Android实现字母导航控件的示例代码

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="LetterView">
        <!--字母颜色-->
        <attr name="letterTextColor" format="color" />
        <!--字母字体大小-->
        <attr name="letterTextSize" format="dimension" />
        <!--整体背景-->
        <attr name="letterTextBackgroundColor" format="color" />
        <!--是否启用指示器-->
        <attr name="letterEnableIndicator" format="boolean" />
        <!--指示器颜色-->
        <attr name="letterIndicatorColor" format="color" />
    </declare-styleable>
</resources>

public LetterView(Context context, @Nullable AttributeSet attrs) {
    super(context, attrs);
    //获取属性
    TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.LetterView);
    int letterTextColor = array.getColor(R.styleable.LetterView_letterTextColor, Color.RED);
    int letterTextBackgroundColor = array.getColor(R.styleable.LetterView_letterTextBackgroundColor, Color.WHITE);
    int letterIndicatorColor = array.getColor(R.styleable.LetterView_letterIndicatorColor, Color.parseColor("#333333"));
    float letterTextSize = array.getDimension(R.styleable.LetterView_letterTextSize, 12);
    enableIndicator = array.getBoolean(R.styleable.LetterView_letterEnableIndicator, true);

    //默认设置
    mContext = context;
    mLetterPaint = new Paint();
    mLetterPaint.setTextSize(letterTextSize);
    mLetterPaint.setColor(letterTextColor);
    mLetterPaint.setAntiAlias(true);

    mLetterIndicatorPaint = new Paint();
    mLetterIndicatorPaint.setStyle(Paint.Style.FILL);
    mLetterIndicatorPaint.setColor(letterIndicatorColor);
    mLetterIndicatorPaint.setAntiAlias(true);

    setBackgroundColor(letterTextBackgroundColor);

    array.recycle();
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    //获取宽高的尺寸大小
    int widthSize = MeasureSpec.getSize(widthMeasureSpec);
    int heightSize = MeasureSpec.getSize(heightMeasureSpec);
    //wrap_content默认宽高
    @SuppressLint("DrawAllocation") Rect mRect = new Rect();
    mLetterPaint.getTextBounds("A", 0, 1, mRect);
    mWidth = mRect.width() + dpToPx(mContext, 12);
    int mHeight = (mRect.height() + dpToPx(mContext, 5)) * letters.length;

    if (getLayoutParams().width == ViewGroup.LayoutParams.WRAP_CONTENT &&
            getLayoutParams().height == ViewGroup.LayoutParams.WRAP_CONTENT) {
        setMeasuredDimension(mWidth, mHeight);
    } else if (getLayoutParams().width == ViewGroup.LayoutParams.WRAP_CONTENT) {
        setMeasuredDimension(mWidth, heightSize);
    } else if (getLayoutParams().height == ViewGroup.LayoutParams.WRAP_CONTENT) {
        setMeasuredDimension(widthSize, mHeight);
    }

    mWidth = getMeasuredWidth();
    int averageItemHeight = getMeasuredHeight() / 28;
    int mOffset = averageItemHeight / 30; //界面调整
    mItemHeight = averageItemHeight + mOffset;
}

@Override
protected void onDraw(Canvas canvas) {
    //获取字母宽高
    @SuppressLint("DrawAllocation") Rect rect = new Rect();
    mLetterPaint.getTextBounds("A", 0, 1, rect);
    int letterWidth = rect.width();
    int letterHeight = rect.height();

    //绘制指示器
    if (enableIndicator){
        for (int i = 1; i < letters.length + 1; i++) {
            if (mTouchIndex == i) {
                canvas.drawCircle(0.5f * mWidth, i * mItemHeight - 0.5f * mItemHeight, 0.5f * mItemHeight, mLetterIndicatorPaint);
            }
        }
    }
    //绘制字母
    for (int i = 1; i < letters.length + 1; i++) {
        canvas.drawText(letters[i - 1], (mWidth - letterWidth) / 2, mItemHeight * i - 0.5f * mItemHeight + letterHeight / 2, mLetterPaint);
    }
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
        case MotionEvent.ACTION_MOVE:
            isTouch = true;
            int y = (int) event.getY();
            Log.i("onTouchEvent","--y->" + y + "-y-dp-->" + DensityUtil.px2dp(getContext(), y));
            int index = y / mItemHeight;

            if (index != mTouchIndex && index < 28 && index > 0) {
                mTouchIndex = index;
                Log.i("onTouchEvent","--mTouchIndex->" + mTouchIndex + "--position->" + mTouchIndex);
            }

            if (mOnLetterChangeListener != null && mTouchIndex > 0) {
                mOnLetterChangeListener.onLetterListener(letters[mTouchIndex - 1]);
            }

            invalidate();
            break;
        case MotionEvent.ACTION_UP:
            isTouch = false;
            if (mOnLetterChangeListener != null && mTouchIndex > 0) {
                mOnLetterChangeListener.onLetterDismissListener();
            }
            break;
    }
    return true;
}

//汉字转换为拼音
public static String getChineseToPinyin(String chinese) {
    StringBuilder builder = new StringBuilder();
    HanyuPinyinOutputFormat format = new HanyuPinyinOutputFormat();
    format.setCaseType(HanyuPinyinCaseType.UPPERCASE);
    format.setToneType(HanyuPinyinToneType.WITHOUT_TONE);

    char[] charArray = chinese.toCharArray();
    for (char aCharArray : charArray) {
        if (Character.isSpaceChar(aCharArray)) {
            continue;
        }
        try {
            String[] pinyinArr = PinyinHelper.toHanyuPinyinStringArray(aCharArray, format);
            if (pinyinArr != null) {
                builder.append(pinyinArr[0]);
            } else {
                builder.append(aCharArray);
            }
        } catch (BadHanyuPinyinOutputFormatCombination badHanyuPinyinOutputFormatCombination) {
            badHanyuPinyinOutputFormatCombination.printStackTrace();
            builder.append(aCharArray);
        }
    }
    return builder.toString();
}