Android SystemBar 碎碎念

1、android systembar 碎碎念android systembar在android中向来饰演着十分重要的角色，google也向来在优化这一部分的用户体验，结合最近的工作体验碎碎念 rom 去掉navigationbar、systembar translucent支持、systembar setcolor支持几个小点。 rom 去掉navigationbar resgrep navigationbar相关的res，发觉在framework/base/core/res/res/config.xml中可以通过config_shownavigationbar配置，继续jgrep showna

2、vigationbar相关的java，发觉在phonewindowmanager中通过boolean变量mhasnavigationbar记录是否有navigationbar，详细代码如下： mhasnavigationbar = res.getboolean(ernal.r.bool.config_shownavigationbar); 需要注重的是mhasnavigationbar也可以通过系统提供的property来标识，详细代码如下： string navbaroverride = systemproperties.get("qemu.h

3、w.mainkeys"); if ("1".equals(navbaroverride) mhasnavigationbar = false; else if ("0".equals(navbaroverride) mhasnavigationbar = true; 在phonewindowmanager中存在一个类型为windowstate的变量mnavigationbar，windowstate是在phonewindowmanger prepareaddwindow时会用到的一个interface，认

4、真看看prepareaddwindowlw办法 switch (attrs.type) case type_navigation_bar: mcontext.enforcecallingorselfpermission(android.manifest.permission.status_bar_service, "phonewindowmanager"); if (mnavigationbar != null) if (mnavigationbar.isalive() return windowmanagerglobal.add_multiple_sing

5、leton; mnavigationbar = win; mnavigationbarcontroller.setwindow(win); if (debug_layout) slog.i(tag, "navigation bar: " + mnavigationbar); break; 推断type为type_navigation_bar的时候，给mnavigationbar赋值，并且mnavigationbarcontroller setwindow，mnavigationbarcontroller是一个用来操纵systembar window的类，有爱

6、好可以具体看看这个类，位于/framework/base/services/core/java/com/android/server/policy。继续扫瞄代码会发觉办法layoutnavigationbar，通过mnavigationbarcontroller对mnavigationbar举行layout。 在framework/base/packages/systemui中phonestatusbar中makestatusbarview有如下一段代码： try boolean shownav = mwindowmanagerservice.hasnavigationbar(); if (d

7、ebug) log.v(tag, "hasnavigationbar=" + shownav); if (shownav) createnavigationbarview(context); catch (remoteexception ex) / no window manager? good luck with that 按照windowmanagerservice中的hasnavigationbar办法推断是否有navigationbar，再看windowmangerservice中是调用了phonewindowmanager中的hasnavigati

8、onbar办法，终于返回的就是最开头提到了mhasnavigationbar这个标识。在phonestatusbar有具体讲到如何createandaddwindows，感爱好可以再进一步了解。 systembar translucent支持 android在api 19的时候添加了两个windowmanager.layoutparams，分离是flag_translucent_navigation、flag_translucent_status。 在官方文档中有提到当为window设置flag_translucent_navigation时，自动设置了system ui visibility

9、 system_ui_flag_layout_stable、system_ui_flag_layout_hide_navigation，当为window设置了flag_translucent_status时，自动设置了system ui visibility system_ui_flag_layout_stable、system_ui_flag_layout_fullscreen。 明显，这时system ui visibility有发生变幻，在phonewindowmanager中有如下一段代码： public int adjustsystemuivisibilitylw(int visib

10、ility) mstatusbarcontroller.adjustsystemuivisibilitylw(mlastsystemuiflags, visibility); mnavigationbarcontroller.adjustsystemuivisibilitylw(mlastsystemuiflags, visibility); mrecentsvisible = (visibility & view.recent_apps_visible) > 0; mtvpictureinpicturevisible = (visibility & vi

