RTEditor/src/main/java/com/onegravity/rteditor/RTEditorMovementMethod.java
private int getCharIndexAt(TextView textView, MotionEvent event) {
        // get coordinates
        int x = (int) event.getX();
        int y = (int) event.getY();
        x -= textView.getTotalPaddingLeft();
        y -= textView.getTotalPaddingTop();
        x += textView.getScrollX();
        y += textView.getScrollY();

        /*
         * Fail-fast check of the line bound.
         * If we're not within the line bound no character was touched
         */
        Layout layout = textView.getLayout();
        int line = layout.getLineForVertical(y);
        synchronized (sLineBounds) {
            layout.getLineBounds(line, sLineBounds);
            if (!sLineBounds.contains(x, y)) {
                return -1;
            }
        }

        // retrieve line text
        Spanned text = (Spanned) textView.getText();
        int lineStart = layout.getLineStart(line);
        int lineEnd = layout.getLineEnd(line);
        int lineLength = lineEnd - lineStart;
        if (lineLength == 0) {
            return -1;
        }
        Spanned lineText = (Spanned) text.subSequence(lineStart, lineEnd);

        // compute leading margin and subtract it from the x coordinate
        int margin = 0;
        LeadingMarginSpan[] marginSpans = lineText.getSpans(0, lineLength, LeadingMarginSpan.class);
        if (marginSpans != null) {
            for (LeadingMarginSpan span : marginSpans) {
                margin += span.getLeadingMargin(true);
            }
        }
        x -= margin;

        // retrieve text widths
        float[] widths = new float[lineLength];
        TextPaint paint = textView.getPaint();
        paint.getTextWidths(lineText, 0, lineLength, widths);

        // scale text widths by relative font size (absolute size / default size)
        final float defaultSize = textView.getTextSize();
        float scaleFactor = 1f;
        AbsoluteSizeSpan[] absSpans = lineText.getSpans(0, lineLength, AbsoluteSizeSpan.class);
        if (absSpans != null) {
            for (AbsoluteSizeSpan span : absSpans) {
                int spanStart = lineText.getSpanStart(span);
                int spanEnd = lineText.getSpanEnd(span);
                scaleFactor = span.getSize() / defaultSize;
                int start = Math.max(lineStart, spanStart);
                int end = Math.min(lineEnd, spanEnd);
                for (int i = start; i < end; i++) {
                    widths[i] *= scaleFactor;
                }
            }
        }

        // find index of touched character
        float startChar = 0;
        float endChar = 0;
        for (int i = 0; i < lineLength; i++) {
            startChar = endChar;
            endChar += widths[i];
            if (endChar >= x) {
                // which "end" is closer to x, the start or the end of the character?
                int index = lineStart + (x - startChar < endChar - x ? i : i + 1);
                //Logger.e(Logger.LOG_TAG, "Found character: " + (text.length()>index ? text.charAt(index) : ""));
                return index;
            }
        }

        return -1;
    }
private int getCharIndexAt(TextView textView, MotionEvent event) {
        // get coordinates
        int x = (int) event.getX();
        int y = (int) event.getY();
        x -= textView.getTotalPaddingLeft();
        y -= textView.getTotalPaddingTop();
        x += textView.getScrollX();
        y += textView.getScrollY();

        /*
         * Fail-fast check of the line bound.
         * If we're not within the line bound no character was touched
         */
        Layout layout = textView.getLayout();
        int line = layout.getLineForVertical(y);
        synchronized (sLineBounds) {
            layout.getLineBounds(line, sLineBounds);
            if (!sLineBounds.contains(x, y)) {
                return -1;
            }
        }

        // retrieve line text
        Spanned text = (Spanned) textView.getText();
        int lineStart = layout.getLineStart(line);
        int lineEnd = layout.getLineEnd(line);
        int lineLength = lineEnd - lineStart;
        if (lineLength == 0) {
            return -1;
        }
        Spanned lineText = (Spanned) text.subSequence(lineStart, lineEnd);

        // compute leading margin and subtract it from the x coordinate
        int margin = 0;
        LeadingMarginSpan[] marginSpans = lineText.getSpans(0, lineLength, LeadingMarginSpan.class);
        if (marginSpans != null) {
            for (LeadingMarginSpan span : marginSpans) {
                margin += span.getLeadingMargin(true);
            }
        }
        x -= margin;

        // retrieve text widths
        float[] widths = new float[lineLength];
        TextPaint paint = textView.getPaint();
        paint.getTextWidths(lineText, 0, lineLength, widths);

        // scale text widths by relative font size (absolute size / default size)
        final float defaultSize = textView.getTextSize();
        float scaleFactor = 1f;
        AbsoluteSizeSpan[] absSpans = lineText.getSpans(0, lineLength, AbsoluteSizeSpan.class);
        if (absSpans != null) {
            for (AbsoluteSizeSpan span : absSpans) {
                int spanStart = lineText.getSpanStart(span);
                int spanEnd = lineText.getSpanEnd(span);
                scaleFactor = span.getSize() / defaultSize;
                int start = Math.max(lineStart, spanStart);
                int end = Math.min(lineEnd, spanEnd);
                for (int i = start; i < end; i++) {
                    widths[i] *= scaleFactor;
                }
            }
        }

        // find index of touched character
        float startChar = 0;
        float endChar = 0;
        for (int i = 0; i < lineLength; i++) {
            startChar = endChar;
            endChar += widths[i];
            if (endChar >= x) {
                // which "end" is closer to x, the start or the end of the character?
                int index = lineStart + (x - startChar < endChar - x ? i : i + 1);
                //Logger.e(Logger.LOG_TAG, "Found character: " + (text.length()>index ? text.charAt(index) : ""));
                return index;
            }
        }

        return -1;
    }
TODO finding links doesn't work with right alignment and potentially other formatting options