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