Android: 擴充WebView 和ViewPager實現viewpager中的水平滑動，類似Gmail的效果

The following is a real working solution which will scroll the WebView on a horizontal swipe as long as it can scroll. If the
WebView cannot further scroll, the next horizontal swipe will be consumed by the
ViewPager to switch the page.

Extending the WebView

With API-Level 14 (ICS) the View method canScrollHorizontally() has been introduced, which we need to solve the problem. If you develop only for ICS or above you can directly use this method and skip to the next section. Otherwise
we need to implement this method on our own, to make the solution work also on pre-ICS.

To do so simply derive your own class from WebView:

public class ExtendedWebView extends WebView {    public ExtendedWebView(Context context) {        super(context);    }    public ExtendedWebView(Context context, AttributeSet attrs) {        super(context, attrs);    }    public boolean canScrollHor(int direction) {        final int offset = computeHorizontalScrollOffset();        final int range = computeHorizontalScrollRange() - computeHorizontalScrollExtent();        if (range == 0) return false;        if (direction < 0) {            return offset > 0;        } else {            return offset < range - 1;        }    }}

Important: Remember to reference your ExtendedWebView inside your layout file instead of the standard
WebView.

Extending the ViewPager

Now you need to extend the ViewPager to handle handle horizontal swipes correctly. This needs to be done in any case -- no matter whether you are using ICS or not:

public class WebViewPager extends ViewPager {    public WebViewPager(Context context, AttributeSet attrs) {        super(context, attrs);    }    @Override    protected boolean canScroll(View v, boolean checkV, int dx, int x, int y) {        if (v instanceof ExtendedWebView) {            return ((ExtendedWebView) v).canScrollHor(-dx);        } else {            return super.canScroll(v, checkV, dx, x, y);        }    }}

Important: Remember to reference your WebViewPager inside your layout file instead of the standard
ViewPager.

That's it!

Update 2012/07/08: I've recently noticed that the stuff shown above seems to be no longer required when using the "current" implementation of the
ViewPager. The "current" implementation seems to check the sub views correctly before capturing the scroll event on it's own (see
canScroll method of ViewPager
here). Don't know exactly, when the implementation has been changed to handle this correctly -- I still need the code above on Android Gingerbread (2.3.x) and before.

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edited Jul 8 at 11:13

answered Mar 29 at 13:07 sven 1,272821