11、ew.tv_picture_in_picture_visible) > 0; / reset any bits in mforceclearingstatusbarvisibility that / are now clear. mresettingsystemuiflags &= visibility; / clear any bits in the new visibility that are currently being / force cleared, before reporting it. return visibility & &

12、mdash;—mresettingsystemuiflags & ——mforceclearedsystemuiflags; 可以看到前边提到的操控systembar的controller这个时候发挥了作用，调用了其adjustsystemuivisibilitylw，继续看barcontroller中相关代码 public void adjustsystemuivisibilitylw(int oldvis, int vis) if (mwin != null && mtransien

13、tbarstate = transient_bar_showing && (vis & mtransientflag) = 0) / sysui requests hide settransientbarstate(transient_bar_hiding); setbarshowinglw(false); else if (mwin != null && (oldvis & munhideflag) != 0 && (vis & munhidefla

14、 = 0) / sysui ready to unhide setbarshowinglw(true); 同时，看到barcontroller中有applytranslucentflaglw，通过查找其调用处，发觉依然是在phonewindowmanager中调用，以下是调用部分 / apply translucent bar vis flags windowstate fullscreentranswin = isstatusbarkeyguard() && !mhidelockscreen ? mstatusbar : mtopfullscreenopaqu

15、ewindowstate; vis = mstatusbarcontroller.applytranslucentflaglw(fullscreentranswin, vis, oldvs); vis = mnavigationbarcontroller.applytranslucentflaglw(fullscreentranswin, vis, oldvis); final int dockedvis = mstatusbarcontroller.applytranslucentflaglw(mtopdockedopaquewindowstate, 0, 0); final boolean

16、 fullscreendrawsstatusbarbackground = (drawssystembarbackground(mtopfullscreenopaquewindowstate) && (vis & view.status_bar_translucent) = 0) | forcesdrawstatusbarbackground(mtopfullscreenopaquewindowstate); final boolean dockeddrawsstatusbarbackground = (drawssystembarbackgro

17、und(mtopdockedopaquewindowstate) && (dockedvis & view.status_bar_translucent) = 0) | forcesdrawstatusbarbackground(mtopdockedopaquewindowstate); 可以看到在phonewindowmanager中通过updatesystembarslw举行了相应的更新systembars。这个地方还有一个比较故意思的问题是，在实际用法这两个flag的时候，会发觉app自动延长到statusbar和navigationbar

18、下方，这是为何？ 猜测，应当是app区域对系统下发的windowinsets值做了处理，查看actionbaroverlaylayout onapplywindowinsets办法，可以发觉通过computefitsystemwindows对actionbaroverlaylayout的measure时用到的insets值做了处理，查看view的computefitsystemwindows办法 protected boolean computefitsystemwindows(rect inoutinsets, rect outlocalinsets) if (mviewflags &

19、;amp; optional_fits_system_windows) = 0 | mattachinfo = null | (mattachinfo.msystemuivisibility & system_ui_layout_flags) = 0 && !mattachinfo.moverscanrequested) outlocalinsets.set(inoutinsets); inoutinsets.set(0, 0, 0, 0); return true; else / the application wants to take ca

20、re of fitting system window for / the content. however we still need to take care of any overscan here. final rect overscan = mattachinfo.moverscaninsets; outlocalinsets.set(overscan); inoutinsets.left -= overscan.left; inoutinsets.top -= overscan.top; inoutinsets.right -= overscan.right; inoutinset

21、s.bottom -= overscan.bottom; return false; 可以发觉这个地方，按照flag的推断通过overscan rect对actionbaroverlaylayout的insets值举行了修改(最近把这个处理移植到api 19以下了，嘿嘿嘿)。固然google也没士气对这个处理一锅端，因此app可以用法fitssystemwindows属性来避开系统做这个处理，通过这个属性可以默认把insets值给到当前view的padding值，固然app也可以自己继承view的fitsystemwindows办法来自己处理insets。 systembar setcolor支持 android在api 21的时候为window添加了setnavigationba