Android悬浮窗的一种实现

this.windowInfo = windowInfo

this.context = context

//‘为浮窗视图设置触摸监听器’

windowInfo.view?.setOnTouchListener(this)

windowInfo.layoutParams = createLayoutParam(x, y)

if (!windowInfo.hasParent().value()) {

val windowManager = this.context?.getSystemService(Context.WINDOW_SERVICE) as WindowManager

windowManager.addView(windowInfo.view, windowInfo.layoutParams)

}

}

override fun onTouch(v: View, event: MotionEvent): Boolean {

return false

}

}

在onTouch(v: View, event: MotionEvent)中可以拿到更详细的触摸事件，比如ACTION_DOWN，ACTION_MOVE、ACTION_UP。这方便了拖拽的实现，但点击事件的捕获变得复杂，因为需要定义上述三个 ACTION 以怎样的序列出现时才判定为点击事件。幸好GestureDetector为我们做了这件事：

public class GestureDetector {

public interface OnGestureListener {

//‘ACTION_DOWN事件’

boolean onDown(MotionEvent e);

//‘单击事件’

boolean onSingleTapUp(MotionEvent e);

//‘拖拽事件’

boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY);

…

}

}

构建GestureDetector实例并将MotionEvent传递给它就能将触摸事件解析成感兴趣的上层事件：

object FloatWindow : View.OnTouchListener{

private var gestureDetector: GestureDetector = GestureDetector(context, GestureListener())

private var clickListener: WindowClickListener? = null

private var lastTouchX: Int = 0

private var lastTouchY: Int = 0

//‘为浮窗设置点击监听器’

fun setClickListener(listener: WindowClickListener) {

clickListener = listener

}

override fun onTouch(v: View, event: MotionEvent): Boolean {

//‘将触摸事件传递给 GestureDetector 解析’

gestureDetector.onTouchEvent(event)

return true

}

//‘记忆起始触摸点坐标’

private fun onActionDown(event: MotionEvent) {

lastTouchX = event.rawX.toInt()

lastTouchY = event.rawY.toInt()

}

private class GestureListener : GestureDetector.OnGestureListener {

//‘记忆起始触摸点坐标’

override fun onDown(e: MotionEvent): Boolean {

onActionDown(e)

return false

}

override fun onSingleTapUp(e: MotionEvent): Boolean {

//‘点击事件发生时，调用监听器’

return clickListener?.onWindowClick(windowInfo) ?: false

}

…

}

//‘浮窗点击监听器’

interface WindowClickListener {

fun onWindowClick(windowInfo: WindowInfo?): Boolean

}

}

拖拽浮窗

---

ViewManager提供了updateViewLayout(View view, ViewGroup.LayoutParams params)用于更新浮窗位置，所以只需监听ACTION_MOVE事件并实时更新浮窗视图位置就可实现拖拽。ACTION_MOVE事件被GestureDetector解析成OnGestureListener.onScroll()回调：

object FloatWindow : View.OnTouchListener{

private var gestureDetector: GestureDetector = GestureDetector(context, GestureListener())

private var lastTouchX: Int = 0

private var lastTouchY: Int = 0

override fun onTouch(v: View, event: MotionEvent): Boolean {

//‘将触摸事件传递给GestureDetector解析’

gestureDetector.onTouchEvent(event)

return true

}

private class GestureListener : GestureDetector.OnGestureListener {

override fun onDown(e: MotionEvent): Boolean {

onActionDown(e)

return false

}

override fun onScroll(e1: MotionEvent,e2: MotionEvent,distanceX: Float,distanceY:Float): Boolean {

//‘响应手指滚动事件’

onActionMove(e2)

return true

}

}

private fun onActionMove(event: MotionEvent) {

//‘获取当前手指坐标’

val currentX = event.rawX.toInt()

val currentY = event.rawY.toInt()

//‘获取手指移动增量’

val dx = currentX - lastTouchX

val dy = currentY - lastTouchY

//‘将移动增量应用到窗口布局参数上’

windowInfo?.layoutParams!!.x += dx

windowInfo?.layoutParams!!.y += dy

val windowManager = context?.getSystemService(Context.WINDOW_SERVICE) as WindowManager

var rightMost = screenWidth - windowInfo?.layoutParams!!.width

var leftMost = 0

val topMost = 0

val bottomMost = screenHeight - windowInfo?.layoutParams!!.height - getNavigationBarHeight(context)

