android圆形等分扇形菜单的实现

最近闲着没事写了一个圆形等分扇形菜单的功能，废话不多说先上图：

如图，实现了旋转功能、点击选中指定菜单等功能。

下面直接上代码：

package com.cm.widget;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.PaintFlagsDrawFilter;
import android.graphics.Path;
import android.graphics.Path.Direction;
import android.graphics.Path.FillType;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Xfermode;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.widget.ImageView;

public class RoundMenuView extends ImageView implements OnGestureListener {
private static final int childMenuSize = 8;
private static final float childAngle = 360f / childMenuSize;
private float offsetAngle = 0;
private Paint paint;
private GestureDetector gestureDetector;
private int selectId = -1;

public RoundMenuView(Context context, AttributeSet attrs) {
	super(context, attrs);
	// TODO Auto-generated constructor stub
	init();
}

private void init() {
	paint = new Paint();
	paint.setColor(Color.BLACK);
	paint.setAntiAlias(true);
	paint.setFlags(Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);

	gestureDetector = new GestureDetector(this);
}

/**
 * 画扇形
 * @param canvas
* @param rectF
*/
private void drawArc(Canvas canvas, RectF rectF) {

	for (int i = 0; i < childMenuSize; i++) {
		paint.setColor(Color.BLUE);

		if(i == selectId){ //如果是选中就将扇形画成实心的,否则画空心的扇形
			paint.setStyle(Style.FILL);
			canvas.drawArc(rectF, i * childAngle + offsetAngle, childAngle,
						true, paint);
		}else{
			paint.setStyle(Style.STROKE);
			canvas.drawArc(rectF, i * childAngle + offsetAngle, childAngle,
						true, paint);
		}

		//计算扇形中心点的坐标
		double x = 200 + getRoundX(200f/3*2, i, childMenuSize, offsetAngle+childAngle/2);
		double y = 200 + getRoundY(200f/3*2, i, childMenuSize, offsetAngle+childAngle/2);

		String str = "菜单"+i;
		//计算文字宽高
		Rect rect = new Rect();  
		paint.getTextBounds(str, 0, str.length(), rect);  
		int strW = rect.width();  
		int strH = rect.height(); 
		paint.setColor(Color.WHITE);
		canvas.drawText(str, (float)x-strW/2, (float)y-strH/2, paint);

	}
}

/**
 * 计算圆形等分扇形的点Y坐标
 * @param r 圆形直径
 * @param i 第几个等分扇形
 * @param n 等分扇形个数
 * @param offset_angle 与X轴偏移角度
 * @return Y坐标
 */
private double getRoundY(float r,int i,int n,float offset_angle) {
	return r * Math.sin(i * 2 * Math.PI / n + Math.PI / 180
			* offset_angle);
}

/**
 * 计算圆形等分扇形的点X坐标
 * @param r 圆形直径
 * @param i 第几个等分扇形
 * @param n 等分扇形个数
 * @param offset_angle 与X轴偏移角度
 * @return x坐标
 */
private double getRoundX(float r,int i,int n,float offset_angle) {
	return r * Math.cos(i * 2 * Math.PI / n + Math.PI / 180
			* offset_angle);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
	// TODO Auto-generated method stub
	switch (event.getAction()) {
	case MotionEvent.ACTION_DOWN:
		selectId = whichSector(event.getX()-200, event.getY()-200, 200);
		invalidate();
		break;
	case MotionEvent.ACTION_MOVE:
		break;
	case MotionEvent.ACTION_UP:
		break;
	}
	gestureDetector.onTouchEvent(event);
	return true;
}

@Override
protected void onDraw(Canvas canvas) {

	RectF rectF = new RectF(0, 0, 400, 400);
	paint.setStyle(Paint.Style.FILL_AND_STROKE);
	paint.setColor(Color.LTGRAY);
	canvas.drawCircle(200, 200, 200, paint);
	paint.setColor(Color.GREEN);
	canvas.drawCircle(200, 200, 190, paint);
	paint.setColor(Color.GRAY);
	canvas.drawCircle(200, 200, 180, paint);

	// 画空心扇形
	paint.setColor(Color.BLUE);
	paint.setStyle(Paint.Style.STROKE);
	drawArc(canvas, new RectF(20, 20, 380, 380));

