ViewPagerIndicator-master源码分析 1

1.ListActivity的使用

Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.viewpagerindicator.sample/.ListSamples }

public class ListSamples extends ListActivity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Intent intent = getIntent();
        String path = intent.getStringExtra("com.jakewharton.android.viewpagerindicator.sample.Path");
        if (path == null) {
            path = "";
        }
// 参数context：上下文，比如this。关联SimpleAdapter运行的视图上下文
// 参数data：Map列表，列表要显示的数据，这部分需要自己实现，如例子中的getData()，类型要与上面的一致，每条项目要与from中指定条目一致
//  参数resource：ListView单项布局文件的Id,这个布局就是你自定义的布局了，你想显示什么样子的布局都在这个布局中。
//   这个布局中必须包括了to中定义的控件id
//  参数 from：一个被添加到Map上关联每一个项目列名称的列表，数组里面是列名称
//  参数 to：是一个int数组，数组里面的id是自定义布局中各个控件的id，需要与上面的from对应
// 从from中获取数据填充到to指定的id 的 view里
        setListAdapter(new SimpleAdapter(this, getData(path),
                android.R.layout.simple_list_item_1, new String[] { "title" },
                new int[] { android.R.id.text1 }));
       // Enables or disables the type filter window. If enabled, typing when this view has focus //will filter the children to match the users input. Note that the Adapter used by this view must //implement the Filterable interface.
        getListView().setTextFilterEnabled(true);
    }

    protected List> getData(String prefix) {
        List> myData = new ArrayList>();

        Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
        mainIntent.addCategory("com.jakewharton.android.viewpagerindicator.sample.SAMPLE");
        // 
        //    android:name=".SampleCirclesDefault"
        //    android:label="Circles/Default">
        //    
        //        
        // 
        //    
       // 

        PackageManager pm = getPackageManager();
        List list = pm.queryIntentActivities(mainIntent, 0);

        if (null == list)
            return myData;

        String[] prefixPath;
        String prefixWithSlash = prefix;

        if (prefix.equals("")) {// 主Activity
            prefixPath = null; 
        } else { // 种类的Activity
            prefixPath = prefix.split("/");
            prefixWithSlash = prefix + "/";
        }

        int len = list.size();
        Map entries = new HashMap();
        // 此处要分两种情况，第一是启动页面的Activity时，会将同一类的进行一次存储，里面的总数就是种类的个数，
        // 如 android:label="Circles/Default"---存储Circles
        // 而对于某一种类的Activity，还会进入这个页面的,此时存储的是同一种类下的所有Activity
        // 如Circles/Default，Circles/Initial Page等等
        for (int i = 0; i < len; i++) {
            ResolveInfo info = list.get(i);
            CharSequence labelSeq = info.loadLabel(pm);
            String label = labelSeq != null
                    ? labelSeq.toString()
                    : info.activityInfo.name;

            if (prefixWithSlash.length() == 0 || label.startsWith(prefixWithSlash)) {
                String[] labelPath = label.split("/");
                // 主Activity的prefixPath == null
                String nextLabel = prefixPath == null ? labelPath[0] : labelPath[prefixPath.length];

                if ((prefixPath != null ? prefixPath.length : 0) == labelPath.length - 1) {
                    addItem(myData, nextLabel, activityIntent(
                            info.activityInfo.applicationInfo.packageName,
                            info.activityInfo.name));
                } else { // 主Activity，只存储种类
                    if (entries.get(nextLabel) == null) {
                        addItem(myData, nextLabel, browseIntent(prefix.equals("") ? nextLabel : prefix + "/" + nextLabel));
                        entries.put(nextLabel, true);
                    }
                }
            }
        }  
        Collections.sort(myData, NAME_COMPARATOR);

        return myData;
    }

    // 比较字符串的比较器，返回负数，则map1在前，map2在后
    private final static Comparator> NAME_COMPARATOR =
        new Comparator>() {
        private final Collator   collator = Collator.getInstance();

        public int compare(Map map1, Map map2) {
            return collator.compare(map1.get("title"), map2.get("title"));
        }
    };

