高仿launcher和墨迹左右拖动效果

首先自定义一个 ViewGroup：

  

源码 打印 ？

1. public class MyScrollLayout extends ViewGroup{  
2.   
3.     private VelocityTracker mVelocityTracker;           // 用于判断甩动手势      
4.     private static final int SNAP_VELOCITY = 600;          
5.     private Scroller  mScroller;                        // 滑动控制器      
6.     private int mCurScreen;                               
7.     private int mDefaultScreen = 0;                            
8.     private float mLastMotionX;         
9.  //   private int mTouchSlop;                             
10.       
11.    private OnViewChangeListener mOnViewChangeListener;    
12.    
13.     public MyScrollLayout(Context context) {  
14.         super(context);  
15.         // TODO Auto-generated constructor stub  
16.         init(context);  
17.     }     
18.     public MyScrollLayout(Context context, AttributeSet attrs) {  
19.         super(context, attrs);  
20.         // TODO Auto-generated constructor stub  
21.         init(context);  
22.     }  
23.       
24.     public MyScrollLayout(Context context, AttributeSet attrs, int defStyle) {  
25.         super(context, attrs, defStyle);  
26.         // TODO Auto-generated constructor stub       
27.         init(context);  
28.     }  
29.       
30.     private void init(Context context)  
31.     {  
32.         mCurScreen = mDefaultScreen;            
33.      //   mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();                  
34.         mScroller = new Scroller(context);   
35.           
36.     }  
37.   
38.     @Override  
39.     protected void onLayout(boolean changed, int l, int t, int r, int b) {  
40.         // TODO Auto-generated method stub        
41.          if (changed) {      
42.                 int childLeft = 0;      
43.                 final int childCount = getChildCount();                       
44.                 for (int i=0; i<childCount; i++) {      
45.                     final View childView = getChildAt(i);      
46.                     if (childView.getVisibility() != View.GONE) {      
47.                         final int childWidth = childView.getMeasuredWidth();      
48.                         childView.layout(childLeft, 0,       
49.                                 childLeft+childWidth, childView.getMeasuredHeight());      
50.                         childLeft += childWidth;      
51.                     }      
52.                 }      
53.             }      
54.     }  
55.   
56.     @Override  
57.     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  
58.         // TODO Auto-generated method stub  
59.         super.onMeasure(widthMeasureSpec, heightMeasureSpec);         
60.         final int width = MeasureSpec.getSize(widthMeasureSpec);         
61.         final int widthMode = MeasureSpec.getMode(widthMeasureSpec);        
62.                   
63.         final int count = getChildCount();         
64.         for (int i = 0; i < count; i++) {         
65.             getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);         
66.         }                  
67.         scrollTo(mCurScreen * width, 0);          
68.     }  
69.   
70.      public void snapToDestination() {      
71.             final int screenWidth = getWidth();      
72.             final int destScreen = (getScrollX()+ screenWidth/2)/screenWidth;      
73.             snapToScreen(destScreen);      
74.      }    
75.       
76.      public void snapToScreen(int whichScreen) {          
77.             // get the valid layout page      
78.             whichScreen = Math.max(0, Math.min(whichScreen, getChildCount()-1));      
79.             if (getScrollX() != (whichScreen*getWidth())) {                       
80.                 final int delta = whichScreen*getWidth()-getScrollX();      
81.                         mScroller.startScroll(getScrollX(), 0,       
82.                         delta, 0, Math.abs(delta)*2);  
83.                   
84.                 mCurScreen = whichScreen;      
85.                 invalidate();       // Redraw the layout                      
86.                 if (mOnViewChangeListener != null)  
87.                 {  
88.                     mOnViewChangeListener.OnViewChange(mCurScreen);  
89.                 }  
90.             }      
91.         }      
92.   
93.     @Override  
94.     public void computeScroll() {  
95.         // TODO Auto-generated method stub  
96.         if (mScroller.computeScrollOffset()) {      
97.             scrollTo(mScroller.getCurrX(), mScroller.getCurrY());    
98.             postInvalidate();      
99.         }     
100.     }  
101.   
102.     @Override  
103.     public boolean onTouchEvent(MotionEvent event) {  
104.         // TODO Auto-generated method stub                            
105.             final int action = event.getAction();      
106.             final float x = event.getX();      
107.             final float y = event.getY();      
108.                   
109.             switch (action) {      
110.             case MotionEvent.ACTION_DOWN:                 
111.                   Log.i("", "onTouchEvent  ACTION_DOWN");                   
112.                 if (mVelocityTracker == null) {      
113.                         mVelocityTracker = VelocityTracker.obtain();      
114.                         mVelocityTracker.addMovement(event);   
115.                 }              
116.                 if (!mScroller.isFinished()){      
117.                     mScroller.abortAnimation();      
118.                 }                  
119.                 mLastMotionX = x;                
120.                 break;      
121.                       
122.             case MotionEvent.ACTION_MOVE:    
123.                int deltaX = (int)(mLastMotionX - x);                 
124.                if (IsCanMove(deltaX))  
125.                {  
126.                  if (mVelocityTracker != null)  
127.                  {  
128.                         mVelocityTracker.addMovement(event);   
129.                  }     
130.                 mLastMotionX = x;       
131.                 scrollBy(deltaX, 0);      
132.                }  
133.            
134.                break;                         
135.             case MotionEvent.ACTION_UP:                       
136.                 int velocityX = 0;  
137.                 if (mVelocityTracker != null)  
138.                 {  
139.                     mVelocityTracker.addMovement(event);   
140.                     mVelocityTracker.computeCurrentVelocity(1000);    
141.                     velocityX = (int) mVelocityTracker.getXVelocity();  
142.                 }                                     
143.                 if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {         
144.                     // Fling enough to move left            
145.                     snapToScreen(mCurScreen - 1);         
146.                 } else if (velocityX < -SNAP_VELOCITY         
147.                         && mCurScreen < getChildCount() - 1) {         
148.                     // Fling enough to move right            
149.                     snapToScreen(mCurScreen + 1);         
150.                 } else {         
151.                     snapToDestination();         
152.                 }        
153.                                   
154.                 if (mVelocityTracker != null) {         
155.                     mVelocityTracker.recycle();         
156.                     mVelocityTracker = null;         
157.                 }         
158.           //      mTouchState = TOUCH_STATE_REST;  
159.                 break;        
160.             }                     
161.             return true;      
162.     }  
163.   
164.     private boolean IsCanMove(int deltaX)  
165.     {  
166.         if (getScrollX() <= 0 && deltaX < 0 ){  
167.             return false;  
168.         }     
169.         if  (getScrollX() >=  (getChildCount() - 1) * getWidth() && deltaX > 0){  
170.             return false;  
171.         }         
172.         return true;  
173.     }  
174.       
175.     public void SetOnViewChangeListener(OnViewChangeListener listener)  
176.     {  
177.         mOnViewChangeListener = listener;  
178.     }  
179. }  

