报点预测功能

开发流程

约束与限制

无

开发步骤

1. 查询当前运行环境是否支持报点预测。

   boolean isSupport = HwStrokeEstimate.isFeatureEnable();
   Log.d(TAG, "isSupportEstimate:" + isSupport);

2. 设置刷新率。
   在onVisibilityChanged方法中设置当前手写View上下文中LCD的刷新率：在不同机型或者同一机型的不同应用中，应用刷新率可能不一样，设置精确的刷新率有助于提高预测的准确性。

   @Override
   public void onVisibilityChanged(View changeView, int visibility) { 
        if (visibility == View.VISIBLE && mActivity != null && mActivity.getWindowManager() != null) { 
            Display display = mActivity.getWindowManager().getDefaultDisplay(); 
            float refreshRate = display.getRefreshRate(); 
            HwStrokeEstimate.setRefreshRate(refreshRate); 
            Log.d(TAG, "estimate, setRefreshRate:" + String.valueOf(refreshRate)); 
        } 
    }

3. 获取预测报点信息。
   在onTouchEvent处理中，针对ACTION_MOVE和ACTION_UP消息，在合适时机调用相应接口获取预测点信息：

   @Override 
   public boolean onTouchEvent(MotionEvent event) { 
       float eventX = event.getX(); 
       float eventY = event.getY(); 
       float pressure = event.getPressure(); 
       switch (event.getActionMasked()) { 
           case MotionEvent.ACTION_DOWN: 
               break; 
           case MotionEvent.ACTION_MOVE: 
               onActionMove(event, eventX, eventY, pressure); 
               break; 
           case MotionEvent.ACTION_UP:mEventQueue.clear(); 
               break; 
           default:break; 
       } 
     
       return true; 
   } 
   
   private void onActionMove(MotionEvent event, float x, float y, float p) { 
       float predictX = x; 
       float predictY = y; 
       long realTime = 0L; 
       long predictTime = 0L; 
       long ts0 = System.nanoTime(); 
       long ts2 = 0L; 
       long ts3 = 0L; 
       int cnt = event.getHistorySize(); 
       if (cnt > 0) {
           mLstEvents.clear(); 
           for (int i = 0; i < cnt; i++) { 
               /** 将真实的报点添加到队列中*/ 
               HwMotionEventInfo hwEvent = new HwMotionEventInfo(event.getHistoricalX(i), 
                       event.getHistoricalY(i), event.getHistoricalPressure(i), 
                       event.getHistoricalAxisValue(MotionEvent.AXIS_TILT, i), 
                       event.getHistoricalEventTime(i)); 
               mLstEvents.add(hwEvent); 
               realTime = event.getHistoricalEventTime(i); 
           } 
           mEventQueue.fill(mLstEvents); 
   
           mLstEvents.clear(); 
           ts2 = System.nanoTime(); 
           /** 使用预测算法进行预测，将预测的点加入到队列中*/ 
           int ret = HwStrokeEstimate.getEstimateEvent(mEventQueue.getQueue(), mLstEvents); 
           ts3 = System.nanoTime(); 
           if ((ret == 0) && (mLstEvents.size() > 0)) { 
               /** 取出预测点中的最后一个点的坐标及其时间戳*/ 
               HwMotionEventInfo lastPredictEvent = mLstEvents.get(mLstEvents.size() - 1); 
               predictX = lastPredictEvent.getX(); 
               predictY = lastPredictEvent.getY(); 
               predictTime = lastPredictEvent.getEventTime(); 
               Log.i(TAG, "predictX: " + predictX + ", predictY: " + predictY + ", predictTime: " + predictTime); 
           } 
       } 
       long ts1 = System.nanoTime(); 
       /** 计算每一次的预测时间*/ 
       long predictPeriod = predictTime > 0 ? predictTime - realTime : 0L; 
       Log.d(TAG, "total cost: " + (ts1 - ts0) + ", estimate cost:" + (ts3 - ts2) + ", predict count:" + mLstEvents.size() + ", predict period:" + predictPeriod + ", dx:" + (predictX - x) + ", dy:" 

调测验证

在实现的报点预测应用中，在日志中查看到有预测后的报点打印出来，可以绘制出该预测点从而提升跟手性。