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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.incallui;
     18 
     19 import android.view.MotionEvent;
     20 import android.view.View;
     21 
     22 /**
     23  * OnTouchListener used to shrink the "hit target" of some onscreen buttons.
     24  *
     25  * We do this for a few specific buttons which are vulnerable to
     26  * "false touches" because either (1) they're near the edge of the
     27  * screen and might be unintentionally touched while holding the
     28  * device in your hand, (2) they're in the upper corners and might
     29  * be touched by the user's ear before the prox sensor has a chance to
     30  * kick in, or (3) they are close to other buttons.
     31  */
     32 public class SmallerHitTargetTouchListener implements View.OnTouchListener {
     33     private static final String TAG = "SmallerHitTargetTouchListener";
     34 
     35     /**
     36      * Edge dimensions where a touch does not register an action (in DIP).
     37      */
     38     private static final int HIT_TARGET_EDGE_IGNORE_DP_X = 30;
     39     private static final int HIT_TARGET_EDGE_IGNORE_DP_Y = 10;
     40     private static final int HIT_TARGET_MIN_SIZE_DP_X = HIT_TARGET_EDGE_IGNORE_DP_X * 3;
     41     private static final int HIT_TARGET_MIN_SIZE_DP_Y = HIT_TARGET_EDGE_IGNORE_DP_Y * 3;
     42 
     43     // True if the most recent DOWN event was a "hit".
     44     boolean mDownEventHit;
     45 
     46     /**
     47      * Called when a touch event is dispatched to a view. This allows listeners to
     48      * get a chance to respond before the target view.
     49      *
     50      * @return True if the listener has consumed the event, false otherwise.
     51      *         (In other words, we return true when the touch is *outside*
     52      *         the "smaller hit target", which will prevent the actual
     53      *         button from handling these events.)
     54      */
     55     @Override
     56     public boolean onTouch(View v, MotionEvent event) {
     57         // if (DBG) log("SmallerHitTargetTouchListener: " + v + ", event " + event);
     58 
     59         if (event.getAction() == MotionEvent.ACTION_DOWN) {
     60             // Note that event.getX() and event.getY() are already
     61             // translated into the View's coordinates.  (In other words,
     62             // "0,0" is a touch on the upper-left-most corner of the view.)
     63             final int touchX = (int) event.getX();
     64             final int touchY = (int) event.getY();
     65 
     66             final int viewWidth = v.getWidth();
     67             final int viewHeight = v.getHeight();
     68 
     69             final float pixelDensity = v.getResources().getDisplayMetrics().density;
     70             final int targetMinSizeX = (int) (HIT_TARGET_MIN_SIZE_DP_X * pixelDensity);
     71             final int targetMinSizeY = (int) (HIT_TARGET_MIN_SIZE_DP_Y * pixelDensity);
     72 
     73             int edgeIgnoreX = (int) (HIT_TARGET_EDGE_IGNORE_DP_X * pixelDensity);
     74             int edgeIgnoreY = (int) (HIT_TARGET_EDGE_IGNORE_DP_Y * pixelDensity);
     75 
     76             // If we are dealing with smaller buttons where the dead zone defined by
     77             // HIT_TARGET_EDGE_IGNORE_DP_[X|Y] is too large.
     78             if (viewWidth < targetMinSizeX || viewHeight < targetMinSizeY) {
     79                 // This really should not happen given our two use cases (as of this writing)
     80                 // in the call edge button and secondary calling card. However, we leave
     81                 // this is as a precautionary measure.
     82                 Log.w(TAG, "onTouch: view is too small for SmallerHitTargetTouchListener");
     83                 edgeIgnoreX = 0;
     84                 edgeIgnoreY = 0;
     85             }
     86 
     87             final int minTouchX = edgeIgnoreX;
     88             final int maxTouchX = viewWidth - edgeIgnoreX;
     89             final int minTouchY = edgeIgnoreY;
     90             final int maxTouchY = viewHeight - edgeIgnoreY;
     91 
     92             if (touchX < minTouchX || touchX > maxTouchX ||
     93                     touchY < minTouchY || touchY > maxTouchY) {
     94                 // Missed!
     95                 // if (DBG) log("  -> MISSED!");
     96                 mDownEventHit = false;
     97                 return true;  // Consume this event; don't let the button see it
     98             } else {
     99                 // Hit!
    100                 // if (DBG) log("  -> HIT!");
    101                 mDownEventHit = true;
    102                 return false;  // Let this event through to the actual button
    103             }
    104         } else {
    105             // This is a MOVE, UP or CANCEL event.
    106             //
    107             // We only do the "smaller hit target" check on DOWN events.
    108             // For the subsequent MOVE/UP/CANCEL events, we let them
    109             // through to the actual button IFF the previous DOWN event
    110             // got through to the actual button (i.e. it was a "hit".)
    111             return !mDownEventHit;
    112         }
    113     }
    114 }
    115