Android Paint breakText new line

Question

I use Paint.breakText() to get the linecount. But it seems that it won't work for '\\n'.

text = "a\n";
int lineCount = 0;
int index = 0;
int length = text.length();
//maxWidthPX is 240
while(index < length - 1) {
    index += paint.breakText(text, index, length, true, maxWidthPX, null);
    lineCount++;
}

It was supposed that lineCount is 2. But it turn out that lineCount is 1. Shouldn't it be 2? Cause text contain a new line separator : '\\n'.

AndroidStudio debug break

Answer 1

According to the official document paint.breakText() requires following parameters:

public int breakText(CharSequence text, int start, int end, boolean measureForwards, float maxWidth, float[] measuredWidth) 

So, it breaks the character sequence from start to end position given by you where you wrote:

paint.breakText(text, index, length, true, maxWidthPX, null);

where, end = length

That's why, it always executes once!

I have edited your code:

text = "a\n";
int lineCount = 0;
int index = 0;
int length = text.length();
//maxWidthPX is 240
while(index <= length - 1) {
    index += paint.breakText(text, index, index + 1, true, maxWidthPX, null);
    lineCount++;
}

And, found lineCount is 2.

Answer 2

At last, I found a solution by using String split()

        String[] textStr = text.split("\\n");
    int allLineCount = 0;
    for (String textTmp : textStr) {
        int lineCount = 0;
        int index = 0;
        int length = textTmp.length();

        while (index < length - 1) {
            index += paint.breakText(textTmp, index, length, true, maxWidthPX, null);
            lineCount++;
        }
        allLineCount += lineCount;
    }