检测TextView是否换行

Question

We are using an ExpandableList of TableViews to display a block of text with line numbers on one side. First, the string for a given paragraph is set into a text view in the right column of the TableView. Then, a line-number string is generated from the paragraph string and a starting line number. For example, from the string (with a starting line number of 1):

Lorem ipsum dolor sit amet, 
consectetur adipiscing elit.   
Donec ultricies a nunc sit amet venenatis.   
Aenean placerat dictum nunc,   
nec pulvinar arcu consequat a.   
Proin dignissim velit ut augue dictum ultricies.  
Fusce lorem dolor, elementum id tempor at,   
pellentesque eu dolor. Vestibulum rhoncus   
arcu in sapien sagittis gravida.   
Nullam vel nisl enim.   
Maecenas scelerisque at quam non congue.   
Nullam quis porttitor purus, nec interdum tellus.   

the following line number string is generated:

\n\n\n\n5.\n\n\n\n\n10.\n\n

This string is then placed in the leftmost column of the TableView to show the line number of the string every five lines.

However, a problem arises when the text size is raised to a point where the lines of text are wrapped (because the line is too big to fit on the screen). When this happens, it seems like it is necessary to insert another \\n into the line number string at the site of the text-wrapping, so as to count the potentially multiple lines of wrapped text as a single line. Is there, therefore, anyway for android to detect whether a line has been wrapped in a TextView, so that the program can know to insert a \\n into the line number string and compensate for line breaks?

Answer 1

First you can compute the on screen width required for the string render. Compare that with your total device/view with to check if you need to insert '\\n' for text wrapping.

PS: The code is not tested but should work. If you using custom typeface, you can replace Typeface.DEFAULT with your own.

public float computeTotalWidthOnScreen(String text) {
        final Typeface typeface = Typeface.DEFAULT;
        final Paint paint = new Paint();
        final Rect bounds = new Rect();
        paint.setTypeface(typeface);
        paint.setAntiAlias(true);
        paint.setTextSize(defaultFontSize);
        paint.getTextBounds(text, 0, text.length(), bounds);

        return bounds.width();
    }