我有一个包含在ScrollView中的长文本段落。有没有办法找到当前可见的文本?
我能够找到TextView中的行数、行高以及ScrollView中的scrollx和scrolly,但无法找到与当前显示的文本相对应的内容。请帮忙!谢谢。
这很简单:
int start = textView.getLayout().getLineStart(0);
int end = textView.getLayout().getLineEnd(textView.getLineCount() - 1);
String displayed = textView.getText().toString().substring(start, end);
在这里,先获取第一行的显示行号。然后获取第二行的显示行号。接着获取文本并计算单词数。
private int getNumberOfWordsDisplayed() {
int start = textView.getLayout().getLineStart(getFirstLineIndex());
int end = textView.getLayout().getLineEnd(getLastLineIndex());
return textView.getText().toString().substring(start, end).split(" ").length;
}
/**
* Gets the first line that is visible on the screen.
*
* @return
*/
public int getFirstLineIndex() {
int scrollY = scrollView.getScrollY();
Layout layout = textView.getLayout();
if (layout != null) {
return layout.getLineForVertical(scrollY);
}
Log.d(TAG, "Layout is null: ");
return -1;
}
/**
* Gets the last visible line number on the screen.
* @return last line that is visible on the screen.
*/
public int getLastLineIndex() {
int height = scrollView.getHeight();
int scrollY = scrollView.getScrollY();
Layout layout = textView.getLayout();
if (layout != null) {
return layout.getLineForVertical(scrollY + height);
}
return -1;
}
getLineStart
+ getLineForVertical
)。 - Nimitz14如果 android:singleLine="true",可以使用 textView.getLayout().getEllipsisStart(0)。
如果设置了 android:maxLines,则可以使用以下解决方案:
public static String getVisibleText(TextView textView) {
// test that we have a textview and it has text
if (textView==null || TextUtils.isEmpty(textView.getText())) return null;
Layout l = textView.getLayout();
if (l!=null) {
// find the last visible position
int end = l.getLineEnd(textView.getMaxLines()-1);
// get only the text after that position
return textView.getText().toString().substring(0,end);
}
return null;
}
textView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
textView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
Log.i("test" ,"VisibleText="+getVisibleText(textView));
}
});
你声称你知道 scrollY
,即当前滚动的像素数。你还知道你正在考虑的窗口的高度(以像素为单位),所以将其称为 scrollViewHeight
。然后
int scrollY; // This is your current scroll position in pixels.
int scrollViewHeight; // This is the height of your scrolling window.
TextView textView; // This is the TextView we're considering.
String text = (String) textView.getText();
int charsPerLine = text.length() / textView.getLineCount();
int lineHeight = textView.getLineHeight();
int startLine = scrollY / lineHeight;
int endLine = startLine + scrollViewHeight/lineHeight + 1;
int startChar = charsPerLine * startLine;
int endChar = charsPerLine * (endLine+1) + 1;
String approxVisibleString = text.substring(startChar, endChar);
这只是一个近似值,所以请把它作为最后的选择。
我自己也遇到了类似的问题。我需要从当前在recyclerview中可见的textview获取第一行。如果你正试图获取recyclerview中textview当前显示的第一行,你可以使用以下代码:
TextView tv = (TextView) recyclerView.getChildAt(0); //gets current visible child view
// this is for top visible
//view or the textview directly
Rect r1 = new Rect();
tv.getHitRect(r1);//gets visible rect of textview
Layout l = tv.getLayout();
int line = l.getLineForVertical(-1 * r1.top);//first visible line
int start = l.getLineStart(line);//visible line start
int end = l.getLineEnd(line);//visible line end
String displayed = tv.getText().toString().substring(start, end);
public String getVisibleText(TextView tv) {
int lastLine = tv.getMaxLines() < 1 || tv.getMaxLines() > tv.getLineCount() ? tv.getLineCount() : tv.getMaxLines();
if (tv.getEllipsize() != null && tv.getEllipsize().equals(TextUtils.TruncateAt.END)) {
int ellCount = tv.getLayout().getEllipsisCount(lastLine - 1);
if (ellCount > 0 && tv.length() > ellCount)
return tv.getText().toString().substring(0, tv_title.getText().length() - ellCount);
return tv.getText().toString();
} else {
int end = tv.getLayout().getLineEnd(lastLine - 1);
return tv.getText().toString().substring(0, end);
}
}
...
textView.post(new Runnable() {
@Override
public void run() {
Log.d(TAG, getVisibleText(textView));
}
});
尝试使用getEllipsisStart()
int end = textView.getLayout().getEllipsisStart(0);
int start = tv.getLayout().getLineStart(scrolllinenumber);
int end=scrolllinenumber+tv.getLayout().getHeight();
String displayedtext = tv.getText().toString().substring(start, end);