转盘按钮。

package com.lixu.circlemenu;


import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
import android.widget.Toast;

import com.lixu.circlemenu.view.CircleImageView;
import com.lixu.circlemenu.view.CircleLayout;
import com.lixu.circlemenu.view.CircleLayout.OnItemClickListener;
import com.lixu.circlemenu.view.CircleLayout.OnItemSelectedListener;
import com.szugyi.circlemenu.R;

public class MainActivity extends Activity implements OnItemSelectedListener, OnItemClickListener{
    
    private    TextView selectedTextView;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        CircleLayout circleMenu = (CircleLayout)findViewById(R.id.main_circle_layout);
        circleMenu.setOnItemSelectedListener(this);
        circleMenu.setOnItemClickListener(this);

        //这个TextView仅仅作为演示转盘按钮以何为默认的选中项，
        //默认的最底部的那一条被选中，然后显示到该TextView中。
        selectedTextView = (TextView)findViewById(R.id.main_selected_textView);
        selectedTextView.setText(((CircleImageView)circleMenu.getSelectedItem()).getName());
    }

    //圆盘转动到底部，则认为该条目被选中
    @Override
    public void onItemSelected(View view, int position, long id, String name) {        
        selectedTextView.setText(name);
    }

    //选择了转盘中的某一条。
    @Override
    public void onItemClick(View view, int position, long id, String name) {
        Toast.makeText(getApplicationContext(), getResources().getString(R.string.start_app) + " " + name, Toast.LENGTH_SHORT).show();
    }
}

引用两个开源类：

package com.lixu.circlemenu.view;

/*
 * Copyright 2013 Csaba Szugyiczki
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.widget.ImageView;

import com.szugyi.circlemenu.R;

/**
 * 
 * @author Szugyi
 * Custom ImageView for the CircleLayout class.
 * Makes it possible for the image to have an angle, position and a name.
 * Angle is used for the positioning in the circle menu.
 */
public class CircleImageView extends ImageView {

    private float angle = 0;
    private int position = 0;
    private String name;

    public float getAngle() {
        return angle;
    }

    public void setAngle(float angle) {
        this.angle = angle;
    }

    public int getPosition() {
        return position;
    }

    public void setPosition(int position) {
        this.position = position;
    }
    
    public String getName(){
        return name;
    }
    
    public void setName(String name){
        this.name = name;
    }

    /**
     * @param context
     */
    public CircleImageView(Context context) {
        this(context, null);
    }

    /**
     * @param context
     * @param attrs
     */
    public CircleImageView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    /**
     * @param context
     * @param attrs
     * @param defStyle
     */
    public CircleImageView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        if (attrs != null) {
            TypedArray a = getContext().obtainStyledAttributes(attrs,
                    R.styleable.CircleImageView);
            
            name = a.getString(R.styleable.CircleImageView_name);
        }
    }

}

package com.lixu.circlemenu.view;

import com.szugyi.circlemenu.R;

/*
 * Copyright 2013 Csaba Szugyiczki
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;


/**
 * 
 * @author Szugyi
 * Creates a rotatable circle menu which can be parameterized by custom attributes.
 * Handles touches and gestures to make the menu rotatable, and to make the 
 * menu items selectable and clickable.
 * 
 */
public class CircleLayout extends ViewGroup {
    // Event listeners
    private OnItemClickListener mOnItemClickListener = null;
    private OnItemSelectedListener mOnItemSelectedListener = null;
    private OnCenterClickListener mOnCenterClickListener = null;
    
    // Background image
    private Bitmap imageOriginal, imageScaled;
    private Matrix matrix;

    private int mTappedViewsPostition = -1;
    private View mTappedView = null;
    private int selected = 0;

    // Child sizes
    private int mMaxChildWidth = 0;
    private int mMaxChildHeight = 0;
    private int childWidth = 0;
    private int childHeight = 0;

    // Sizes of the ViewGroup
    private int circleWidth, circleHeight;
    private int radius = 0;

    // Touch detection
    private GestureDetector mGestureDetector;
    // needed for detecting the inversed rotations
    private boolean[] quadrantTouched;

    // Settings of the ViewGroup
    private boolean allowRotating = true;
    private float angle = 90;
    private float firstChildPos = 90;
    private boolean rotateToCenter = true;
    private boolean isRotating = true;

