diff options
Diffstat (limited to 'src/com/android/launcher3/util/VerticalFlingDetector.java')
-rw-r--r-- | src/com/android/launcher3/util/VerticalFlingDetector.java | 88 |
1 files changed, 88 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..7236c2d1b --- /dev/null +++ b/src/com/android/launcher3/util/VerticalFlingDetector.java @@ -0,0 +1,88 @@ +/* + * 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() { + if (mVelocityTracker == null) { + return; + } + mVelocityTracker.recycle(); + mVelocityTracker = null; + } +} |