Android转盘按钮效果巧妙实现

想实现这样一种效果：一个转盘，旁边有几个按钮分布。每个按钮都可以点击：

表面上看，有5个按钮，其实其中每个按钮都是一个大圆圈，放置的位置都是重叠的。只是按下去的那部分才会有颜色，其他都是透明。

看看这个布局文件你就知道是怎么摆放的：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/back_ground_yellow"
    tools:context="com.example.circle.MainActivity$PlaceholderFragment" >

           <ImageView
           android:id="@+id/imageView1"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
		   android:layout_centerInParent="true"
           android:src="@drawable/picture" />

          <ImageView
           android:id="@+id/imageView2"
           android:layout_width="wrap_content"
           android:layout_height="wrap_content"
		   android:layout_centerInParent="true"
           android:src="@drawable/white_picture" />

       <com.example.circle.TrapezoidImageButton
        android:id="@+id/telId1"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/select_menu_1"
        android:tag="telId1" />

      <com.example.circle.TrapezoidImageButton
        android:id="@+id/telId2"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/select_menu_2"
        android:tag="telId12" />

            <com.example.circle.TrapezoidImageButton
        android:id="@+id/telId3"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/select_menu_3"
        android:tag="telId3" />

       <com.example.circle.TrapezoidImageButton
        android:id="@+id/telId4"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/select_menu_4"
        android:tag="telId4" />

       <com.example.circle.TrapezoidImageButton
        android:id="@+id/telId5"
        android:layout_centerInParent="true"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/select_menu_5"
        android:tag="telId5" />

</RelativeLayout>

其中自定义的ImageButton

public class TrapezoidImageButton extends ImageButton {

    public TrapezoidImageButton(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    }

    public TrapezoidImageButton(Context context, AttributeSet attrs) {
    super(context, attrs);
    }

    public TrapezoidImageButton(Context context) {
    super(context);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
    if (isTouchPointInView(event.getX(),event.getY())||
        event.getAction() != MotionEvent.ACTION_DOWN){
        return super.onTouchEvent(event);
    }else{
        return false;
    }
    }

    protected boolean isTouchPointInView(float localX, float localY){
    Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Config.ARGB_8888);
    Canvas canvas = new Canvas(bitmap);
    draw(canvas);
    int x = (int)localX;
    int y = (int)localY;
    if (x < 0 || x >= getWidth())
        return false;
    if (y < 0 || y >= getHeight())
        return false;
    int pixel = bitmap.getPixel(x,y);
    if ((pixel&0xff000000) != 0){  //不是透明的，这里是最关键所在。
        return true;
    }else{
        return false;
    }
    }
}

主Activity：

package com.example.circle;

import android.app.Activity;
import android.app.ActionBar;
import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.Toast;
import android.os.Build;

public class MainActivity extends Activity {

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		if (savedInstanceState == null) {
			getFragmentManager().beginTransaction()
					.add(R.id.container, new PlaceholderFragment()).commit();
		}
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {

		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) {
			return true;
		}
		return super.onOptionsItemSelected(item);
	}

	/**
	 * A placeholder fragment containing a simple view.
	 */
	public static class PlaceholderFragment extends Fragment {

		private Activity mactivity;

		public PlaceholderFragment() {
		}

		@Override
		public View onCreateView(LayoutInflater inflater, ViewGroup container,
				Bundle savedInstanceState) {
			View rootView = inflater.inflate(R.layout.fragment_main, container,
					false);
			mactivity = getActivity();

			rootView.findViewById(R.id.telId1).setOnClickListener(onclick);
			rootView.findViewById(R.id.telId2).setOnClickListener(onclick);
			rootView.findViewById(R.id.telId3).setOnClickListener(onclick);
			rootView.findViewById(R.id.telId4).setOnClickListener(onclick);
			rootView.findViewById(R.id.telId5).setOnClickListener(onclick);

			return rootView;
		}

		public  OnClickListener onclick = new OnClickListener() {  

			@Override
			public void onClick(View v) {

				   Toast.makeText(mactivity, v.getTag().toString(), 1*1000).show(); 

			}
		}; 

	}

}

在这里也分享一个demo源代码下载地址点击打开链接