    /**
     * @param context
     */
    public CircleLayout(Context context) {
        this(context, null);
    }

    /**
     * @param context
     * @param attrs
     */
    public CircleLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }
    
    /**
     * @param context
     * @param attrs
     * @param defStyle
     */
    public CircleLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(attrs);
    }

    /**
     * Initializes the ViewGroup and modifies it's default behavior by the passed attributes
     * @param attrs    the attributes used to modify default settings
     */
    protected void init(AttributeSet attrs) {
        mGestureDetector = new GestureDetector(getContext(),
                new MyGestureListener());
        quadrantTouched = new boolean[] { false, false, false, false, false };

        if (attrs != null) {
            TypedArray a = getContext().obtainStyledAttributes(attrs,
                    R.styleable.Circle);
            
            // The angle where the first menu item will be drawn
            angle = a.getInt(R.styleable.Circle_firstChildPosition, 90);
            firstChildPos = angle;

            rotateToCenter = a.getBoolean(R.styleable.Circle_rotateToCenter,
                    true);            
            isRotating = a.getBoolean(R.styleable.Circle_isRotating, true);
            
            // If the menu is not rotating then it does not have to be centered
            // since it cannot be even moved
            if (!isRotating) {
                rotateToCenter = false;
            }

            if (imageOriginal == null) {
                int picId = a.getResourceId(
                        R.styleable.Circle_circleBackground, -1);
                
                // If a background image was set as an attribute, 
                // retrieve the image
                if (picId != -1) {
                    imageOriginal = BitmapFactory.decodeResource(
                            getResources(), picId);
                }
            }

            a.recycle();

            // initialize the matrix only once
            if (matrix == null) {
                matrix = new Matrix();
            } else {
                // not needed, you can also post the matrix immediately to
                // restore the old state
                matrix.reset();
            }
            // Needed for the ViewGroup to be drawn
            setWillNotDraw(false);
        }
    }

    /**
     * Returns the currently selected menu
     * @return the view which is currently the closest to the start position
     */
    public View getSelectedItem() {
        return (selected >= 0) ? getChildAt(selected) : null;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // the sizes of the ViewGroup
        circleHeight = getHeight();
        circleWidth = getWidth();

        if (imageOriginal != null) {
            // Scaling the size of the background image
            if (imageScaled == null) {
                matrix = new Matrix();
                float sx = (((radius + childWidth / 4) * 2) / (float) imageOriginal
                        .getWidth());
                float sy = (((radius + childWidth / 4) * 2) / (float) imageOriginal
                        .getHeight());
                matrix.postScale(sx, sy);
                imageScaled = Bitmap.createBitmap(imageOriginal, 0, 0,
                        imageOriginal.getWidth(), imageOriginal.getHeight(),
                        matrix, false);
            }

            if (imageScaled != null) {
                // Move the background to the center
                int cx = (circleWidth - imageScaled.getWidth()) / 2;
                int cy = (circleHeight - imageScaled.getHeight()) / 2;

                Canvas g = canvas;
                canvas.rotate(0, circleWidth / 2, circleHeight / 2);
                g.drawBitmap(imageScaled, cx, cy, null);

            }
        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        mMaxChildWidth = 0;
        mMaxChildHeight = 0;

        // Measure once to find the maximum child size.
        int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
                MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.AT_MOST);
        int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
                MeasureSpec.getSize(widthMeasureSpec), MeasureSpec.AT_MOST);

        final int count = getChildCount();
        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() == GONE) {
                continue;
            }

            child.measure(childWidthMeasureSpec, childHeightMeasureSpec);

            mMaxChildWidth = Math.max(mMaxChildWidth, child.getMeasuredWidth());
            mMaxChildHeight = Math.max(mMaxChildHeight,
                    child.getMeasuredHeight());
        }

        // Measure again for each child to be exactly the same size.
        childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(mMaxChildWidth,
                MeasureSpec.EXACTLY);
        childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(mMaxChildHeight,
                MeasureSpec.EXACTLY);

        for (int i = 0; i < count; i++) {
            final View child = getChildAt(i);
            if (child.getVisibility() == GONE) {
                continue;
            }

            child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
        }

        setMeasuredDimension(resolveSize(mMaxChildWidth, widthMeasureSpec),
                resolveSize(mMaxChildHeight, heightMeasureSpec));
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        int layoutWidth = r - l;
        int layoutHeight = b - t;

