ViewTreeObserver示例(二)

main.xml如下:

<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/LinearLayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
   >

    <TextView
        android:id="@+id/touchModeChangeTextView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello_world" 
        android:layout_marginTop="30dip"
        android:gravity="center"
        android:textColor="@android:color/black"
        android:textSize="25sp"
        />
    
    <EditText
        android:id="@+id/firstEditText"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dip"
        android:gravity="center"
        android:textColor="@android:color/black"
        android:textSize="25sp"
        />
    
    <EditText
        android:id="@+id/secondEditText"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dip"
        android:gravity="center"
        android:textColor="@android:color/black"
        android:textSize="25sp"
        />
    <TextView
        android:id="@+id/globalFocusChangeTextView"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:hint="显示焦点的变化"
        android:layout_marginTop="30dip"
        android:gravity="center"
        android:textColor="@android:color/black"
        android:textSize="15sp"
      />
     
    
    <Button
        android:id="@+id/button"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="30dip"
        android:gravity="center"
        android:text="切换第二个EditText的显示和隐藏"
        android:textColor="@android:color/black"
        android:textSize="15sp"
      />
    
    
</LinearLayout>

MainActivity如下:

package cn.com.testviewtreeobserver2;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewTreeObserver;
import android.view.ViewTreeObserver.OnGlobalFocusChangeListener;
import android.view.ViewTreeObserver.OnGlobalLayoutListener;
import android.view.ViewTreeObserver.OnPreDrawListener;
import android.view.ViewTreeObserver.OnTouchModeChangeListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.app.Activity;
/**
 * Demo描述:
 * ViewTreeObserver的测试
 * 备注说明:
 * OnTouchModeChangeListener的相关
 * 测试未实现
 * 重要参考:
 * http://blog.csdn.net/pathuang68/article/details/6431035
 * Thank you
 *
 */
public class MainActivity extends Activity {
	private View mLinearLayout;
	private TextView mTouchModeChangeTextView;
	private EditText mFirstEditText;
	private EditText mSecondEditText;
	private TextView mGlobalFocusChangeTextView;
	private Button mButton;
	private ViewTreeObserver mViewTreeObserver;
	private boolean isClick=false;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		init();
	}
    private void init(){
    	mLinearLayout=findViewById(R.id.LinearLayout);
    	mTouchModeChangeTextView=(TextView) findViewById(R.id.touchModeChangeTextView);
    	mFirstEditText=(EditText) findViewById(R.id.firstEditText);
    	mSecondEditText=(EditText) findViewById(R.id.secondEditText);
    	mGlobalFocusChangeTextView=(TextView) findViewById(R.id.globalFocusChangeTextView);
    	mButton=(Button) findViewById(R.id.button);
    	mButton.setOnClickListener(new ButtonOnClickListenerImpl());
    	mViewTreeObserver=mLinearLayout.getViewTreeObserver();
    	viewTreeObserverAddListeners();
    }
    //为ViewTreeObserver设置各种监听
    private void viewTreeObserverAddListeners(){
    	//当一个视图树的触摸模式发生改变时,调用该方法
    	//在该实例中未实现对于该方法的相关测试
    	mViewTreeObserver.addOnTouchModeChangeListener(new OnTouchModeChangeListener() {
			@Override
			public void onTouchModeChanged(boolean isInTouchMode) {
				if (isInTouchMode) {
					mTouchModeChangeTextView.setText("In touch mode");
				}else{
					mTouchModeChangeTextView.setText("Not in touch mode");
				}
			}
		});
    	//当在一个视图树中全局布局发生改变
    	//或者视图树中的某个视图的可视状态发生改变时调用该方法
    	mViewTreeObserver.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
			@Override
			public void onGlobalLayout() {
				if (isClick) {
					if (mSecondEditText.isShown()) {
						mFirstEditText.setText("监听到第二个TextView被显示");
					} else {
						mFirstEditText.setText("监听到第二个TextView被隐藏");
					}
				}
			}
		});
    	//当一个视图树将要绘制时,调用该方法
    	//此处当mFirstEditText将要绘制时给其设置了hint和字体大小
    	//注意:必须返回true,否则整个界面不能完整显示
    	mViewTreeObserver.addOnPreDrawListener(new OnPreDrawListener() {
			@Override
			public boolean onPreDraw() {
				mFirstEditText.setHint("调用了OnPreDrawListener");
				mFirstEditText.setTextSize((float)15.0);
				return true;
			}
		});
    	//当在一个视图树中的焦点状态发生改变时,调用该方法
    	mViewTreeObserver.addOnGlobalFocusChangeListener(new OnGlobalFocusChangeListener() {
			@Override
			public void onGlobalFocusChanged(View oldFocus, View newFocus) {
				if (oldFocus!=null&&newFocus!=null) {
					mGlobalFocusChangeTextView.setText
					("Focus FROM:" + oldFocus.toString()+ " TO:" + newFocus.toString());
				}
			}
		});
    }
    
    //注意使用View.INVISIBLE不会调用OnGlobalLayoutListener
	//因为View.INVISIBLE只是控件不可见却还占据着位置,此时
	//布局在实质上没有发生变化
    private class ButtonOnClickListenerImpl implements OnClickListener{
		@Override
		public void onClick(View v) {
			mLinearLayout.setClickable(false);
			isClick=true;
			if (mSecondEditText.isShown()) {
				mSecondEditText.setVisibility(View.GONE);
			} else {
				mSecondEditText.setVisibility(View.VISIBLE);
			}
		}
    }
}