以编程方式滑动时更改ViewPageranimation持续时间

我正在改变幻灯片

viewPager.setCurrentItem(index++, true); 

但是变化很快。 有没有办法手动设置animation速度？

search，只发现有人要求相同的地方（除了StackOverflow，也许我有运气:)），没有答案。

喜欢：

https://groups.google.com/group/android-developers/browse_thread/thread/a13405c0b5833893?fwc=1

提前致谢。

Answer 1

我想做自己，并已经达到了一个解决scheme（然而，使用反思）。 我还没有testing过，但它应该工作或需要最小的修改。 在Galaxy Nexus JB 4.2.1上testing。 您需要在XML中使用ViewPagerCustomDuration而不是ViewPager ，然后才能执行此操作：

 ViewPagerCustomDuration vp = (ViewPagerCustomDuration) findViewById(R.id.myPager); vp.setScrollDurationFactor(2); // make the animation twice as slow 

ViewPagerCustomDuration.java ：

 import android.content.Context; import android.support.v4.view.ViewPager; import android.util.AttributeSet; import android.view.animation.Interpolator; import java.lang.reflect.Field; public class ViewPagerCustomDuration extends ViewPager { public ViewPagerCustomDuration(Context context) { super(context); postInitViewPager(); } public ViewPagerCustomDuration(Context context, AttributeSet attrs) { super(context, attrs); postInitViewPager(); } private ScrollerCustomDuration mScroller = null; /** * Override the Scroller instance with our own class so we can change the * duration */ private void postInitViewPager() { try { Field scroller = ViewPager.class.getDeclaredField("mScroller"); scroller.setAccessible(true); Field interpolator = ViewPager.class.getDeclaredField("sInterpolator"); interpolator.setAccessible(true); mScroller = new ScrollerCustomDuration(getContext(), (Interpolator) interpolator.get(null)); scroller.set(this, mScroller); } catch (Exception e) { } } /** * Set the factor by which the duration will change */ public void setScrollDurationFactor(double scrollFactor) { mScroller.setScrollDurationFactor(scrollFactor); } } 

ScrollerCustomDuration.java ：

 import android.annotation.SuppressLint; import android.content.Context; import android.view.animation.Interpolator; import android.widget.Scroller; public class ScrollerCustomDuration extends Scroller { private double mScrollFactor = 1; public ScrollerCustomDuration(Context context) { super(context); } public ScrollerCustomDuration(Context context, Interpolator interpolator) { super(context, interpolator); } @SuppressLint("NewApi") public ScrollerCustomDuration(Context context, Interpolator interpolator, boolean flywheel) { super(context, interpolator, flywheel); } /** * Set the factor by which the duration will change */ public void setScrollDurationFactor(double scrollFactor) { mScrollFactor = scrollFactor; } @Override public void startScroll(int startX, int startY, int dx, int dy, int duration) { super.startScroll(startX, startY, dx, dy, (int) (duration * mScrollFactor)); } } 

希望这可以帮助别人！

Answer 2

基于@ df778899的回答和Android ValueAnimator API ，我find了更好的解决scheme。 它工作正常，没有reflection，非常灵活。 也没有必要制作自定义ViewPager并将其放入android.support.v4.view包中。 这里是一个例子：

 private void animatePagerTransition(final boolean forward) { ValueAnimator animator = ValueAnimator.ofInt(0, viewPager.getWidth()); animator.addListener(new Animator.AnimatorListener() { @Override public void onAnimationStart(Animator animation) { } @Override public void onAnimationEnd(Animator animation) { viewPager.endFakeDrag(); } @Override public void onAnimationCancel(Animator animation) { viewPager.endFakeDrag(); } @Override public void onAnimationRepeat(Animator animation) { } }); animator.setInterpolator(new AccelerateInterpolator()); animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { private int oldDragPosition = 0; @Override public void onAnimationUpdate(ValueAnimator animation) { int dragPosition = (Integer) animation.getAnimatedValue(); int dragOffset = dragPosition - oldDragPosition; oldDragPosition = dragPosition; viewPager.fakeDragBy(dragOffset * (forward ? -1 : 1)); } }); animator.setDuration(AppConstants.PAGER_TRANSITION_DURATION_MS); viewPager.beginFakeDrag(); animator.start(); } 