    protected Intent activityIntent(String pkg, String componentName) {
        Intent result = new Intent(); // 具体的子Activity
        result.setClassName(pkg, componentName);
        return result;
    }

    protected Intent browseIntent(String path) {
        Intent result = new Intent(); // 某一种类的activity
        result.setClass(this, ListSamples.class);
        result.putExtra("com.jakewharton.android.viewpagerindicator.sample.Path", path);
        return result;
    }

    protected void addItem(List> data, String name, Intent intent) {
        Map temp = new HashMap();
        temp.put("title", name);
        temp.put("intent", intent); // down
        data.add(temp);
    }

    @Override
    @SuppressWarnings("unchecked")
    protected void onListItemClick(ListView l, View v, int position, long id) {
        Map map = (Map)l.getItemAtPosition(position);
        Intent intent = (Intent) map.get("intent"); //up
        startActivity(intent);
    }
}

2 CirclePageIndicator

public class CirclePageIndicator extends View implements PageIndicator {
    private static final int INVALID_POINTER = -1;

    private float mRadius;// 圆的半径，两个圆心之间的距离是3个R，所有外间距是R
    private final Paint mPaintPageFill = new Paint(ANTI_ALIAS_FLAG); // 画未选中圆内部的实心
    private final Paint mPaintStroke = new Paint(ANTI_ALIAS_FLAG); // 画未选中圆的外轮廓
    private final Paint mPaintFill = new Paint(ANTI_ALIAS_FLAG); // 画选中的圆
    private ViewPager mViewPager;
    private ViewPager.OnPageChangeListener mListener;
    private int mCurrentPage; // 注意滑动时随时变化
    private int mSnapPage;
    private float mPageOffset;
    private int mScrollState;
    private int mOrientation;
    private boolean mCentered;
    private boolean mSnap;

    private int mTouchSlop;
    private float mLastMotionX = -1;
    private int mActivePointerId = INVALID_POINTER;
    private boolean mIsDragging;

    public CirclePageIndicator(Context context) {
        this(context, null);
    }
    public CirclePageIndicator(Context context, AttributeSet attrs) {
        this(context, attrs, R.attr.vpiCirclePageIndicatorStyle);// 必要时从主题中获取属性
    }
    public CirclePageIndicator(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        if (isInEditMode()) return;

        //Load defaults from resources
        final Resources res = getResources();
        final int defaultPageColor = res.getColor(R.color.default_circle_indicator_page_color);
        // 略....

        //Retrieve styles attributes
        // 注意，defStyle代表如果优先级满足了则从主题中获取需要的属性，因为有些Activity的主题中配置了CirclePageIndicator的属性
        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.CirclePageIndicator, defStyle, 0);
        mCentered = a.getBoolean(R.styleable.CirclePageIndicator_centered, defaultCentered);
        mOrientation = a.getInt(R.styleable.CirclePageIndicator_android_orientation, defaultOrientation);
        mPaintPageFill.setStyle(Style.FILL);
        mPaintPageFill.setColor(a.getColor(R.styleable.CirclePageIndicator_pageColor, defaultPageColor));
        mPaintPageFill.setColor(Color.parseColor("#FFFF0000"));
        mPaintStroke.setStyle(Style.STROKE);
        mPaintStroke.setColor(a.getColor(R.styleable.CirclePageIndicator_strokeColor, defaultStrokeColor));
        mPaintStroke.setStrokeWidth(a.getDimension(R.styleable.CirclePageIndicator_strokeWidth, defaultStrokeWidth));
        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);

        Drawable background = a.getDrawable(R.styleable.CirclePageIndicator_android_background);
        if (background != null) {
            setBackgroundDrawable(background);
        }
        a.recycle();
        // ViewConfigurationCompat的后缀Compat注意，v4
        final ViewConfiguration configuration = ViewConfiguration.get(context);
        mTouchSlop = ViewConfigurationCompat.getScaledPagingTouchSlop(configuration);
    }
    // get set 方法   略...

