Android仿IOS的AssistiveTouch的控件EasyTouch实现

概述：

  之前我听到过一则新闻，就是说Ipone中的AssistiveTouch的设计初衷是给残疾人使用的。而这一功能在亚洲（中国）的使用最为频繁。

  虽不知道这新闻的可靠性，但无庸置疑的是它的确给我们操作手机带来了很大的便捷。在这个设计之前，可能比较容易想到的就是建立快捷方式，而快捷方式的操作结果还是要去加载界面（有时可能是繁重的界面）。一旦走上了这条路，那距离快捷操作的方向可能就渐行渐远了。

  AssistiveTouch的设计的确很赞。Android也是值得拥有这一棒棒的功能，下面我就来简单说明一下在Android上要如何实现这一功能。

思路整理：

  一眼看到这样的功能，我们可能困惑的是在Android中要怎么在系统桌面的上方添加控件。是的，这是一个难点。从大小上，可能你想到了Dialog，不过Android中的Dialog可不能在系统的桌面上显示。那你可能又会说不是一种是针对Activity的Dialog主题的模式吗？是的，这样的确是解决了在系统桌面的上方弹出窗口了。可是，我们又要对控件进行随意拖拽，这一点可能对于Android而言并非易事。

  但是，Android中允许我们在WindowManager上添加View。Android中的窗口机制就是基于WindowManager实现的。WindowManager的作用就是添加View到屏幕，或是从屏幕中移除View。它是显示View的最底层。

  好了，的确是这样的。WindowManger就是实现的关键。下面就来实现它吧。

  不过还有一点需要注意，就我们的EasyTouchView是要基于一个常在的Context来创建，如果EasyTouchView基于了像Activity这样的短生命周期的Context创建，那么EasyTouchView就会很快随着Activity的暂停或是销毁而消失。

实现过程：

EasyTouchView：

package com.bumblebee.remindeasy.widgets;

import java.util.Timer;
import java.util.TimerTask;
import com.bumblebee.remindeasy.R;
import android.content.Context;
import android.graphics.Color;
import android.graphics.drawable.BitmapDrawable;
import android.os.Handler;
import android.os.Message;
import android.view.Gravity;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.view.WindowManager.LayoutParams;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.PopupWindow;
import android.widget.Toast;

public class EasyTouchView extends View {
    private Context mContext;
    private WindowManager mWManager;
    private WindowManager.LayoutParams mWMParams;
    private View mTouchView;
    private ImageView mIconImageView = null;
    private PopupWindow mPopuWin;
    private ServiceListener mSerLisrener;
    private View mSettingTable;
    private int mTag = 0;
    private int midX;
    private int midY;
    private int mOldOffsetX;
    private int mOldOffsetY;

    private Toast mToast;
    private Timer mTimer = null;
    private TimerTask mTask = null;

    public EasyTouchView(Context context, ServiceListener listener) {
        super(context);
        mContext = context;
        mSerLisrener = listener;
    }

    public void initTouchViewEvent() {
        initEasyTouchViewEvent();
        
        initSettingTableView();
    }
    
    private void initEasyTouchViewEvent() {
        // 设置载入view WindowManager参数
        mWManager = (WindowManager) mContext.getSystemService(Context.WINDOW_SERVICE);
        midX = mWManager.getDefaultDisplay().getWidth() / 2 - 25;
        midY = mWManager.getDefaultDisplay().getHeight() / 2 - 44;
        mTouchView = LayoutInflater.from(mContext).inflate(R.layout.easy_touch_view, null);
        mIconImageView = (ImageView) mTouchView.findViewById(R.id.easy_touch_view_imageview);
        mTouchView.setBackgroundColor(Color.TRANSPARENT);
        
        mTouchView.setOnTouchListener(mTouchListener);
        WindowManager wm = mWManager;
        WindowManager.LayoutParams wmParams = new WindowManager.LayoutParams();
        mWMParams = wmParams;
        wmParams.type = 2003; // 这里的2002表示系统级窗口，你也可以试试2003。
        wmParams.flags = 40; // 设置桌面可控
        wmParams.width = 100;
        wmParams.height = 100;
        wmParams.format = -3; // 透明
        wm.addView(mTouchView, wmParams);
    }
    
    private void initSettingTableView() {
        mSettingTable = LayoutInflater.from(mContext).inflate(R.layout.show_setting_table, null);
        Button commonUseButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_common_use_button);
        Button screenLockButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_screen_lock_button);
        Button notificationButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_notification_button);
        
