Fixes #1914574. An NPE could be causes in lists by ViewGroup.dispatchDraw().

ViewGroup was trying to access the AttachInfo without checking whether the
info object is null. The object can be null at varioous times in the lifecycle
of a list.

2 files changed, 72 insertions, 70 deletions

diff --git a/core/java/android/view/MotionEvent.java b/core/java/android/view/MotionEvent.java
index 86261c4..ca01448 100644
--- a/core/java/android/view/MotionEvent.java
+++ b/core/java/android/view/MotionEvent.java
@@ -59,32 +59,32 @@ public final class MotionEvent implements Parcelable {
     public static final int ACTION_OUTSIDE          = 4;
 
     private static final boolean TRACK_RECYCLED_LOCATION = false;
-    
+
     /**
      * Flag indicating the motion event intersected the top edge of the screen.
      */
     public static final int EDGE_TOP = 0x00000001;
-    
+
     /**
      * Flag indicating the motion event intersected the bottom edge of the screen.
      */
     public static final int EDGE_BOTTOM = 0x00000002;
-    
+
     /**
      * Flag indicating the motion event intersected the left edge of the screen.
      */
     public static final int EDGE_LEFT = 0x00000004;
-    
+
     /**
      * Flag indicating the motion event intersected the right edge of the screen.
      */
     public static final int EDGE_RIGHT = 0x00000008;
-    
+
     static private final int MAX_RECYCLED = 10;
     static private Object gRecyclerLock = new Object();
     static private int gRecyclerUsed = 0;
     static private MotionEvent gRecyclerTop = null;
-    
+
     private long mDownTime;
     private long mEventTime;
     private int mAction;
@@ -109,7 +109,7 @@ public final class MotionEvent implements Parcelable {
 
     private MotionEvent() {
     }
-    
+
     static private MotionEvent obtain() {
         synchronized (gRecyclerLock) {
             if (gRecyclerTop == null) {
@@ -123,26 +123,26 @@ public final class MotionEvent implements Parcelable {
             return ev;
         }
     }
-    
+
     /**
      * Create a new MotionEvent, filling in all of the basic values that
      * define the motion.
-     * 
-     * @param downTime The time (in ms) when the user originally pressed down to start 
+     *
+     * @param downTime The time (in ms) when the user originally pressed down to start
      * a stream of position events.  This must be obtained from {@link SystemClock#uptimeMillis()}.
-     * @param eventTime  The the time (in ms) when this specific event was generated.  This 
+     * @param eventTime  The the time (in ms) when this specific event was generated.  This
      * must be obtained from {@link SystemClock#uptimeMillis()}.
      * @param action The kind of action being performed -- one of either
      * {@link #ACTION_DOWN}, {@link #ACTION_MOVE}, {@link #ACTION_UP}, or
      * {@link #ACTION_CANCEL}.
      * @param x The X coordinate of this event.
      * @param y The Y coordinate of this event.
-     * @param pressure The current pressure of this event.  The pressure generally 
-     * ranges from 0 (no pressure at all) to 1 (normal pressure), however 
-     * values higher than 1 may be generated depending on the calibration of 
+     * @param pressure The current pressure of this event.  The pressure generally
+     * ranges from 0 (no pressure at all) to 1 (normal pressure), however
+     * values higher than 1 may be generated depending on the calibration of
      * the input device.
      * @param size A scaled value of the approximate size of the area being pressed when
-     * touched with the finger. The actual value in pixels corresponding to the finger 
+     * touched with the finger. The actual value in pixels corresponding to the finger
      * touch is normalized with a device specific range of values
      * and scaled to a value between 0 and 1.
      * @param metaState The state of any meta / modifier keys that were in effect when
@@ -174,15 +174,15 @@ public final class MotionEvent implements Parcelable {
 
         return ev;
     }
-    
+
     /**
      * Create a new MotionEvent, filling in a subset of the basic motion
      * values.  Those not specified here are: device id (always 0), pressure
      * and size (always 1), x and y precision (always 1), and edgeFlags (always 0).
-     * 
-     * @param downTime The time (in ms) when the user originally pressed down to start 
+     *
+     * @param downTime The time (in ms) when the user originally pressed down to start
      * a stream of position events.  This must be obtained from {@link SystemClock#uptimeMillis()}.
-     * @param eventTime  The the time (in ms) when this specific event was generated.  This 
+     * @param eventTime  The the time (in ms) when this specific event was generated.  This
      * must be obtained from {@link SystemClock#uptimeMillis()}.
      * @param action The kind of action being performed -- one of either
      * {@link #ACTION_DOWN}, {@link #ACTION_MOVE}, {@link #ACTION_UP}, or
@@ -229,9 +229,10 @@ public final class MotionEvent implements Parcelable {
                 float[] history = mHistory;
                 int length = history.length;
                 for (int i = 0; i < length; i += 4) {
-                    history[i] *= scale;
-                    history[i + 2] *= scale;
-                    history[i + 3] *= scale;
+                    history[i] *= scale;        // X
+                                                // history[i + 2] == pressure
+                    history[i + 1] *= scale;    // Y
+                    history[i + 3] *= scale;    // Size, TODO: square this?
                 }
             }
         }
@@ -265,7 +266,7 @@ public final class MotionEvent implements Parcelable {
         }
         return ev;
     }
-    
+
     /**
      * Recycle the MotionEvent, to be re-used by a later caller.  After calling
      * this function you must not ever touch the event again.
@@ -291,7 +292,7 @@ public final class MotionEvent implements Parcelable {
             }
         }
     }
-    
+
     /**
      * Return the kind of action being performed -- one of either
      * {@link #ACTION_DOWN}, {@link #ACTION_MOVE}, {@link #ACTION_UP}, or
@@ -302,8 +303,8 @@ public final class MotionEvent implements Parcelable {
     }
 
