public void setRotatBitmap(Bitmap bitmap) {
rotatBitmap = bitmap;
initSize();
postInvalidate();
} public void setRotatDrawableResource(int id) { BitmapDrawable drawable = (BitmapDrawable)getContext().getResources().getDrawable(id); setRotatDrawable(drawable);
} public void setRotatDrawable(BitmapDrawable drawable) {
rotatBitmap = drawable.getBitmap();
initSize();
postInvalidate();
}

private void initSize() {
if (rotatBitmap == null) { // throw new NoBitMapError("Error,No bitmap in RotatView!");
return;
}
width = rotatBitmap.getWidth();
height = rotatBitmap.getHeight(); maxwidth = Math.sqrt(width * width + height * height);
o_x = o_y = (float)(maxwidth / 2);//确定圆心坐标
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
// TODO Auto-generated method stub
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
// 它的宽高不是图片的宽高，而是以宽高为直角的矩形的对角线的长度
setMeasuredDimension((int)maxwidth, (int)maxwidth); }

/**
* 当前圆盘所转的弧度(以该 view 的中心为圆点)
*/
float deta_degree;

@Override
protected void onDraw(Canvas canvas) { Matrix matrix = new Matrix();
// 设置转轴位置
matrix.setTranslate((float)width / 2, (float)height / 2); // 开始转
matrix.preRotate(deta_degree);
// 转轴还原
matrix.preTranslate(-(float)width / 2, -(float)height / 2); // 将位置送到view的中心
matrix.postTranslate((float)(maxwidth - width) / 2, (float)(maxwidth - height) / 2); canvas.drawBitmap(rotatBitmap, matrix,paint); super.onDraw(canvas);
}

/**
* 通过此方法来控制旋转度数，如果超过360，让它求余，防止，该值过大造成越界
*
* @param added
*/
private void addDegree(float added) {
deta_degree += added;
if (deta_degree > 360 || deta_degree < -360) {
deta_degree = deta_degree % 360;
} }

/** * 计算以(src_x,src_y)为坐标圆点，建立直角体系，求出(target_x,target_y)坐标与x轴的夹角 * 主要是利用反正切函数的知识求出夹角 *  * @param src_x * @param src_y * @param target_x * @param target_y * @return */float detaDegree(float src_x, float src_y, float target_x, float target_y) { float detaX = target_x - src_x; float detaY = target_y - src_y; double d; //坐标在四个象限里 if (detaX != 0) { float tan = Math.abs(detaY / detaX); if (detaX > 0) { //第一象限 if (detaY >= 0) { d = Math.atan(tan); } else { //第四象限 d = 2 * Math.PI - Math.atan(tan); } } else { if (detaY >= 0) { //第二象限 d = Math.PI - Math.atan(tan); } else { //第三象限 d = Math.PI + Math.atan(tan); } } } else { //坐标在y轴上 if (detaY > 0) { //坐标在y>0上 d = Math.PI / 2; } else { //坐标在y<0上 d = -Math.PI / 2; } } return (float)((d * 180) / Math.PI); }

@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
if (rotatBitmap == null) { throw new NoBitMapError("Error,No bitmap in RotatView!");
}
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN: {
down_x = event.getX();
down_y = event.getY();
current_degree = detaDegree(o_x, o_y, down_x, down_y); break; }
case MotionEvent.ACTION_MOVE: {
down_x = target_x = event.getX();
down_y = target_y = event.getY();
float degree = detaDegree(o_x, o_y, target_x, target_y); // 滑过的弧度增量
float dete = degree - current_degree;
// 如果小于-90度说明 它跨周了，需要特殊处理350->17,
if (dete < -270) {
dete = dete + 360; // 如果大于90度说明 它跨周了，需要特殊处理-350->-17,
} else if (dete > 270) {
dete = dete - 360;
} addDegree(dete);
current_degree = degree;
invalidate(); break;
}

/**
* 最大速度
*/
public static final double max_speed = 8; /**
* 通过数组里所装载的数据分析出即时速度<br>
* 原理是：计算数组里的时间长度和增量的总数，然后求出每毫秒所走过的弧度<br>
* 当然不能超过{@link VRecord#max_speed}
*
* @return
*/
public double getSpeed() { if (addCount == 0) {
return 0;
}
int maxIndex = Math.min(addCount, length) - 1; if ((record[0][1] - record[maxIndex][1]) == 0) {
return 0;
} double detaTime = record[0][1] - record[maxIndex][1];
double sumdegree = 0;
for (int i = 0; i < length - 1; i++) { sumdegree += record<I>[0];
// System.out.println(record[0]);
} // System.out.println("----------");
// System.out.println(sumdegree);
// System.out.println(detaTime);
double result = sumdegree / detaTime;
if (result > 0) {
return Math.min(result, max_speed);
} else {
return Math.max(result, -max_speed);
}
// System.out.println("v=" + result); }

/**
* 二维数组，1.保存弧度增量.2.保存产生这个增量的时间点
*/
double[][] record = new double[length][2]; /**
* 为二维数组装载数据* 注：通过此方法，有个特点，能把最后的length组数据记录下来，length以外的会丢失
*
* @param detadegree
* @param time
*/
public void add(double detadegree, double time) { for (int i = length - 1; i > 0; i--) {
record[0] = record[i - 1][0];
record[1] = record[i - 1][1];
}
record[0][0] = detadegree;
record[0][1] = time;
addCount++; }

@Override
public void handleMessage(Message msg) { double detaTime = System.currentTimeMillis() - currentTime;
switch (msg.what) { case play: {
//如果是顺时针
if (isClockWise) {
speed = speed - a * detaTime;//减速
if (speed <= 0) {
return;
} else {
handler.sendEmptyMessageDelayed(play, delayedTime);
}
} else {
speed = speed + a * detaTime;
if (speed >= 0) {
return;
} else {
handler.sendEmptyMessageDelayed(play, delayedTime);
}
} addDegree((float)(speed * detaTime + (a * detaTime * detaTime) / 2));//高中物理算路程S=vt+at2 // if (a < a_max) {
// a = (float)(a + a_add*detaTime);
// System.out.println("a:"+a);
// }
currentTime = System.currentTimeMillis();
invalidate(); break;
}
case stop: {
speed = 0;
handler.removeMessages(play);
}
} super.handleMessage(msg);
}
};