public class TempControlView extends View {
    // 控件寬    private int width;    // 控件高    private int height;    // 刻度盤半徑    private int dialRadius;    // 圓弧半徑    private int arcRadius;    // 刻度高    private int scaleHeight = dp2px(10);    // 刻度盤畫筆    private Paint dialPaint;    // 圓弧畫筆    private Paint arcPaint;    // 標題畫筆    private Paint titlePaint;    // 溫度標識畫筆    private Paint tempFlagPaint;    // 旋轉(zhuǎn)按鈕畫筆    private Paint buttonPaint;    // 溫度顯示畫筆    private Paint tempPaint;    // 文本提示    private String title = "最高溫度設(shè)置";    // 溫度    private int temperature;    // 最低溫度    private int minTemp = 15;    // 最高溫度    private int maxTemp = 30;    // 四格（每格4.5度，共18度）代表溫度1度    private int angleRate = 4;    // 按鈕圖片    private Bitmap buttonImage = BitmapFactory.decodeResource(getResources(),            R.mipmap.btn_rotate);    // 按鈕圖片陰影    private Bitmap buttonImageShadow = BitmapFactory.decodeResource(getResources(),            R.mipmap.btn_rotate_shadow);    // 抗鋸齒    private PaintFlagsDrawFilter paintFlagsDrawFilter;    // 溫度改變監(jiān)聽    private OnTempChangeListener onTempChangeListener;
    // 以下為旋轉(zhuǎn)按鈕相關(guān)
    // 當前按鈕旋轉(zhuǎn)的角度    private float rotateAngle;    // 當前的角度    private float currentAngle;
    ...
    @Override    protected void onSizeChanged(int w, int h, int oldw, int oldh) {        super.onSizeChanged(w, h, oldw, oldh);        // 控件寬、高        width = height = Math.min(h, w);        // 刻度盤半徑        dialRadius = width / 2 - dp2px(20);        // 圓弧半徑        arcRadius = dialRadius - dp2px(20);    }
    ...}

/** * 繪制刻度盤 * * @param canvas 畫布 */private void drawScale(Canvas canvas) {    canvas.save();    canvas.translate(getWidth() / 2, getHeight() / 2);    // 逆時針旋轉(zhuǎn)135-2度    canvas.rotate(-133);    dialPaint.setColor(Color.parseColor("#3CB7EA"));    for (int i = 0; i < 60; i++) {        canvas.drawLine(0, -dialRadius, 0, -dialRadius + scaleHeight, dialPaint);        canvas.rotate(4.5f);    }
    canvas.rotate(90);    dialPaint.setColor(Color.parseColor("#E37364"));    for (int i = 0; i < (temperature - minTemp) * angleRate; i++) {        canvas.drawLine(0, -dialRadius, 0, -dialRadius + scaleHeight, dialPaint);        canvas.rotate(4.5f);    }    canvas.restore();}

/** * 繪制刻度盤下的圓弧 * * @param canvas 畫布 */private void drawArc(Canvas canvas) {    canvas.save();    canvas.translate(getWidth() / 2, getHeight() / 2);    canvas.rotate(135 + 2);    RectF rectF = new RectF(-arcRadius, -arcRadius, arcRadius, arcRadius);    canvas.drawArc(rectF, 0, 265, false, arcPaint);    canvas.restore();}

    /**     * 繪制標題與溫度標識     *     * @param canvas 畫布     */    private void drawText(Canvas canvas) {        canvas.save();
        // 繪制標題        float titleWidth = titlePaint.measureText(title);        canvas.drawText(title, (width - titleWidth) / 2, dialRadius * 2 + dp2px(15), titlePaint);
        // 繪制最小溫度標識        // 最小溫度如果小于10，顯示為0x        String minTempFlag = minTemp < 10 ? "0" + minTemp : minTemp + "";        float tempFlagWidth = titlePaint.measureText(maxTemp + "");        canvas.rotate(55, width / 2, height / 2);        canvas.drawText(minTempFlag, (width - tempFlagWidth) / 2, height + dp2px(5), tempFlagPaint);
        // 繪制最大溫度標識        canvas.rotate(-105, width / 2, height / 2);        canvas.drawText(maxTemp + "", (width - tempFlagWidth) / 2, height + dp2px(5), tempFlagPaint);        canvas.restore();    }

