前言

之前写过屏蔽系统导航栏功能的文章，具体可看Android6.0 源码修改之屏蔽导航栏虚拟按键（Home和RecentAPP）/动态显示和隐藏NavigationBar

在某些特殊定制的版本中要求完全去掉导航栏，那么当用户点进一些系统自带的应用界面如设置、联系人等，就没法退出了，虽然可以在actionBar中添加back按钮，但总不能每一个app都去添加吧。所以灵机一动我们就给系统添加一个全屏可拖拽的浮窗按钮，点击的时候处理返回键的逻辑。它大概长这样(审美可能丑了点，你们可以*发挥)

Android6.0 源码修改之仿IOS添加全屏可拖拽浮窗返回按钮

图1 最终效果图

思路分析

通过分析之前的NavigationBar代码，发现系统是通过WindowManager添加View的方式来实现，此处我们也可以模拟这种方法来添加
添加悬浮窗以后监听触摸事件，跟随手指移动重新修改view的layoutParam
松手后获取当前X坐标，小于屏幕width的一半则平移归位至屏幕左边
添加系统的返回按键功能

一、添加悬浮窗

private void showFloatingWindow() {

    DisplayMetrics outMetrics = new DisplayMetrics();

    mWindowManager.getDefaultDisplay().getMetrics(outMetrics);

    screenWidth = outMetrics.widthPixels;

    screenHeight = outMetrics.heightPixels;

    layoutParams = new WindowManager.LayoutParams();

    layoutParams.type = WindowManager.LayoutParams.TYPE_PHONE;

    layoutParams.format = PixelFormat.RGBA_8888;

    layoutParams.gravity = Gravity.LEFT | Gravity.TOP;

    layoutParams.flags = WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL | WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE;

    layoutParams.width = 100;

    layoutParams.height = 100;

    layoutParams.x = 200;

    layoutParams.y = 200;

    button = new ImageButton(mContext);

    button.setBackground(mContext.getResources().getDrawable(R.drawable.fab_background));//系统通讯录里的蓝色圆形图标

    button.setImageResource(R.drawable.ic_sysbar_back);//系统本身的back图标

    mWindowManager.addView(button, layoutParams);

    isShowFloatingView = true;

}

代码很简单，就是通过windowManager添加一个ImageButton，宽高都是100的，位置在屏幕左上角为原点的200,200。需要注意的是因为我们是在源码里添加，而且是M的版本，所以type为WindowManager.LayoutParams.TYPE_PHONE。如果是在普通的app里注意事项可参考这篇

二、添加触摸事件监听

button.setOnTouchListener(new FloatingOnTouchListener());

private class FloatingOnTouchListener implements View.OnTouchListener {

    private int lastX;

    private int lastY;

    @Override

    public boolean onTouch(View view, MotionEvent event) {

        switch (event.getAction()) {

            case MotionEvent.ACTION_DOWN:

                isDrag = false;

                lastX = (int) event.getRawX();

                lastY = (int) event.getRawY();

                break;

            case MotionEvent.ACTION_MOVE:

                isDrag = true;

                int nowX = (int) event.getRawX();

                int nowY = (int) event.getRawY();

                int movedX = nowX - lastX;

                int movedY = nowY - lastY;

                lastX = nowX;

                lastY = nowY;

                layoutParams.x = layoutParams.x + movedX;

                layoutParams.y = layoutParams.y + movedY;

				//获取当前手指移动的x和y，通过updateViewLayout方法将改变后的x和y设置给button

                mWindowManager.updateViewLayout(view, layoutParams);

                break;

            case MotionEvent.ACTION_UP:

                if (isDrag) {

                    log("lastX=" + lastX + "  screenWidth=" + screenWidth);

					//手指抬起时，判断是需要滑动到屏幕左边还是屏幕右边

                    if (lastX >= screenWidth / 2) {

                        setAnimation(view, lastX, screenWidth);

                    } else {

                        setAnimation(view, -lastX, 0);

                    }

                }

                break;

        }

		//返回true则消费事件，返回false则传递事件，此处特殊处理是为了和点击事件区分

        return isDrag || view.onTouchEvent(event);

    }

三、添加抬起滑动归位动画

private void setAnimation(final View view, int fromX, int toX) {

        final ValueAnimator animator = ValueAnimator.ofInt(fromX, toX);

        if (Math.abs(fromX) < screenWidth / 4 || fromX > screenWidth * 3 / 4)

            animator.setDuration(300);

        else

            animator.setDuration(600);

        animator.setInterpolator(new LinearInterpolator());

        animator.addListener(new Animator.AnimatorListener() {

            @Override

            public void onAnimationStart(Animator animation) {}

            @Override

            public void onAnimationEnd(Animator animation) {

                log("onAnimationEnd=");

                savePreValue(layoutParams.x, layoutParams.y);

            }

            @Override

            public void onAnimationCancel(Animator animation) {}

            @Override

            public void onAnimationRepeat(Animator animation) {}

        });

        animator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {

            @Override

            public void onAnimationUpdate(ValueAnimator animation) {

                int current = (int) animator.getAnimatedValue();

                log("current=" + current);

                layoutParams.x = Math.abs(current);

                mWindowManager.updateViewLayout(view, layoutParams);

