Android10.0 锁屏分析-KeyguardPatternView图案锁分析

首先一起看看下面这张图：

通过前面锁屏加载流程可以知道在KeyguardSecurityContainer中使用getSecurityView()根据不同的securityMode inflate出来，并添加到界面上的。
我们知道，Pattern锁所使用的layout是 R.layout.keyguard_pattern_view；

<com.android.keyguard.KeyguardPatternView ...>
...<com.android.internal.widget.LockPatternViewandroid:id="@+id/lockPatternView"android:layout_width="match_parent"android:layout_height="0dp"android:layout_weight="1"android:layout_marginEnd="8dip"android:layout_marginBottom="4dip"android:layout_marginStart="8dip"android:layout_gravity="center_horizontal"android:gravity="center"android:clipChildren="false"android:clipToPadding="false" />
...</FrameLayout>
</com.android.keyguard.KeyguardPatternView>

那么图案解锁的滑动事件处理，就是在LockPatternView，是一个系统公共控件，下面我们就分析一下这个view是如何处理触摸输入的：
frameworks/base/core/java/com/android/internal/widget/LockPatternView.java

    @Overridepublic boolean onTouchEvent(MotionEvent event) {if (!mInputEnabled || !isEnabled()) {return false;}switch(event.getAction()) {case MotionEvent.ACTION_DOWN:handleActionDown(event);return true;case MotionEvent.ACTION_UP:handleActionUp();return true;case MotionEvent.ACTION_MOVE:handleActionMove(event);return true;case MotionEvent.ACTION_CANCEL:if (mPatternInProgress) {setPatternInProgress(false);resetPattern();notifyPatternCleared();}if (PROFILE_DRAWING) {if (mDrawingProfilingStarted) {Debug.stopMethodTracing();mDrawingProfilingStarted = false;}}return true;}return false;}

几种事件类型：

事件	简介
ACTION_DOWN	手指初次触摸到屏幕时触发
ACTION_MOVE	手指在屏幕上滑动时触发，会多次触发
ACTION_UP	手指离开屏幕时触发
ACTION_CANCEL	事件被上层拦截时触发
ACTION_OUTSIDE	手指不在控件区域时触发

不同的MotionEvent对应几个不同的handle方法处理，代码行数太多，我们这里大致总结如下:

• ACTION_DOWN(handleActionDown)：根据触摸事件的坐标，使用算法detectAndAddHit(x, y)获取是否有命中的点，如果有，会调用addCellToPattern将命中的Cell添加到mPattern中，后即回调mOnPatternListener.onPatternStart()通知监听器，KeyguardPatternView实现并监听了OnPatternListener，做了清除安全提示内容的动作。另外计算需要重绘区域，并调用invalidate进行局部重绘。
• ACTION_MOVE(handleActionMove)：在这里 LockPatternView会对所有的历史坐标加当前事件坐标遍历for (int i = 0; i < historySize + 1; i++)，获取命中点，另外如果ACTION_DOWN时没有获取到命中点，流程同上面的ACTION_UP,然后也会回调mOnPatternListener.onPatternStart()。最后会把所有motionevent对应的重绘区域进行union，并调用invalidate进行局部重绘。

关于历史坐标
  为了效率，Android系统在处理ACTION_MOVE事件时会将连续的几个多触点移动事件打包到一个MotionEvent对象中。我们可以通过getX(int)和getY(int)来获得最近发生的一个触摸点事件的坐标，然后使用getHistorical(int,int)和getHistorical(int,int)来获得时间稍早的触点事件的坐标，二者是发生时间先后的关系。所以，我们应该先处理通过getHistoricalXX相关函数获得的事件信息，然后在处理当前的事件信息。

for (int i = 0; i < historySize + 1; i++) {final float x = i < historySize ? event.getHistoricalX(i) : event.getX();final float y = i < historySize ? event.getHistoricalY(i) : event.getY();...
}

• ACTION_UP(handleActionUp)：如果mPattern不为空的话，会重置mPatternInProgress，取消动画，然后回调mOnPatternListener.onPatternDetected(final List<LockPatternView.Cell> pattern)，这时候就开始图案解锁的验证了。
• ACTION_CANCEL：重置pattern状态，回调mOnPatternListener.onPatternCleared()

