java - Android ScrollView 仅在您已经到达底部时才滚动到底部

Question

我有一个基本的 Android 应用程序，设置了 ScrollView 并动态添加文本。我希望它在添加文本时滚动到底部(这已经发生了)，但我只希望它在您已经位于底部时滚动到底部，所以如果您正在阅读某些内容，它不会只是滚动。这是我到目前为止所拥有的。

private void AddText(final String msg){
    this.runOnUiThread(new Runnable() {
        public void run() {
            TextView log = (TextView) findViewById(R.id.chatlog);
            if(log.getText().equals("Loading...")){
                log.setText(msg);
            }else{
                ScrollView scroller = (ScrollView) findViewById(R.id.scroll_container);
                //set current scroll position
                int scroll_pos = scroller.getScrollY();
                //scroll to bottom
                scroller.fullScroll(ScrollView.FOCUS_DOWN);
                //set bottom position
                int scroll_bot = scroller.getScrollY();
                //add the text
                log.append("\r\n" + msg);
                //if you weren't at the bottom
                //scroll back to where you were.
                //This isn't working, scroll bot is the same
                //as scroll pos.
                if(scroll_pos != scroll_bot){
                    scroller.scrollTo(0, scroll_pos);
                }
                //System.out.println("Pos: " + scroll_pos);
                //System.out.println("Bot: " + scroll_bot);
            }
        }
    });
}

Answer 1

到目前为止，我发现的最佳解决方案是使用带有可运行对象的scrollView.post()方法，该方法将在文本更改后调用:

final ScrollView scrollView = (ScrollView) findViewById(R.id.consoleTab);
TextView textView = (TextView) findViewById(R.id.consoleView);
boolean autoScroll = (textView.getBottom() - (scrollView.getHeight() + scrollView.getScrollY())) <= 0;
textView.setText(state.getConsole().getText());

if (autoScroll) {
   scrollView.post(new Runnable() {
      public void run() {
         scrollView.fullScroll(ScrollView.FOCUS_DOWN);
      }
   });
}