源码 打印 ？

1. public class SwitchViewDemoActivity extends Activity implements OnViewChangeListener, OnClickListener{  
2.     /** Called when the activity is first created. */  
3.   
4.     private MyScrollLayout mScrollLayout;     
5.     private ImageView[] mImageViews;      
6.     private int mViewCount;   
7.     private int mCurSel;  
8.       
9.     @Override  
10.     public void onCreate(Bundle savedInstanceState) {  
11.         super.onCreate(savedInstanceState);  
12.         setContentView(R.layout.main);          
13.         init();  
14.           
15.     }  
16.       
17.     private void init()  
18.     {  
19.         mScrollLayout = (MyScrollLayout) findViewById(R.id.ScrollLayout);     
20.         LinearLayout linearLayout = (LinearLayout) findViewById(R.id.llayout);  
21.         //动态添加一个layout控件  
22.         LinearLayout layout=new LinearLayout(this);  
23.         layout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));  
24.         layout.setBackgroundResource(R.drawable.guide01);  
25.         mScrollLayout.addView(layout);  
26.         //动态添加一个imageView控件          
27.         ImageView imageView=new ImageView(this);  
28.         imageView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));  
29.         imageView.setPadding(15, 15, 15, 15);  
30.         imageView.setImageResource(R.drawable.guide_round);  
31.         linearLayout.addView(imageView);  
32.           
33.         mViewCount = mScrollLayout.getChildCount();  
34.         mImageViews = new ImageView[mViewCount];      
35.         for(int i = 0; i < mViewCount; i++)      {  
36.             mImageViews[i] = (ImageView) linearLayout.getChildAt(i);  
37.             mImageViews[i].setEnabled(true);  
38.             mImageViews[i].setOnClickListener(this);  
39.             mImageViews[i].setTag(i);  
40.         }         
41.         mCurSel = 0;  
42.         mImageViews[mCurSel].setEnabled(false);       
43.         mScrollLayout.SetOnViewChangeListener(this);  
44.           
45.     }  
46.   
47.     private void setCurPoint(int index)  
48.     {  
49.         if (index < 0 || index > mViewCount - 1 || mCurSel == index)      {  
50.             return ;  
51.         }         
52.         mImageViews[mCurSel].setEnabled(true);  
53.         mImageViews[index].setEnabled(false);         
54.         mCurSel = index;  
55.     }  
56.   
57.     @Override  
58.     public void OnViewChange(int view) {  
59.         // TODO Auto-generated method stub  
60.         setCurPoint(view);  
61.     }  
62.   
63.     @Override  
64.     public void onClick(View v) {  
65.         // TODO Auto-generated method stub  
66.         int pos = (Integer)(v.getTag());  
67.         setCurPoint(pos);  
68.         mScrollLayout.snapToScreen(pos);  
69.     }  
70. }  

