android-Viewpager

ViewPager是google SDk中自带的一个附加包的一个类（在android-compatibility这个文件夹下），可以用来实现屏幕间的切换。

如可以仿一个workspace的效果。

 

Actviity:

 import com.viewpagerindicator.CirclePageIndicator;
 import android.os.Bundle;
 import android.support.v4.app.FragmentActivity;
 import android.support.v4.view.ViewPager;
 public class ViewpagerActivity extends FragmentActivity {
 TestFragmentAdapter mAdapter;
 ViewPager mPager;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);


     //The look of this sample is set via a style in the manifest
     setContentView(R.layout.simple_circles);

     mAdapter = new TestFragmentAdapter(getSupportFragmentManager());

     mPager = (ViewPager)findViewById(R.id.pager);
     mPager.setAdapter(mAdapter);

     CirclePageIndicator indicator = (CirclePageIndicator)findViewById(R.id.indicator);
     indicator.setViewPager(mPager);
 }


 }

simple_circles.xml:

 <?xml version="1.0" encoding="utf-8"?>

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

     <android.support.v4.view.ViewPager
         android:id="@+id/pager"
         android:layout_width="fill_parent"
         android:layout_height="0dp"
         android:layout_weight="1"
         />
     <com.viewpagerindicator.CirclePageIndicator
         android:id="@+id/indicator"
         android:padding="10dip"
         android:layout_height="wrap_content"
         android:layout_width="fill_parent"
         />
 </LinearLayout>

TestFragmentAdapter:

 import android.support.v4.app.Fragment;
 import android.support.v4.app.FragmentManager;
 import android.support.v4.app.FragmentPagerAdapter;

 class TestFragmentAdapter extends FragmentPagerAdapter {
     protected static final String[] CONTENT = new String[] { "第一页", "第二页", "第三页", "第四页", };

     private int mCount = CONTENT.length;

     public TestFragmentAdapter(FragmentManager fm) {
         super(fm);
     }

     @Override
     public Fragment getItem(int position) {
         return TestFragment.newInstance(CONTENT[position % CONTENT.length]);
     }

     @Override
     public int getCount() {
         return mCount;
     }

     public void setCount(int count) {
         if (count > 0 && count <= 10) {
             mCount = count;
             notifyDataSetChanged();
         }
     }
 }

TestFragment:

 package com.shao.pager;


 import android.os.Bundle;
 import android.support.v4.app.Fragment;
 import android.view.Gravity;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.LinearLayout;
 import android.widget.LinearLayout.LayoutParams;
 import android.widget.TextView;

 public final class TestFragment extends Fragment {
     private static final String KEY_CONTENT = "TestFragment:Content";

     public static TestFragment newInstance(String content) {
         TestFragment fragment = new TestFragment();

         fragment.mContent = content;

         return fragment;
     }

     private String mContent = "???";

     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         if ((savedInstanceState != null) && savedInstanceState.containsKey(KEY_CONTENT)) {
             mContent = savedInstanceState.getString(KEY_CONTENT);
         }

         TextView text = new TextView(getActivity());
         text.setGravity(Gravity.CENTER);
         text.setText(mContent);
         text.setTextSize(20 * getResources().getDisplayMetrics().density);
         text.setPadding(20, 20, 20, 20);

         LinearLayout layout = new LinearLayout(getActivity());
         layout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
         layout.setGravity(Gravity.CENTER);
         layout.addView(text);

         return layout;
     }

     @Override
     public void onSaveInstanceState(Bundle outState) {
         super.onSaveInstanceState(outState);
         outState.putString(KEY_CONTENT, mContent);
     }
 }

