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<Map<String, Object>> getData(String prefix) {        List<Map<String, Object>> myData = new ArrayList<Map<String, Object>>();        Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);        mainIntent.addCategory("com.jakewharton.android.viewpagerindicator.sample.SAMPLE");        // <activity   原因，除了主Activity，其余的配置        //    android:name=".SampleCirclesDefault"        //    android:label="Circles/Default">        //    <intent-filter>        //        <action android:name="android.intent.action.MAIN" />        // <category android:name="com.jakewharton.android.viewpagerindicator.sample.SAMPLE" />        //    </intent-filter>       // </activity>        PackageManager pm = getPackageManager();        List<ResolveInfo> 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<String, Boolean> entries = new HashMap<String, Boolean>();        // 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<Map<String, Object>> NAME_COMPARATOR =        new Comparator<Map<String, Object>>() {        private final Collator   collator = Collator.getInstance();        public int compare(Map<String, Object> map1, Map<String, Object> 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<Map<String, Object>> data, String name, Intent intent) {        Map<String, Object> temp = new HashMap<String, Object>();        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<String, Object> map = (Map<String, Object>)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<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];            }        };    }}

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);    }}