ViewPager 手指滑動切換時會不靈敏，我們檢視ViewPager源碼，切換的判斷是由mFlingDistance和mMinimumVelocity決定的。
private int determineTargetPage(int currentPage, float pageOffset, int velocity, int deltaX) {
int targetPage;
if (Math.abs(deltaX) > mFlingDistance && Math.abs(velocity) > mMinimumVelocity) {
targetPage = velocity > 0 ? currentPage : currentPage + 1;
} else {
final float truncator = currentPage >= mCurItem ? 0.4f : 0.6f;
targetPage = currentPage + (int) (pageOffset + truncator);
}
......
而mFlingDistance和mMinimumVelocity是類内部計算的，并沒有公開接口提供設定。
private static final int MIN_DISTANCE_FOR_FLING = 25; // dips
private static final int MIN_FLING_VELOCITY = 400; // dips
void initViewPager() {
mMinimumVelocity = (int) (MIN_FLING_VELOCITY * density);
mFlingDistance = (int) (MIN_DISTANCE_FOR_FLING * density
}
我們可以通過反射來調整這2個值，解決滑動靈敏度的問題
val mFlingDistance: Field
mFlingDistance = ViewPager::class.java.getDeclaredField("mFlingDistance")
mFlingDistance.setAccessible(true)
val distance = mFlingDistance.get(mViewPager)//擷取值
mFlingDistance.set(mViewPager, 10) //你定義的值
val mMinimumVelocity: Field
mMinimumVelocity = ViewPager::class.java.getDeclaredField("mMinimumVelocity ")
mMinimumVelocity.setAccessible(true)
val velocity = mMinimumVelocity.get(mViewPager)//擷取值
mMinimumVelocity.set(mViewPager, 5)//你定義的值