State	Transition Cause	New State	Notes
INACTIVE		INACTIVE	Never changes

State	Transition Cause	New State	Notes
INACTIVE	AF_TRIGGER	ACTIVE_SCAN	Start AF sweep, Lens now moving
ACTIVE_SCAN	AF sweep done	FOCUSED_LOCKED	Focused, Lens now locked
ACTIVE_SCAN	AF sweep done	NOT_FOCUSED_LOCKED	Not focused, Lens now locked
ACTIVE_SCAN	AF_CANCEL	INACTIVE	Cancel/reset AF, Lens now locked
FOCUSED_LOCKED	AF_CANCEL	INACTIVE	Cancel/reset AF
FOCUSED_LOCKED	AF_TRIGGER	ACTIVE_SCAN	Start new sweep, Lens now moving
NOT_FOCUSED_LOCKED	AF_CANCEL	INACTIVE	Cancel/reset AF
NOT_FOCUSED_LOCKED	AF_TRIGGER	ACTIVE_SCAN	Start new sweep, Lens now moving
Any state	Mode change	INACTIVE

State	Transition Cause	New State	Notes
INACTIVE	AF_TRIGGER	FOCUSED_LOCKED	Focus is already good or good after a scan, lens is now locked.
INACTIVE	AF_TRIGGER	NOT_FOCUSED_LOCKED	Focus failed after a scan, lens is now locked.
FOCUSED_LOCKED	AF_TRIGGER	FOCUSED_LOCKED	Focus is already good or good after a scan, lens is now locked.
NOT_FOCUSED_LOCKED	AF_TRIGGER	FOCUSED_LOCKED	Focus is good after a scan, lens is not locked.

State	Transition Cause	New State	Notes
INACTIVE	Camera device initiates new scan	PASSIVE_SCAN	Start AF scan, Lens now moving
INACTIVE	AF_TRIGGER	NOT_FOCUSED_LOCKED	AF state query, Lens now locked
PASSIVE_SCAN	Camera device completes current scan	PASSIVE_FOCUSED	End AF scan, Lens now locked
PASSIVE_SCAN	Camera device fails current scan	PASSIVE_UNFOCUSED	End AF scan, Lens now locked
PASSIVE_SCAN	AF_TRIGGER	FOCUSED_LOCKED	Immediate transition, if focus is good. Lens now locked
PASSIVE_SCAN	AF_TRIGGER	NOT_FOCUSED_LOCKED	Immediate transition, if focus is bad. Lens now locked
PASSIVE_SCAN	AF_CANCEL	INACTIVE	Reset lens position, Lens now locked
PASSIVE_FOCUSED	Camera device initiates new scan	PASSIVE_SCAN	Start AF scan, Lens now moving
PASSIVE_UNFOCUSED	Camera device initiates new scan	PASSIVE_SCAN	Start AF scan, Lens now moving
PASSIVE_FOCUSED	AF_TRIGGER	FOCUSED_LOCKED	Immediate transition, lens now locked
PASSIVE_UNFOCUSED	AF_TRIGGER	NOT_FOCUSED_LOCKED	Immediate transition, lens now locked
FOCUSED_LOCKED	AF_TRIGGER	FOCUSED_LOCKED	No effect
FOCUSED_LOCKED	AF_CANCEL	INACTIVE	Restart AF scan
NOT_FOCUSED_LOCKED	AF_TRIGGER	NOT_FOCUSED_LOCKED	No effect
NOT_FOCUSED_LOCKED	AF_CANCEL	INACTIVE	Restart AF scan

