我有一个显示 html 文件的 webview.当用户在 webview 中滚动到该文件的底部时，我希望显示一个以前隐藏的按钮，然后用户可以按下该按钮来执行一些活动
I have a webview which shows an html file. When the user scrolls to the bottom of this file in webview, I want a button that was previously hidden to show up, which the user can then press to do some activity
我在 iOS 中做了类似的事情，我只是将委托设置为 ViewController 并将按钮设置为可见.我如何在 Android 上做类似的事情?我注意到没有像 iOS 那样的回调方法.
I did something similar in iOS, where I just set the delegate to the ViewController and just set the button as visible. How do I do something similar on Android? I noticed there isn't a callback method like in iOS.
现在，我有一个包含 2 个对象的活动:一个包含我的文本的 web 视图和一个当前不可见的按钮.我希望我的活动在 webview 文本滚动到底部时收到一条消息，并使按钮可见
Right now, I have an activity with 2 objects: a webview containing my text, and a button which is currently invisible. I want my activity to receive a message when the webview text scrolls to the bottom, and make the button visible
为了在用户滚动到 EULA 底部后显示我同意"按钮，我必须自己执行此操作.律师，嗯?
I had to do this myself, in order to display an "I Agree" button once the user has scrolled to the bottom of a EULA. Lawyers, huh?
事实上，当您覆盖 WebView(而不是 @JackTurky 的答案中的 ScrollView)时，您可以调用 computeVerticalScrollRange() 来获取内容的高度，而不是 getBottom() 返回可见底部而不是有用.
In fact when you override the WebView (rather than the ScrollView as in the answer from @JackTurky) you can call computeVerticalScrollRange() to get the height of the content, rather than getBottom() which returns the visible bottom and is not useful.
这是我的综合解决方案.据我所知，这都是 API Level 1 的东西，所以它应该可以在任何地方工作.
This is my comprehensive solution. As far as I can see this is all API Level 1 stuff, so it should work anywhere.
public class EulaWebView extends WebView {
public EulaWebView(Context context)
{
this(context, null);
}
public EulaWebView(Context context, AttributeSet attrs)
{
this(context, attrs, 0);
}
public EulaWebView(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
}
public OnBottomReachedListener mOnBottomReachedListener = null;
private int mMinDistance = 0;
/**
* Set the listener which will be called when the WebView is scrolled to within some
* margin of the bottom.
* @param bottomReachedListener
* @param allowedDifference
*/
public void setOnBottomReachedListener(OnBottomReachedListener bottomReachedListener, int allowedDifference ) {
mOnBottomReachedListener = bottomReachedListener;
mMinDistance = allowedDifference;
}
/**
* Implement this interface if you want to be notified when the WebView has scrolled to the bottom.
*/
public interface OnBottomReachedListener {
void onBottomReached(View v);
}
@Override
protected void onScrollChanged(int left, int top, int oldLeft, int oldTop) {
if ( mOnBottomReachedListener != null ) {
if ( (computeVerticalScrollRange() - (top + getHeight())) <= mMinDistance )
mOnBottomReachedListener.onBottomReached(this);
}
super.onScrollChanged(left, top, oldLeft, oldTop);
}
}
一旦用户滚动到 WebView 的底部，我就使用它来显示我同意"按钮，我在这里这样称呼它(在实现 OnBottomReachedListener"的类中:
I use this to display an "I Agree" button once the user has scrolled to the bottom of the WebView, where I call it like this (in a class which "implements OnBottomReachedListener":
EulaWebView mEulaContent;
Button mEulaAgreed;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.eula);
mEulaContent = (EulaWebView) findViewById(R.id.eula_content);
StaticHelpers.loadWebView(this, mEulaContent, R.raw.stylesheet, StaticHelpers.readRawTextFile(this, R.raw.eula), null);
mEulaContent.setVerticalScrollBarEnabled(true);
mEulaContent.setOnBottomReachedListener(this, 50);
mEulaAgreed = (Button) findViewById(R.id.eula_agreed);
mEulaAgreed.setOnClickListener(this);
mEulaAgreed.setVisibility(View.GONE);
}
@Override
public void onBottomReached(View v) {
mEulaAgreed.setVisibility(View.VISIBLE);
}
所以当到达底部时(或者在这种情况下，当他们到达底部 50 像素以内时)我同意"按钮就会出现.
So when the bottom is reached (or in this case, when they get within 50 pixels of it) the "I Agree" button appears.
这篇关于Android:一旦 webview 完成滚动，就使按钮可见的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持跟版网！