        Button phoneButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_phone_button);
        Button pageButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_page_button);
        Button cameraButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_camera_button);
        
        Button backButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_back_button);
        Button homeButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_home_button);
        Button exitTouchButton = (Button) mSettingTable.findViewById(R.id.show_setting_table_item_exit_touch_button);
        
        commonUseButton.setOnClickListener(mClickListener);
        screenLockButton.setOnClickListener(mClickListener);
        notificationButton.setOnClickListener(mClickListener);
        
        phoneButton.setOnClickListener(mClickListener);
        pageButton.setOnClickListener(mClickListener);
        cameraButton.setOnClickListener(mClickListener);
        
        backButton.setOnClickListener(mClickListener);
        homeButton.setOnClickListener(mClickListener);
        exitTouchButton.setOnClickListener(mClickListener);
    }

    private OnClickListener mClickListener = new OnClickListener() {
        @Override
        public void onClick(View v) {
            switch (v.getId()) {
            case R.id.show_setting_table_item_common_use_button:
                hideSettingTable("常用");
                break;
            case R.id.show_setting_table_item_screen_lock_button:
                hideSettingTable("锁屏");
                break;
            case R.id.show_setting_table_item_notification_button:
                hideSettingTable("通知");
                break;
                
            case R.id.show_setting_table_item_phone_button:
                hideSettingTable("电话");
                break;
            case R.id.show_setting_table_item_page_button:
                hideSettingTable("1");
                break;
            case R.id.show_setting_table_item_camera_button:
                hideSettingTable("相机");
                break;
                
            case R.id.show_setting_table_item_back_button:
                hideSettingTable("返回");
                break;
            case R.id.show_setting_table_item_home_button:
                hideSettingTable("主页");
                break;
            case R.id.show_setting_table_item_exit_touch_button:
                quitTouchView();
                break;
            }

        }
    };
    
    private void quitTouchView() {
        hideSettingTable("退出");
        
        mWManager.removeView(mTouchView);
        mSerLisrener.OnCloseService(true);
        
        clearTimerThead();
    }
    
    private OnTouchListener mTouchListener = new OnTouchListener() {
        float lastX, lastY;
        int paramX, paramY;

        public boolean onTouch(View v, MotionEvent event) {
            final int action = event.getAction();

            float x = event.getRawX();
            float y = event.getRawY();

            if (mTag == 0) {
                mOldOffsetX = mWMParams.x; // 偏移量
                mOldOffsetY = mWMParams.y; // 偏移量
            }

            switch (action) {
            case MotionEvent.ACTION_DOWN:
                motionActionDownEvent(x, y);
                break;
                
            case MotionEvent.ACTION_MOVE:
                motionActionMoveEvent(x, y);
                break;
                
            case MotionEvent.ACTION_UP:
                motionActionUpEvent(x, y);
                break;

            default:
                break;
            }
            
            return true;
        }
        
        private void motionActionDownEvent(float x, float y) {
            lastX = x;
            lastY = y;
            paramX = mWMParams.x;
            paramY = mWMParams.y;
        }
        
        private void motionActionMoveEvent(float x, float y) {
            int dx = (int) (x - lastX);
            int dy = (int) (y - lastY);
            mWMParams.x = paramX + dx;
            mWMParams.y = paramY + dy;
            mTag = 1;
            
            // 更新悬浮窗位置
            mWManager.updateViewLayout(mTouchView, mWMParams);
        }
        
        private void motionActionUpEvent(float x, float y) {
            int newOffsetX = mWMParams.x;
            int newOffsetY = mWMParams.y;
            if (mOldOffsetX == newOffsetX && mOldOffsetY == newOffsetY) {
                mPopuWin = new PopupWindow(mSettingTable, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
                mPopuWin.setTouchInterceptor(new OnTouchListener() {

                    public boolean onTouch(View v, MotionEvent event) {
                        if (event.getAction() == MotionEvent.ACTION_OUTSIDE) {
                            hideSettingTable();
                            return true;
                        }
                        return false;
                    }
                });
                
                mPopuWin.setBackgroundDrawable(new BitmapDrawable());
                mPopuWin.setTouchable(true);
                mPopuWin.setFocusable(true);
                mPopuWin.setOutsideTouchable(true);
                mPopuWin.setContentView(mSettingTable);
                
