))
+    return false;
+
+  RegisterConstants(env);
+
+  return true;
+}
+
+}  // namespace content