     /**
-     * Returns the time (in ms) when the user originally pressed down to start 
-     * a stream of position events. 
+     * Returns the time (in ms) when the user originally pressed down to start
+     * a stream of position events.
      */
     public final long getDownTime() {
         return mDownTime;
@@ -317,25 +318,25 @@ public final class MotionEvent implements Parcelable {
     }
 
     /**
-     * Returns the X coordinate of this event.  Whole numbers are pixels; the 
-     * value may have a fraction for input devices that are sub-pixel precise. 
+     * Returns the X coordinate of this event.  Whole numbers are pixels; the
+     * value may have a fraction for input devices that are sub-pixel precise.
      */
     public final float getX() {
         return mX;
     }
 
     /**
-     * Returns the Y coordinate of this event.  Whole numbers are pixels; the 
-     * value may have a fraction for input devices that are sub-pixel precise. 
+     * Returns the Y coordinate of this event.  Whole numbers are pixels; the
+     * value may have a fraction for input devices that are sub-pixel precise.
      */
     public final float getY() {
         return mY;
     }
 
     /**
-     * Returns the current pressure of this event.  The pressure generally 
-     * ranges from 0 (no pressure at all) to 1 (normal pressure), however 
-     * values higher than 1 may be generated depending on the calibration of 
+     * Returns the current pressure of this event.  The pressure generally
+     * ranges from 0 (no pressure at all) to 1 (normal pressure), however
+     * values higher than 1 may be generated depending on the calibration of
      * the input device.
      */
     public final float getPressure() {
@@ -344,9 +345,9 @@ public final class MotionEvent implements Parcelable {
 
     /**
      * Returns a scaled value of the approximate size, of the area being pressed when
-     * touched with the finger. The actual value in pixels corresponding to the finger 
+     * touched with the finger. The actual value in pixels corresponding to the finger
      * touch  is normalized with the device specific range of values
-     * and scaled to a value between 0 and 1. The value of size can be used to 
+     * and scaled to a value between 0 and 1. The value of size can be used to
      * determine fat touch events.
      */
     public final float getSize() {
@@ -396,7 +397,7 @@ public final class MotionEvent implements Parcelable {
     public final float getXPrecision() {
         return mXPrecision;
     }
-    
+
     /**
      * Return the precision of the Y coordinates being reported.  You can
      * multiple this number with {@link #getY} to find the actual hardware
@@ -406,89 +407,89 @@ public final class MotionEvent implements Parcelable {
     public final float getYPrecision() {
         return mYPrecision;
     }
-    
+
     /**
      * Returns the number of historical points in this event.  These are
      * movements that have occurred between this event and the previous event.
      * This only applies to ACTION_MOVE events -- all other actions will have
      * a size of 0.
-     * 
+     *
      * @return Returns the number of historical points in the event.
      */
     public final int getHistorySize() {
         return mNumHistory;
     }
-    
+
     /**
      * Returns the time that a historical movement occurred between this event
      * and the previous event.  Only applies to ACTION_MOVE events.
-     * 
+     *
      * @param pos Which historical value to return; must be less than
      * {@link #getHistorySize}
-     * 
+     *
      * @see #getHistorySize
      * @see #getEventTime
      */
     public final long getHistoricalEventTime(int pos) {
         return mHistoryTimes[pos];
     }
-    
+
     /**
      * Returns a historical X coordinate that occurred between this event
      * and the previous event.  Only applies to ACTION_MOVE events.
-     * 
+     *
      * @param pos Which historical value to return; must be less than
      * {@link #getHistorySize}
-     * 
+     *
      * @see #getHistorySize
      * @see #getX
      */
     public final float getHistoricalX(int pos) {
         return mHistory[pos*4];
     }
-    
+
     /**
      * Returns a historical Y coordinate that occurred between this event
      * and the previous event.  Only applies to ACTION_MOVE events.
-     * 
+     *
      * @param pos Which historical value to return; must be less than
      * {@link #getHistorySize}
-     * 
+     *
      * @see #getHistorySize
      * @see #getY
      */
     public final float getHistoricalY(int pos) {
         return mHistory[pos*4 + 1];
     }
-    
+
     /**
      * Returns a historical pressure coordinate that occurred between this event
      * and the previous event.  Only applies to ACTION_MOVE events.
-     * 
+     *
      * @param pos Which historical value to return; must be less than
      * {@link #getHistorySize}
-     * 
+     *
      * @see #getHistorySize
      * @see #getPressure
      */
     public final float getHistoricalPressure(int pos) {
         return mHistory[pos*4 + 2];
     }
-    
+
     /**
      * Returns a historical size coordinate that occurred between this event
      * and the previous event.  Only applies to ACTION_MOVE events.
-     * 
+     *
      * @param pos Which historical value to return; must be less than
      * {@link #getHistorySize}
-     * 
+     *
      * @see #getHistorySize
      * @see #getSize
      */
     public final float getHistoricalSize(int pos) {
         return mHistory[pos*4 + 3];
     }
-    
+
     /**
      * Return the id for the device that this event came from.  An id of
      * zero indicates that the event didn't come from a physical device; other
@@ -497,12 +498,12 @@ public final class MotionEvent implements Parcelable {
     public final int getDeviceId() {
         return mDeviceId;
     }
-    
+
     /**
      * Returns a bitfield indicating which edges, if any, where touched by this
-     * MotionEvent. For touch events, clients can use this to determine if the 
-     * user's finger was touching the edge of the display. 
-     * 
+     * MotionEvent. For touch events, clients can use this to determine if the
+     * user's finger was touching the edge of the display.
+     *
      * @see #EDGE_LEFT
      * @see #EDGE_TOP
      * @see #EDGE_RIGHT
@@ -511,12 +512,12 @@ public final class MotionEvent implements Parcelable {
     public final int getEdgeFlags() {
         return mEdgeFlags;
     }
-    
+
 
