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      1 package com.android.launcher3;
      2 
      3 import android.view.MotionEvent;
      4 import android.view.View;
      5 import android.view.ViewConfiguration;
      6 
      7 /**
      8  * Helper for identifying when a stylus touches a view while the primary stylus button is pressed.
      9  * This can occur in {@value MotionEvent#ACTION_DOWN} or {@value MotionEvent#ACTION_MOVE}. On a
     10  * stylus button press this performs the view's {@link View#performLongClick()} method, if the view
     11  * is long clickable.
     12  */
     13 public class StylusEventHelper {
     14     private boolean mIsButtonPressed;
     15     private View mView;
     16 
     17     public StylusEventHelper(View view) {
     18         mView = view;
     19     }
     20 
     21     /**
     22      * Call this in onTouchEvent method of a view to identify a stylus button press and perform a
     23      * long click (if the view is long clickable).
     24      *
     25      * @param event The event to check for a stylus button press.
     26      * @return Whether a stylus event occurred and was handled.
     27      */
     28     public boolean checkAndPerformStylusEvent(MotionEvent event) {
     29         final float slop = ViewConfiguration.get(mView.getContext()).getScaledTouchSlop();
     30 
     31         if (!mView.isLongClickable()) {
     32             // We don't do anything unless the view is long clickable.
     33             return false;
     34         }
     35 
     36         final boolean stylusButtonPressed = isStylusButtonPressed(event);
     37         switch (event.getAction()) {
     38             case MotionEvent.ACTION_DOWN:
     39                 mIsButtonPressed = false;
     40                 if (stylusButtonPressed && mView.performLongClick()) {
     41                     mIsButtonPressed = true;
     42                     return true;
     43                 }
     44                 break;
     45             case MotionEvent.ACTION_MOVE:
     46                 if (Utilities.pointInView(mView, event.getX(), event.getY(), slop)) {
     47                     if (!mIsButtonPressed && stylusButtonPressed && mView.performLongClick()) {
     48                         mIsButtonPressed = true;
     49                         return true;
     50                     } else if (mIsButtonPressed && !stylusButtonPressed) {
     51                         mIsButtonPressed = false;
     52                     }
     53                 }
     54                 break;
     55             case MotionEvent.ACTION_UP:
     56             case MotionEvent.ACTION_CANCEL:
     57                 mIsButtonPressed = false;
     58                 break;
     59         }
     60         return false;
     61     }
     62 
     63     /**
     64      * Whether a stylus button press is occurring.
     65      */
     66     public boolean inStylusButtonPressed() {
     67         return mIsButtonPressed;
     68     }
     69 
     70     /**
     71      * Identifies if the provided {@link MotionEvent} is a stylus with the primary stylus button
     72      * pressed.
     73      *
     74      * @param event The event to check.
     75      * @return Whether a stylus button press occurred.
     76      */
     77     private static boolean isStylusButtonPressed(MotionEvent event) {
     78         return event.getToolType(0) == MotionEvent.TOOL_TYPE_STYLUS
     79                 && ((event.getButtonState() & MotionEvent.BUTTON_SECONDARY)
     80                         == MotionEvent.BUTTON_SECONDARY);
     81     }
     82 }