        // Laying out the child views
        final int childCount = getChildCount();
        int left, top;
        radius = (layoutWidth <= layoutHeight) ? layoutWidth / 3
                : layoutHeight / 3;
        
        childWidth = (int) (radius / 1.5);
        childHeight = (int) (radius / 1.5);
        
        float angleDelay = 360 / getChildCount();
        
        for (int i = 0; i < childCount; i++) {
            final CircleImageView child = (CircleImageView) getChildAt(i);
            if (child.getVisibility() == GONE) {
                continue;
            }

            if (angle > 360) {
                angle -= 360;
            } else {
                if (angle < 0) {
                    angle += 360;
                }
            }

            child.setAngle(angle);
            child.setPosition(i);

            left = Math
                    .round((float) (((layoutWidth / 2) - childWidth / 2) + radius
                            * Math.cos(Math.toRadians(angle))));
            top = Math
                    .round((float) (((layoutHeight / 2) - childHeight / 2) + radius
                            * Math.sin(Math.toRadians(angle))));

            child.layout(left, top, left + childWidth, top + childHeight);
            angle += angleDelay;
        }
    }

    /**
     * Rotate the buttons.
     * 
     * @param degrees The degrees, the menu items should get rotated.
     */
    private void rotateButtons(float degrees) {
        int left, top, childCount = getChildCount();
        float angleDelay = 360 / childCount;
        angle += degrees;
        
        if (angle > 360) {
            angle -= 360;
        } else {
            if (angle < 0) {
                angle += 360;
            }
        }

        for (int i = 0; i < childCount; i++) {
            if (angle > 360) {
                angle -= 360;
            } else {
                if (angle < 0) {
                    angle += 360;
                }
            }

            final CircleImageView child = (CircleImageView) getChildAt(i);
            if (child.getVisibility() == GONE) {
                continue;
            }
            left = Math
                    .round((float) (((circleWidth / 2) - childWidth / 2) + radius
                            * Math.cos(Math.toRadians(angle))));
            top = Math
                    .round((float) (((circleHeight / 2) - childHeight / 2) + radius
                            * Math.sin(Math.toRadians(angle))));

            child.setAngle(angle);

            if (Math.abs(angle - firstChildPos) < (angleDelay / 2)
                    && selected != child.getPosition()) {
                selected = child.getPosition();

                if (mOnItemSelectedListener != null && rotateToCenter) {
                    mOnItemSelectedListener.onItemSelected(child, selected,
                            child.getId(), child.getName());
                }
            }

            child.layout(left, top, left + childWidth, top + childHeight);
            angle += angleDelay;
        }
    }

    /**
     * @return The angle of the unit circle with the image view's center
     */
    private double getAngle(double xTouch, double yTouch) {
        double x = xTouch - (circleWidth / 2d);
        double y = circleHeight - yTouch - (circleHeight / 2d);

        switch (getQuadrant(x, y)) {
        case 1:
            return Math.asin(y / Math.hypot(x, y)) * 180 / Math.PI;

        case 2:
        case 3:
            return 180 - (Math.asin(y / Math.hypot(x, y)) * 180 / Math.PI);

        case 4:
            return 360 + Math.asin(y / Math.hypot(x, y)) * 180 / Math.PI;

        default:
            // ignore, does not happen
            return 0;
        }
    }

    /**
     * @return The selected quadrant.
     */
    private static int getQuadrant(double x, double y) {
        if (x >= 0) {
            return y >= 0 ? 1 : 4;
        } else {
            return y >= 0 ? 2 : 3;
        }
    }

    private double startAngle;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (isEnabled()) {
            if (isRotating) {
                switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:

                    // reset the touched quadrants
                    for (int i = 0; i < quadrantTouched.length; i++) {
                        quadrantTouched[i] = false;
                    }

                    allowRotating = false;

                    startAngle = getAngle(event.getX(), event.getY());
                    break;
                case MotionEvent.ACTION_MOVE:
                    double currentAngle = getAngle(event.getX(), event.getY());
                    rotateButtons((float) (startAngle - currentAngle));
                    startAngle = currentAngle;
                    break;
                case MotionEvent.ACTION_UP:
                    allowRotating = true;
                    rotateViewToCenter((CircleImageView) getChildAt(selected),
                            false);
                    break;
                }
            }

