Android开发之——手势识别

前言

使用浏览器或者输入法应用时会有一些手势操作，还可以自定义手势。这些神奇的操作是怎么做的呢？这一篇重点记录手势的识别和创建。这篇的内容使用到了android.gesture包，具体的例子参考的是Sample中的GestureBuilder程序。

手势识别的一般步骤

手势创建

手势创建主要用到了GestureOverlayView和GestureLibrary。GestrueOverlayView的父类为android.widget.FrameLayout，是手势绘图区。GestureLibrary类主要对手势进行保存、删除等操作的，存放手势的仓库。下面给出创建手势的例子，如下图，可以定义如图手势打开csdn.net

创建绘图区

GestureOverlayView overlay = (GestureOverlayView) findViewById(R.id.gestures_overlay);  
overlay.setGestureStrokeType(GestureOverlayView.GESTURE_STROKE_TYPE_MULTIPLE);    
overlay.setFadeOffset(2000);  //多笔画每两次的间隔时间  
overlay.setGestureColor(Color.CYAN);//画笔颜色  
overlay.setGestureStrokeWidth(6);//画笔粗细值   
overlay.addOnGestureListener(new GesturesProcessor());  

监听绘制

private class GesturesProcessor implements estureOverlayView.OnGestureListener 
{  
   public void onGestureStarted(GestureOverlayView overlay, MotionEvent event) 
    {  
       mDoneButton.setEnabled(false);  
       mGesture = null;  
       }  
   public void onGesture(GestureOverlayView overlay, MotionEvent event) {}  

   public void onGestureEnded(GestureOverlayView overlay, MotionEvent event) {  
       mGesture = overlay.getGesture();  
       if (mGesture.getLength() < LENGTH_THRESHOLD) {overlay.clear(false);}  
       mDoneButton.setEnabled(true);  
   }  
   public void onGestureCancelled(GestureOverlayView overlay, MotionEvent event) {}  
}  

保存手势

public void addGesture(View v) 
{  
   if (mGesture != null) 
    {  
       final TextView input = (TextView) findViewById(R.id.gesture_name);  
       final CharSequence name = input.getText();  
       if (name.length() == 0) 
        {  
           input.setError(getString(R.string.error_missing_name));  
           return;  
        }  

       /** 
        * 获取手势库 
        *   private final File mStoreFile = new File(Environment.getExternalStorageDirectory(), "gestures"); 
        *   GestureLibrary sStore = GestureLibraries.fromFile(mStoreFile); 
        *  
        */  
       final GestureLibrary store = GestureBuilderActivity.getStore();  
       store.addGesture(name.toString(), mGesture);  
       store.save();  
       setResult(RESULT_OK);  
       final String path = new File(Environment.getExternalStorageDirectory(),  
               "gestures").getAbsolutePath();  
       Toast.makeText(this, getString(R.string.save_success, path), Toast.LENGTH_LONG).show();  
   } else {  
       setResult(RESULT_CANCELED);  
   }  

   finish();  
}  

手势识别

手势识别也是经过创建绘图区、监听绘制、比对结果三个过程，这里直接给出代码。

public class GesturePerformedActivity extends Activity 
{  
private final File mStoreFile = new File(Environment.getExternalStorageDirectory(), "gestures");  

// 手势库  
GestureLibrary mGestureLib;  
@Override  
protected void onCreate(Bundle savedInstanceState) {  
    // TODO Auto-generated method stub  
    super.onCreate(savedInstanceState);  
    setContentView(R.layout.gesture_perform);  
    // 手势画板  
    GestureOverlayView gestures = (GestureOverlayView) findViewById(R.id.gestures_overlay);  
    gestures.setGestureStrokeType(GestureOverlayView.GESTURE_STROKE_TYPE_MULTIPLE);  
    gestures.setFadeOffset(2000); // 多笔画每两次的间隔时间  
    gestures.setGestureColor(Color.CYAN);// 画笔颜色  
    gestures.setGestureStrokeWidth(6);// 画笔粗细值  

    // 手势识别的监听器  
    gestures.addOnGesturePerformedListener(new GestureOverlayView.OnGesturePerformedListener() {  
        @Override  
        public void onGesturePerformed(GestureOverlayView overlay,  
                Gesture gesture) {  
            // 从手势库中查询匹配的内容，匹配的结果可能包括多个相似的结果，匹配度高的结果放在最前面  
            ArrayList<Prediction> predictions = mGestureLib  
                    .recognize(gesture);      
            if (predictions.size() > 0) {  
                Prediction prediction = (Prediction) predictions.get(0);  
                // 匹配的手势  
                if (prediction.score > 1.0) { // 越匹配score的值越大，最大为10  
                    Toast.makeText(GesturePerformedActivity.this,  
                            prediction.name, Toast.LENGTH_SHORT).show();  
                }  
            }  
        }  
    });  

    if (mGestureLib == null) {  
        mGestureLib = GestureLibraries.fromFile(mStoreFile);  
        mGestureLib.load();  
    }  
}  

} 

效果

参考：
android手势创建及识别
札记：android手势识别，MotionEvent
Android-手势识别