PageIndicator:

 package com.viewpagerindicator;

 import android.support.v4.view.ViewPager;

 public interface PageIndicator extends ViewPager.OnPageChangeListener {
     public void setViewPager(ViewPager view);

     public void setViewPager(ViewPager view, int initialPosition);
     public void setCurrentItem(int item);

     public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener);
 }

CliclePageIndicator:

 package com.viewpagerindicator;

 import android.content.Context;
 import android.content.res.Resources;
 import android.content.res.TypedArray;
 import android.graphics.Canvas;
 import android.graphics.Paint;
 import android.graphics.Paint.Style;
 import android.os.Parcel;
 import android.os.Parcelable;
 import android.support.v4.view.ViewPager;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;

 import com.shao.pager.R;


 public class CirclePageIndicator extends View implements PageIndicator {
     public static final int HORIZONTAL = 0;
     public static final int VERTICAL = 1;

     private float mRadius;
     private final Paint mPaintStroke;
     private final Paint mPaintFill;
     private ViewPager mViewPager;
     private ViewPager.OnPageChangeListener mListener;
     private int mCurrentPage;
     private int mSnapPage;
     private int mCurrentOffset;
     private int mScrollState;
     private int mPageSize;
     private int mOrientation;
     private boolean mCentered;
     private boolean mSnap;


     public CirclePageIndicator(Context context) {
         this(context, null);
     }

     public CirclePageIndicator(Context context, AttributeSet attrs) {
         this(context, attrs, R.attr.circlePageIndicatorStyle);
     }

     public CirclePageIndicator(Context context, AttributeSet attrs, int defStyle) {
         super(context, attrs, defStyle);

         //Load defaults from resources
         final Resources res = getResources();
         final int defaultFillColor = res.getColor(R.color.default_circle_indicator_fill_color);
         final int defaultOrientation = res.getInteger(R.integer.default_circle_indicator_orientation);
         final int defaultStrokeColor = res.getColor(R.color.default_circle_indicator_stroke_color);
         final float defaultStrokeWidth = res.getDimension(R.dimen.default_circle_indicator_stroke_width);
         final float defaultRadius = res.getDimension(R.dimen.default_circle_indicator_radius);
         final boolean defaultCentered = res.getBoolean(R.bool.default_circle_indicator_centered);
         final boolean defaultSnap = res.getBoolean(R.bool.default_circle_indicator_snap);

         //Retrieve styles attributes
         TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CirclePageIndicator, defStyle, R.style.Widget_CirclePageIndicator);

         mCentered = a.getBoolean(R.styleable.CirclePageIndicator_centered, defaultCentered);
         mOrientation = a.getInt(R.styleable.CirclePageIndicator_orientation, defaultOrientation);
         mPaintStroke = new Paint(Paint.ANTI_ALIAS_FLAG);
         mPaintStroke.setStyle(Style.STROKE);
         mPaintStroke.setColor(a.getColor(R.styleable.CirclePageIndicator_strokeColor, defaultStrokeColor));
         mPaintStroke.setStrokeWidth(a.getDimension(R.styleable.CirclePageIndicator_strokeWidth, defaultStrokeWidth));
         mPaintFill = new Paint(Paint.ANTI_ALIAS_FLAG);
         mPaintFill.setStyle(Style.FILL);
         mPaintFill.setColor(a.getColor(R.styleable.CirclePageIndicator_fillColor, defaultFillColor));
         mRadius = a.getDimension(R.styleable.CirclePageIndicator_radius, defaultRadius);
         mSnap = a.getBoolean(R.styleable.CirclePageIndicator_snap, defaultSnap);

         a.recycle();
     }


     public void setCentered(boolean centered) {
         mCentered = centered;
         invalidate();
     }

     public boolean isCentered() {
         return mCentered;
     }

     public void setFillColor(int fillColor) {
         mPaintFill.setColor(fillColor);
         invalidate();
     }

     public int getFillColor() {
         return mPaintFill.getColor();
     }

     public void setOrientation(int orientation) {
         switch (orientation) {
             case HORIZONTAL:
             case VERTICAL:
                 mOrientation = orientation;
                 updatePageSize();
                 requestLayout();
                 break;

             default:
                 throw new IllegalArgumentException("Orientation must be either HORIZONTAL or VERTICAL.");
         }
     }

     public int getOrientation() {
         return mOrientation;
     }

     public void setStrokeColor(int strokeColor) {
         mPaintStroke.setColor(strokeColor);
         invalidate();
     }

     public int getStrokeColor() {
         return mPaintStroke.getColor();
     }

     public void setStrokeWidth(float strokeWidth) {
         mPaintStroke.setStrokeWidth(strokeWidth);
         invalidate();
     }

