Merge "Camera: Document flashStrength and preCaptureTrigger interaction" into main
diff --git a/core/java/android/hardware/camera2/CaptureRequest.java b/core/java/android/hardware/camera2/CaptureRequest.java
index fbed50a..ac72116 100644
--- a/core/java/android/hardware/camera2/CaptureRequest.java
+++ b/core/java/android/hardware/camera2/CaptureRequest.java
@@ -1537,9 +1537,14 @@
* be made, and for firing pre-capture flash pulses to estimate
* scene brightness and required final capture flash power, when
* the flash is enabled.</p>
- * <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>Flash is enabled during precapture sequence when:</p>
+ * <ul>
+ * <li>AE mode is ON_ALWAYS_FLASH</li>
+ * <li>AE mode is ON_AUTO_FLASH and the scene is deemed too dark without flash, or</li>
+ * <li>AE mode is ON and flash mode is TORCH or SINGLE</li>
+ * </ul>
+ * <p>Normally, this entry should be set to START for only 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>).
@@ -2705,6 +2710,13 @@
* in {@link CameraCharacteristics#FLASH_SINGLE_STRENGTH_DEFAULT_LEVEL android.flash.singleStrengthDefaultLevel}.
* If {@link CaptureRequest#CONTROL_AE_MODE android.control.aeMode} is set to any of <code>ON_AUTO_FLASH</code>, <code>ON_ALWAYS_FLASH</code>,
* <code>ON_AUTO_FLASH_REDEYE</code>, <code>ON_EXTERNAL_FLASH</code> values, then the strengthLevel will be ignored.</p>
+ * <p>When AE mode is ON and flash mode is TORCH or SINGLE, the application should make sure
+ * the AE mode, flash mode, and flash strength level remain the same between precapture
+ * trigger request and final capture request. The flash strength level being set during
+ * precapture sequence is used by the camera device as a reference. The actual strength
+ * may be less, and the auto-exposure routine makes sure proper conversions of sensor
+ * exposure time and sensitivities between precapture and final capture for the specified
+ * strength level.</p>
* <p><b>Range of valid values:</b><br>
* <code>[1-{@link CameraCharacteristics#FLASH_TORCH_STRENGTH_MAX_LEVEL android.flash.torchStrengthMaxLevel}]</code> when the {@link CaptureRequest#FLASH_MODE android.flash.mode} is
* set to TORCH;
diff --git a/core/java/android/hardware/camera2/CaptureResult.java b/core/java/android/hardware/camera2/CaptureResult.java
index d652b4c..98f635d 100644
--- a/core/java/android/hardware/camera2/CaptureResult.java
+++ b/core/java/android/hardware/camera2/CaptureResult.java
@@ -935,9 +935,14 @@
* be made, and for firing pre-capture flash pulses to estimate
* scene brightness and required final capture flash power, when
* the flash is enabled.</p>
- * <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>Flash is enabled during precapture sequence when:</p>
+ * <ul>
+ * <li>AE mode is ON_ALWAYS_FLASH</li>
+ * <li>AE mode is ON_AUTO_FLASH and the scene is deemed too dark without flash, or</li>
+ * <li>AE mode is ON and flash mode is TORCH or SINGLE</li>
+ * </ul>
+ * <p>Normally, this entry should be set to START for only 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>).
@@ -2996,6 +3001,13 @@
* in {@link CameraCharacteristics#FLASH_SINGLE_STRENGTH_DEFAULT_LEVEL android.flash.singleStrengthDefaultLevel}.
* If {@link CaptureRequest#CONTROL_AE_MODE android.control.aeMode} is set to any of <code>ON_AUTO_FLASH</code>, <code>ON_ALWAYS_FLASH</code>,
* <code>ON_AUTO_FLASH_REDEYE</code>, <code>ON_EXTERNAL_FLASH</code> values, then the strengthLevel will be ignored.</p>
+ * <p>When AE mode is ON and flash mode is TORCH or SINGLE, the application should make sure
+ * the AE mode, flash mode, and flash strength level remain the same between precapture
+ * trigger request and final capture request. The flash strength level being set during
+ * precapture sequence is used by the camera device as a reference. The actual strength
+ * may be less, and the auto-exposure routine makes sure proper conversions of sensor
+ * exposure time and sensitivities between precapture and final capture for the specified
+ * strength level.</p>
* <p><b>Range of valid values:</b><br>
* <code>[1-{@link CameraCharacteristics#FLASH_TORCH_STRENGTH_MAX_LEVEL android.flash.torchStrengthMaxLevel}]</code> when the {@link CaptureRequest#FLASH_MODE android.flash.mode} is
* set to TORCH;