Home | History | Annotate | Download | only in phone 
      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.phone;
     18 
     19 import android.util.Log;
     20 import android.view.MotionEvent;
     21 import android.view.View;
     22 
     23 /**
     24  * OnTouchListener used to shrink the "hit target" of some onscreen buttons.
     25  *
     26  * We do this for a few specific buttons which are vulnerable to
     27  * "false touches" because either (1) they're near the edge of the
     28  * screen and might be unintentionally touched while holding the
     29  * device in your hand, (2) they're in the upper corners and might
     30  * be touched by the user's ear before the prox sensor has a chance to
     31  * kick in, or (3) they are close to other buttons.
     32  */
     33 public class SmallerHitTargetTouchListener implements View.OnTouchListener {
     34     private static final String TAG = "SmallerHitTargetTouchListener";
     35 
     36     /**
     37      * Edge dimensions where a touch does not register an action (in DIP).
     38      */
     39     private static final int HIT_TARGET_EDGE_IGNORE_DP_X = 30;
     40     private static final int HIT_TARGET_EDGE_IGNORE_DP_Y = 10;
     41     private static final int HIT_TARGET_MIN_SIZE_DP_X = HIT_TARGET_EDGE_IGNORE_DP_X * 3;
     42     private static final int HIT_TARGET_MIN_SIZE_DP_Y = HIT_TARGET_EDGE_IGNORE_DP_Y * 3;
     43 
     44     // True if the most recent DOWN event was a "hit".
     45     boolean mDownEventHit;
     46 
     47     /**
     48      * Called when a touch event is dispatched to a view. This allows listeners to
     49      * get a chance to respond before the target view.
     50      *
     51      * @return True if the listener has consumed the event, false otherwise.
     52      *         (In other words, we return true when the touch is *outside*
     53      *         the "smaller hit target", which will prevent the actual
     54      *         button from handling these events.)
     55      */
     56     @Override
     57     public boolean onTouch(View v, MotionEvent event) {
     58         // if (DBG) log("SmallerHitTargetTouchListener: " + v + ", event " + event);
     59 
     60         if (event.getAction() == MotionEvent.ACTION_DOWN) {
     61             // Note that event.getX() and event.getY() are already
     62             // translated into the View's coordinates.  (In other words,
     63             // "0,0" is a touch on the upper-left-most corner of the view.)
     64             final int touchX = (int) event.getX();
     65             final int touchY = (int) event.getY();
     66 
     67             final int viewWidth = v.getWidth();
     68             final int viewHeight = v.getHeight();
     69 
     70             final float pixelDensity = v.getResources().getDisplayMetrics().density;
     71             final int targetMinSizeX = (int) (HIT_TARGET_MIN_SIZE_DP_X * pixelDensity);
     72             final int targetMinSizeY = (int) (HIT_TARGET_MIN_SIZE_DP_Y * pixelDensity);
     73 
     74             int edgeIgnoreX = (int) (HIT_TARGET_EDGE_IGNORE_DP_X * pixelDensity);
     75             int edgeIgnoreY = (int) (HIT_TARGET_EDGE_IGNORE_DP_Y * pixelDensity);
     76 
     77             // If we are dealing with smaller buttons where the dead zone defined by
     78             // HIT_TARGET_EDGE_IGNORE_DP_[X|Y] is too large.
     79             if (viewWidth < targetMinSizeX || viewHeight < targetMinSizeY) {
     80                 // This really should not happen given our two use cases (as of this writing)
     81                 // in the call edge button and secondary calling card. However, we leave
     82                 // this is as a precautionary measure.
     83                 Log.w(TAG, "onTouch: view is too small for SmallerHitTargetTouchListener");
     84                 edgeIgnoreX = 0;
     85                 edgeIgnoreY = 0;
     86             }
     87 
     88             final int minTouchX = edgeIgnoreX;
     89             final int maxTouchX = viewWidth - edgeIgnoreX;
     90             final int minTouchY = edgeIgnoreY;
     91             final int maxTouchY = viewHeight - edgeIgnoreY;
     92 
     93             if (touchX < minTouchX || touchX > maxTouchX ||
     94                     touchY < minTouchY || touchY > maxTouchY) {
     95                 // Missed!
     96                 // if (DBG) log("  -> MISSED!");
     97                 mDownEventHit = false;
     98                 return true;  // Consume this event; don't let the button see it
     99             } else {
    100                 // Hit!
    101                 // if (DBG) log("  -> HIT!");
    102                 mDownEventHit = true;
    103                 return false;  // Let this event through to the actual button
    104             }
    105         } else {
    106             // This is a MOVE, UP or CANCEL event.
    107             //
    108             // We only do the "smaller hit target" check on DOWN events.
    109             // For the subsequent MOVE/UP/CANCEL events, we let them
    110             // through to the actual button IFF the previous DOWN event
    111             // got through to the actual button (i.e. it was a "hit".)
    112             return !mDownEventHit;
    113         }
    114     }
    115 }
    116