Dotted underline in TextView using SpannableString in Android

Question

I want dotted underline below SpannableString Like here is my string

Hello, How are you?

I want to develop dotted underline below How word so how to set it? If i add clickable that its give me underline but i want dotted underline below How word. Can anyone help me ? Actually on click of that How word i am opening a dialog so that thing i achieved with clickable but i want to design that How word with dotted underline.

Editted: Using below post dotted underline appears but text color is not showing using ForegroundColorSpan class. can anybody help me to resolve this issue.

Answer 1

You should use two SpannableString for it as

SpannableString ss = new SpannableString("Hello, how are you ?");
    ClickableSpan clickableSpan = new ClickableSpan() {
        @Override
        public void onClick(View textView) {
         //perform operation on click

        }

        @Override
        public void updateDrawState(TextPaint ds) {
            super.updateDrawState(ds);
            ds.setUnderlineText(false);
        }
    };
    ss.setSpan(clickableSpan, 0, 9, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    ss.setSpan(new ForegroundColorSpan(getActivity().getResources().getColor(android.R.color.holo_blue_light)), 0, 9, Spanned.SPAN_EXCLUSIVE_EXCLUSIVE);
    textView_understand.setText(ss);
    textView_understand.setMovementMethod(LinkMovementMethod.getInstance());
    textView_understand.setHighlightColor(Color.TRANSPARENT);
    textView_understand
            .setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                //On click
                }
            });

And for make it dotted underline you should use

private static class DottedUnderlineSpan extends ReplacementSpan {
private Paint p;
private int mWidth;
private String mSpan;

private float mSpanLength;
private boolean mLengthIsCached = false;

public DottedUnderlineSpan(int _color, String _spannedText){
    p = new Paint();
    p.setColor(_color);
    p.setStyle(Paint.Style.STROKE);
    p.setPathEffect(new DashPathEffect(new float[]{mDashPathEffect, mDashPathEffect}, 0));
    p.setStrokeWidth(mStrokeWidth);
    mSpan = _spannedText;
}

@Override
public int getSize(Paint paint, CharSequence text, int start, int end, Paint.FontMetricsInt fm) {
    mWidth = (int) paint.measureText(text, start, end);
    return mWidth;
}

@Override
public void draw(Canvas canvas, CharSequence text, int start, int end, float x, int top, int y, int bottom, Paint paint) {
    canvas.drawText(text, start, end, x, y, paint);
    if(!mLengthIsCached)
        mSpanLength = paint.measureText(mSpan);

    // https://code.google.com/p/android/issues/detail?id=29944
    // canvas.drawLine can't draw dashes when hardware acceleration is enabled,
    // but canvas.drawPath can
    Path path = new Path();
    path.moveTo(x, y + mOffsetY);
    path.lineTo(x + mSpanLength, y + mOffsetY);
    canvas.drawPath(path, this.p);
}
}

and use this class for span as:

  DottedUnderlineSpan dottedUnderlineSpan = new DottedUnderlineSpan(0xFF00FF00, spannedText);

To make your underline look the same on all densities set that dimens in dp

mStrokeWidth = context.getResources().getDimension(R.dimen.stroke_width);
mDashPathEffect = context.getResources().getDimension(R.dimen.dash_path_effect);
mOffsetY = context.getResources().getDimension(R.dimen.offset_y);