Upstream android's fling animator.

webkit/glue/fling_animator_impl_android.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 "webkit/glue/fling_animator_impl_android.h"
+
+#include "base/android/jni_android.h"
+#include "base/android/scoped_java_ref.h"
+#include "base/logging.h"
+
+using namespace base::android;
+
+namespace webkit_glue {
+
+FlingAnimatorImpl::FlingAnimatorImpl()
+    : is_active_(false) {
+  // hold the global reference of the Java objects.
+  JNIEnv* env = AttachCurrentThread();
+  DCHECK(env);
+  ScopedJavaLocalRef<jclass> cls(GetClass(env, "android/widget/OverScroller"));
+  jmethodID constructor = GetMethodID(env, cls, "<init>",
+                                      "(Landroid/content/Context;)V");
+  ScopedJavaLocalRef<jobject> tmp(env, env->NewObject(cls.obj(), constructor,
+                                                      GetApplicationContext()));
+  DCHECK(tmp.obj());
+  java_scroller_.Reset(tmp);
+
+  fling_method_id_ = GetMethodID(env, cls, "fling", "(IIIIIIIIII)V");
+  abort_method_id_ = GetMethodID(env, cls, "abortAnimation", "()V");
+  compute_method_id_ = GetMethodID(env, cls, "computeScrollOffset", "()Z");
+  getX_method_id_ = GetMethodID(env, cls, "getCurrX", "()I");
+  getY_method_id_ = GetMethodID(env, cls, "getCurrY", "()I");
+}
+
+FlingAnimatorImpl::~FlingAnimatorImpl()
+{
+}
+
+void FlingAnimatorImpl::startFling(const WebKit::WebFloatPoint& velocity,
+                                   const WebKit::WebRect& range)
+{
+  DCHECK(velocity.x || velocity.y);
+  if (is_active_)
+    cancelFling();
+
+  is_active_ = true;
+
+  JNIEnv* env = AttachCurrentThread();
+  env->CallVoidMethod(java_scroller_.obj(), fling_method_id_, 0, 0,
+                      (int) -velocity.x, (int) -velocity.y,
+                      range.x, range.x + range.width,
+                      range.y, range.y + range.height, 0, 0);
+  CheckException(env);
+}
+
+void FlingAnimatorImpl::cancelFling()
+{
+  if (!is_active_)
+    return;
+
+  is_active_ = false;
+  JNIEnv* env = AttachCurrentThread();
+  env->CallVoidMethod(java_scroller_.obj(), abort_method_id_);
+  CheckException(env);
+}
+
+bool FlingAnimatorImpl::updatePosition()
+{
+  JNIEnv* env = AttachCurrentThread();
+  bool result = env->CallBooleanMethod(java_scroller_.obj(),
+                                       compute_method_id_);
+  CheckException(env);
+  return is_active_ = result;
+}
+
+WebKit::WebPoint FlingAnimatorImpl::getCurrentPosition()
+{
+  JNIEnv* env = AttachCurrentThread();
+  WebKit::WebPoint position(
+      env->CallIntMethod(java_scroller_.obj(), getX_method_id_),
+      env->CallIntMethod(java_scroller_.obj(), getY_method_id_));
+  CheckException(env);
+  return position;
+}
+
+} // namespace webkit_glue