     public float getStrokeWidth() {
         return mPaintStroke.getStrokeWidth();
     }

     public void setRadius(float radius) {
         mRadius = radius;
         invalidate();
     }

     public float getRadius() {
         return mRadius;
     }

     public void setSnap(boolean snap) {
         mSnap = snap;
         invalidate();
     }

     public boolean isSnap() {
         return mSnap;
     }

     /*
      * (non-Javadoc)
      *
      * @see android.view.View#onDraw(android.graphics.Canvas)
      */
     @Override
     protected void onDraw(Canvas canvas) {
         super.onDraw(canvas);

         int longSize;
         int longPaddingBefore;
         int longPaddingAfter;
         int shortPaddingBefore;
         if (mOrientation == HORIZONTAL) {
             longSize = getWidth();
             longPaddingBefore = getPaddingLeft();
             longPaddingAfter = getPaddingRight();
             shortPaddingBefore = getPaddingTop();
         } else {
             longSize = getHeight();
             longPaddingBefore = getPaddingTop();
             longPaddingAfter = getPaddingBottom();
             shortPaddingBefore = getPaddingLeft();
         }

         final int count = mViewPager.getAdapter().getCount();
         final float threeRadius = mRadius * 3;
         final float shortOffset = shortPaddingBefore + mRadius;
         float longOffset = longPaddingBefore + mRadius;
         if (mCentered) {
             longOffset += ((longSize - longPaddingBefore - longPaddingAfter) / 2.0f) - ((count * threeRadius) / 2.0f);
         }

         float dX;
         float dY;

         //Draw stroked circles
         for (int iLoop = 0; iLoop < count; iLoop++) {
             float drawLong = longOffset + (iLoop * threeRadius);
             if (mOrientation == HORIZONTAL) {
                 dX = drawLong;
                 dY = shortOffset;
             } else {
                 dX = shortOffset;
                 dY = drawLong;
             }
             canvas.drawCircle(dX, dY, mRadius, mPaintStroke);
         }

         //Draw the filled circle according to the current scroll
         float cx = (mSnap ? mSnapPage : mCurrentPage) * threeRadius;
         if (!mSnap && (mPageSize != 0)) {
             cx += (mCurrentOffset * 1.0f / mPageSize) * threeRadius;
         }
         if (mOrientation == HORIZONTAL) {
             dX = longOffset + cx;
             dY = shortOffset;
         } else {
             dX = shortOffset;
             dY = longOffset + cx;
         }
         canvas.drawCircle(dX, dY, mRadius, mPaintFill);
     }

     @Override
     public boolean onTouchEvent(MotionEvent event) {
         if (event.getAction() == MotionEvent.ACTION_DOWN) {
             final int count = mViewPager.getAdapter().getCount();
             final int longSize = (mOrientation == HORIZONTAL) ? getWidth() : getHeight();
             final float halfLongSize = longSize / 2;
             final float halfCircleLongSize = (count * 3 * mRadius) / 2;
             final float pointerValue = (mOrientation == HORIZONTAL) ? event.getX() : event.getY();

             if ((mCurrentPage > 0) && (pointerValue < halfLongSize - halfCircleLongSize)) {
                 setCurrentItem(mCurrentPage - 1);
                 return true;
             } else if ((mCurrentPage < count - 1) && (pointerValue > halfLongSize + halfCircleLongSize)) {
                 setCurrentItem(mCurrentPage + 1);
                 return true;
             }
         }

         return super.onTouchEvent(event);
     }

     @Override
     public void setViewPager(ViewPager view) {
         if (view.getAdapter() == null) {
             throw new IllegalStateException("ViewPager does not have adapter instance.");
         }
         mViewPager = view;
         mViewPager.setOnPageChangeListener(this);
         updatePageSize();
         invalidate();
     }

     private void updatePageSize() {
         if (mViewPager != null) {
             mPageSize = (mOrientation == HORIZONTAL) ? mViewPager.getWidth() : mViewPager.getHeight();
         }
     }

     @Override
     public void setViewPager(ViewPager view, int initialPosition) {
         setViewPager(view);
         setCurrentItem(initialPosition);
     }

