Using viewPager's onPageChangeListener with CirclePageIndicator

Question

I'm using a circlePageIndicator with my Viewpager in MainActivity.

circlePagerIndicator.setViewPager(mPager);

But the problem is, now I can't use the PageChangeListener in my main activity since it's already being used in circlePagerIndicator (see the code below:) How can I use a onPageChangeListener in my main activity while keeping the circlePageIndicator? I've seen some similar questions but couldn't find any answers.

public class CirclePagerIndicator extends LinearLayout {

private final String TAG = "CirclePagerIndicator";
private int indicatorColor;
private int indicatorColorSelected;
private float indicatorRadius;
private Paint selectedIndicatorPaint;
private LayoutParams containerLayoutParams;
private float containerPadding;
private float indicatorPadding;
private LayoutParams indicatorLayoutParams;
private ViewPager pager;
private int indicatorCount;
private int currentPosition;
private float currentPositionOffset;
private PagerIndicatorPageListener pageListener;
private ShapeDrawable indicatorShape;
boolean wasSetViewPagerCalled = false;

public CirclePagerIndicator(Context context, AttributeSet attrs) {
    super(context, attrs);

    setWillNotDraw(false);

    //set default values
    indicatorColor = Color.parseColor("#33ffffff");
    indicatorColorSelected = Color.parseColor("#ffffff");
    indicatorRadius = Utils.convertDpToPixel(4);
    containerPadding = Utils.convertDpToPixel(15);
    indicatorPadding = Utils.convertDpToPixel(3);

    //set up selectedIndicatorPaint
    selectedIndicatorPaint = new Paint();
    selectedIndicatorPaint.setAntiAlias(true);
    selectedIndicatorPaint.setStyle(Paint.Style.FILL);
    selectedIndicatorPaint.setColor(indicatorColorSelected);

    //set up current lin layout that will be used as a container for indicators
    containerLayoutParams = new LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
    setLayoutParams(containerLayoutParams);
    setOrientation(LinearLayout.HORIZONTAL);
    setPadding((int) containerPadding, (int) containerPadding, (int) containerPadding, (int) containerPadding);
    setGravity(Gravity.CENTER);

    //set up indicator shape
    indicatorShape = new ShapeDrawable(new OvalShape());
    indicatorShape.setIntrinsicWidth((int) indicatorRadius*2);
    indicatorShape.setIntrinsicHeight((int) indicatorRadius*2);
    indicatorShape.getPaint().setColor(indicatorColor);
    indicatorShape.getPaint().setAntiAlias(true);
    indicatorShape.getPaint().setStyle(Paint.Style.FILL);

    indicatorLayoutParams = new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);

}

public void setViewPager(ViewPager pager) {
    if (pager.getAdapter() == null) {
        throw new IllegalStateException("ViewPager does not have an adapter attached to it");
    } else {
        this.pager = pager;
        pageListener = new PagerIndicatorPageListener();
        pager.setOnPageChangeListener(pageListener);
        notifyDataSetChanged();
        wasSetViewPagerCalled = true;
    }
}

public void notifyDataSetChanged() {
    this.indicatorCount = pager.getAdapter().getCount();
    updateStyles();

    //add indicators to container
    removeAllViews();
    for (int i = 0; i < indicatorCount; i++) {
        addIndicator(i);
    }
}

private void updateStyles() {
    selectedIndicatorPaint.setColor(indicatorColorSelected);
    indicatorShape.getPaint().setColor(indicatorColor);
    indicatorShape.setIntrinsicWidth((int) indicatorRadius*2);
    indicatorShape.setIntrinsicHeight((int) indicatorRadius*2);
}

private void addIndicator(int position) {
    ImageView indicatorImageView = new ImageView(getContext());
    indicatorImageView.setLayoutParams(indicatorLayoutParams);
    indicatorImageView.setImageDrawable(indicatorShape);
    indicatorImageView.setPadding((int) indicatorPadding, (int) indicatorPadding, (int) indicatorPadding, (int) indicatorPadding);
    addView(indicatorImageView, position);
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);

    if (isInEditMode() || indicatorCount == 0) {
        return;
    }

    int height = getHeight();

    View indicator = getChildAt(currentPosition);
    float cx = indicator.getLeft() + (indicatorRadius) + indicatorPadding;

    if (currentPositionOffset > 0f && currentPosition < indicatorCount - 1) {
        View nextIndicator = getChildAt(currentPosition + 1);
        float nextCx = nextIndicator.getLeft() + (indicatorRadius) + indicatorPadding;
        cx = lerp(cx, nextCx, currentPositionOffset);
    }

    canvas.drawCircle(cx, (float) height / 2, (float) indicatorRadius, selectedIndicatorPaint);
}

float lerp(float v0, float v1, float t) {
    return (1 - t) * v0 + t * v1;
}

private class PagerIndicatorPageListener implements ViewPager.OnPageChangeListener {

    @Override
    public void onPageScrolled(int pos, float offset, int offsetPx) {
        currentPosition = pos;
        currentPositionOffset = offset;
        invalidate();
    }

    @Override
    public void onPageSelected(int i) {
    }

    @Override
    public void onPageScrollStateChanged(int i) {

    }
}

public void setIndicatorColor(int indicatorColor) {
    if (!wasSetViewPagerCalled) {
        this.indicatorColor = indicatorColor;
    } else {
        throw new IllegalStateException("setIndicatorColor must be called before setting ViewPager");
    }
}

public void setSelectedIndicatorColor(int indicatorColorSelected) {
    if (!wasSetViewPagerCalled) {
        this.indicatorColorSelected = indicatorColorSelected;
    } else {
        throw new IllegalStateException("setSelectedIndicatorColor must be called before setting ViewPager");
    }
}

public void setIndicatorRadius(int dp) {
    if (!wasSetViewPagerCalled) {
        this.indicatorRadius = Utils.convertDpToPixel(dp);
    } else {
        throw new IllegalStateException("setIndicatorRadius must be called before setting ViewPager");
    }
}

public void setIndicatorPadding(int dp) {
    if (!wasSetViewPagerCalled) {
        this.indicatorPadding = Utils.convertDpToPixel(dp);
    } else {
        throw new IllegalStateException("setIndicatorPadding must be called before setting ViewPager");
    }
}

}

Answer 1

It looks like you've got the same problem I've just come across. Basically, you need to set the OnPageChangeListener on the ViewPagerIndicator , not on the ViewPager .

So instead of doing this:

pageListener = new PagerIndicatorPageListener();
pager.setOnPageChangeListener(pageListener);

do this:

circlePagerIndicator.setOnPageChangeListener(pageListener);

Source: http://viewpagerindicator.com/