                if (Math.abs(mOldOffsetX) > midX) {
                    if (mOldOffsetX > 0) {
                        mOldOffsetX = midX;
                    } else {
                        mOldOffsetX = -midX;
                    }
                }
                
                if (Math.abs(mOldOffsetY) > midY) {
                    if (mOldOffsetY > 0) {
                        mOldOffsetY = midY;
                    } else {
                        mOldOffsetY = -midY;
                    }
                }
                
                mPopuWin.setAnimationStyle(R.style.AnimationPreview);
                mPopuWin.setFocusable(true);
                mPopuWin.update();
                mPopuWin.showAtLocation(mTouchView, Gravity.CENTER, -mOldOffsetX, -mOldOffsetY);
                
                if (mTimer == null) {
                    catchSettingTableDismiss();
                }
            } else {
                mTag = 0;
            }
        }
    };
    
    private void catchSettingTableDismiss() {
        mTimer = new Timer();
        mTask = new TimerTask() {
            
            @Override
            public void run() {
                if (mPopuWin == null || !mPopuWin.isShowing()) {
                    handler.sendEmptyMessage(0x0);
                } else {
                    handler.sendEmptyMessage(0x1);
                }
            }
        };
        
        mTimer.schedule(mTask, 0, 100);
    }
    
    private void clearTimerThead() {
        if (mTask != null) {
            mTask.cancel();
            mTask = null;
        }
        
        if (mTimer != null) {
            mTimer.cancel();
            mTimer = null;
        }
    }

    Handler handler = new Handler() {
        public void handleMessage(Message msg) {
            if (msg.what == 0x0) {
                mIconImageView.setBackgroundDrawable(getResources().getDrawable(R.drawable.touch_ic));
            } else if (msg.what == 0x1) {
                mIconImageView.setBackgroundDrawable(getResources().getDrawable(R.drawable.transparent));
            }
        };
    };
    
    public void showToast(Context context, String text) {
        if (mToast == null) {
            mToast = Toast.makeText(context, text, Toast.LENGTH_SHORT);
        } else {
            mToast.setText(text);
            mToast.setDuration(Toast.LENGTH_SHORT);
        }
        mToast.show();
    }

    private void hideSettingTable(String content) {
        hideSettingTable();
        showToast(mContext, content);
    }
    
    private void hideSettingTable() {
        if (null != mPopuWin) {
            mPopuWin.dismiss();
        }
    }

    public interface ServiceListener {
        public void OnCloseService(boolean isClose);
    }
}

AuxiliaryService：

public class AuxiliaryService extends Service implements ServiceListener {
    private Intent mIntent;

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    public void onCreate() {
        super.onCreate();
        new EasyTouchView(this, this).initTouchViewEvent();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        mIntent = intent;
        return super.onStartCommand(intent, flags, startId);
    }

    @Override
    public void OnCloseService(boolean isClose) {
        stopService(mIntent);
    }
}

   这里有一点需要注意一下。大家可以通过上面的代码看出，我们启动EasyTouchView是通过Service来启动的。一般的EasyTouch都会提供一个锁屏的功能。要使用一键锁屏就需要激活设备管理器，就要去跳转到系统的一些界面，而这些界面的启动不可以是基于Service的，需要基于Activity来做处理。基于Service启动的过程是闪烁一下后就消失了。

  这里我们可以在Service中启动一个我们自己的Activity，然后在这个Activity中启动这个设置设备管理器的界面。

代码如下：

public class AuxiliaryActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        lockScreen();
    }
    
    private void lockScreen() {
        DevicePolicyManager mDevicePolicyManager;
        ComponentName mComponentName;
        
        mDevicePolicyManager = (DevicePolicyManager) getSystemService(Context.DEVICE_POLICY_SERVICE);
        mComponentName = new ComponentName(this, LockReceiver.class);

        // 判断是否有权限
        if (mDevicePolicyManager.isAdminActive(mComponentName)) {
            mDevicePolicyManager.lockNow();
            finish();
        } else {
            activeManager(mComponentName);
        }
    }
    
    /**
     * 激活设备管理器获取权限
     */
    private void activeManager(ComponentName componentName) {
        Intent intent = new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
        intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, componentName);
        intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION, "One key lock the screen");
        startActivity(intent);
        finish();
    }
}

效果图：