我需要知道如何检测用户是否无法在webView中滚动。我想在用户向左或向右滑动时生成一个动作,但仅当用户无法滚动时才会生成:
IF the user swipes to the left AND the webview can't scroll to left THEN
do something
ELSE
let the webview scroll
答案 0 :(得分:11)
我找到了一个适合我的解决方案,我在2.3 API中查看了WebView类的源代码,并找到了如何使用2.1 API。也许它适用于较旧的API:
public class CustomWebView extends WebView {
private float oldX;
// indicate if horizontal scrollbar can't go more to the left
private boolean overScrollLeft = false;
// indicate if horizontal scrollbar can't go more to the right
private boolean overScrollRight = false;
// indicate if horizontal scrollbar can't go more to the left OR right
private boolean isScrolling = false;
public CustomWebView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
public CustomWebView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
}
public CustomWebView(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// width of the vertical scrollbar
int scrollBarWidth = getVerticalScrollbarWidth();
// width of the view depending of you set in the layout
int viewWidth = computeHorizontalScrollExtent();
// width of the webpage depending of the zoom
int innerWidth = computeHorizontalScrollRange();
// position of the left side of the horizontal scrollbar
int scrollBarLeftPos = computeHorizontalScrollOffset();
// position of the right side of the horizontal scrollbar, the width of scroll is the width of view minus the width of vertical scrollbar
int scrollBarRightPos = scrollBarLeftPos + viewWidth - scrollBarWidth;
// if left pos of scroll bar is 0 left over scrolling is true
if(scrollBarLeftPos == 0) {
overScrollLeft = true;
} else {
overScrollLeft = false;
}
// if right pos of scroll bar is superior to webpage width: right over scrolling is true
if(scrollBarRightPos >= innerWidth) {
overScrollRight = true;
} else {
overScrollRight = false;
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: // when user touch the screen
// if scrollbar is the most left or right
if(overScrollLeft || overScrollRight) {
isScrolling = false;
} else {
isScrolling = true;
}
oldX = event.getX();
break;
case MotionEvent.ACTION_UP: // when user stop to touch the screen
// if scrollbar can't go more to the left OR right
// this allow to force the user to do another gesture when he reach a side
if(!isScrolling) {
if(event.getX() > oldX && overScrollLeft) {
// left action
}
if(event.getX() < oldX && overScrollRight) {
// right actio
}
}
break;
default:
break;
}
return super.onTouchEvent(event);
}
}
答案 1 :(得分:3)
API中有一些有趣的方法,但它们受到保护,我认为您可以创建自己的WebView(扩展WebView)并使用这些方法并将它们公开。 具体来说,也许你可以使用这两个 onScrollChanged和onOverScroll。
答案 2 :(得分:0)
我认为这样可以解决这个问题:
int horizontalOffset = computeHorizontalScrollOffset();
int contentWidth = (int) Math.floor(getContentWidth() * getScale());
int viewportWidth = getWidth();
// 1 just for random error
boolean reachRightEnd = ((horizontalOffset + viewportWidth) >= (contentWidth - 1));
boolean reachLeftEnd = (horizontalOffset == 0);