Android自定義控件實現通用驗證碼輸入框（二）

<?xml version="1.0" encoding="utf-8"?>
<resources>

  <declare-styleable name="CodeInputView">
    <!-- 邊框寬度 -->
    <attr name="borderWidth"
      format="dimension" />
    <!-- 邊框高度 -->
    <attr name="borderHeight"
      format="dimension" />
    <!-- 邊框間距 -->
    <attr name="borderSpacing"
      format="dimension" />
    <!-- 邊框背景圖 -->
    <attr name="borderImage"
      format="reference" />
    <!-- 最大輸入長度 -->
    <attr name="android:maxLength" />
  </declare-styleable>

</resources>

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

  <item android:state_focused="true">
    <shape android:shape="rectangle">
      <corners android:radius="5mm" />
      <stroke android:width="2mm"
        android:color="@color/colorMain" />
    </shape>
  </item>

  <item android:state_enabled="true">
    <shape android:shape="rectangle">
      <corners android:radius="5mm" />
      <stroke android:width="2mm"
        android:color="@color/colorTextLight" />
    </shape>
  </item>

</selector>

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Build;
import android.text.InputFilter;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.widget.EditText;

import androidx.annotation.RequiresApi;
import androidx.core.content.ContextCompat;

/**
 * <pre>
 *   <b>author</b>  ：BraveTou
 *   <b>blog</b>   ：https://blog.csdn.net/bravetou
 *   <b>time</b>   ：2020/9/8 11:49
 *   <b>desc</b>   ：<pre>
 *     自定義驗證碼輸入框
 *   </pre>
 * </pre>
 */
@SuppressLint("AppCompatCustomView")
public class CodeInputView extends EditText {
  // <!-- 最大輸入長度 -->
  private int mMaxLength = 4;
  // <!-- 邊框寬度 -->
  private int mBorderWidth = 100;
  // <!-- 邊框高度 -->
  private int mBorderHeight = 100;
  // <!-- 邊框間距 -->
  private int mBorderSpacing = 24;
  // <!-- 邊框背景圖 -->
  private Drawable mBorderImage;

  // 用矩形來保存方框的位置、大小信息
  private final Rect mRect = new Rect();

  // 文本顏色
  private int mTextColor;

  public CodeInputView(Context context) {
    super(context);
    init(context, null);
  }

  public CodeInputView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init(context, attrs);
  }

  public CodeInputView(Context context, AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context, attrs);
  }

  @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
  public CodeInputView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
    super(context, attrs, defStyleAttr, defStyleRes);
    init(context, attrs);
  }

  // 初始化
  private void init(Context context, AttributeSet attrs) {
    if (null == mBorderImage) {
      mBorderImage = ContextCompat.getDrawable(context,
          R.drawable.code_input_view_border_bg);
    }
    initAttrs(context, attrs);
    // 設置最大輸入長度
    setMaxLength(mMaxLength);
    // 禁止長按
    setLongClickable(false);
    // 去掉背景顏色
    setBackgroundColor(Color.TRANSPARENT);
    // 不顯示光標
    setCursorVisible(false);
  }

  // 設置最大長度
  private void setMaxLength(int maxLength) {
    if (maxLength >= 0) {
      setFilters(new InputFilter[]{new InputFilter.LengthFilter(maxLength)});
    } else {
      setFilters(new InputFilter[0]);
    }
  }

  // 初始化屬性
  private void initAttrs(Context context, AttributeSet attrs) {
    if (null != attrs) {
      // AttributeSet 屬性值的索引
      TypedArray o = context.obtainStyledAttributes(attrs, R.styleable.CodeInputView);
      // <!-- 最大輸入長度 -->
      mMaxLength = o.getInteger(R.styleable.CodeInputView_android_maxLength, 4);
      // <!-- 邊框寬度 -->
      mBorderWidth = (int) o.getDimension(R.styleable.CodeInputView_borderWidth, 100f);
      // <!-- 邊框高度 -->
      mBorderHeight = (int) o.getDimension(R.styleable.CodeInputView_borderHeight, 100f);
      // <!-- 邊框間距 -->
      mBorderSpacing = (int) o.getDimension(R.styleable.CodeInputView_borderSpacing, 24);
      // <!-- 邊框背景圖 -->
      Drawable drawable = o.getDrawable(R.styleable.CodeInputView_borderImage);
      if (null != drawable) {
        mBorderImage = drawable;
      }
      // 回收資源
      o.recycle();
    }
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    // 當前輸入框的寬高信息
    int width = getMeasuredWidth();
    int height = getMeasuredHeight();
    int widthMode = MeasureSpec.getMode(widthMeasureSpec);
    int heightMode = MeasureSpec.getMode(heightMeasureSpec);

