WordPress/src/main/java/org/wordpress/android/ui/notifications/blocks/NoteBlockLinkMovementMethod.java

package org.wordpress.android.ui.notifications.blocks;

import android.support.annotation.NonNull;
import android.text.Layout;
import android.text.Selection;
import android.text.Spannable;
import android.text.method.LinkMovementMethod;
import android.view.MotionEvent;
import android.widget.TextView;

/**
 * Allows links to be highlighted when tapped on note blocks.
 * See: http://stackoverflow.com/a/20905824/309558
 */
class NoteBlockLinkMovementMethod extends LinkMovementMethod {

    private NoteBlockClickableSpan mPressedSpan;

    @Override
    public boolean onTouchEvent(@NonNull TextView textView, @NonNull Spannable spannable, @NonNull MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            mPressedSpan = getPressedSpan(textView, spannable, event);
            if (mPressedSpan != null) {
                mPressedSpan.setPressed(true);
                Selection.setSelection(spannable, spannable.getSpanStart(mPressedSpan),
                        spannable.getSpanEnd(mPressedSpan));
            }
        } else if (event.getAction() == MotionEvent.ACTION_MOVE) {
            NoteBlockClickableSpan touchedSpan = getPressedSpan(textView, spannable, event);
            if (mPressedSpan != null && touchedSpan != mPressedSpan) {
                mPressedSpan.setPressed(false);
                mPressedSpan = null;
                Selection.removeSelection(spannable);
            }
        } else {
            if (mPressedSpan != null) {
                mPressedSpan.setPressed(false);
                super.onTouchEvent(textView, spannable, event);
            }
            mPressedSpan = null;
            Selection.removeSelection(spannable);
        }
        return true;
    }

    private NoteBlockClickableSpan getPressedSpan(TextView textView, Spannable spannable, MotionEvent event) {

        int x = (int) event.getX();
        int y = (int) event.getY();

        x -= textView.getTotalPaddingLeft();
        y -= textView.getTotalPaddingTop();

        x += textView.getScrollX();
        y += textView.getScrollY();

        Layout layout = textView.getLayout();
        int line = layout.getLineForVertical(y);
        int off = layout.getOffsetForHorizontal(line, x);

        NoteBlockClickableSpan[] link = spannable.getSpans(off, off, NoteBlockClickableSpan.class);
        NoteBlockClickableSpan touchedSpan = null;
        if (link.length > 0) {
            touchedSpan = link[0];
        }

        return touchedSpan;
    }

}