	// 画中心外圆
	paint.setColor(Color.WHITE);
	paint.setStyle(Style.FILL);
	canvas.drawCircle(200, 200, 25, paint);

	// 画三角形
	Path path = new Path();
	path.moveTo(175, 200);// 此点为多边形的起点
	path.lineTo(225, 200);
	path.lineTo(200, 240);
	path.close(); // 使这些点构成封闭的多边形
	canvas.drawPath(path, paint);

	// 画中心内圆
	paint.setColor(Color.MAGENTA);
	canvas.drawCircle(200, 200, 20, paint);

}

/**
 * 计算两个坐标点与圆点之间的夹角
 * @param px1 点1的x坐标
 * @param py1 点1的y坐标
 * @param px2 点2的x坐标
 * @param py2 点2的y坐标
 * @return 夹角度数
 */
private double calculateScrollAngle(float px1, float py1, float px2,
			float py2) {
	double radian1 = Math.atan2(py1, px1);
	double radian2 = Math.atan2(py2, px2);
	double diff = radian2 - radian1;
	return Math.round(diff / Math.PI * 180);
}

@Override
public boolean onDown(MotionEvent e) {
	// TODO Auto-generated method stub
	return false;
}

@Override
public void onShowPress(MotionEvent e) {
	// TODO Auto-generated method stub

}

@Override
public boolean onSingleTapUp(MotionEvent e) {
	// TODO Auto-generated method stub
	return false;
}

@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX,
			float distanceY) {
	float tpx = e2.getX() - 200;
	float tpy = e2.getY() - 200;
	float disx = (int) distanceX;
	float disy = (int) distanceY;
	double scrollAngle = calculateScrollAngle(tpx, tpy, tpx + disx, tpy
				+ disy);
	offsetAngle -= scrollAngle;
	selectId = whichSector(0, 40, 200);//0,40是中心三角定点相对于圆点的坐标
	invalidate();
	Log.e("CM", "offsetAngle:" + offsetAngle);
	return true;
}

@Override
public void onLongPress(MotionEvent e) {
	// TODO Auto-generated method stub

}

@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
		float velocityY) {
	// TODO Auto-generated method stub
	return false;
}

/**
* 计算点在那个扇形区域
* @param X
* @param Y
* @param R 半径
* @return
*/
private int whichSector(double X, double Y, double R) {

	double mod;
	mod = Math.sqrt(X * X + Y * Y); //将点(X,Y)视为复平面上的点，与复数一一对应，现求复数的模。
	double offset_angle;
	double arg;
	arg = Math.round(Math.atan2(Y, X) / Math.PI * 180);//求复数的辐角。
	arg = arg < 0? arg+360:arg;
	if(offsetAngle%360 < 0){ 	    	
		offset_angle = 360+offsetAngle%360; 	    
	}else{ 	    	
		offset_angle = offsetAngle%360; 	   
	} 	     	    	   
	if (mod > R) { //如果复数的模大于预设的半径，则返回0。
	       	return -2;
	} else { //根据复数的辐角来判别该点落在那个扇区。
	   	for(int i=0;i<childMenuSize;i++){ 	    		
			if(isSelect(arg, i,offset_angle) || isSelect(360+arg, i,offset_angle)){
 	    			return i; 	    		
			} 	    	
		} 	   
	} 	   
	return -1; 	
} 	 	 
/** 	  
* 判读该区域是否被选中 	  
* @param arg 角度 	 
* @param i  	  
* @param offsetAngle 偏移角度 	  
* @return 是否被选中 	  
*/ 	
private boolean isSelect(double arg, int i, double offsetAngle) { 		
	return arg>(i*childAngle+offsetAngle%360) &amp;&amp; arg<((i+1)*childAngle+offsetAngle%360);
}

}

需要特别说明的是代码里很多用到坐标的地方都进行了加200或者减200的操作，这是因为这里我是以圆的中心为坐标圆点计算的而不是以view的左上角为圆点。
如图所示：
)
这里的坐标系与常规的坐标系有些不同，象限是相反的，所以计算坐标的时候需要注意。
最后贴上在布局中使用的方法：

<com.com.widget.RoundMenuView
    android:id="@+id/myRoundMenu"
    android:layout_width="400dp"
    android:layout_height="400dp"/>

这里是将控件大小固定死的，可以根据需求修改，当然代码里相应的也要做修改