先看下效果

demo.gif

说在前面的话

开发这个控件是因为在仿探探的图片选择器组件的时候，他们有这样的一个控件。照猫画虎，我也做了一个。
想来，其实还是有很多的朋友需要这样的控件。
所以开源出来给大家使用。

使用方式

项目放在gihub上，欢迎使用。
github地址：https://github.com/klisly/RoundChoiceView
已经发布到jitpack
源配置

 allprojects {
    repositories {
       jcenter()
       maven { url "https://jitpack.io" }
    }
}

依赖配置
compile 'com.github.klisly:RoundChoiceView:v1.1'

设计步骤

1.定义样式属性

定义了控件的的属性有如下几个：
borderColor：border的颜色
backgroundColor：控件未选中状态的时候的背景颜色
checkedColor：选中状态时控件填充颜色
crossType：选中状态时的类型（数字或者打勾）
crossColor：类型是打勾时，勾的颜色
rippleBorderWidth：border的宽度
rippleduration：选中时的动画过渡时间
checked：控件选中状态
number：如果是crossType是数字时，默认显示的数字
textSize：数字的字体size

  <declare-styleable name="RoundChoiceView">
    <attr name="borderColor" format="color" />
    <attr name="checkedColor" format="color" />
    <attr name="backgroundColor" format="color" />
    <attr name="crossColor" format="color" />
    <attr name="rippleBorderWidth" format="dimension" />
    <attr name="rippleduration" format="integer" />
    <attr name="checked" format="boolean" />
    <attr name="crossType" format="string" >
        <enum name="cross" value="2" />
        <enum name="number" value="1" />
    </attr>
    <attr name="number" format="integer" />
    <attr name="textSize" format="dimension" />
</declare-styleable>

2.读取样式

这一步骤获取已经定义好的属性，并初始化所需要的画笔

mDensity = getContext().getResources().getDisplayMetrics().density;
scaledDensity = getContext().getResources().getDisplayMetrics().scaledDensity;

    // Load attributes
    final TypedArray a = getContext().obtainStyledAttributes(
            attrs, R.styleable.RoundChoiceView, defStyle, 0);
    mUnCheckColor = a.getColor(R.styleable.RoundChoiceView_borderColor, mUnCheckColor);
    mCheckColor = a.getColor(R.styleable.RoundChoiceView_checkedColor, mCheckColor);
    mCrossColor = a.getColor(R.styleable.RoundChoiceView_crossColor, mCrossColor);
    mBgColor = a.getColor(R.styleable.RoundChoiceView_backgroundColor, mBgColor);
    mTextSize = a.getDimension(R.styleable.RoundChoiceView_textSize, mTextSize);
    int crossType = a.getInt(R.styleable.RoundChoiceView_crossType, TYPE_CROSS_CROSS);
    if (crossType == TYPE_CROSS_NUMBER) {
        mCrossType = TYPE_CROSS_NUMBER;
    } else {
        mCrossType = TYPE_CROSS_CROSS;
    }
    mBorderWidth = a.getDimension(R.styleable.RoundChoiceView_rippleBorderWidth, dp2px(2));
    mDuration = a.getInt(R.styleable.RoundChoiceView_rippleduration, mDuration);
    mChecked = a.getBoolean(R.styleable.RoundChoiceView_checked, mChecked);
    mNumber = a.getInt(R.styleable.RoundChoiceView_number, mNumber);
    a.recycle();
    mHookDuration = (int) (mDuration * 0.3);
    mCircleDuration = mDuration - mHookDuration;
    mUncheckPaint = new Paint();
    mUncheckPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
    mUncheckPaint.setStrokeWidth(mBorderWidth);
    mUncheckPaint.setColor(mUnCheckColor);
    mUncheckPaint.setStyle(Paint.Style.STROKE);
    mCheckPaint = new Paint();
    mCheckPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
    mCheckPaint.setColor(mCheckColor);
    mCheckPaint.setStyle(Paint.Style.STROKE);
    isHookShow = mChecked;
    mFraction = mChecked ? 1.0f : 0.0f;

3.确定尺寸

onSizeChanged方法回调的时候可以获得控件的最终尺寸，在此可以初始化
勾的起点start，折点 middle，终点的坐标。

protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    width = w;
    height = h;
    mRectF = new RectF(getPaddingLeft(), getPaddingTop(),
            w - getPaddingRight(), h - getPaddingBottom());
    mRadius = Math.min(mRectF.width(), mRectF.height()) / 2;
    hookStart = new PointF(mRectF.centerX() - mRadius / 2, mRectF.centerY() + mRadius / 10);
    hookMiddle = new PointF(mRectF.centerX() - mRadius * 1 / 6, mRectF.centerY() + mRadius * 2 / 5);
    hookEnd = new PointF(mRectF.centerX() + mRadius / 2, mRectF.centerY() - mRadius * 1 / 3);
}

