Android 16系统源码_分屏模式（二）全屏分屏模式层级树信息

前言

上一篇我们通过一个简单demo初步认识了分屏模式。本篇文章我们先具体来看下全屏和分屏场景下的层级树信息，并对二者做个简单比较，以便对分屏模式的实现方案有个更深入的认识。

全屏模式层级树信息

全屏模式下层级树的DefaultTaskDisplayArea节点信息如下所示。

       #1 DefaultTaskDisplayArea type=undefined mode=fullscreen override-mode=fullscreen requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
        #2 Task=8 type=standard mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
         #0 ActivityRecord{f6cfd18 u0 com.example.myapplication/.MainActivity t8} type=standard mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
          #0 40df6b5 com.example.myapplication/com.example.myapplication.MainActivity type=standard mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
        #1 Task=1 type=home mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
         #0 Task=7 type=home mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
          #0 ActivityRecord{58c8437 u0 com.android.launcher3/.uioverrides.QuickstepLauncher t7} type=home mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
           #0 324fb94 com.android.launcher3/com.android.launcher3.uioverrides.QuickstepLauncher type=home mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
        #0 Task=2 type=undefined mode=fullscreen override-mode=fullscreen requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
         #1 Task=4 type=undefined mode=multi-window override-mode=multi-window requested-bounds=[0,2400][1080,3600] bounds=[0,2400][1080,3600]
         #0 Task=3 type=undefined mode=multi-window override-mode=multi-window requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]

在全屏模式下MainActivity的相关信息如下：

• 根Task的mode=fullscreen(全屏模式)，bounds=[0,0][1080,2400]
• 父节点ActivityRecord的mode=fullscreen(全屏模式)，bounds=[0,0][1080,2400]
• MainActivity的mode=fullscreen(全屏模式)，bounds=[0,0][1080,2400]

分屏模式层级树信息

分屏模式下层级树的DefaultTaskDisplayArea节点信息如下所示。

       #1 DefaultTaskDisplayArea type=undefined mode=fullscreen override-mode=fullscreen requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
        #1 Task=2 type=standard mode=fullscreen override-mode=fullscreen requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
         #1 Task=3 type=standard mode=multi-window override-mode=multi-window requested-bounds=[0,1213][1080,2400] bounds=[0,1213][1080,2400]
          #0 Task=9 type=standard mode=multi-window override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,1213][1080,2400]
           #0 ActivityRecord{d7a81a6 u0 com.android.dialer/.main.impl.MainActivity t9} type=standard mode=multi-window override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,1213][1080,2400]
            #0 a2bfc4a com.android.dialer/com.android.dialer.main.impl.MainActivity type=standard mode=multi-window override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,1213][1080,2400]
         #0 Task=4 type=standard mode=multi-window override-mode=multi-window requested-bounds=[0,0][1080,1187] bounds=[0,0][1080,1187]
          #0 Task=8 type=standard mode=multi-window override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,1187]
           #0 ActivityRecord{f6cfd18 u0 com.example.myapplication/.MainActivity t8} type=standard mode=multi-window override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,1187]
            #0 40df6b5 com.example.myapplication/com.example.myapplication.MainActivity type=standard mode=multi-window override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,1187]
        #0 Task=1 type=home mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
         #0 Task=7 type=home mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
          #0 ActivityRecord{58c8437 u0 com.android.launcher3/.uioverrides.QuickstepLauncher t7} type=home mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]
           #0 324fb94 com.android.launcher3/com.android.launcher3.uioverrides.QuickstepLauncher type=home mode=fullscreen override-mode=undefined requested-bounds=[0,0][0,0] bounds=[0,0][1080,2400]

在分屏窗口模式下MainActivity的相关信息如下：

• 处于分屏模式的的两个Activity共用一个根Task。
• 每个Activity的父节点是ActivityRecord，然后又连续被两个Task包裹，最终共同挂载在一个Task上，该Task再挂载到DefaultTaskDisplayArea节点上。

分屏模式SurfaceFlinger信息

Display 4619827259835644672 (active) HWC layers:
---------------------------------------------------------------------------------------------------------------------------------------------------------------
 Layer name
           Z |  Window Type |  Comp Type |  Transform |   Disp Frame (LTRB) |          Source Crop (LTRB) |     Frame Rate (Explicit) (Seamlessness) [Focused]
---------------------------------------------------------------------------------------------------------------------------------------------------------------
 com.example.myapplication/com.example.myapplication.MainActivity#179
  rel      0 |            1 |     DEVICE |          0 |    0    0 1080 1187 |    0.0    0.0 1080.0 1187.0 |                                              [ ]
---------------------------------------------------------------------------------------------------------------------------------------------------------------
 com.android.dialer/com.android.dialer.main.impl.MainActivity#180
  rel      0 |            1 |     DEVICE |          0 |    0 1213 1080 2400 |    0.0    0.0 1080.0 1187.0 |                                              [*]
---------------------------------------------------------------------------------------------------------------------------------------------------------------
 StageCoordinatorSplitDivider#187
  rel      0 |            0 |     DEVICE |          0 |    0 1137 1080 1263 |    0.0    0.0 1080.0  126.0 |                                              [ ]
---------------------------------------------------------------------------------------------------------------------------------------------------------------
 StatusBar#84
  rel      0 |         2000 |     DEVICE |          0 |    0    0 1080   63 |    0.0    0.0 1080.0   63.0 |                                              [ ]
---------------------------------------------------------------------------------------------------------------------------------------------------------------
 NavigationBar0#83
  rel      0 |         2019 |     DEVICE |          0 |    0 2274 1080 2400 |    0.0    0.0 1080.0  126.0 |                                              [ ]
---------------------------------------------------------------------------------------------------------------------------------------------------------------

• StageCoordinatorSplitDivider 分屏模式中间的分割线视图
  

总结

• 当应用Activity处于全屏模式的时候，其父类ActivityRecord，ActivityRecord的父类为Task，该Task直接挂载在DefaultTaskDisplayArea节点上。
• 当应用Activity处于分屏模式的时候，其父类为ActivityRecord，该Task没有直接挂载到直接挂载在DefaultTaskDisplayArea节点上，而是连续被两个Task包裹，最终共同挂载在同一个根Task上，然后该根Task直接挂载在DefaultTaskDisplayArea叶子节点上。
• 当处于分屏模式的时候，系统会添加一个名为StageCoordinatorSplitDivider的分割线视图。

理解了这点，后面我们再结合Android系统任务栈的特性，才能够更好的理解分屏模式框架的实现思路。

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