图案解锁验证

src/com/android/keyguard/KeyguardPatternView.java

    private class UnlockPatternListener implements LockPatternView.OnPatternListener {...@Overridepublic void onPatternDetected(final List<LockPatternView.Cell> pattern) {if (DEBUG) Log.d(TAG, "onPatternDetected");mKeyguardUpdateMonitor.setCredentialAttempted();mLockPatternView.disableInput();if (mPendingLockCheck != null) {mPendingLockCheck.cancel(false);}final int userId = KeyguardUpdateMonitor.getCurrentUser();if (pattern.size() < LockPatternUtils.MIN_PATTERN_REGISTER_FAIL) {mLockPatternView.enableInput();onPatternChecked(userId, false, 0, false /* not valid - too short */);return;}if (LatencyTracker.isEnabled(mContext)) {LatencyTracker.getInstance(mContext).onActionStart(ACTION_CHECK_CREDENTIAL);LatencyTracker.getInstance(mContext).onActionStart(ACTION_CHECK_CREDENTIAL_UNLOCKED);}mPendingLockCheck = LockPatternChecker.checkCredential(mLockPatternUtils,LockscreenCredential.createPattern(pattern),    // 这里跟进去，会发现将 pattern转化成了 byte[]userId,new LockPatternChecker.OnCheckCallback() {@Overridepublic void onEarlyMatched() {if (DEBUG) Log.d(TAG, "onEarlyMatched");if (LatencyTracker.isEnabled(mContext)) {LatencyTracker.getInstance(mContext).onActionEnd(ACTION_CHECK_CREDENTIAL);}onPatternChecked(userId, true /* matched */, 0 /* timeoutMs */,true /* isValidPattern */);}@Overridepublic void onChecked(boolean matched, int timeoutMs) {if (DEBUG) Log.d(TAG, "onChecked matched:" + matched);if (LatencyTracker.isEnabled(mContext)) {LatencyTracker.getInstance(mContext).onActionEnd(ACTION_CHECK_CREDENTIAL_UNLOCKED);}mLockPatternView.enableInput();mPendingLockCheck = null;if (!matched) {onPatternChecked(userId, false /* matched */, timeoutMs,true /* isValidPattern */);}}@Overridepublic void onCancelled() {if (DEBUG) Log.d(TAG, "onCancelled");// We already got dismissed with the early matched callback, so we// cancelled the check. However, we still need to note down the latency.if (LatencyTracker.isEnabled(mContext)) {LatencyTracker.getInstance(mContext).onActionEnd(ACTION_CHECK_CREDENTIAL_UNLOCKED);}}});if (pattern.size() > MIN_PATTERN_BEFORE_POKE_WAKELOCK) {mCallback.userActivity();mCallback.onUserInput();}}...}

在绘制密码后手指抬起的时候，如果已存的有效点数达到4个及以上，就会使用LockPatternChecker.checkCredential 方法调用 task.execute() 启动一个AsyncTask， 并在doInBackground中调用LockPatternUtils.checkCredential 进行密码验证，此时pattern会被转化成字节形式（LockscreenCredential.createPattern(pattern) 这里跟进去，会发现将 pattern转化成了 byte[]）

// LockPatternUtils.java
public static byte[] patternToByteArray(List<LockPatternView.Cell> pattern) {if (pattern == null) {return new byte[0];}final int patternSize = pattern.size();byte[] res = new byte[patternSize];for (int i = 0; i < patternSize; i++) {LockPatternView.Cell cell = pattern.get(i);res[i] = (byte) (cell.getRow() * 3 + cell.getColumn() + '1');}return res;
}

最终和密码锁PIN码锁一样，都是远程调用到LockSettingsService 的 checkCredential 接口进行验证。
Keyguard接收用户输入的密码会通过Binder到framework层的LockSettingsService，LockSettingsService经过一系列调用会通过getGateKeeperService获取GateKeeperService然后调用verifyChallenge方法将密码继续忘底层传递，framework的调用栈如下：

java.lang.Throwab
comandroid.locksettings.1locksettings.LockSettingsService. spBasedDoVerifyCredential(LockSettingsService. java:2724)COT3767075server.ocksettingsLockSettingsService.doVerifyCredentia1(LockSettingsSeryice.java:2020comandroservercom android.server.locksettings.LockSettingsService.doVerifyCredential(LockSettingsService. jaya:1999atcom android.server.locksettings.LockSettingsService. checkCredential(LockSettingsService. java:1972)com android.internal.widget.ILockSettings$Stub.onTransact(ILockSettings.java:542atatexecTransactInternal(Binder.java:1159)execTransact(Binder.java:1123)atSyntheticPasswordllanager. unwrapPasswordBasedSyntheticPassword(SyntheticPasswordllanager. java: 1016
android.os.Binderandroid.os.Binder