/** * 繪制旋轉(zhuǎn)按鈕 * * @param canvas 畫布 */private void drawButton(Canvas canvas) {    // 按鈕寬高    int buttonWidth = buttonImage.getWidth();    int buttonHeight = buttonImage.getHeight();    // 按鈕陰影寬高    int buttonShadowWidth = buttonImageShadow.getWidth();    int buttonShadowHeight = buttonImageShadow.getHeight();
    // 繪制按鈕陰影    canvas.drawBitmap(buttonImageShadow, (width - buttonShadowWidth) / 2,            (height - buttonShadowHeight) / 2, buttonPaint);
    Matrix matrix = new Matrix();    // 設(shè)置按鈕位置    matrix.setTranslate(buttonWidth / 2, buttonHeight / 2);    // 設(shè)置旋轉(zhuǎn)角度    matrix.preRotate(45 + rotateAngle);    // 按鈕位置還原，此時按鈕位置在左上角    matrix.preTranslate(-buttonWidth / 2, -buttonHeight / 2);    // 將按鈕移到中心位置    matrix.postTranslate((width - buttonWidth) / 2, (height - buttonHeight) / 2);
    //設(shè)置抗鋸齒    canvas.setDrawFilter(paintFlagsDrawFilter);    canvas.drawBitmap(buttonImage, matrix, buttonPaint);}

/** * 繪制溫度 * * @param canvas 畫布 */private void drawTemp(Canvas canvas) {    canvas.save();    canvas.translate(getWidth() / 2, getHeight() / 2);
    float tempWidth = tempPaint.measureText(temperature + "");    float tempHeight = (tempPaint.ascent() + tempPaint.descent()) / 2;    canvas.drawText(temperature + "°", -tempWidth / 2 - dp2px(5), -tempHeight, tempPaint);    canvas.restore();}

private boolean isDown;private boolean isMove;
@Overridepublic boolean onTouchEvent(MotionEvent event) {    switch (event.getAction()) {        case MotionEvent.ACTION_DOWN:            isDown = true;            float downX = event.getX();            float downY = event.getY();            currentAngle = calcAngle(downX, downY);            break;
        case MotionEvent.ACTION_MOVE:            isMove = true;            float targetX;            float targetY;            downX = targetX = event.getX();            downY = targetY = event.getY();            float angle = calcAngle(targetX, targetY);
            // 滑過的角度增量            float angleIncreased = angle - currentAngle;
            // 防止越界            if (angleIncreased < -270) {                angleIncreased = angleIncreased + 360;            } else if (angleIncreased > 270) {                angleIncreased = angleIncreased - 360;            }
            IncreaseAngle(angleIncreased);            currentAngle = angle;            invalidate();            break;
        case MotionEvent.ACTION_CANCEL:        case MotionEvent.ACTION_UP: {            if (isDown && isMove) {                // 糾正指針位置                rotateAngle = (float) ((temperature - minTemp) * angleRate * 4.5);                invalidate();                // 回調(diào)溫度改變監(jiān)聽                onTempChangeListener.change(temperature);                isDown = false;                isMove = false;            }            break;        }    }    return true;}
/** * 以按鈕圓心為坐標圓點，建立坐標系，求出(targetX, targetY)坐標與x軸的夾角 * * @param targetX x坐標 * @param targetY y坐標 * @return (targetX, targetY)坐標與x軸的夾角 */private float calcAngle(float targetX, float targetY) {    float x = targetX - width / 2;    float y = targetY - height / 2;    double radian;
    if (x != 0) {        float tan = Math.abs(y / x);        if (x > 0) {            if (y >= 0) {                radian = Math.atan(tan);            } else {                radian = 2 * Math.PI - Math.atan(tan);            }        } else {            if (y >= 0) {                radian = Math.PI - Math.atan(tan);            } else {                radian = Math.PI + Math.atan(tan);            }        }    } else {        if (y > 0) {            radian = Math.PI / 2;        } else {            radian = -Math.PI / 2;        }    }    return (float) ((radian * 180) / Math.PI);}
/** * 增加旋轉(zhuǎn)角度 * * @param angle 增加的角度 */private void IncreaseAngle(float angle) {    rotateAngle += angle;    if (rotateAngle < 0) {        rotateAngle = 0;    } else if (rotateAngle > 270) {        rotateAngle = 270;    }    temperature = (int) (rotateAngle / 4.5) / angleRate + minTemp;}

/** * 設(shè)置溫度 * * @param minTemp 最小溫度 * @param maxTemp 最大溫度 * @param temp    設(shè)置的溫度 */public void setTemp(int minTemp, int maxTemp, int temp) {    this.minTemp = minTemp;    this.maxTemp = maxTemp;    this.temperature = temp;    this.angleRate = 60 / (maxTemp - minTemp);    rotateAngle = (float) ((temp - minTemp) * angleRate * 4.5);    invalidate();}
/** * 設(shè)置溫度改變監(jiān)聽 * * @param onTempChangeListener 監(jiān)聽接口 */public void setOnTempChangeListener(OnTempChangeListener onTempChangeListener) {    this.onTempChangeListener = onTempChangeListener;}
/** * 溫度改變監(jiān)聽接口 */public interface OnTempChangeListener {    /**     * 回調(diào)方法     *     * @param temp 溫度     */    void change(int temp);}