更新：

刚刚检查过这个解决scheme是否可以用来一次刷几页（例如，如果第一页应显示在最后一页之后）。 这是稍微修改的代码来处理指定的页数：

 private int oldDragPosition = 0; private void animatePagerTransition(final boolean forward, int pageCount) { // if previous animation have not finished we can get exception if (pagerAnimation != null) { pagerAnimation.cancel(); } pagerAnimation = getPagerTransitionAnimation(forward, pageCount); if (viewPager.beginFakeDrag()) { // checking that started drag correctly pagerAnimation.start(); } } private Animator getPagerTransitionAnimation(final boolean forward, int pageCount) { ValueAnimator animator = ValueAnimator.ofInt(0, viewPager.getWidth() - 1); animator.addListener(new Animator.AnimatorListener() { @Override public void onAnimationStart(Animator animation) { } @Override public void onAnimationEnd(Animator animation) { viewPager.endFakeDrag(); } @Override public void onAnimationCancel(Animator animation) { viewPager.endFakeDrag(); } @Override public void onAnimationRepeat(Animator animation) { viewPager.endFakeDrag(); oldDragPosition = 0; viewPager.beginFakeDrag(); } }); animator.setInterpolator(new AccelerateInterpolator()); animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { int dragPosition = (Integer) animation.getAnimatedValue(); int dragOffset = dragPosition - oldDragPosition; oldDragPosition = dragPosition; viewPager.fakeDragBy(dragOffset * (forward ? -1 : 1)); } }); animator.setDuration(AppConstants.PAGER_TRANSITION_DURATION_MS / pageCount); // remove divider if you want to make each transition have the same speed as single page transition animator.setRepeatCount(pageCount); return animator; } 

Answer 3

更好的解决scheme是通过在支持包中创build类来访问私有字段。 编辑这是绑定到600毫秒的MAX_SETTLE_DURATION ，由ViewPager类设置。

 package android.support.v4.view; import android.content.Context; import android.util.AttributeSet; public class SlowViewPager extends ViewPager { // The speed of the scroll used by setCurrentItem() private static final int VELOCITY = 200; public SlowViewPager(Context context) { super(context); } public SlowViewPager(Context context, AttributeSet attrs) { super(context, attrs); } @Override void setCurrentItemInternal(int item, boolean smoothScroll, boolean always) { setCurrentItemInternal(item, smoothScroll, always, VELOCITY); } } 

当然，您可以添加一个自定义属性，以便通过XML进行设置。

Answer 4

  public class PresentationViewPager extends ViewPager { public static final int DEFAULT_SCROLL_DURATION = 250; public static final int PRESENTATION_MODE_SCROLL_DURATION = 1000; public PresentationViewPager (Context context) { super(context); } public PresentationViewPager (Context context, AttributeSet attrs) { super(context, attrs); } public void setDurationScroll(int millis) { try { Class<?> viewpager = ViewPager.class; Field scroller = viewpager.getDeclaredField("mScroller"); scroller.setAccessible(true); scroller.set(this, new OwnScroller(getContext(), millis)); } catch (Exception e) { e.printStackTrace(); } } public class OwnScroller extends Scroller { private int durationScrollMillis = 1; public OwnScroller(Context context, int durationScroll) { super(context, new DecelerateInterpolator()); this.durationScrollMillis = durationScroll; } @Override public void startScroll(int startX, int startY, int dx, int dy, int duration) { super.startScroll(startX, startY, dx, dy, durationScrollMillis); } } }