     @Override
     public void setCurrentItem(int item) {
         if (mViewPager == null) {
             throw new IllegalStateException("ViewPager has not been bound.");
         }
         mViewPager.setCurrentItem(item);
         mCurrentPage = item;
         invalidate();
     }

     @Override
     public void onPageScrollStateChanged(int state) {
         mScrollState = state;

         if (mListener != null) {
             mListener.onPageScrollStateChanged(state);
         }
     }

     @Override
     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
         mCurrentPage = position;
         mCurrentOffset = positionOffsetPixels;
         updatePageSize();
         invalidate();

         if (mListener != null) {
             mListener.onPageScrolled(position, positionOffset, positionOffsetPixels);
         }
     }

     @Override
     public void onPageSelected(int position) {
         if (mSnap || mScrollState == ViewPager.SCROLL_STATE_IDLE) {
             mCurrentPage = position;
             mSnapPage = position;
             invalidate();
         }

         if (mListener != null) {
             mListener.onPageSelected(position);
         }
     }

     @Override
     public void setOnPageChangeListener(ViewPager.OnPageChangeListener listener) {
         mListener = listener;
     }


     @Override
     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
         if (mOrientation == HORIZONTAL) {
             setMeasuredDimension(measureLong(widthMeasureSpec), measureShort(heightMeasureSpec));
         } else {
             setMeasuredDimension(measureShort(widthMeasureSpec), measureLong(heightMeasureSpec));
         }
     }

     /**
      * Determines the width of this view
      *
      * @param measureSpec
      *            A measureSpec packed into an int
      * @return The width of the view, honoring constraints from measureSpec
      */
     private int measureLong(int measureSpec) {
         int result = 0;
         int specMode = MeasureSpec.getMode(measureSpec);
         int specSize = MeasureSpec.getSize(measureSpec);

         if (specMode == MeasureSpec.EXACTLY) {
             //We were told how big to be
             result = specSize;
         } else {
             //Calculate the width according the views count
             final int count = mViewPager.getAdapter().getCount();
             result = (int)(getPaddingLeft() + getPaddingRight()
                     + (count * 2 * mRadius) + (count - 1) * mRadius + 1);
             //Respect AT_MOST value if that was what is called for by measureSpec
             if (specMode == MeasureSpec.AT_MOST) {
                 result = Math.min(result, specSize);
             }
         }
         return result;
     }


     private int measureShort(int measureSpec) {
         int result = 0;
         int specMode = MeasureSpec.getMode(measureSpec);
         int specSize = MeasureSpec.getSize(measureSpec);

         if (specMode == MeasureSpec.EXACTLY) {
             //We were told how big to be
             result = specSize;
         } else {
             //Measure the height
             result = (int)(2 * mRadius + getPaddingTop() + getPaddingBottom() + 1);
             //Respect AT_MOST value if that was what is called for by measureSpec
             if (specMode == MeasureSpec.AT_MOST) {
                 result = Math.min(result, specSize);
             }
         }
         return result;
     }

     @Override
     public void onRestoreInstanceState(Parcelable state) {
         SavedState savedState = (SavedState)state;
         super.onRestoreInstanceState(savedState.getSuperState());
         mCurrentPage = savedState.currentPage;
         mSnapPage = savedState.currentPage;
         requestLayout();
     }

     @Override
     public Parcelable onSaveInstanceState() {
         Parcelable superState = super.onSaveInstanceState();
         SavedState savedState = new SavedState(superState);
         savedState.currentPage = mCurrentPage;
         return savedState;
     }

     static class SavedState extends BaseSavedState {
         int currentPage;

         public SavedState(Parcelable superState) {
             super(superState);
         }

         private SavedState(Parcel in) {
             super(in);
             currentPage = in.readInt();
         }

         @Override
         public void writeToParcel(Parcel dest, int flags) {
             super.writeToParcel(dest, flags);
             dest.writeInt(currentPage);
         }

         public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() {
             @Override
             public SavedState createFromParcel(Parcel in) {
                 return new SavedState(in);
             }

             @Override
             public SavedState[] newArray(int size) {
                 return new SavedState[size];
             }
         };
     }
 }

代码下载http://download.csdn.net/detail/shaojie519/4256481