Pull down should start search.

b/31458165

Change-Id: If4821e3d89a05a00551af6a5209ebc1693a1389b

1 files changed, 85 insertions, 0 deletions

diff --git a/src/com/android/launcher3/util/VerticalFlingDetector.java b/src/com/android/launcher3/util/VerticalFlingDetector.java
new file mode 100644
index 000000000..5f2b3f3ac
--- /dev/null
+++ b/src/com/android/launcher3/util/VerticalFlingDetector.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2016 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 com.android.launcher3.util;
+
+import android.content.Context;
+import android.view.MotionEvent;
+import android.view.VelocityTracker;
+import android.view.View;
+import android.view.ViewConfiguration;
+
+public class VerticalFlingDetector implements View.OnTouchListener {
+
+    private static final float CUSTOM_SLOP_MULTIPLIER = 2.2f;
+    private static final int SEC_IN_MILLIS = 1000;
+
+    private VelocityTracker mVelocityTracker;
+    private float mMinimumFlingVelocity;
+    private float mMaximumFlingVelocity;
+    private float mDownX, mDownY;
+    private boolean mShouldCheckFling;
+    private double mCustomTouchSlop;
+
+    public VerticalFlingDetector(Context context) {
+        ViewConfiguration vc = ViewConfiguration.get(context);
+        mMinimumFlingVelocity = vc.getScaledMinimumFlingVelocity();
+        mMaximumFlingVelocity = vc.getScaledMaximumFlingVelocity();
+        mCustomTouchSlop = CUSTOM_SLOP_MULTIPLIER * vc.getScaledTouchSlop();
+    }
+
+    @Override
+    public boolean onTouch(View v, MotionEvent ev) {
+        if (mVelocityTracker == null) {
+            mVelocityTracker = VelocityTracker.obtain();
+        }
+        mVelocityTracker.addMovement(ev);
+        switch (ev.getAction()) {
+            case MotionEvent.ACTION_DOWN:
+                mDownX = ev.getX();
+                mDownY = ev.getY();
+                mShouldCheckFling = false;
+                break;
+            case MotionEvent.ACTION_MOVE:
+                if (mShouldCheckFling) {
+                    break;
+                }
+                if (Math.abs(ev.getY() - mDownY) > mCustomTouchSlop &&
+                        Math.abs(ev.getY() - mDownY) > Math.abs(ev.getX() - mDownX)) {
+                    mShouldCheckFling = true;
+                }
+                break;
+            case MotionEvent.ACTION_UP:
+                if (mShouldCheckFling) {
+                    mVelocityTracker.computeCurrentVelocity(SEC_IN_MILLIS, mMaximumFlingVelocity);
+                    // only when fling is detected in down direction
+                    if (mVelocityTracker.getYVelocity() > mMinimumFlingVelocity) {
+                        cleanUp();
+                        return true;
+                    }
+                }
+                // fall through.
+            case MotionEvent.ACTION_CANCEL:
+                cleanUp();
+        }
+        return false;
+    }
+
+    private void cleanUp() {
+        mVelocityTracker.recycle();
+        mVelocityTracker = null;
+    }
+}