//‘将浮窗移动区域限制在屏幕内’

if (windowInfo?.layoutParams!!.x < leftMost) {

windowInfo?.layoutParams!!.x = leftMost

}

if (windowInfo?.layoutParams!!.x > rightMost) {

windowInfo?.layoutParams!!.x = rightMost

}

if (windowInfo?.layoutParams!!.y < topMost) {

windowInfo?.layoutParams!!.y = topMost

}

if (windowInfo?.layoutParams!!.y > bottomMost) {

windowInfo?.layoutParams!!.y = bottomMost

}

//‘更新浮窗位置’

windowManager.updateViewLayout(windowInfo?.view, windowInfo?.layoutParams)

lastTouchX = currentX

lastTouchY = currentY

}

}

浮窗自动贴边

---

新的需求来了，拖拽浮窗松手后，需要自动贴边。

把贴边理解成一个水平位移动画。在松手时求出动画起点和终点横坐标，利用动画值不断更新浮窗位置：

object FloatWindow : View.OnTouchListener{

private var gestureDetector: GestureDetector = GestureDetector(context, GestureListener())

private var lastTouchX: Int = 0

private var lastTouchY: Int = 0

//‘贴边动画’

private var weltAnimator: ValueAnimator? = null

override fun onTouch(v: View, event: MotionEvent): Boolean {

//‘将触摸事件传递给GestureDetector解析’

gestureDetector.onTouchEvent(event)

//‘处理ACTION_UP事件’

val action = event.action

when (action) {

MotionEvent.ACTION_UP -> onActionUp(event, screenWidth, windowInfo?.width ?: 0)

else -> {

}

}

return true

}

private fun onActionUp(event: MotionEvent, screenWidth: Int, width: Int) {

if (!windowInfo?.hasView().value()) { return }

//‘记录抬手横坐标’

val upX = event.rawX.toInt()

//‘贴边动画终点横坐标’

val endX = if (upX > screenWidth / 2) {

screenWidth - width

} else {

0

}

//‘构建贴边动画’

if (weltAnimator == null) {

weltAnimator = ValueAnimator.ofInt(windowInfo?.layoutParams!!.x, endX).apply {

interpolator = LinearInterpolator()

duration = 300

addUpdateListener { animation ->

val x = animation.animatedValue as Int

if (windowInfo?.layoutParams != null) {

windowInfo?.layoutParams!!.x = x

}

val windowManager = context?.getSystemService(Context.WINDOW_SERVICE) as WindowManager

//‘更新窗口位置’

if (windowInfo?.hasParent().value()) {

windowManager.updateViewLayout(windowInfo?.view, windowInfo?.layoutParams)

}

}

}

}

weltAnimator?.setIntValues(windowInfo?.layoutParams!!.x, endX)

weltAnimator?.start()

}

//为空Boolean提供默认值

fun Boolean?.value() = this ?: false

}

• GestureDetector解析后ACTION_UP事件被吞掉了，所以只能在onTouch()中截获它。

• 根据抬手横坐标和屏幕中点横坐标的大小关系，来决定浮窗贴向左边还是右边。

管理多个浮窗

---

若 app 的不同业务界面同时需要显示浮窗：进入 界面A 时显示 浮窗A，然后它被拖拽到右下角，退出 界面A 进入 界面B，显示浮窗B，当再次进入 界面A 时，期望还原上次离开时的浮窗A的位置。

当前FloatWindow中用windowInfo成员存储单个浮窗参数，为了同时管理多个浮窗，需要将所有浮窗参数保存在Map结构中用 tag 区分：

object FloatWindow : View.OnTouchListener {

//‘浮窗参数容器’

private var windowInfoMap: HashMap<String, WindowInfo?> = HashMap()

