一个侧屏滑动操作的实例（仿遇见）之三：代码分析

一个侧屏滑动操作的实例（仿遇见）之三：代码分析

分类： android UI android view 2012-08-12 22:43  134人阅读  评论(0)  收藏  举报

首先看一下主activity：

 package grimbo.android.demo.slidingmenu;

 import android.app.Activity;
 import android.graphics.Color;
 import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.widget.Button;

 public class MainActivity extends Activity {
     private MyHorizontalScrollView scrollView;
     private View leftMenu;
     private View rightMenu;

     private View tab01;
     private Button leftButton;
     private Button rightButton;

     @Override
     public void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);

         LayoutInflater inflater = LayoutInflater.from(this);
         setContentView(inflater.inflate(R.layout.main, null));

         scrollView = (MyHorizontalScrollView) findViewById(R.id.myScrollView);
         leftMenu = findViewById(R.id.leftmenu);
         rightMenu = findViewById(R.id.rightmenu);

         tab01 = inflater.inflate(R.layout.tab01, null);
         leftButton = (Button) tab01.findViewById(R.id.leftButton);
         rightButton = (Button)tab01.findViewById(R.id.rightButton);

         leftButton.setOnClickListener(new View.OnClickListener() {

             @Override
             public void onClick(View v) {
                 scrollView.clickLeftButton(leftButton.getMeasuredWidth());
             }
         });

         rightButton.setOnClickListener(new View.OnClickListener() {

             @Override
             public void onClick(View v) {
                 scrollView.clickRightButton(rightButton.getMeasuredWidth());
             }
         });


         View leftView = new View(this);//左边透明视图
         View rightView = new View(this);//右边透明视图
         leftView.setBackgroundColor(Color.TRANSPARENT);
         rightView.setBackgroundColor(Color.TRANSPARENT);
         final View[] children = new View[] {leftView, tab01,rightView };
         //初始化滚动布局
         scrollView.initViews(children, new SizeCallbackForMenu(leftButton),leftMenu,rightMenu);
     }
 }

其中tab01是一个由布局文件tab01.xml定义的view，放置“左边”和“右边”两个按钮

View leftView = new View(this);//左边透明视图
View rightView = new View(this);//右边透明视图
leftView.setBackgroundColor(Color.TRANSPARENT);
rightView.setBackgroundColor(Color.TRANSPARENT);

四句定义两个透明视图，透明视图就是只占用空间，不遮挡放置在其下面的视图

scrollView.initViews把两个透明视图和一个中间的tab视图放入HorizontalScrollView 的LinearLayout里，LinearLayout是横向布局，这样tab移到屏幕可视范围的时候就遮住了底下的leftmenu和rightmenu，当两侧透明视图移入屏幕可视范围的时候，底下的leftmenu或rightmenu就显现出来了，以此实现侧滑效果

然后看一下自定义的滑动类MyHorizontalScrollView

 package grimbo.android.demo.slidingmenu;

 import android.content.Context;
 import android.os.Handler;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.GestureDetector;
 import android.view.GestureDetector.SimpleOnGestureListener;
 import android.view.MotionEvent;
 import android.view.VelocityTracker;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.GestureDetector.OnGestureListener;
 import android.view.ViewTreeObserver.OnGlobalLayoutListener;
 import android.widget.HorizontalScrollView;
 import android.widget.Scroller;

 public class MyHorizontalScrollView extends HorizontalScrollView {

     private final String tag = "MyHorizontalScrollView";

     private MyHorizontalScrollView me;//当前控件
     private View leftMenu;//左边菜单
     private View rightMenu;//右边菜单
     private boolean leftMenuOut = false;//左边菜单状态
     private boolean rightMenuOut = false;//左边菜单状态
     private final int ENLARGE_WIDTH = 20;//扩展宽度

     public MyHorizontalScrollView(Context context, AttributeSet attrs, int defStyle) {
         super(context, attrs, defStyle);
         init(context);
     }

     public MyHorizontalScrollView(Context context, AttributeSet attrs) {
         super(context, attrs);
         init(context);
     }

     public MyHorizontalScrollView(Context context) {
         super(context);
         init(context);
     }

     void init(Context context) {
         // remove the fading as the HSV looks better without it
         //setHorizontalFadingEdgeEnabled(true);
         //setVerticalFadingEdgeEnabled(true);
         me = this;
         me.setVisibility(View.INVISIBLE);
     }


     public void initViews(View[] children, SizeCallback sizeCallback,View leftMenu,View rightMenu) {
         this.leftMenu = leftMenu;
         this.rightMenu = rightMenu;
         ViewGroup parent = (ViewGroup) getChildAt(0);

         // Add all the children, but add them invisible so that the layouts are calculated, but you can't see the Views
         for (int i = 0; i < children.length; i++) {
             children[i].setVisibility(View.INVISIBLE);
             parent.addView(children[i]);
         }