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (mViewPager == null) {
            return;
        }
        final int count = mViewPager.getAdapter().getCount();
        if (count == 0) {
            return;
        }
        if (mCurrentPage >= count) {
            setCurrentItem(count - 1);
            return;
        }
        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 float threeRadius = mRadius * 3; //除了第一个，其余每个圆要占据3R的长度，即左边距R和自身的2R
        // 但是第一个圆左边是半个R，最后一个圆右边是半个R，这样才完美
        final float shortOffset = shortPaddingBefore + mRadius; //高度中心值，参考下面onMeasure的设置
        // 前提1，移动到了第一个圆的圆心位置处，之所以是圆心，因为在这个横坐标就开始画圆了，这样左边距是半R
        float longOffset = longPaddingBefore + mRadius; 
        if (mCentered) {
        // 先不考虑上面前提1，这里即计算出了圆们的开始位置，包括边距
            longOffset += ((longSize - longPaddingBefore - longPaddingAfter) / 2.0f) - ((count * threeRadius) / 2.0f);
            // 这里会有一处小bug，即当宽度设定为wrap-content时，如果mCentered仍为true，当在xml中配置padding
            // 为0时，上面计算的结果就是负的了，即第一个圆左边会有一小块看不到了，原因就在下面的onMeasure，
            // 因为longSize的值小于count *threeRadius，longSize就是getWidth()，就是onMeasure设定的
        }
        float dX;
        float dY;
        float pageFillRadius = mRadius;
        if (mPaintStroke.getStrokeWidth() > 0) { //内部实心小圆
            pageFillRadius -= mPaintStroke.getStrokeWidth() / 2.0f;
        }
        //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;
            }
//             Only paint fill if not completely transparent
            if (mPaintPageFill.getAlpha() > 0) {
                canvas.drawCircle(dX, dY, pageFillRadius, mPaintPageFill);
            }
            // Only paint stroke if a stroke width was non-zero
            if (pageFillRadius != mRadius) {
                canvas.drawCircle(dX, dY, mRadius, mPaintStroke);
            }
        }

        //Draw the filled circle according to the current scroll
        float cx = (mSnap ? mSnapPage : mCurrentPage) * threeRadius;
        if (!mSnap) { // mSnap为true代表pager切换以后再动，切换的结果，而false为切换的过程
            cx += mPageOffset * threeRadius;//跟随pager的细微滑动而动，否则就是pager切换以后再动
        }
        if (mOrientation == HORIZONTAL) {
            dX = longOffset + cx;
            dY = shortOffset;
        } else {
            dX = shortOffset;
            dY = longOffset + cx;
        }
        canvas.drawCircle(dX, dY, mRadius, mPaintFill);
    }

    public boolean onTouchEvent(android.view.MotionEvent ev) {
        if (super.onTouchEvent(ev)) {
            return true;
        }
        if ((mViewPager == null) || (mViewPager.getAdapter().getCount() == 0)) {
            return false;
        }
        // 同样，注意MotionEventCompat的后缀Compat, v4
        // 总结，根据index拿id和x坐标的方法，MotionEventCompat.getPointerId和MotionEventCompat.getX
        // 而根据id需要找index的，因此MotionEventCompat.findPointerIndex
        // 根据多手指事件down或者up时，寻找index为MotionEventCompat.getActionIndex
        final int action = ev.getAction() & MotionEventCompat.ACTION_MASK;
        switch (action) {
            case MotionEvent.ACTION_DOWN:
                mActivePointerId = MotionEventCompat.getPointerId(ev, 0);// index肯定是0啦
                mLastMotionX = ev.getX();// down时直接拿就是了
                break;

            case MotionEvent.ACTION_MOVE: {
                final int activePointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
                final float x = MotionEventCompat.getX(ev, activePointerIndex);
                final float deltaX = x - mLastMotionX;
                if (!mIsDragging) {
                    if (Math.abs(deltaX) > mTouchSlop) {
                        mIsDragging = true;
                    }
                }
                if (mIsDragging) { // 如何代码操纵viewpager滑动!!!!!!!!!!!!!
                    mLastMotionX = x;
                    if (mViewPager.isFakeDragging() || mViewPager.beginFakeDrag()) {
                        mViewPager.fakeDragBy(deltaX);
                    }
                }
                break;
            }