     /**
      * Sets the bitfield indicating which edges, if any, where touched by this
-     * MotionEvent. 
-     * 
+     * MotionEvent.
+     *
      * @see #getEdgeFlags()
      */
     public final void setEdgeFlags(int flags) {
@@ -548,11 +549,11 @@ public final class MotionEvent implements Parcelable {
             pos[i+1] += deltaY;
         }
     }
- 
+
     /**
      * Set this event's location.  Applies {@link #offsetLocation} with a
      * delta from the current location to the given new location.
-     * 
+     *
      * @param x New absolute X location.
      * @param y New absolute Y location.
      */
@@ -563,13 +564,13 @@ public final class MotionEvent implements Parcelable {
             offsetLocation(deltaX, deltaY);
         }
     }
-    
+
     /**
      * Add a new movement to the batch of movements in this event.  The event's
      * current location, position and size is updated to the new values.  In
      * the future, the current values in the event will be added to a list of
      * historic values.
-     * 
+     *
      * @param x The new X position.
      * @param y The new Y position.
      * @param pressure The new pressure.
@@ -599,16 +600,16 @@ public final class MotionEvent implements Parcelable {
                 mHistoryTimes = historyTimes = newHistoryTimes;
             }
         }
-        
+
         historyTimes[N] = mEventTime;
-        
+
         final int pos = N*4;
         history[pos] = mX;
         history[pos+1] = mY;
         history[pos+2] = mPressure;
         history[pos+3] = mSize;
         mNumHistory = N+1;
-        
+
         mEventTime = eventTime;
         mX = mRawX = x;
         mY = mRawY = y;
@@ -616,7 +617,7 @@ public final class MotionEvent implements Parcelable {
         mSize = size;
         mMetaState |= metaState;
     }
-    
+
     @Override
     public String toString() {
         return "MotionEvent{" + Integer.toHexString(System.identityHashCode(this))
diff --git a/core/java/android/view/ViewGroup.java b/core/java/android/view/ViewGroup.java
index af05501..f803b5a 100644
--- a/core/java/android/view/ViewGroup.java
+++ b/core/java/android/view/ViewGroup.java
@@ -1449,7 +1449,7 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
         if ((flags & FLAG_CHILDREN_DRAWN_WITH_CACHE) == FLAG_CHILDREN_DRAWN_WITH_CACHE ||
                 (flags & FLAG_ALWAYS_DRAWN_WITH_CACHE) == FLAG_ALWAYS_DRAWN_WITH_CACHE) {
             cache = child.getDrawingCache();
-            scalingRequired = mAttachInfo.mScalingRequired;
+            if (mAttachInfo != null) scalingRequired = mAttachInfo.mScalingRequired;
         }
 
         final boolean hasNoCache = cache == null;
@@ -1460,6 +1460,7 @@ public abstract class ViewGroup extends View implements ViewParent, ViewManager
         } else {
             canvas.translate(cl, ct);
             if (scalingRequired) {
+                // mAttachInfo cannot be null, otherwise scalingRequired == false
                 final float scale = 1.0f / mAttachInfo.mApplicationScale;
                 canvas.scale(scale, scale);
             }