最后是布局文件 ：

源码 打印 ？

1. <?xml version="1.0" encoding="utf-8"?>  
2. <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
3.     android:layout_width="fill_parent"  
4.     android:layout_height="fill_parent" >  
5.   
6.     <cn.com.karl.scroll.MyScrollLayout  
7.         xmlns:android="http://schemas.android.com/apk/res/android"  
8.         android:id="@+id/ScrollLayout"  
9.         android:layout_width="fill_parent"  
10.         android:layout_height="fill_parent" >  
11.   
12.         <LinearLayout  
13.             android:layout_width="fill_parent"  
14.             android:layout_height="fill_parent"  
15.             android:background="@drawable/guide01" >  
16.         </LinearLayout>  
17.   
18.         <LinearLayout  
19.             android:layout_width="fill_parent"  
20.             android:layout_height="fill_parent"  
21.             android:background="@drawable/guide02" >  
22.         </LinearLayout>  
23.   
24.         <LinearLayout  
25.             android:layout_width="fill_parent"  
26.             android:layout_height="fill_parent"  
27.             android:background="@drawable/guide03" >  
28.         </LinearLayout>  
29.   
30.         <LinearLayout  
31.             android:layout_width="fill_parent"  
32.             android:layout_height="fill_parent"  
33.             android:background="@drawable/guide04" >  
34.         </LinearLayout>  
35.   
36.         <LinearLayout  
37.             android:layout_width="fill_parent"  
38.             android:layout_height="fill_parent"  
39.             android:background="@drawable/guide05" >  
40.         </LinearLayout>  
41.     </cn.com.karl.scroll.MyScrollLayout>  
42.   
43.     <LinearLayout  
44.         android:id="@+id/llayout"  
45.         android:layout_width="wrap_content"  
46.         android:layout_height="wrap_content"  
47.         android:layout_alignParentBottom="true"  
48.         android:layout_centerHorizontal="true"  
49.         android:layout_marginBottom="24.0dip"  
50.         android:orientation="horizontal" >  
51.   
52.         <ImageView  
53.             android:layout_width="wrap_content"  
54.             android:layout_height="wrap_content"  
55.             android:layout_gravity="center_vertical"  
56.             android:clickable="true"  
57.             android:padding="15.0dip"  
58.             android:src="@drawable/guide_round" />  
59.   
60.         <ImageView  
61.             android:layout_width="wrap_content"  
62.             android:layout_height="wrap_content"  
63.             android:layout_gravity="center_vertical"  
64.             android:clickable="true"  
65.             android:padding="15.0dip"  
66.             android:src="@drawable/guide_round" />  
67.   
68.         <ImageView  
69.             android:layout_width="wrap_content"  
70.             android:layout_height="wrap_content"  
71.             android:layout_gravity="center_vertical"  
72.             android:clickable="true"  
73.             android:padding="15.0dip"  
74.             android:src="@drawable/guide_round" />  
75.   
76.         <ImageView  
77.             android:layout_width="wrap_content"  
78.             android:layout_height="wrap_content"  
79.             android:layout_gravity="center_vertical"  
80.             android:clickable="true"  
81.             android:padding="15.0dip"  
82.             android:src="@drawable/guide_round" />  
83.   
84.         <ImageView  
85.             android:layout_width="wrap_content"  
86.             android:layout_height="wrap_content"  
87.             android:layout_gravity="center_vertical"  
88.             android:clickable="true"  
89.             android:padding="15.0dip"  
90.             android:src="@drawable/guide_round" />  
91.     </LinearLayout>  
92.   
93. </RelativeLayout>  

看看运行后的效果到底怎么样吧！