            case MotionEvent.ACTION_CANCEL:
            case MotionEvent.ACTION_UP:
                if (!mIsDragging) {// 点击的效果
                    final int count = mViewPager.getAdapter().getCount();
                    final int width = getWidth();
                    final float halfWidth = width / 2f;
                    final float sixthWidth = width / 6f;

                    if ((mCurrentPage > 0) && (ev.getX() < halfWidth - sixthWidth)) {//点到左边了
                        if (action != MotionEvent.ACTION_CANCEL) {
                            mViewPager.setCurrentItem(mCurrentPage - 1);
                        }
                        return true;
                    } else if ((mCurrentPage < count - 1) && (ev.getX() > halfWidth + sixthWidth)) {
                        if (action != MotionEvent.ACTION_CANCEL) {
                            mViewPager.setCurrentItem(mCurrentPage + 1);
                        }
                        return true;
                    }
                }
                mIsDragging = false;
                mActivePointerId = INVALID_POINTER;
                if (mViewPager.isFakeDragging()) mViewPager.endFakeDrag();// 取消滑动控制
                break;

            case MotionEventCompat.ACTION_POINTER_DOWN: {
                final int index = MotionEventCompat.getActionIndex(ev);
                mLastMotionX = MotionEventCompat.getX(ev, index);
                mActivePointerId = MotionEventCompat.getPointerId(ev, index);
                break;
            }

            case MotionEventCompat.ACTION_POINTER_UP:
                final int pointerIndex = MotionEventCompat.getActionIndex(ev);
                final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);
                if (pointerId == mActivePointerId) {//参考的手指抬起了，换一个就是了
                    final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
                    mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex);
                }
                mLastMotionX = MotionEventCompat.getX(ev, MotionEventCompat.findPointerIndex(ev, mActivePointerId));
                break;
        }

        return true;
    }

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

    @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 notifyDataSetChanged() {
        invalidate();
    }

    @Override
    public void onPageScrollStateChanged(int state) {
        mScrollState = state; // 随时记录状态
        if (mListener != null) {
            mListener.onPageScrollStateChanged(state);
        }
    }

    @Override
    public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
        mCurrentPage = position; // 重要，滑动时随时更新mCurrentPage
        mPageOffset = positionOffset;
        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);
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see android.view.View#onMeasure(int, int)
     */
    @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;
        int specMode = MeasureSpec.getMode(measureSpec);
        int specSize = MeasureSpec.getSize(measureSpec);

        if ((specMode == MeasureSpec.EXACTLY) || (mViewPager == null)) {
            //We were told how big to be
            result = specSize;
        } else {
            //Calculate the width according the views count
            final int count = mViewPager.getAdapter().getCount();
            // 实际占据的宽度值，从第一个圆左边到最后一个圆右边，加1为了误差吧
            // count * 2 * mRadius为圆的长度，(count - 1)为间距的长度
            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;
    }

    /**
     * Determines the height of this view
     *
     * @param measureSpec A measureSpec packed into an int
     * @return The height of the view, honoring constraints from measureSpec
     */
    private int measureShort(int measureSpec) {
        int result;
        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 加1是为了颜值高吧，对应上面的高度设置，正好处于中心位置
            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);
        }

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

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

3 TestFragment

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

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

        StringBuilder builder = new StringBuilder();
        for (int i = 0; i < 20; i++) {
            builder.append(content).append(" ");
        }
        builder.deleteCharAt(builder.length() - 1);
        fragment.mContent = builder.toString();
        return fragment;
    }

    private String mContent = "???";

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if ((savedInstanceState != null) && savedInstanceState.containsKey(KEY_CONTENT)) {
            mContent = savedInstanceState.getString(KEY_CONTENT);
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        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);
    }
}