撸一个Android高性能日历控件，高仿魅族

Android原生的CalendarView根本无法满足我们日常开发的需要，在开发吾记APP的过程中，我觉得需要来一款高性能且美观简洁的日历控件，觉得魅族的日历风格十分适合，于是打算撸一款。

github地址：https://github.com/huanghaibin-dev/CalendarView

compile 'com.haibin:calendarview:3.2.4'

先上效果图：

动手之前我们需要分析一下魅族是怎么设计如此高性能的日历的，我们打开开发者选项中的显示布局边界：

好吧，一开始我以为日历界面是ViewPager+RecyclerView的，但是这么一看明显就不是了，如果是RecyclerView，那么我们假设每个月的卡片都有5*7=35个item，每个item根布局是RelativeLayout+3个TextView，我们大概估算一下日历初始化时要加载的控件：

3个ViewPager的item * 35个RecyclerView的Item * 4（每个item的控件数） + 8 （星期栏）= 420+ 

我的天，这可不能这么干，明显性能大打折扣，我们再来看看月份控件：

好吧，这里看上去就是ViewPager+RecyclerView来做的，每个RecyclerView的item都只是一个控件，里面绘制了文本 ，这里大概就分析清楚了。

我们采取折中的方式，日历界面和月份卡界面均采用ViewPager+RecyclerView的方式，不同的是所有的item我们都采用自定义ViewCanvas绘制的方式来做，这样性能虽然比不上魅族，但速度体验基本差不多，下面先看日历界面的item代码：只需要绘制3个文本即可

public class CellView extends View {

    private int mDay = 20;
    private String mLunar;
    private String mScheme;
    private Paint mDayPaint = new Paint();
    private Paint mLunarPaint = new Paint();
    private Paint mSchemePaint = new Paint();
    private Paint mCirclePaint = new Paint();
    private int mRadius;
    private int mCirclePadding;
    private int mCircleColor;

    public CellView(Context context) {
        this(context, null);
    }

    public CellView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);

        mDayPaint.setAntiAlias(true);
        mDayPaint.setColor(Color.BLACK);
        mDayPaint.setFakeBoldText(true);
        mDayPaint.setTextAlign(Paint.Align.CENTER);

        mLunarPaint.setAntiAlias(true);
        mLunarPaint.setColor(Color.GRAY);
        mLunarPaint.setTextAlign(Paint.Align.CENTER);

        mSchemePaint.setAntiAlias(true);
        mSchemePaint.setColor(Color.WHITE);
        mSchemePaint.setFakeBoldText(true);
        mSchemePaint.setTextAlign(Paint.Align.CENTER);

        mCirclePaint.setAntiAlias(true);
        mCirclePaint.setStyle(Paint.Style.FILL);

        TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.CellView);
        mDayPaint.setTextSize(array.getDimensionPixelSize(R.styleable.CellView_cell_day_text_size, 18));
        mLunarPaint.setTextSize(array.getDimensionPixelSize(R.styleable.CellView_cell_lunar_text_size, 12));
        mRadius = (int) array.getDimension(R.styleable.CellView_cell_scheme_radius, 8);
        mSchemePaint.setTextSize(array.getDimensionPixelSize(R.styleable.CellView_cell_scheme_text_size, 6));
        mCirclePadding = array.getDimensionPixelSize(R.styleable.CellView_cell_circle_padding, 4);
        mCirclePaint.setColor(array.getColor(R.styleable.CellView_cell_circle_color, 0xff16BB7F));
        array.recycle();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int width = getWidth();
        int height = getHeight();
        int w = (width - getPaddingLeft() - getPaddingRight());
        int h = (height - getPaddingTop() - getPaddingBottom()) / 4;
        canvas.drawText(String.valueOf(mDay), w / 2, 2 * h + getPaddingTop(), mDayPaint);
        canvas.drawText(mLunar, w / 2, 4 * h + getPaddingTop(), mLunarPaint);
        if (!TextUtils.isEmpty(mScheme)) {
            canvas.drawCircle(w / 2 + mCirclePadding + mDayPaint.getTextSize(), getPaddingTop() + h, mRadius, mCirclePaint);
            canvas.drawText(mScheme, w / 2 + mCirclePadding + mDayPaint.getTextSize(), getPaddingTop() + mRadius / 2 + h, mSchemePaint);
        }
    }