    // 判斷高度是否小於自定義邊框高度
    height = height < mBorderHeight ? mBorderHeight : height;

    // 自定義輸入框寬度 = 邊框寬度 * 數量 + 邊框間距 * (數量 - 1)
    int customWidth = mBorderWidth * mMaxLength
        + mBorderSpacing * ((mMaxLength - 1) > 0 ? (mMaxLength - 1) : 0);

    // 判斷寬度是否小於自定義寬度
    width = width < customWidth ? customWidth : width;

    widthMeasureSpec = MeasureSpec.makeMeasureSpec(width, widthMode);
    heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, heightMode);

    // 重新設置測量佈局
    setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
  }

  @Override
  protected void onDraw(Canvas canvas) {
    // 獲取當前輸入文本顏色
    mTextColor = getCurrentTextColor();
    // 屏蔽系統文本顏色，直接透明
    setTextColor(Color.TRANSPARENT);
    // 父類繪制
    super.onDraw(canvas);
    // 重新設置文本顏色
    setTextColor(mTextColor);
    // 重繪背景
    drawBorderBackground(canvas);
    // 重繪文本
    drawText(canvas);
  }

  // 繪制背景
  private void drawBorderBackground(Canvas canvas) {
    // 下面繪制方框背景顏色
    // 確定反饋位置
    mRect.left = 0;
    mRect.top = 0;
    mRect.right = mBorderWidth;
    mRect.bottom = mBorderHeight;
    // 當前畫佈保存的狀態
    int count = canvas.getSaveCount();
    // 保存畫佈
    canvas.save();
    // 獲取當前輸入字符串長度
    int length = getEditableText().length();
    for (int i = 0; i < mMaxLength; i++) {
      // 設置位置
      mBorderImage.setBounds(mRect);
      // 設置圖像狀態
      if (i == length) {
        // 當前輸入位高亮的索引
        mBorderImage.setState(new int[]{android.R.attr.state_focused});
      } else {
        // 其他輸入位置默認
        mBorderImage.setState(new int[]{android.R.attr.state_enabled});
      }
      // 畫到畫佈上
      mBorderImage.draw(canvas);
      // 確定下一個方框的位置
      // X坐標位置
      float dx = mRect.right + mBorderSpacing;
      // 保存畫佈
      canvas.save();
      // [註意細節] 移動畫佈到下一個位置
      canvas.translate(dx, 0);
    }
    // [註意細節] 把畫佈還原到畫反饋之前的狀態，這樣就還原到最初位置瞭
    canvas.restoreToCount(count);
    // 畫佈歸位
    canvas.translate(0, 0);
  }

  // 繪制文本
  private void drawText(Canvas canvas) {
    int count = canvas.getSaveCount();
    canvas.translate(0, 0);
    int length = getEditableText().length();
    for (int i = 0; i < length; i++) {
      String text = String.valueOf(getEditableText().charAt(i));
      TextPaint textPaint = getPaint();
      textPaint.setColor(mTextColor);
      // 獲取文本大小
      textPaint.getTextBounds(text, 0, 1, mRect);
      // 計算(x,y) 坐標
      int x = mBorderWidth / 2 + (mBorderWidth + mBorderSpacing) * i - (mRect.centerX());
      int y = canvas.getHeight() / 2 + mRect.height() / 2;
      canvas.drawText(text, x, y, textPaint);
    }
    canvas.restoreToCount(count);
  }
}

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <*.*.*.widget.CodeInputView
      android:id="@+id/mCodeInputView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:layout_marginTop="56mm"
      android:maxLength="5"
      android:text="156"
      android:textSize="48mm"
      app:borderHeight="88mm"
      app:borderSpacing="24mm"
      app:borderWidth="88mm" />

</RelativeLayout>