Android实现网易严选标签栏滑动效果

// 根据当前选定的tab，得到indicator应该移动到的位置 private Pair<Float, Float> getIndicatorTargetLeftRight(int position, float positionOffset) {   View tab = tabsContainer.getChildAt(position);   Pair<Float, Float> indicator = getIndicatorLeftRight(tab);   float targetLeft = indicator.first;   float targetRight = indicator.second;   // 如果positionOffset不为0，indicator正处于两个tab之间，需进行加权计算得到它的位置   if (positionOffset > 0f && position < tabCount - 1) {     View nextTab = tabsContainer.getChildAt(position + 1);     Pair<Float, Float> indicatorForNextTab = getIndicatorLeftRight(nextTab);     float left = indicatorForNextTab.first;     float right = indicatorForNextTab.second;     targetLeft = (positionOffset * left + (1f - positionOffset) * targetLeft);     targetRight = (positionOffset * right + (1f - positionOffset) * targetRight);   }   return new Pair<>(targetLeft, targetRight); }  private Pair<Float, Float> getIndicatorLeftRight(View tab) {   float left = tab.getLeft();   float right = tab.getRight();   if (indicatorMode == IndicatorMode.WRAP && tab instanceof TextView) {     TextView tabTextView = (TextView) tab;     paint.setTextSize(tabTextView.getTextSize());     float textLength = paint.measureText(tabTextView.getText().toString());     float middle = (left + right) / 2f;     left = middle - textLength / 2f;     right = middle + textLength / 2f;   }   return new Pair<>(left, right); } 

private boolean isAnimateRunning = false; private static final String TARGET_LEFT = "targetLeft"; private static final String TARGET_RIGHT = "targetRight";  private void startIndicatorAnimate(final float targetLeft, final float targetRight) {   // 在indicator超出屏幕范围时，让其从屏幕边界处开始移动   float move = 0;   if (indicatorCurrentRight < getScrollX()) {     move = getScrollX() - indicatorCurrentRight;   } else if (indicatorCurrentLeft > getScrollX() + DimenUtil.getScreenWidth(getContext())) {     move = getScrollX() + DimenUtil.getScreenWidth(getContext()) - indicatorCurrentLeft;   }   indicatorCurrentLeft += move;   indicatorCurrentRight += move;    PropertyValuesHolder valuesHolderLeft = PropertyValuesHolder.ofFloat(       TARGET_LEFT, indicatorCurrentLeft, targetLeft);   PropertyValuesHolder valuesHolderRight = PropertyValuesHolder.ofFloat(       TARGET_RIGHT, indicatorCurrentRight, targetRight);   ValueAnimator animator = ValueAnimator.ofPropertyValuesHolder(valuesHolderLeft, valuesHolderRight)       .setDuration(SCROLL_DURATION);   animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {     @Override     public void onAnimationUpdate(ValueAnimator animation) {       if (indicatorCurrentLeft != targetLeft) {         indicatorCurrentLeft = (float) animation.getAnimatedValue(TARGET_LEFT);       }       if (indicatorCurrentRight != targetRight) {         indicatorCurrentRight = (float) animation.getAnimatedValue(TARGET_RIGHT);       }       if (indicatorCurrentLeft == targetLeft && indicatorCurrentRight == targetRight) {         isAnimateRunning = false;       }       invalidate();     }   });   animator.start();   isAnimateRunning = true; }