    /**
     * 初始化日历
     * @param day 天
     * @param lunar 农历
     * @param scheme 事件标记
     */
    void init(int day, String lunar, String scheme) {
        this.mDay = day;
        this.mLunar = lunar;
        this.mScheme = scheme;
    }

    void setTextColor(int textColor) {
        mDayPaint.setColor(textColor);
        mLunarPaint.setColor(textColor);
    }

    void setCircleColor(int circleColor) {
        mCirclePaint.setColor(circleColor);
        invalidate();
    }
}

月份卡自定义View

public class MonthView extends View {
    private int mDiff;//第一天偏离周日多少天
    private int mCount;//总数
    private int mLastCount;//最后一行的天数
    private int mLine;//多少行
    private Paint mPaint = new Paint();
    private Paint mSchemePaint = new Paint();
    private List mSchemes;
    private Calendar mCalendar;

    public MonthView(Context context) {
        this(context, null);
    }

    public MonthView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        mPaint.setAntiAlias(true);
        mPaint.setTextAlign(Paint.Align.CENTER);
        mSchemePaint.setAntiAlias(true);
        mSchemePaint.setTextAlign(Paint.Align.CENTER);
        TypedArray array = context.obtainStyledAttributes(attrs, R.styleable.MonthView);
        mPaint.setTextSize(array.getDimensionPixelSize(R.styleable.MonthView_month_view_text_size, 12));
        mSchemePaint.setTextSize(array.getDimensionPixelSize(R.styleable.MonthView_month_view_text_size, 12));
        mPaint.setColor(array.getColor(R.styleable.MonthView_month_view_text_color, Color.BLACK));
        mSchemePaint.setColor(array.getColor(R.styleable.MonthView_month_view_remark_color, Color.RED));
        array.recycle();
        measureLine();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int width = getWidth();
        int height = getHeight();
        int pLeft = getPaddingLeft();
        int w = (width - getPaddingLeft() - getPaddingRight()) / 7;
        int h = (height - getPaddingTop() - getPaddingBottom()) / 6;
        int d = 0;
        for (int i = 0; i < mLine; i++) {
            if (i == 0) {//第一行
                for (int j = 0; j < (7 - mDiff); j++) {
                    ++d;
                    canvas.drawText(String.valueOf(j + 1), mDiff * w + j * w + pLeft + w / 2, h, isScheme(d) ? mSchemePaint : mPaint);
                }
            } else if (i == mLine - 1 && mLastCount != 0) {
                int first = mCount - mLastCount + 1;
                for (int j = 0; j < mLastCount; j++) {
                    ++d;
                    canvas.drawText(String.valueOf(first), j * w + pLeft + w / 2, (i + 1) * h, isScheme(d) ? mSchemePaint : mPaint);
                    ++first;
                }
            } else {
                int first = i * 7 - mDiff + 1;
                for (int j = 0; j < 7; j++) {
                    ++d;
                    canvas.drawText(String.valueOf(first), j * w + pLeft + w / 2, (i + 1) * h, isScheme(d) ? mSchemePaint : mPaint);
                    ++first;
                }
            }
        }
    }

    /**
     * 计算行数
     */
    private void measureLine() {
        int offset = mCount - (7 - mDiff);
        mLine = 1 + (offset % 7 == 0 ? 0 : 1) + offset / 7;
        mLastCount = offset % 7;
    }

    /**
     * 初始化月份卡
     * @param mDiff 偏离天数
     * @param mCount 当月总天数
     * @param mYear 哪一年
     * @param mMonth 哪一月
     */
     void init(int mDiff, int mCount, int mYear, int mMonth) {
        this.mDiff = mDiff;
        this.mCount = mCount;
        mCalendar = new Calendar();
        mCalendar.setYear(mYear);
        mCalendar.setMonth(mMonth);
        measureLine();
        invalidate();
    }

    void setSchemes(List mSchemes) {
        this.mSchemes = mSchemes;
    }

    void setSchemeColor(int schemeColor) {
        if (schemeColor != 0)
            mSchemePaint.setColor(schemeColor);
        if(schemeColor == 0xff30393E)
            mSchemePaint.setColor(Color.RED);
    }

    private boolean isScheme(int day) {
        if (mSchemes == null || mSchemes.size() == 0)
            return false;
        mCalendar.setDay(day);
        return mSchemes.contains(mCalendar);
    }
}

其它代码没有什么难度，日历算法是github上找的，更多详情请看仓库地址： https://github.com/huanghaibin-dev/CalendarView