1 files changed, 93 insertions, 0 deletions
diff --git a/src/android/support/v4/view/VelocityTrackerCompat.java b/src/android/support/v4/view/VelocityTrackerCompat.java
new file mode 100644
index 0000000..99286d0
--- /dev/null
+++ b/src/android/support/v4/view/VelocityTrackerCompat.java
@@ -0,0 +1,93 @@
+/*
+ * 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.
+ */
+
+package android.support.v4.view;
+
+import android.view.VelocityTracker;
+
+/**
+ * Helper for accessing features in {@link VelocityTracker}
+ * introduced after API level 4 in a backwards compatible fashion.
+ */
+public class VelocityTrackerCompat {
+    /**
+     * Interface for the full API.
+     */
+    interface VelocityTrackerVersionImpl {
+        public float getXVelocity(VelocityTracker tracker, int pointerId);
+        public float getYVelocity(VelocityTracker tracker, int pointerId);
+    }
+
+    /**
+     * Interface implementation that doesn't use anything about v4 APIs.
+     */
+    static class BaseVelocityTrackerVersionImpl implements VelocityTrackerVersionImpl {
+        @Override
+        public float getXVelocity(VelocityTracker tracker, int pointerId) {
+            return tracker.getXVelocity();
+        }
+        @Override
+        public float getYVelocity(VelocityTracker tracker, int pointerId) {
+            return tracker.getYVelocity();
+        }
+    }
+
+    /**
+     * Interface implementation for devices with at least v11 APIs.
+     */
+    static class HoneycombVelocityTrackerVersionImpl implements VelocityTrackerVersionImpl {
+        @Override
+        public float getXVelocity(VelocityTracker tracker, int pointerId) {
+            return VelocityTrackerCompatHoneycomb.getXVelocity(tracker, pointerId);
+        }
+        @Override
+        public float getYVelocity(VelocityTracker tracker, int pointerId) {
+            return VelocityTrackerCompatHoneycomb.getYVelocity(tracker, pointerId);
+        }
+    }
+
+    /**
+     * Select the correct implementation to use for the current platform.
+     */
+    static final VelocityTrackerVersionImpl IMPL;
+    static {
+        if (android.os.Build.VERSION.SDK_INT >= 11) {
+            IMPL = new HoneycombVelocityTrackerVersionImpl();
+        } else {
+            IMPL = new BaseVelocityTrackerVersionImpl();
+        }
+    }
+
+    // -------------------------------------------------------------------
+
+    /**
+     * Call {@link VelocityTracker#getXVelocity(int)}.
+     * If running on a pre-{@link android.os.Build.VERSION_CODES#HONEYCOMB} device,
+     * returns {@link VelocityTracker#getXVelocity()}.
+     */
+    public static float getXVelocity(VelocityTracker tracker, int pointerId) {
+        return IMPL.getXVelocity(tracker, pointerId);
+    }
+
+    /**
+     * Call {@link VelocityTracker#getYVelocity(int)}.
+     * If running on a pre-{@link android.os.Build.VERSION_CODES#HONEYCOMB} device,
+     * returns {@link VelocityTracker#getYVelocity()}.
+     */
+    public static float getYVelocity(VelocityTracker tracker, int pointerId) {
+        return IMPL.getYVelocity(tracker, pointerId);
+    }
+}