void updateAdapter(PagerAdapter oldAdapter, PagerAdapter newAdapter) {
if (oldAdapter != null) {
oldAdapter.unregisterDataSetObserver(mPageListener);
}
if (newAdapter != null) {
newAdapter.registerDataSetObserver(mPageListener);
}
if (mPager != null) {
mLastKnownCurrentPage = -1;
mLastKnownPositionOffset = -1;
updateText(mPager.getCurrentItem(), newAdapter);
requestLayout();
}
}
void updateTextPositions(int position, float positionOffset) {
if (position != mLastKnownCurrentPage) {
updateText(position, mPager.getAdapter());
} else if (positionOffset == mLastKnownPositionOffset) {
return;
}
mUpdatingPositions = true;
final int prevWidth = mPrevText.getMeasuredWidth();
final int currWidth = mCurrText.getMeasuredWidth();
final int nextWidth = mNextText.getMeasuredWidth();
final int halfCurrWidth = currWidth / 2;
final int stripWidth = getWidth();
final int paddingLeft = getPaddingLeft();
final int paddingRight = getPaddingRight();
final int paddingTop = getPaddingTop();
final int textPaddedLeft = paddingLeft + halfCurrWidth;
final int textPaddedRight = paddingRight + halfCurrWidth;
final int contentWidth = stripWidth - textPaddedLeft - textPaddedRight;
float currOffset = positionOffset + 0.5f;
if (currOffset > 1.f) {
currOffset -= 1.f;
}
final int currCenter = stripWidth - textPaddedRight - (int) (contentWidth * currOffset);
final int currLeft = currCenter - currWidth / 2;
final int currRight = currLeft + currWidth;
mCurrText.layout(currLeft, paddingTop, currRight, paddingTop + mCurrText.getMeasuredHeight());
final int prevLeft = Math.min(paddingLeft, currLeft - mScaledTextSpacing - prevWidth);
mPrevText.layout(
prevLeft, paddingTop, prevLeft + prevWidth, paddingTop + mPrevText.getMeasuredHeight());
final int nextLeft =
Math.max(stripWidth - paddingRight - nextWidth, currRight + mScaledTextSpacing);
mNextText.layout(
nextLeft, paddingTop, nextLeft + nextWidth, paddingTop + mNextText.getMeasuredHeight());
mLastKnownPositionOffset = positionOffset;
mUpdatingPositions = false;
}