android ViewPager 指示器 PageIndicator

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一款 google写的 ViewPager 指示器 PageIndicator
这里写图片描述

下面是pagedindicator代码

package com.lmjssjj.pagedindicator;import android.animation.Animator;import android.animation.AnimatorListenerAdapter;import android.animation.AnimatorSet;import android.animation.ObjectAnimator;import android.animation.ValueAnimator;import android.animation.ValueAnimator.AnimatorUpdateListener;import android.content.Context;import android.graphics.Canvas;import android.graphics.Outline;import android.graphics.Paint;import android.graphics.Paint.Style;import android.graphics.RectF;import android.util.AttributeSet;import android.util.Log;import android.util.Property;import android.view.View;import android.view.ViewGroup;import android.view.ViewOutlineProvider;import android.view.animation.Interpolator;import android.view.animation.OvershootInterpolator;import android.widget.FrameLayout;/** * Base class for a page indicator. */public class PageIndicator extends FrameLayout {    private static final float SHIFT_PER_ANIMATION = 0.5f;    private static final float SHIFT_THRESHOLD = 0.1f;    private static final long ANIMATION_DURATION = 150;    private static final int ENTER_ANIMATION_START_DELAY = 300;    private static final int ENTER_ANIMATION_STAGGERED_DELAY = 150;    private static final int ENTER_ANIMATION_DURATION = 400;    // This value approximately overshoots to 1.5 times the original size.    private static final float ENTER_ANIMATION_OVERSHOOT_TENSION = 4.9f;    private static final RectF sTempRect = new RectF();    private static final Property<PageIndicator, Float> CURRENT_POSITION = new Property<PageIndicator, Float>(            float.class, "current_position") {        @Override        public Float get(PageIndicator obj) {            return obj.mCurrentPosition;        }        @Override        public void set(PageIndicator obj, Float pos) {            obj.mCurrentPosition = pos;            obj.invalidate();            obj.invalidateOutline();        }    };    /**     * Listener for keep running the animation until the final state is reached.     */    private final AnimatorListenerAdapter mAnimCycleListener = new AnimatorListenerAdapter() {        @Override        public void onAnimationEnd(Animator animation) {            mAnimator = null;            animateToPostion(mFinalPosition);        }    };    private final Paint mCirclePaint;    private final float mDotRadius;    private final int mActiveColor;    private final int mInActiveColor;    private final boolean mIsRtl;    private int mActivePage;    /**     * The current position of the active dot including the animation progress.     * For ex: 0.0 => Active dot is at position 0 0.33 => Active dot is at     * position 0 and is moving towards 1 0.50 => Active dot is at position [0,     * 1] 0.77 => Active dot has left position 0 and is collapsing towards     * position 1 1.0 => Active dot is at position 1     */    private float mCurrentPosition;    private float mFinalPosition;    private ObjectAnimator mAnimator;    private float[] mEntryAnimationRadiusFactors;    private ViewGroup parentView;    protected int mNumPages = 1;    public PageIndicator(Context context) {        this(context, null);    }    public PageIndicator(Context context, AttributeSet attrs) {        this(context, attrs, 0);    }    public PageIndicator(Context context, AttributeSet attrs, int defStyleAttr) {        super(context, attrs, defStyleAttr);        mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);        mCirclePaint.setStyle(Style.FILL);        mDotRadius = getResources().getDimension(R.dimen.page_indicator_dot_size) / 2;        setOutlineProvider(new MyOutlineProver());        mActiveColor = Utilities.getColorAccent(context);        mInActiveColor = getResources().getColor(R.color.page_indicator_dot_color);        mIsRtl = Utilities.isRtl(getResources());        setWillNotDraw(false);    }    public void addMarker() {        mNumPages++;        onPageCountChanged();    }    public void removeMarker() {        mNumPages--;        onPageCountChanged();    }    public void setMarkersCount(int numMarkers) {        mNumPages = numMarkers;        onPageCountChanged();    }    public void setScroll(int currentScroll, int totalScroll) {        Log.v("lmjssjj", "currentScroll:" + currentScroll);        Log.v("lmjssjj", "totalScroll:" + totalScroll);        if (mNumPages > 1) {            if (mIsRtl) {                currentScroll = totalScroll - currentScroll;            }            int scrollPerPage = totalScroll / (mNumPages - 1);            int absScroll = mActivePage * scrollPerPage;            float scrollThreshold = SHIFT_THRESHOLD * scrollPerPage;            if ((absScroll - currentScroll) > scrollThreshold) {                // current scroll is before absolute scroll                animateToPostion(mActivePage - SHIFT_PER_ANIMATION);            } else if ((currentScroll - absScroll) > scrollThreshold) {                // current scroll is ahead of absolute scroll                animateToPostion(mActivePage + SHIFT_PER_ANIMATION);            } else {                animateToPostion(mActivePage);            }        }    }    private void animateToPostion(float position) {        Log.v("lmjssjj", "mFinalPosition:" + mFinalPosition);        mFinalPosition = position;        if (Math.abs(mCurrentPosition - mFinalPosition) < SHIFT_THRESHOLD) {            mCurrentPosition = mFinalPosition;        }        if (mAnimator == null && Float.compare(mCurrentPosition, mFinalPosition) != 0) {            float positionForThisAnim = mCurrentPosition > mFinalPosition ? mCurrentPosition - SHIFT_PER_ANIMATION                    : mCurrentPosition + SHIFT_PER_ANIMATION;            mAnimator = ObjectAnimator.ofFloat(this, CURRENT_POSITION, positionForThisAnim);            mAnimator.addListener(mAnimCycleListener);            mAnimator.setDuration(ANIMATION_DURATION);            mAnimator.start();        }    }    public void stopAllAnimations() {        if (mAnimator != null) {            mAnimator.removeAllListeners();            mAnimator.cancel();            mAnimator = null;        }        mFinalPosition = mActivePage;        CURRENT_POSITION.set(this, mFinalPosition);    }    /**     * Sets up up the page indicator to play the entry animation.     * {@link #playEntryAnimation()} must be called after this.     */    public void prepareEntryAnimation() {        mEntryAnimationRadiusFactors = new float[mNumPages];        invalidate();    }    public void playEntryAnimation() {        int count = mEntryAnimationRadiusFactors.length;        if (count == 0) {            mEntryAnimationRadiusFactors = null;            invalidate();            return;        }        Interpolator interpolator = new OvershootInterpolator(ENTER_ANIMATION_OVERSHOOT_TENSION);        AnimatorSet animSet = new AnimatorSet();        for (int i = 0; i < count; i++) {            ValueAnimator anim = ValueAnimator.ofFloat(0, 1).setDuration(ENTER_ANIMATION_DURATION);            final int index = i;            anim.addUpdateListener(new AnimatorUpdateListener() {                @Override                public void onAnimationUpdate(ValueAnimator animation) {                    mEntryAnimationRadiusFactors[index] = (Float) animation.getAnimatedValue();                    invalidate();                }            });            anim.setInterpolator(interpolator);            anim.setStartDelay(ENTER_ANIMATION_START_DELAY + ENTER_ANIMATION_STAGGERED_DELAY * i);            animSet.play(anim);        }        animSet.addListener(new AnimatorListenerAdapter() {            @Override            public void onAnimationEnd(Animator animation) {                mEntryAnimationRadiusFactors = null;                invalidateOutline();                invalidate();            }        });        animSet.start();    }    public void setActiveMarker(int activePage) {        if (mActivePage != activePage) {            mActivePage = activePage;            invalidate();        }    }    protected void onPageCountChanged() {        requestLayout();    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        // Add extra spacing of mDotRadius on all sides so than entry animation        // could be run.        int width = MeasureSpec.getMode(widthMeasureSpec) == MeasureSpec.EXACTLY ? MeasureSpec.getSize(widthMeasureSpec)                : (int) ((mNumPages * 3 + 2) * mDotRadius);        int height = MeasureSpec.getMode(heightMeasureSpec) == MeasureSpec.EXACTLY                ? MeasureSpec.getSize(heightMeasureSpec) : (int) (4 * mDotRadius);        setMeasuredDimension(width, height);    }    @Override    protected void onDraw(Canvas canvas) {        // Draw all page indicators;        float circleGap = 3 * mDotRadius;        float startX = (getWidth() - mNumPages * circleGap + mDotRadius) / 2;        float x = startX + mDotRadius;        float y = canvas.getHeight() / 2;        if (mEntryAnimationRadiusFactors != null) {            // During entry animation, only draw the circles            if (mIsRtl) {                x = getWidth() - x;                circleGap = -circleGap;            }            for (int i = 0; i < mEntryAnimationRadiusFactors.length; i++) {                mCirclePaint.setColor(i == mActivePage ? mActiveColor : mInActiveColor);                canvas.drawCircle(x, y, mDotRadius * mEntryAnimationRadiusFactors[i], mCirclePaint);                x += circleGap;            }        } else {            mCirclePaint.setColor(mInActiveColor);            for (int i = 0; i < mNumPages; i++) {                canvas.drawCircle(x, y, mDotRadius, mCirclePaint);                x += circleGap;            }            mCirclePaint.setColor(mActiveColor);            canvas.drawRoundRect(getActiveRect(), mDotRadius, mDotRadius, mCirclePaint);        }    }    private RectF getActiveRect() {        float startCircle = (int) mCurrentPosition;        float delta = mCurrentPosition - startCircle;        float diameter = 2 * mDotRadius;        float circleGap = 3 * mDotRadius;        float startX = (getWidth() - mNumPages * circleGap + mDotRadius) / 2;        sTempRect.top = getHeight() * 0.5f - mDotRadius;        sTempRect.bottom = getHeight() * 0.5f + mDotRadius;        sTempRect.left = startX + startCircle * circleGap;        sTempRect.right = sTempRect.left + diameter;        Log.v("lmjssjj", "delta:" + delta);        if (delta < SHIFT_PER_ANIMATION) {            // dot is capturing the right circle.            sTempRect.right += delta * circleGap * 2;        } else {            // Dot is leaving the left circle.            sTempRect.right += circleGap;            delta -= SHIFT_PER_ANIMATION;            sTempRect.left += delta * circleGap * 2;        }        if (mIsRtl) {            float rectWidth = sTempRect.width();            sTempRect.right = getWidth() - sTempRect.left;            sTempRect.left = sTempRect.right - rectWidth;        }        Log.v("lmjssjj", "sTempRect:" + sTempRect.toString());        return sTempRect;    }    private class MyOutlineProver extends ViewOutlineProvider {        @Override        public void getOutline(View view, Outline outline) {            if (mEntryAnimationRadiusFactors == null) {                RectF activeRect = getActiveRect();                outline.setRoundRect((int) activeRect.left, (int) activeRect.top, (int) activeRect.right,                        (int) activeRect.bottom, mDotRadius);            }        }    }}

通过监听setOnScrollChangeListener 来改变状态

@Override    public void onScrollChange(View v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {        pi.setScroll(scrollX, vp.getMeasuredWidth() *( mImgIds.length-1));        //Log.v("lmjssjj", "scrollX" + scrollX);    }

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