Android自定义控件实现温度旋转按钮效果

public class TempControlView extends View { // 控件宽 private int width; // 控件高 private int height; // 刻度盘半径 private int dialRadius; // 圆弧半径 private int arcRadius; // 刻度高 private int scaleHeight = dp2px(10); // 刻度盘画笔 private Paint dialPaint; // 圆弧画笔 private Paint arcPaint; // 标题画笔 private Paint titlePaint; // 温度标识画笔 private Paint tempFlagPaint; // 旋转按钮画笔 private Paint buttonPaint; // 温度显示画笔 private Paint tempPaint; // 文本提示 private String title = "最高温度设置"; // 温度 private int temperature; // 最低温度 private int minTemp = 15; // 最高温度 private int maxTemp = 30; // 四格（每格4.5度，共18度）代表温度1度 private int angleRate = 4; // 按钮图片 private Bitmap buttonImage = BitmapFactory.decodeResource(getResources(),   R.mipmap.btn_rotate); // 按钮图片阴影 private Bitmap buttonImageShadow = BitmapFactory.decodeResource(getResources(),   R.mipmap.btn_rotate_shadow); // 抗锯齿 private PaintFlagsDrawFilter paintFlagsDrawFilter; // 温度改变监听 private OnTempChangeListener onTempChangeListener; // 以下为旋转按钮相关 // 当前按钮旋转的角度 private float rotateAngle; // 当前的角度 private float currentAngle; ... @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) {  super.onSizeChanged(w, h, oldw, oldh);  // 控件宽、高  width = height = Math.min(h, w);  // 刻度盘半径  dialRadius = width / 2 - dp2px(20);  // 圆弧半径  arcRadius = dialRadius - dp2px(20); } ...}

/** * 绘制刻度盘 * * @param canvas 画布 */private void drawScale(Canvas canvas) { canvas.save(); canvas.translate(getWidth() / 2, getHeight() / 2); // 逆时针旋转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();}

/** * 绘制刻度盘下的圆弧 * * @param canvas 画布 */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();}

 /**  * 绘制标题与温度标识  *  * @param canvas 画布  */ private void drawText(Canvas canvas) {  canvas.save();  // 绘制标题  float titleWidth = titlePaint.measureText(title);  canvas.drawText(title, (width - titleWidth) / 2, dialRadius * 2 + dp2px(15), titlePaint);  // 绘制最小温度标识  // 最小温度如果小于10，显示为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);  // 绘制最大温度标识  canvas.rotate(-105, width / 2, height / 2);  canvas.drawText(maxTemp + "", (width - tempFlagWidth) / 2, height + dp2px(5), tempFlagPaint);  canvas.restore(); }

/** * 绘制旋转按钮 * * @param canvas 画布 */private void drawButton(Canvas canvas) { // 按钮宽高 int buttonWidth = buttonImage.getWidth(); int buttonHeight = buttonImage.getHeight(); // 按钮阴影宽高 int buttonShadowWidth = buttonImageShadow.getWidth(); int buttonShadowHeight = buttonImageShadow.getHeight(); // 绘制按钮阴影 canvas.drawBitmap(buttonImageShadow, (width - buttonShadowWidth) / 2,   (height - buttonShadowHeight) / 2, buttonPaint); Matrix matrix = new Matrix(); // 设置按钮位置 matrix.setTranslate(buttonWidth / 2, buttonHeight / 2); // 设置旋转角度 matrix.preRotate(45 + rotateAngle); // 按钮位置还原，此时按钮位置在左上角 matrix.preTranslate(-buttonWidth / 2, -buttonHeight / 2); // 将按钮移到中心位置 matrix.postTranslate((width - buttonWidth) / 2, (height - buttonHeight) / 2); //设置抗锯齿 canvas.setDrawFilter(paintFlagsDrawFilter); canvas.drawBitmap(buttonImage, matrix, buttonPaint);}

/** * 绘制温度 * * @param canvas 画布 */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);   // 滑过的角度增量   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) {    // 纠正指针位置    rotateAngle = (float) ((temperature - minTemp) * angleRate * 4.5);    invalidate();    // 回调温度改变监听    onTempChangeListener.change(temperature);    isDown = false;    isMove = false;   }   break;  } } return true;}/** * 以按钮圆心为坐标圆点，建立坐标系，求出(targetX, targetY)坐标与x轴的夹角 * * @param targetX x坐标 * @param targetY y坐标 * @return (targetX, targetY)坐标与x轴的夹角 */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);}/** * 增加旋转角度 * * @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;}

/** * 设置温度 * * @param minTemp 最小温度 * @param maxTemp 最大温度 * @param temp 设置的温度 */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();}/** * 设置温度改变监听 * * @param onTempChangeListener 监听接口 */public void setOnTempChangeListener(OnTempChangeListener onTempChangeListener) { this.onTempChangeListener = onTempChangeListener;}/** * 温度改变监听接口 */public interface OnTempChangeListener { /**  * 回调方法  *  * @param temp 温度  */ void change(int temp);}