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 {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);if (savedInstanceState == null) {getFragmentManager().beginTransaction().add(R.id.container, new PlaceholderFragment()).commit();}}@Overridepublic 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;}@Overridepublic 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() {}@Overridepublic 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() {  @Overridepublic 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