camera-metadata: clarify the AE precapture trigger spec
Doc only change.
Bug: 19301706
Change-Id: I8f94ee5ace6dd3040ee2f350d589e24e53694f1b
diff --git a/core/java/android/hardware/camera2/CaptureResult.java b/core/java/android/hardware/camera2/CaptureResult.java
index 1396940..f17100d 100644
--- a/core/java/android/hardware/camera2/CaptureResult.java
+++ b/core/java/android/hardware/camera2/CaptureResult.java
@@ -718,9 +718,9 @@
* metering sequence when it processes this request.</p>
* <p>This entry is normally set to IDLE, or is not
* included at all in the request settings. When included and
- * set to START, the camera device will trigger the autoexposure
+ * set to START, the camera device will trigger the auto-exposure (AE)
* precapture metering sequence.</p>
- * <p>The precapture sequence should triggered before starting a
+ * <p>The precapture sequence should be triggered before starting a
* high-quality still capture for final metering decisions to
* be made, and for firing pre-capture flash pulses to estimate
* scene brightness and required final capture flash power, when
@@ -728,6 +728,14 @@
* <p>Normally, this entry should be set to START for only a
* single request, and the application should wait until the
* sequence completes before starting a new one.</p>
+ * <p>When a precapture metering sequence is finished, the camera device
+ * may lock the auto-exposure routine internally to be able to accurately expose the
+ * subsequent still capture image (<code>{@link CaptureRequest#CONTROL_CAPTURE_INTENT android.control.captureIntent} == STILL_CAPTURE</code>).
+ * For this case, the AE may not resume normal scan if no subsequent still capture is
+ * submitted. To ensure that the AE routine restarts normal scan, the application should
+ * submit a request with <code>{@link CaptureRequest#CONTROL_AE_LOCK android.control.aeLock} == true</code>, followed by a request
+ * with <code>{@link CaptureRequest#CONTROL_AE_LOCK android.control.aeLock} == false</code>, if the application decides not to submit a
+ * still capture request after the precapture sequence completes.</p>
* <p>The exact effect of auto-exposure (AE) precapture trigger
* depends on the current AE mode and state; see
* {@link CaptureResult#CONTROL_AE_STATE android.control.aeState} for AE precapture state transition
@@ -746,7 +754,9 @@
* Present on all camera devices that report being at least {@link CameraCharacteristics#INFO_SUPPORTED_HARDWARE_LEVEL_LIMITED HARDWARE_LEVEL_LIMITED} devices in the
* {@link CameraCharacteristics#INFO_SUPPORTED_HARDWARE_LEVEL android.info.supportedHardwareLevel} key</p>
*
+ * @see CaptureRequest#CONTROL_AE_LOCK
* @see CaptureResult#CONTROL_AE_STATE
+ * @see CaptureRequest#CONTROL_CAPTURE_INTENT
* @see CameraCharacteristics#INFO_SUPPORTED_HARDWARE_LEVEL
* @see #CONTROL_AE_PRECAPTURE_TRIGGER_IDLE
* @see #CONTROL_AE_PRECAPTURE_TRIGGER_START