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; // 溫度改變監聽 private OnTempChangeListener onTempChangeListener; // 以下為旋轉按鈕相關 // 當前按鈕旋轉的角度 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(); // 設置按鈕位置 matrix.setTranslate(buttonWidth / 2, buttonHeight / 2); // 設置旋轉角度 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();    // 回調溫度改變監聽    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;}

/** * 設置溫度 * * @param minTemp 最小溫度 * @param maxTemp 最大溫度 * @param temp 設置的溫度 */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();}/** * 設置溫度改變監聽 * * @param onTempChangeListener 監聽接口 */public void setOnTempChangeListener(OnTempChangeListener onTempChangeListener) { this.onTempChangeListener = onTempChangeListener;}/** * 溫度改變監聽接口 */public interface OnTempChangeListener { /**  * 回調方法  *  * @param temp 溫度  */ void change(int temp);}