//‘当前浮窗参数’

var windowInfo: WindowInfo? = null

//‘显示浮窗’

fun show(

context: Context,

//‘浮窗标签’

tag: String,

//‘若不提供浮窗参数则从参数容器中获取该tag上次保存的参数’

windowInfo: WindowInfo? = windowInfoMap[tag],

x: Int = windowInfo?.layoutParams?.x.value(),

y: Int = windowInfo?.layoutParams?.y.value()

) {

if (windowInfo == null) { return }

if (windowInfo.view == null) { return }

//‘更新当前浮窗参数’

this.windowInfo = windowInfo

//‘将浮窗参数存入容器’

windowInfoMap[tag] = windowInfo

windowInfo.view?.setOnTouchListener(this)

this.context = context

windowInfo.layoutParams = createLayoutParam(x, y)

if (!windowInfo.hasParent().value()) {

val windowManager =this.context?.getSystemService(Context.WINDOW_SERVICE) as WindowManager

windowManager.addView(windowInfo.view, windowInfo.layoutParams)

}

}

}

在显示浮窗时，增加tag标签参数用以唯一标识浮窗，并且为windowInfo提供默认参数，当恢复原有浮窗时，可以不提供windowInfo参数，FloatWindow就会去windowInfoMap中根据给定tag寻找对应windowInfo。

监听浮窗界外点击事件

---

新的需求来了，点击浮窗时，贴边的浮窗像抽屉一样展示，点击浮窗以外区域时，抽屉收起。

刚开始接到这个新需求时，没什么思路。转念一想PopupWindow有一个setOutsideTouchable()：

public class PopupWindow {

/**

• Controls whether the pop-up will be informed of touch events outside

• of its window.

• @param touchable true if the popup should receive outside

• touch events, false otherwise

*/

public void setOutsideTouchable(boolean touchable) {

mOutsideTouchable = touchable;

}

}

该函数用于设置是否允许 window 边界外的触摸事件传递给 window。跟踪mOutsideTouchable变量应该就能找到更多线索：

public class PopupWindow {

private int computeFlags(int curFlags) {

curFlags &= ~(

WindowManager.LayoutParams.FLAG_IGNORE_CHEEK_PRESSES |

WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE |

WindowManager.LayoutParams.FLAG_NOT_TOUCHABLE |

WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH |

WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS |

WindowManager.LayoutParams.FLAG_ALT_FOCUSABLE_IM |

WindowManager.LayoutParams.FLAG_SPLIT_TOUCH);

…

//‘如果界外可触摸，则将FLAG_WATCH_OUTSIDE_TOUCH赋值给flag’

if (mOutsideTouchable) {

curFlags |= WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH;

}

…

}

}

继续往上跟踪computeFlags()调用的地方：

public class PopupWindow {

protected final WindowManager.LayoutParams createPopupLayoutParams(IBinder token) {

final WindowManager.LayoutParams p = new WindowManager.LayoutParams();

p.gravity = computeGravity();

//‘计算窗口布局参数flag属性并赋值’

p.flags = computeFlags(p.flags);

p.type = mWindowLayoutType;

p.token = token;

…

}

}

而createPopupLayoutParams()会在窗口显示的时候被调用：

public class PopupWindow {

public void showAtLocation(IBinder token, int gravity, int x, int y) {

if (isShowing() || mContentView == null) { return; }

TransitionManager.endTransitions(mDecorView);

detachFromAnchor();

mIsShowing = true;

mIsDropdown = false;

mGravity = gravity;

//‘构建窗口布局参数’

final WindowManager.LayoutParams p = createPopupLayoutParams(token);

preparePopup§;

p.x = x;

p.y = y;

invokePopup§;

}

}

想在源码中继续搜索，但到FLAG_WATCH_OUTSIDE_TOUCH，线索就断了。现在只知道为了让界外点击事件传递给 window，必须为布局参数设置FLAG_WATCH_OUTSIDE_TOUCH。但事件响应逻辑应该写在哪里？

当调用PopupWindow.setOutsideTouchable(true)，在窗口界外点击后，窗口会消失。这必然是调用了dismiss()，沿着dismiss()的调用链往上找一定能找到界外点击事件的响应逻辑：

public class PopupWindow {

//‘窗口根视图’

private class PopupDecorView extends FrameLayout {

//‘窗口根视图触摸事件’