State	Transition Cause	New State	Notes
INACTIVE	Camera device initiates new scan	PASSIVE_SCAN	Start AF scan, Lens now moving
INACTIVE	AF_TRIGGER	NOT_FOCUSED_LOCKED	AF state query, Lens now locked
PASSIVE_SCAN	Camera device completes current scan	PASSIVE_FOCUSED	End AF scan, Lens now locked
PASSIVE_SCAN	Camera device fails current scan	PASSIVE_UNFOCUSED	End AF scan, Lens now locked
PASSIVE_SCAN	AF_TRIGGER	FOCUSED_LOCKED	Eventual transition once the focus is good. Lens now locked
PASSIVE_SCAN	AF_TRIGGER	NOT_FOCUSED_LOCKED	Eventual transition if cannot find focus. Lens now locked
PASSIVE_SCAN	AF_CANCEL	INACTIVE	Reset lens position, Lens now locked
PASSIVE_FOCUSED	Camera device initiates new scan	PASSIVE_SCAN	Start AF scan, Lens now moving
PASSIVE_UNFOCUSED	Camera device initiates new scan	PASSIVE_SCAN	Start AF scan, Lens now moving
PASSIVE_FOCUSED	AF_TRIGGER	FOCUSED_LOCKED	Immediate trans. Lens now locked
PASSIVE_UNFOCUSED	AF_TRIGGER	NOT_FOCUSED_LOCKED	Immediate trans. Lens now locked
FOCUSED_LOCKED	AF_TRIGGER	FOCUSED_LOCKED	No effect
FOCUSED_LOCKED	AF_CANCEL	INACTIVE	Restart AF scan
NOT_FOCUSED_LOCKED	AF_TRIGGER	NOT_FOCUSED_LOCKED	No effect
NOT_FOCUSED_LOCKED	AF_CANCEL	INACTIVE	Restart AF scan

State	Transition Cause	New State	Notes
any state	CAF-->AUTO mode switch	INACTIVE	Mode switch without trigger, initial state must be INACTIVE
any state	CAF-->AUTO mode switch with AF_TRIGGER	trigger-reachable states from INACTIVE	Mode switch with trigger, INACTIVE is skipped
any state	AUTO-->CAF mode switch	passively reachable states from INACTIVE	Mode switch without trigger, passive transient state is skipped

Current state of auto-focus (AF) algorithm.

Switching between or enabling AF modes (CaptureRequest.ControlAfMode) always resets the AF state to INACTIVE. Similarly, switching between CaptureRequest.ControlMode, or CaptureRequest.ControlSceneMode if CaptureRequest.ControlMode == USE_SCENE_MODE resets all the algorithm states to INACTIVE.

The camera device can do several state transitions between two results, if it is allowed by the state transition table. For example: INACTIVE may never actually be seen in a result.

The state in the result is the state for this image (in sync with this image): if AF state becomes FOCUSED, then the image data associated with this result should be sharp.

Below are state transition tables for different AF modes.

When CaptureRequest.ControlAfMode is AF_MODE_OFF or AF_MODE_EDOF:

When CaptureRequest.ControlAfMode is AF_MODE_AUTO or AF_MODE_MACRO:

For the above table, the camera device may skip reporting any state changes that happen without application intervention (i.e. mode switch, trigger, locking). Any state that can be skipped in that manner is called a transient state.

For example, for these AF modes (AF_MODE_AUTO and AF_MODE_MACRO), in addition to the state transitions listed in above table, it is also legal for the camera device to skip one or more transient states between two results. See below table for examples:

When CaptureRequest.ControlAfMode is AF_MODE_CONTINUOUS_VIDEO:

When CaptureRequest.ControlAfMode is AF_MODE_CONTINUOUS_PICTURE:

When switch between AF_MODE_CONTINUOUS_* (CAF modes) and AF_MODE_AUTO/AF_MODE_MACRO (AUTO modes), the initial INACTIVE or PASSIVE_SCAN states may be skipped by the camera device. When a trigger is included in a mode switch request, the trigger will be evaluated in the context of the new mode in the request. See below table for examples:

Possible values:

• CameraMetadata.CONTROL_AF_STATE_INACTIVE
• CameraMetadata.CONTROL_AF_STATE_PASSIVE_SCAN
• CameraMetadata.CONTROL_AF_STATE_PASSIVE_FOCUSED
• CameraMetadata.CONTROL_AF_STATE_ACTIVE_SCAN
• CameraMetadata.CONTROL_AF_STATE_FOCUSED_LOCKED
• CameraMetadata.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED
• CameraMetadata.CONTROL_AF_STATE_PASSIVE_UNFOCUSED

This key is available on all devices.

[Android Documentation]