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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#define LOG_TAG "VelocityTracker-JNI"
#include "JNIHelp.h"
#include <android_runtime/AndroidRuntime.h>
#include <utils/Log.h>
#include <ui/Input.h>
#include "android_view_MotionEvent.h"
namespace android {
// Special constant to request the velocity of the active pointer.
static const int ACTIVE_POINTER_ID = -1;
// --- VelocityTrackerState ---
class VelocityTrackerState {
public:
VelocityTrackerState();
void clear();
void addMovement(const MotionEvent* event);
void computeCurrentVelocity(int32_t units, float maxVelocity);
void getVelocity(int32_t id, float* outVx, float* outVy);
private:
struct Velocity {
float vx, vy;
};
VelocityTracker mVelocityTracker;
int32_t mActivePointerId;
BitSet32 mCalculatedIdBits;
Velocity mCalculatedVelocity[MAX_POINTERS];
};
VelocityTrackerState::VelocityTrackerState() : mActivePointerId(-1) {
}
void VelocityTrackerState::clear() {
mVelocityTracker.clear();
mActivePointerId = -1;
mCalculatedIdBits.clear();
}
void VelocityTrackerState::addMovement(const MotionEvent* event) {
mVelocityTracker.addMovement(event);
}
void VelocityTrackerState::computeCurrentVelocity(int32_t units, float maxVelocity) {
BitSet32 idBits(mVelocityTracker.getCurrentPointerIdBits());
mCalculatedIdBits = idBits;
for (uint32_t index = 0; !idBits.isEmpty(); index++) {
uint32_t id = idBits.firstMarkedBit();
idBits.clearBit(id);
float vx, vy;
mVelocityTracker.getVelocity(id, &vx, &vy);
vx = vx * units / 1000;
vy = vy * units / 1000;
if (vx > maxVelocity) {
vx = maxVelocity;
} else if (vx < -maxVelocity) {
vx = -maxVelocity;
}
if (vy > maxVelocity) {
vy = maxVelocity;
} else if (vy < -maxVelocity) {
vy = -maxVelocity;
}
Velocity& velocity = mCalculatedVelocity[index];
velocity.vx = vx;
velocity.vy = vy;
}
}
void VelocityTrackerState::getVelocity(int32_t id, float* outVx, float* outVy) {
if (id == ACTIVE_POINTER_ID) {
id = mVelocityTracker.getActivePointerId();
}
float vx, vy;
if (id >= 0 && id <= MAX_POINTER_ID && mCalculatedIdBits.hasBit(id)) {
uint32_t index = mCalculatedIdBits.getIndexOfBit(id);
const Velocity& velocity = mCalculatedVelocity[index];
vx = velocity.vx;
vy = velocity.vy;
} else {
vx = 0;
vy = 0;
}
if (outVx) {
*outVx = vx;
}
if (outVy) {
*outVy = vy;
}
}
// --- JNI Methods ---
static jint android_view_VelocityTracker_nativeInitialize(JNIEnv* env, jclass clazz) {
return reinterpret_cast<jint>(new VelocityTrackerState());
}
static void android_view_VelocityTracker_nativeDispose(JNIEnv* env, jclass clazz, jint ptr) {
VelocityTrackerState* state = reinterpret_cast<VelocityTrackerState*>(ptr);
delete state;
}
static void android_view_VelocityTracker_nativeClear(JNIEnv* env, jclass clazz, jint ptr) {
VelocityTrackerState* state = reinterpret_cast<VelocityTrackerState*>(ptr);
state->clear();
}
static void android_view_VelocityTracker_nativeAddMovement(JNIEnv* env, jclass clazz, jint ptr,
jobject eventObj) {
const MotionEvent* event = android_view_MotionEvent_getNativePtr(env, eventObj);
if (!event) {
LOGW("nativeAddMovement failed because MotionEvent was finalized.");
return;
}
VelocityTrackerState* state = reinterpret_cast<VelocityTrackerState*>(ptr);
state->addMovement(event);
}
static void android_view_VelocityTracker_nativeComputeCurrentVelocity(JNIEnv* env, jclass clazz,
jint ptr, jint units, jfloat maxVelocity) {
VelocityTrackerState* state = reinterpret_cast<VelocityTrackerState*>(ptr);
state->computeCurrentVelocity(units, maxVelocity);
}
static jfloat android_view_VelocityTracker_nativeGetXVelocity(JNIEnv* env, jclass clazz,
jint ptr, jint id) {
VelocityTrackerState* state = reinterpret_cast<VelocityTrackerState*>(ptr);
float vx;
state->getVelocity(id, &vx, NULL);
return vx;
}
static jfloat android_view_VelocityTracker_nativeGetYVelocity(JNIEnv* env, jclass clazz,
jint ptr, jint id) {
VelocityTrackerState* state = reinterpret_cast<VelocityTrackerState*>(ptr);
float vy;
state->getVelocity(id, NULL, &vy);
return vy;
}
// --- JNI Registration ---
static JNINativeMethod gVelocityTrackerMethods[] = {
/* name, signature, funcPtr */
{ "nativeInitialize",
"()I",
(void*)android_view_VelocityTracker_nativeInitialize },
{ "nativeDispose",
"(I)V",
(void*)android_view_VelocityTracker_nativeDispose },
{ "nativeClear",
"(I)V",
(void*)android_view_VelocityTracker_nativeClear },
{ "nativeAddMovement",
"(ILandroid/view/MotionEvent;)V",
(void*)android_view_VelocityTracker_nativeAddMovement },
{ "nativeComputeCurrentVelocity",
"(IIF)V",
(void*)android_view_VelocityTracker_nativeComputeCurrentVelocity },
{ "nativeGetXVelocity",
"(II)F",
(void*)android_view_VelocityTracker_nativeGetXVelocity },
{ "nativeGetYVelocity",
"(II)F",
(void*)android_view_VelocityTracker_nativeGetYVelocity },
};
int register_android_view_VelocityTracker(JNIEnv* env) {
int res = jniRegisterNativeMethods(env, "android/view/VelocityTracker",
gVelocityTrackerMethods, NELEM(gVelocityTrackerMethods));
LOG_FATAL_IF(res < 0, "Unable to register native methods.");
return 0;
}
} // namespace android
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