AndroidView教程之自定义验证码输入框效果

/**
 * 验证码输入框,重写EditText的绘制方法实现。
 * @author RAE
 */
public class CodeEditText extends AppCompatEditText {
 
 // 验证码文本颜色
 private int mTextColor;
 // 输入的最大长度
 private int mMaxLength = 4;
 // 边框宽度
 private int mStrokeWidth;
 // 边框高度
 private int mStrokeHeight;
 // 边框之间的距离
 private int mStrokePadding = 20;
 // 用矩形来保存方框的位置、大小信息
 private final Rect mRect = new Rect();
 // 方框的背景
 private Drawable mStrokeDrawable;

 /**
 * 构造方法
 *
 */
 public CodeEditText(Context context, AttributeSet attrs) {
 super(context, attrs);
 TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.CodeEditText);
 int indexCount = typedArray.getIndexCount();
 for (int i = 0; i < indexCount; i++) {
  int index = typedArray.getIndex(i);
  if (index == R.styleable.CodeEditText_strokeHeight) {
  this.mStrokeHeight = (int) typedArray.getDimension(index, 60);
  } else if (index == R.styleable.CodeEditText_strokeWidth) {
  this.mStrokeWidth = (int) typedArray.getDimension(index, 60);

  } else if (index == R.styleable.CodeEditText_strokePadding) {
  this.mStrokePadding = (int) typedArray.getDimension(index, 20);

  } else if (index == R.styleable.CodeEditText_strokeBackground) {
  this.mStrokeDrawable = typedArray.getDrawable(index);

  } else if (index == R.styleable.CodeEditText_strokeLength) {
  this.mMaxLength = typedArray.getInteger(index, 4);
  }
 }
 typedArray.recycle();

 if (mStrokeDrawable == null) {
  throw new NullPointerException("stroke drawable not allowed to be null!");
 }

 setMaxLength(mMaxLength);
 setLongClickable(false);
 // 去掉背景颜色
 setBackgroundColor(Color.TRANSPARENT);
 // 不显示光标
 setCursorVisible(false);
 }

 @Override
 public boolean onTextContextMenuItem(int id) {
 return false;
 }

 /**
 * 设置最大长度
 */
 private void setMaxLength(int maxLength) {
 if (maxLength >= 0) {
  setFilters(new InputFilter[]{new InputFilter.LengthFilter(maxLength)});
 } else {
  setFilters(new InputFilter[0]);
 }
 }
}

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
 super.onMeasure(widthMeasureSpec, heightMeasureSpec);
 // 当前输入框的宽高信息
 int width = getMeasuredWidth();
 int height = getMeasuredHeight();
 int widthMode = MeasureSpec.getMode(widthMeasureSpec);
 int heightMode = MeasureSpec.getMode(heightMeasureSpec);

 // 判断高度是否小于推荐高度
 if (height < mStrokeHeight) {
  height = mStrokeHeight;
 }

 // 输入框宽度 = 边框宽度 * 数量 + 边框间距 *(数量-1)
 int recommendWidth = mStrokeWidth * mMaxLength + mStrokePadding * (mMaxLength - 1);
 // 判断宽度是否小于推荐宽度
 if (width < recommendWidth) {
  width = recommendWidth;
 }

 widthMeasureSpec = MeasureSpec.makeMeasureSpec(width, widthMode);
 heightMeasureSpec = MeasureSpec.makeMeasureSpec(height, heightMode);
 // 设置测量布局
 setMeasuredDimension(widthMeasureSpec, heightMeasureSpec);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  // 在画支持设置文本颜色，把系统化的文本透明掉，相当于覆盖
  mTextColor = getCurrentTextColor();
  setTextColor(Color.TRANSPARENT);
  // 系统画的方法
  super.onDraw(canvas);
  // 重新设置文本颜色
  setTextColor(mTextColor);
  // 重绘背景颜色
  drawStrokeBackground(canvas);
  // 重绘文本
  drawText(canvas);
 }

 /**
  * 绘制方框
  */
 private void drawStrokeBackground(Canvas canvas) {
  // 下面绘制方框背景颜色
  // 确定反馈位置
  mRect.left = 0;
  mRect.top = 0;
  mRect.right = mStrokeWidth;
  mRect.bottom = mStrokeHeight;
  int count = canvas.getSaveCount(); // 当前画布保存的状态
  canvas.save(); // 保存画布
  for (int i = 0; i < mMaxLength; i++) {
   mStrokeDrawable.setBounds(mRect); // 设置位置
   mStrokeDrawable.setState(new int[]{android.R.attr.state_enabled}); // 设置图像状态
   mStrokeDrawable.draw(canvas); // 画到画布上
   // 确定下一个方框的位置
   float dx = mRect.right + mStrokePadding; // X坐标位置
   // 保存画布
   canvas.save();
   // [注意细节] 移动画布到下一个位置
   canvas.translate(dx, 0);
  }
  // [注意细节] 把画布还原到画反馈之前的状态，这样就还原到最初位置了
  canvas.restoreToCount(count);
  // 画布归位
  canvas.translate(0, 0);

  // 下面绘制高亮状态的边框
  // 当前高亮的索引
  int activatedIndex = Math.max(0, getEditableText().length());
  mRect.left = mStrokeWidth * activatedIndex + mStrokePadding * activatedIndex;
  mRect.right = mRect.left + mStrokeWidth;
  mStrokeDrawable.setState(new int[]{android.R.attr.state_focused});
  mStrokeDrawable.setBounds(mRect);
  mStrokeDrawable.draw(canvas);
 }

 /**
  * 重绘文本
  */
 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);
   // 获取文本大小
   textPaint.getTextBounds(text, 0, 1, mRect);
   // 计算(x,y) 坐标
   int x = mStrokeWidth / 2 + (mStrokeWidth + mStrokePadding) * i - (mRect.centerX());
   int y = canvas.getHeight() / 2 + mRect.height() / 2;
   canvas.drawText(text, x, y, textPaint);
  }
  canvas.restoreToCount(count);
 }

 @Override
 protected void onTextChanged(CharSequence text, int start,
         int lengthBefore, int lengthAfter) {
  super.onTextChanged(text, start, lengthBefore, lengthAfter);

  // 当前文本长度
  int textLength = getEditableText().length();

  if (textLength == mMaxLength) {
   hideSoftInput();
   if (mOnInputFinishListener != null) {
    mOnInputFinishListener.onTextFinish(getEditableText().toString(), mMaxLength);
   }
  }

 }