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小编给大家分享一下Android悬浮窗如何实现，相信大部分人都还不怎么了解，因此分享这篇文章给大家参考一下，希望大家阅读完这篇文章后大有收获，下面让我们一起去了解一下吧！
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效果如下：
原生ViewManager接口提供了向窗口添加并操纵View的方法：
public interface ViewManager{ //'向窗口添加视图'
public void addView(View view, ViewGroup.LayoutParams params); //'更新窗口中视图'
public void updateViewLayout(View view, ViewGroup.LayoutParams params); //'移除窗口中视图'
public void removeView(View view);
}
复制代码使用这个接口显示窗口的模版代码如下：
//'解析布局文件为视图'val windowView = LayoutInflater.from(context).inflate(R.id.window_view, null)//'获取WindowManager系统服务'val windowManager = context.getSystemService(Context.WINDOW_SERVICE) as WindowManager//'构建窗口布局参数'WindowManager.LayoutParams().apply {
type = WindowManager.LayoutParams.TYPE_APPLICATION
width = WindowManager.LayoutParams.WRAP_CONTENT
height = WindowManager.LayoutParams.WRAP_CONTENT
gravity = Gravity.START or Gravity.TOP
x = 0
y = 0}.let { layoutParams-> //'将视图添加到窗口'
windowManager.addView(windowView, layoutParams)
}
复制代码上述代码在当前界面的左上角显示R.id.window_view.xml中定义的布局。
为避免重复，将这段代码抽象成一个函数，其中窗口视图内容和展示位置会随着需求而变，遂将其参数化：
object FloatWindow{ private var context: Context? = null //'当前窗口参数'
var windowInfo: WindowInfo? = null //'把和Window布局有关的参数打包成一个内部类'
class WindowInfo(var view: View?) {
var layoutParams: WindowManager.LayoutParams? = null //'窗口宽'
var width: Int = 0
//'窗口高'
var height: Int = 0
//'窗口中是否有视图'
fun hasView() = view != null && layoutParams != null //'窗口中视图是否有父亲'
fun hasParent() = hasView() && view?.parent != null
} //'显示窗口'
fun show(
context: Context,
windowInfo: WindowInfo?,
x: Int = windowInfo?.layoutParams?.x.value(),
y: Int = windowInfo?.layoutParams?.y.value(),
) { if (windowInfo == null) { return } if (windowInfo.view == null) { return } this.windowInfo = windowInfo this.context = context //'创建窗口布局参数'
windowInfo.layoutParams = createLayoutParam(x, y) //'显示窗口'
if (!windowInfo.hasParent().value()) {
val windowManager = this.context?.getSystemService(Context.WINDOW_SERVICE) as WindowManager
windowManager.addView(windowInfo.view, windowInfo.layoutParams)
}
} //'创建窗口布局参数'
private fun createLayoutParam(x: Int, y: Int): WindowManager.LayoutParams { if (context == null) { return WindowManager.LayoutParams() } return WindowManager.LayoutParams().apply { //'该类型不需要申请权限'
type = WindowManager.LayoutParams.TYPE_APPLICATION
format = PixelFormat.TRANSLUCENT
flags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE or WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS
gravity = Gravity.START or Gravity.TOP
width = windowInfo?.width.value()
height = windowInfo?.height.value() this.x = x this.y = y
}
} //'为空Int提供默认值'
fun Int?.value() = this ?: 0}
复制代码将FloatWindow声明成了单例，目的是在 app 整个生命周期，任何界面都可以方便地显示浮窗。
为了方便统一管理窗口的参数，抽象了内部类WindowInfo
现在就可以像这样在屏幕左上角显示一个浮窗了：
val windowView = LayoutInflater.from(context).inflate(R.id.window_view, null)
WindowInfo(windowView).apply{
width = 100
height = 100
}.let{ windowInfo ->
FloatWindow.show(context, windowInfo, 0, 0)
}
复制代码产品要求当浮窗显示时，屏幕变暗。设置WindowManager.LayoutParams.FLAG_DIM_BEHIND标签配合dimAmount就能轻松实现：
object FloatWindow{ //当前窗口参数
var windowInfo: WindowInfo? = null
private fun createLayoutParam(x: Int, y: Int): WindowManager.LayoutParams { if (context == null) { return WindowManager.LayoutParams() } return WindowManager.LayoutParams().apply {
type = WindowManager.LayoutParams.TYPE_APPLICATION
format = PixelFormat.TRANSLUCENT
flags =
WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE or
WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS or //'设置浮窗背景变暗'
WindowManager.LayoutParams.FLAG_DIM_BEHIND //'设置默认变暗程度为0，即不变暗，1表示全黑'
dimAmount = 0f
gravity = Gravity.START or Gravity.TOP
width = windowInfo?.width.value()
height = windowInfo?.height.value() this.x = x this.y = y
}
} //'供业务界面在需要的时候调整浮窗背景亮暗'
fun setDimAmount(amount:Float){
windowInfo?.layoutParams?.let { it.dimAmount = amount }
}
}
复制代码为浮窗设置点击事件等价于为浮窗视图设置点击事件，但如果直接对浮窗视图使用setOnClickListener()的话，浮窗的触摸事件就不会被响应，那拖拽就无法实现。所以只能从更底层的触摸事件着手：
object FloatWindow : View.OnTouchListener{
//'显示窗口'
fun show(
context: Context,
windowInfo: WindowInfo?,
x: Int = windowInfo?.layoutParams?.x.value(),
y: Int = windowInfo?.layoutParams?.y.value(),
) { if (windowInfo == null) { return } if (windowInfo.view == null) { return } 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
}
}
复制代码在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);
...
}
}
复制代码构建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
}
}
复制代码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
}
}
复制代码新的需求来了，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}
复制代码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。
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 = 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)
}
}
}
复制代码 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。
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;
}
}
复制代码
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;
}
...
}
}
复制代码继续往上跟踪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;
...
}
}
复制代码而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);
p.x = x;
p.y = y;
invokePopup(p);
}
}
复制代码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);
}
}
}
}
复制代码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 -> {
}
}
} return true
}
}
复制代码以上是“Android悬浮窗如何实现”这篇文章的所有内容，感谢各位的阅读！相信大家都有了一定的了解，希望分享的内容对大家有所帮助，如果还想学习更多知识，欢迎关注创新互联行业资讯频道！
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