         // Add a layout listener to this HSV
         // This listener is responsible for arranging the child views.
         OnGlobalLayoutListener listener = new MyOnGlobalLayoutListener(parent, children, sizeCallback);
         getViewTreeObserver().addOnGlobalLayoutListener(listener);
     }





     @Override
     public boolean onInterceptTouchEvent(MotionEvent ev) {
         // Do not allow touch events.
         return false;
     }


     class MyOnGlobalLayoutListener implements OnGlobalLayoutListener {
         ViewGroup parent;
         View[] children;
         int scrollToViewPos = 0;
         SizeCallback sizeCallback;


         public MyOnGlobalLayoutListener(ViewGroup parent, View[] children, SizeCallback sizeCallback) {
             this.parent = parent;
             this.children = children;
             this.sizeCallback = sizeCallback;
         }

         @Override
         public void onGlobalLayout() {

             me.getViewTreeObserver().removeGlobalOnLayoutListener(this);

             sizeCallback.onGlobalLayout();

             parent.removeViewsInLayout(0, children.length);

             final int w = me.getMeasuredWidth();
             final int h = me.getMeasuredHeight();

             int[] dims = new int[2];
             scrollToViewPos = 0;
             for (int i = 0; i < children.length; i++) {
                 sizeCallback.getViewSize(i, w, h, dims);
                 children[i].setVisibility(View.VISIBLE);
                 parent.addView(children[i], dims[0], dims[1]);
                 if (i == 0) {
                     scrollToViewPos += dims[0];
                 }
                 Log.d(tag, children[i]+": w=" + dims[0] + ", h=" + dims[1]);
                 Log.d(tag, "scrollToViewIdx:"+0+",scrollToViewPos:"+scrollToViewPos);
             }


             new Handler().post(new Runnable() {
                 @Override
                 public void run() {
                     me.scrollBy(scrollToViewPos,0);
                     //因为这些控件默认都为隐藏，控件加载完成后，设置成显示
                     me.setVisibility(View.VISIBLE);
                     leftMenu.setVisibility(View.VISIBLE);
                     rightMenu.setVisibility(View.VISIBLE);
                 }
             });
         }
     }


     public void clickLeftButton(int leftButtonWidth){

     rightMenu.setVisibility(View.GONE);
     leftMenu.setVisibility(View.VISIBLE);
         int menuWidth = leftMenu.getMeasuredWidth()-(leftButtonWidth+ENLARGE_WIDTH);
         System.out.println("leftmenuWidth:"+menuWidth);
         if (!leftMenuOut) {
             int left = 0;
             me.smoothScrollTo(left, 0);
         } else {
             int left = menuWidth;
             me.smoothScrollTo(left, 0);
         }
         leftMenuOut = !leftMenuOut;
     }


     public void clickRightButton(int rightButtonWidth){
 <span style="white-space:pre">  </span>leftMenu.setVisibility(View.GONE);
     rightMenu.setVisibility(View.VISIBLE);
     int menuWidth = rightMenu.getMeasuredWidth() - (rightButtonWidth+ENLARGE_WIDTH);
         if (!rightMenuOut) {
             int right = menuWidth + me.getMeasuredWidth();
             System.out.println("rightmenuWidth:"+right);
             me.smoothScrollTo(right, 0);
         } else {
             int right = menuWidth;
             System.out.println("rightmenuWidth:"+right);
             me.smoothScrollTo(right, 0);
         }
         rightMenuOut = !rightMenuOut;
     }



     @Override
 <span style="white-space:pre">  </span>public boolean onTouchEvent(MotionEvent ev) {
         return false;
     }


     public interface SizeCallback {

         public void onGlobalLayout();

         public void getViewSize(int idx, int w, int h, int[] dims);
     }
 }

initViews：把传入的view加入第0个viewgroup，也就是xml中配置的LinearLayout中，并把一个MyOnGlobalLayoutListener对象设置为layout变化的观察者,initViews中放入的view只是占了个位置，后面的onGlobalLayout中会重新给这些view分配高和宽并加到LinearLayout中，但是在这之前需要预先放上去以得到某些控件的size（sizeCallback.onGlobalLayout()中），所以需要在这先加一次

onGlobalLayout：作为观察者，会在view的layout发生发生改变时自动调用此方法，由于只需要调用一次，所以方法里第一句就是调用removeGlobalOnLayoutListener，这个方法的主要功能就是把需要加入layout的views按照计算的宽度并加上去，然后调用me.scrollBy(scrollToViewPos,0);使加上去的view偏移，让tab01这个view偏移到屏幕可视范围中

clickLeftButton，clickRightButton：点击左边和右边的按钮时，控制MyHorizontalScrollView自身移动，显示出侧面相应的功能菜单，注意在移动之前，最左侧和最右侧是屏幕外的leftview和rightview，所以：

int left = 0;
me.smoothScrollTo(left, 0);

是把leftview移进来，中间的tab01向右移

完整源码下载地址:

http://download.csdn.net/detail/lamp_zy/4494989