1 files changed, 208 insertions, 0 deletions
diff --git a/core/jni/android_view_VelocityTracker.cpp b/core/jni/android_view_VelocityTracker.cpp
new file mode 100644
index 0000000..daa0adc
--- /dev/null
+++ b/core/jni/android_view_VelocityTracker.cpp
@@ -0,0 +1,208 @@
+/*
+ * 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