            // set the touched quadrant to true
            quadrantTouched[getQuadrant(event.getX() - (circleWidth / 2),
                    circleHeight - event.getY() - (circleHeight / 2))] = true;
            mGestureDetector.onTouchEvent(event);
            return true;
        }
        return false;
    }

    private class MyGestureListener extends SimpleOnGestureListener {
        @Override
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                float velocityY) {
            if (!isRotating) {
                return false;
            }
            // get the quadrant of the start and the end of the fling
            int q1 = getQuadrant(e1.getX() - (circleWidth / 2), circleHeight
                    - e1.getY() - (circleHeight / 2));
            int q2 = getQuadrant(e2.getX() - (circleWidth / 2), circleHeight
                    - e2.getY() - (circleHeight / 2));

            // the inversed rotations
            if ((q1 == 2 && q2 == 2 && Math.abs(velocityX) < Math
                    .abs(velocityY))
                    || (q1 == 3 && q2 == 3)
                    || (q1 == 1 && q2 == 3)
                    || (q1 == 4 && q2 == 4 && Math.abs(velocityX) > Math
                            .abs(velocityY))
                    || ((q1 == 2 && q2 == 3) || (q1 == 3 && q2 == 2))
                    || ((q1 == 3 && q2 == 4) || (q1 == 4 && q2 == 3))
                    || (q1 == 2 && q2 == 4 && quadrantTouched[3])
                    || (q1 == 4 && q2 == 2 && quadrantTouched[3])) {

                CircleLayout.this.post(new FlingRunnable(-1
                        * (velocityX + velocityY)));
            } else {
                // the normal rotation
                CircleLayout.this
                        .post(new FlingRunnable(velocityX + velocityY));
            }

            return true;

        }

        @Override
        public boolean onSingleTapUp(MotionEvent e) {
            mTappedViewsPostition = pointToPosition(e.getX(), e.getY());
            if (mTappedViewsPostition >= 0) {
                mTappedView = getChildAt(mTappedViewsPostition);
                mTappedView.setPressed(true);
            } else {
                float centerX = circleWidth / 2;
                float centerY = circleHeight / 2;

                if (e.getX() < centerX + (childWidth / 2)
                        && e.getX() > centerX - childWidth / 2
                        && e.getY() < centerY + (childHeight / 2)
                        && e.getY() > centerY - (childHeight / 2)) {
                    if (mOnCenterClickListener != null) {
                        mOnCenterClickListener.onCenterClick();
                        return true;
                    }
                }
            }

            if (mTappedView != null) {
                CircleImageView view = (CircleImageView) (mTappedView);
                if (selected != mTappedViewsPostition) {
                    rotateViewToCenter(view, false);
                    if (!rotateToCenter) {
                        if (mOnItemSelectedListener != null) {
                            mOnItemSelectedListener.onItemSelected(mTappedView,
                                    mTappedViewsPostition, mTappedView.getId(), view.getName());
                        }

                        if (mOnItemClickListener != null) {
                            mOnItemClickListener.onItemClick(mTappedView,
                                    mTappedViewsPostition, mTappedView.getId(), view.getName());
                        }
                    }
                } else {
                    rotateViewToCenter(view, false);

                    if (mOnItemClickListener != null) {
                        mOnItemClickListener.onItemClick(mTappedView,
                                mTappedViewsPostition, mTappedView.getId(), view.getName());
                    }
                }
                return true;
            }
            return super.onSingleTapUp(e);
        }
    }

    /**
     * Rotates the given view to the center of the menu.
     * @param view            the view to be rotated to the center
     * @param fromRunnable    if the method is called from the runnable which animates the rotation
     *                         then it should be true, otherwise false 
     */
    private void rotateViewToCenter(CircleImageView view, boolean fromRunnable) {
        if (rotateToCenter) {
            float velocityTemp = 1;
            float destAngle = (float) (firstChildPos - view.getAngle());
            float startAngle = 0;
            int reverser = 1;

            if (destAngle < 0) {
                destAngle += 360;
            }

            if (destAngle > 180) {
                reverser = -1;
                destAngle = 360 - destAngle;
            }

            while (startAngle < destAngle) {
                startAngle += velocityTemp / 75;
                velocityTemp *= 1.0666F;
            }