            }

        });

        animator.start();

    }

}

同样是通过改变button的x和y值来达到滑动效果，只不过我只需要x平移，y为0，需要斜着滑的你们可*发挥，为了使滑动看上去平滑，给动画添加了一个线性插值器，设置滑动时间，监听返回插值进度，这样动态设置给button。为了保存button的最终位置，添加了一个动画完成监听，并将x和y写入到SharedPreferences中保存。

四、添加点击返回功能

通过打印日志分析，系统导航栏的返回按键，发现其原理是通过KeyButtonView的触摸事件发送一个KeyEvent事件给系统来实现返回功能

源码位置frameworks\base\packages\SystemUI\src\com\android\systemui\statusbar\policy\KeyButtonView.java

public boolean onTouchEvent(MotionEvent ev) {

    final int action = ev.getAction();

    int x, y;

    if (action == MotionEvent.ACTION_DOWN) {

        mGestureAborted = false;

    }

    if (mGestureAborted) {

        return false;

    }

    switch (action) {

        case MotionEvent.ACTION_DOWN:

			//按下的时间

            mDownTime = SystemClock.uptimeMillis();

            setPressed(true);

            if (mCode != 0) {//按下事件

                sendEvent(KeyEvent.ACTION_DOWN, 0, mDownTime);

            } else {

                // Provide the same haptic feedback that the system offers for virtual keys.

                performHapticFeedback(HapticFeedbackConstants.VIRTUAL_KEY);

            }

            removeCallbacks(mCheckLongPress);

            postDelayed(mCheckLongPress, ViewConfiguration.getLongPressTimeout());

            break;

        case MotionEvent.ACTION_MOVE:

            x = (int)ev.getX();

            y = (int)ev.getY();

            setPressed(x >= -mTouchSlop

                    && x < getWidth() + mTouchSlop

                    && y >= -mTouchSlop

                    && y < getHeight() + mTouchSlop);

            break;

        case MotionEvent.ACTION_CANCEL:

            setPressed(false);

            if (mCode != 0) {

                sendEvent(KeyEvent.ACTION_UP, KeyEvent.FLAG_CANCELED);

            }

            removeCallbacks(mCheckLongPress);

            break;

        case MotionEvent.ACTION_UP:

            final boolean doIt = isPressed();

            setPressed(false);

            if (mCode != 0) {

                if (doIt) {//抬起事件

                    sendEvent(KeyEvent.ACTION_UP, 0);

                    sendAccessibilityEvent(AccessibilityEvent.TYPE_VIEW_CLICKED);

                    playSoundEffect(SoundEffectConstants.CLICK);

                } else {

                    sendEvent(KeyEvent.ACTION_UP, KeyEvent.FLAG_CANCELED);

                }

            } else {

                // no key code, just a regular ImageView

                if (doIt) {

                    performClick();

                }

            }

            removeCallbacks(mCheckLongPress);

            break;

    }

    return true;

}

//以下为我们给button添加的点击事件

private void sendEvent(int action, int flags, long when) {

    int mCode = 4;

    Log.e(TAG, "mCode="+mCode + "  flags="+flags);

    final int repeatCount = (flags & KeyEvent.FLAG_LONG_PRESS) != 0 ? 1 : 0;

    final KeyEvent ev = new KeyEvent(when - 100, when, action, mCode, repeatCount,

            0, KeyCharacterMap.VIRTUAL_KEYBOARD, 0,

            flags | KeyEvent.FLAG_FROM_SYSTEM | KeyEvent.FLAG_VIRTUAL_HARD_KEY,

            InputDevice.SOURCE_KEYBOARD);

    InputManager.getInstance().injectInputEvent(ev,

            InputManager.INJECT_INPUT_EVENT_MODE_ASYNC);

}

button.setOnClickListener(new View.OnClickListener() {

        @Override

        public void onClick(View v) {

            Log.e(TAG,"click dragButton ...");

            final long mDownTime = SystemClock.uptimeMillis();

            //onBackPressed();

            sendEvent(KeyEvent.ACTION_DOWN, 0, mDownTime);

            new Handler().postDelayed(new Runnable() {

                @Override

                public void run() {

                    sendEvent(KeyEvent.ACTION_UP, 0, SystemClock.uptimeMillis());

                }

            }, 300);

        }

    });

需要注意的地方，系统返回键对应的code为4，所以mCode=4，KeyButtonView的触摸事件包含按下和抬起，所以我们只需模拟发送按下和抬起事件，可以看到抬起事件加了300ms的延时发送，这是关键不然系统不会处理。

秒客网

Android6.0 源码修改之仿IOS添加全屏可拖拽浮窗返回按钮

前言

思路分析

一、添加悬浮窗

二、添加触摸事件监听

三、添加抬起滑动归位动画

四、添加点击返回功能

相关文章

Android6.0 源码修改之 仿IOS添加全屏可拖拽浮窗返回按钮

前言

思路分析

一、添加悬浮窗

二、添加触摸事件监听

三、添加抬起滑动归位动画

四、添加点击返回功能

相关文章

Android6.0 源码修改之仿IOS添加全屏可拖拽浮窗返回按钮