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The introduction of shell transitions consolidated and codified the method of
running animations within the system, allowing for the retrieval of centralized
information regarding the animations slated for execution.
The transition trace includes data on every transition that occurs within the
WindowManager (WM) shell, originating from both the system server and shell
sides. This trace is permanently enabled in Droidfood and automatically embedded
in bug reports.
Winscope's Transitions viewer displays this information for transition
traces containing both server and client-side information. The viewer consists
of a table log view containing the high-level information about the transition
on the left and a detailed view for each transition at the right:
Targets are the elements involved in the transition (normally activities or
tasks). For each target we record:
layerId: Layer that is being animated (from SurfaceFlinger hierarchy).
mode: Type of animation performed on this layer.
windowId: Window that is being animated (from WindowManager hierarchy).
flags: New set of flags being applied to the layer.
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Last updated 2025-08-29 UTC.
[null,null,["Last updated 2025-08-29 UTC."],[],[],null,["# Shell transitions\n\nThe introduction of shell transitions consolidated and codified the method of\nrunning animations within the system, allowing for the retrieval of centralized\ninformation regarding the animations slated for execution.\n\nThe transition trace includes data on every transition that occurs within the\nWindowManager (WM) shell, originating from both the system server and shell\nsides. This trace is permanently enabled in Droidfood and automatically embedded\nin bug reports.\n| **Note:** The transitions are stored in a ring buffer, which is recorded by different processes. As a result, it's possible that portions (usually the initial segments) of a transition might have been removed from the buffer. For example, when sending a transition creation time followed by a start and finish time, the buffer might contain all three segments, only the start and finish times, or even only the finish time. This limitation is consistent with other Perfetto data segments and, similar to Perfetto, the limitation is handled during rendering rather than during data creation or parsing.\n\nFor more information about trace collection, see\n[Shell transitions](/docs/core/graphics/winscope/capture/adb#capture-adb-transitions).\n\nWinscope's Transitions viewer displays this information for transition\ntraces containing both server and client-side information. The viewer consists\nof a table log view containing the high-level information about the transition\non the left and a detailed view for each transition at the right:\n\n**Figure 1.** Shell transition trace analysis.\n\nTable view\n----------\n\nThe table view contains:\n\n- **Id:** Transition ID generated only for debugging.\n- **Type:** Transition type, as defined in [`Transitions.java`](https://cs.android.com/android/platform/superproject/+/android-latest-release:frameworks/base/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java)\n- **Send Time:** Timestamp the transition was sent over from server to shell to be handled.\n- **Dispatch Time:** Timestamp when the transition is dispatched to the handler to start playing.\n- **Duration:** Time the transition took from starting to play to finished.\n- **Status:** If the transition was:\n - **PLAYED:**: Played.\n - **ABORTED**: Aborted before playing. A transition can be aborted from from shell or WM side.\n - **MERGED**: Merged by the transition handler into some other already playing transition (the handler decides how to handle this).\n\nDetailed view\n-------------\n\nIn addition to the details on the table view, the detailed transition view\nin the **SELECTED TRANSITION** section contains:\n\n- `handler`: The transition handler that handled this animation.\n- `createTimeNs`: Timestamp the transition was created on the WM server side.\n- `finishTimeNs`: Timestamp when the WM server side is notified that the transition has finished running on the shell side.\n- `endTransactionId`: Final SurfaceFlinger transaction included in this transition.\n- `startTransactionId`: Initial SurfaceFlinger transaction included in this transition.\n- `targets`: List of transition participants.\n- `type`: Transition type, as defined in [`Transitions.java`](https://cs.android.com/android/platform/superproject/+/android-latest-release:frameworks/base/libs/WindowManager/Shell/src/com/android/wm/shell/transition/Transitions.java)\n\n### Targets\n\nTargets are the elements involved in the transition (normally activities or\ntasks). For each target we record:\n\n- `layerId`: Layer that is being animated (from SurfaceFlinger hierarchy).\n- `mode`: Type of animation performed on this layer.\n- `windowId`: Window that is being animated (from WindowManager hierarchy).\n- `flags`: New set of flags being applied to the layer."]]
