java 带有信用卡掩码的Android TextInputLayout

Posted 2021-05-08

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


    <android.support.design.widget.TextInputLayout
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:layout_centerInParent="true"
        app:counterMaxLength="16"
        app:counterEnabled="true">

        <android.support.design.widget.TextInputEditText
            android:id="@+id/cc"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="Credit Card Number"
            android:digits="1234567890"
            android:inputType="number|textNoSuggestions"
            />

    </android.support.design.widget.TextInputLayout>


</RelativeLayout>

In this example I will explain how you can build a TextInputLayout that shows credit card numeber.  

The goal is to add a margin between every four digits without adding a space (" ") while you are inserting text.  
  
![Screen](https://s14.postimg.org/ru7rngjfl/ezgif_2.gif)  
  
You need to put a [TextWatcher](https://developer.android.com/reference/android/text/TextWatcher.html) on a [EditText](https://developer.android.com/reference/android/widget/EditText.html).  
The [TextWatcher](https://developer.android.com/reference/android/text/TextWatcher.html) needs to add a margin every four digits.  

Example:
```java

    private EditText etCreditCard;
    private TextWatcher tv;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        etCreditCard = (EditText) findViewById(R.id.cc);

        tv = new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {
            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {

            }

            @Override
            public void afterTextChanged(Editable s) {
                int textLength = etCreditCard.length();
                if(etCreditCard.length() > 4){
                    etCreditCard.removeTextChangedListener(tv);
                    if(textLength > 15){
                        s.replace(16, textLength, "");
                    }else {
                        for(int i = 1; i <= (textLength / 4); i++){
                            MarginSpan marginSPan = new MarginSpan(20);
                            s.setSpan(marginSPan, (i * 4)-1, (i * 4), Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
                        }
                    }
                    etCreditCard.addTextChangedListener(tv);
                }
            }
        };
        etCreditCard.addTextChangedListener(tv);

    }

```

package com.liberorignanese.android.gist;

import android.graphics.Canvas;
import android.graphics.Paint;
import android.text.style.ReplacementSpan;

/**
 * Created by Libero Rignanese.
 */


public class MarginSpan extends ReplacementSpan {

    private int mPadding;

    public MarginSpan(int padding) {
        mPadding = padding;
    }

    @Override
    public int getSize(Paint paint, CharSequence text, int start, int end, Paint.FontMetricsInt fm) {
        float[] widths = new float[end - start];
        paint.getTextWidths(text, start, end, widths);
        int sum = mPadding;
        for (int i = 0; i < widths.length; i++) {
            sum += widths[i];
        }
        return sum;
    }

    @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);
    }

}