@Override

public boolean onTouchEvent(MotionEvent event) {

final int x = (int) event.getX();

final int y = (int) event.getY();

if ((event.getAction() == MotionEvent.ACTION_DOWN)

&& ((x < 0) || (x >= getWidth()) || (y < 0) || (y >= getHeight()))) {

dismiss();

return true;

//‘如果发生了界外触摸事件则解散窗口’

} else if (event.getAction() == MotionEvent.ACTION_OUTSIDE) {

dismiss();

return true;

} else {

return super.onTouchEvent(event);

}

}

}

}

所以只需要在窗口根视图的触摸事件回调中捕获ACTION_OUTSIDE即可：

object FloatWindow : View.OnTouchListener {

//‘界外触摸事件回调’

private var onTouchOutside: (() -> Unit)? = null

//‘设置是否响应界外点击事件’

fun setOutsideTouchable(enable: Boolean, onTouchOutside: (() -> Unit)? = null) {

windowInfo?.layoutParams?.let { layoutParams ->

layoutParams.flags = layoutParams.flags or WindowManager.LayoutParams.FLAG_WATCH_OUTSIDE_TOUCH

this.onTouchOutside = onTouchOutside

}

}

override fun onTouch(v: View, event: MotionEvent): Boolean {

//‘界外触摸事件处理’

if (event.action == MotionEvent.ACTION_OUTSIDE) {

onTouchOutside?.invoke()

return true

}

//‘点击和拖拽事件处理’

gestureDetector.onTouchEvent(event).takeIf { !it }?.also {

//there is no ACTION_UP event in GestureDetector

val action = event.action

when (action) {

MotionEvent.ACTION_UP -> onActionUp(event, screenWidth, windowInfo?.width ?: 0)

else -> {

}

尾声

对于很多初中级Android工程师而言，想要提升技能，往往是自己摸索成长，不成体系的学习效果低效漫长且无助。 整理的这些架构技术希望对Android开发的朋友们有所参考以及少走弯路，本文的重点是你有没有收获与成长，其余的都不重要，希望读者们能谨记这一点。

最后想要拿高薪实现技术提升薪水得到质的飞跃。最快捷的方式，就是有人可以带着你一起分析，这样学习起来最为高效，所以为了大家能够顺利进阶中高级、架构师，我特地为大家准备了一套高手学习的源码和框架视频等精品Android架构师教程，保证你学了以后保证薪资上升一个台阶。

• 思维脑图
  
• 性能优化学习笔记
  
  

• 性能优化视频
  
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  n

when (action) {

MotionEvent.ACTION_UP -> onActionUp(event, screenWidth, windowInfo?.width ?: 0)

else -> {

}

尾声

对于很多初中级Android工程师而言，想要提升技能，往往是自己摸索成长，不成体系的学习效果低效漫长且无助。 整理的这些架构技术希望对Android开发的朋友们有所参考以及少走弯路，本文的重点是你有没有收获与成长，其余的都不重要，希望读者们能谨记这一点。

最后想要拿高薪实现技术提升薪水得到质的飞跃。最快捷的方式，就是有人可以带着你一起分析，这样学习起来最为高效，所以为了大家能够顺利进阶中高级、架构师，我特地为大家准备了一套高手学习的源码和框架视频等精品Android架构师教程，保证你学了以后保证薪资上升一个台阶。

• 思维脑图
  [外链图片转存中…(img-0S8f9AeQ-1714788038589)]
• 性能优化学习笔记
  [外链图片转存中…(img-qw0i4QsM-1714788038591)]
  [外链图片转存中…(img-WdTirT1g-1714788038592)]

[外链图片转存中…(img-NurihOiY-1714788038593)]
[外链图片转存中…(img-N4XG6Qa0-1714788038594)]

• 性能优化视频
  [外链图片转存中…(img-rqIRAQzQ-1714788038595)]
  当你有了学习线路，学习哪些内容，也知道以后的路怎么走了，理论看多了总要实践的。
  《Android学习笔记总结+移动架构视频+大厂面试真题+项目实战源码》，点击传送门，即可获取！