            CircleLayout.this.post(new FlingRunnable(reverser * velocityTemp,
                    !fromRunnable));
        }
    }

    /**
     * A {@link Runnable} for animating the menu rotation.
     */
    private class FlingRunnable implements Runnable {

        private float velocity;
        float angleDelay;
        boolean isFirstForwarding = true;

        public FlingRunnable(float velocity) {
            this(velocity, true);
        }

        public FlingRunnable(float velocity, boolean isFirst) {
            this.velocity = velocity;
            this.angleDelay = 360 / getChildCount();
            this.isFirstForwarding = isFirst;
        }

        public void run() {
            if (Math.abs(velocity) > 5 && allowRotating) {
                if (rotateToCenter) {
                    if (!(Math.abs(velocity) < 200 && (Math.abs(angle
                            - firstChildPos)
                            % angleDelay < 2))) {
                        rotateButtons(velocity / 75);
                        velocity /= 1.0666F;

                        CircleLayout.this.post(this);
                    }
                } else {
                    rotateButtons(velocity / 75);
                    velocity /= 1.0666F;

                    CircleLayout.this.post(this);
                }
            } else {
                if (isFirstForwarding) {
                    isFirstForwarding = false;
                    CircleLayout.this.rotateViewToCenter(
                            (CircleImageView) getChildAt(selected), true);
                }
            }
        }
    }

    private int pointToPosition(float x, float y) {

        for (int i = 0; i < getChildCount(); i++) {

            View item = (View) getChildAt(i);
            if (item.getLeft() < x && item.getRight() > x & item.getTop() < y
                    && item.getBottom() > y) {
                return i;
            }

        }
        return -1;
    }

    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
        this.mOnItemClickListener = onItemClickListener;
    }

    public interface OnItemClickListener {
        void onItemClick(View view, int position, long id, String name);
    }

    public void setOnItemSelectedListener(
            OnItemSelectedListener onItemSelectedListener) {
        this.mOnItemSelectedListener = onItemSelectedListener;
    }

    public interface OnItemSelectedListener {
        void onItemSelected(View view, int position, long id, String name);
    }

    public interface OnCenterClickListener {
        void onCenterClick();
    }

    public void setOnCenterClickListener(
            OnCenterClickListener onCenterClickListener) {
        this.mOnCenterClickListener = onCenterClickListener;
    }
}

xml文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:circle="http://schemas.android.com/apk/res/com.szugyi.circlemenu"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <com.lixu.circlemenu.view.CircleLayout
        android:id="@+id/main_circle_layout"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_above="@+id/main_selected_textView"
        android:layout_gravity="center_horizontal"
        circle:firstChildPosition="South" 
        circle:rotateToCenter="true" 
        circle:isRotating="true" >       
<!--         circle:circleBackground="@drawable/green"  > -->


        <com.lixu.circlemenu.view.CircleImageView
            android:id="@+id/main_facebook_image"
            android:layout_width="35dp"
            android:layout_height="35dp"
            android:src="@drawable/icon_facebook"
            circle:name="@string/facebook" />

        <com.lixu.circlemenu.view.CircleImageView
            android:id="@+id/main_myspace_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/icon_myspace"
            circle:name="@string/myspace" />

        <com.lixu.circlemenu.view.CircleImageView
            android:id="@+id/main_google_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/icon_google"
            circle:name="@string/google" />

        <com.lixu.circlemenu.view.CircleImageView
            android:id="@+id/main_linkedin_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/icon_linkedin"
            circle:name="@string/linkedin" />

        <com.lixu.circlemenu.view.CircleImageView
            android:id="@+id/main_twitter_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/icon_twitter"
            circle:name="@string/twitter" />

        <com.lixu.circlemenu.view.CircleImageView
            android:id="@+id/main_wordpress_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/icon_wordpress"
            circle:name="@string/wordpress" />
    </com.lixu.circlemenu.view.CircleLayout>

    <TextView
        android:id="@+id/main_selected_textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="50dp"
        android:textAppearance="?android:attr/textAppearanceLarge" />

</RelativeLayout>

 运行效果：