4.绘制控件

绘制逻辑：
1.绘制未选中状态时的圆形和border
2.绘制过渡状态的选中的圆形
3.绘制勾或者数字

   @Override
   protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    mUncheckPaint.setColor(mBgColor);
    mUncheckPaint.setStyle(Paint.Style.FILL);
    canvas.drawCircle(mRectF.centerX(), mRectF.centerY(), mRadius - mBorderWidth, mUncheckPaint);
    mUncheckPaint.setColor(mUnCheckColor);
    mUncheckPaint.setStyle(Paint.Style.STROKE);
    canvas.drawCircle(mRectF.centerX(), mRectF.centerY(), mRadius - mBorderWidth + 1, mUncheckPaint);
    if (mChecked || mIsAnimating) {
        float stroke = mFraction * mRadius;
        if (!mIsAnimating) {
            stroke = mRadius;
        }

        if (mChecked) {
            mCheckPaint.setStrokeWidth(stroke);
        } else {
            mCheckPaint.setStrokeWidth(mRadius - stroke);
        }

        if (isHookShow) {
            mNRectF.left = getPaddingLeft() + mRadius / 2;
            mNRectF.top = getPaddingTop() + mRadius / 2;
            mNRectF.right = width - getPaddingRight() - mRadius / 2;
            mNRectF.bottom = height - getPaddingBottom() - mRadius / 2;
            mCheckPaint.setStrokeWidth(mRadius);
        } else if (mChecked) {
            mNRectF.left = getPaddingLeft() + stroke / 2;
            mNRectF.top = getPaddingTop() + stroke / 2;
            mNRectF.right = width - getPaddingRight() - stroke / 2;
            mNRectF.bottom = height - getPaddingBottom() - stroke / 2;
        } else {
            mNRectF.left = getPaddingLeft() + (mRadius - stroke) / 2;
            mNRectF.top = getPaddingTop() + (mRadius - stroke) / 2;
            mNRectF.right = width - getPaddingRight() - (mRadius - stroke) / 2;
            mNRectF.bottom = height - getPaddingBottom() - (mRadius - stroke) / 2;
        }
        canvas.drawArc(mNRectF, 0f, 360f, false, mCheckPaint);
    }

    mUncheckPaint.setColor(mCrossColor);
    if (mCrossType == TYPE_CROSS_NUMBER) {
        if (mChecked) {
            mUncheckPaint.setTextSize(mTextSize);
            mUncheckPaint.setStyle(Paint.Style.FILL);
            Paint.FontMetrics metrics = mUncheckPaint.getFontMetrics();
            int baseline = (int) ((mRectF.bottom + mRectF.top - metrics.bottom - metrics.top) / 2);
            mUncheckPaint.setTextAlign(Paint.Align.CENTER);
            canvas.drawText(String.valueOf(mNumber), mRectF.centerX(), baseline, mUncheckPaint);
            mUncheckPaint.setStyle(Paint.Style.STROKE);
        }
    } else {

        if (mIsAnimating) {
            if (!mChecked && isHookShow) {
                mFraction = 1 - mFraction;
            }

            if (isHookShow && mFraction > 0) {// y1 - x1
                Log.i("isHookShow", isHookShow + " " + mFraction);
                if (mFraction < 0.4) {
                    canvas.drawLine(hookStart.x, hookStart.y, getr1x((float) (mFraction / 0.4)), getr1y((float) (mFraction / 0.4)), mUncheckPaint);
                } else {
                    canvas.drawLine(hookStart.x, hookStart.y, hookMiddle.x + 2, hookMiddle.y + 2, mUncheckPaint);
                    canvas.drawLine(hookMiddle.x, hookMiddle.y, getr2x((float) ((mFraction - 0.4) / 0.6)), getr2y((float) ((mFraction - 0.4f) / 0.6)), mUncheckPaint);
                }
            }
        } else {
            if (mChecked && isHookShow) {
                canvas.drawLine(hookStart.x, hookStart.y, hookMiddle.x + 2, hookMiddle.y + 2, mUncheckPaint);
                canvas.drawLine(hookMiddle.x, hookMiddle.y, getr2x((float) ((1 - 0.4) / 0.6)), getr2y((float) ((1 - 0.4f) / 0.6)), mUncheckPaint);
            }
        }
    }
}

4.事件控制

1.在ACTION_DOWN时捕获事件
2.在ACTION_UP中判断是否处理选中状态的监听，并处理动画的绘制

@Override
public boolean onTouchEvent(MotionEvent event) {
    int x = (int) event.getX();
    int y = (int) event.getY();
    int action = event.getAction();
    switch (action) {
        case MotionEvent.ACTION_DOWN:
            if (!isEnabled()) {
                return false;
            }
            break;
        case MotionEvent.ACTION_MOVE:
            break;
        case MotionEvent.ACTION_UP:
            if (mIsAnimating) {
                return true;
            }
            if (x + getLeft() < getRight() && y + getTop() < getBottom()) {
                mChecked = !mChecked;
                if (mIsAnimating) {
                    mFractionAnimator.cancel();
                }
                if (mChecked) {
                    initValueAnimator(mCircleDuration);
                } else {
                    initValueAnimator(mHookDuration);
                }
                mFractionAnimator.start();
                if (onCheckedChangeListener != null) {
                    onCheckedChangeListener.onCheckedChanged(this, mChecked);
                }
            }
            break;
    }
    return true;
}