CameraNDK: fill in more NDK API documents

This change adds document for ACaptureRequest, ACameraMetadata,
AImage and AImageReader.

Bug: 27102995
Change-Id: I79d88f73258c01ebeabcd5b4e3b90996759cb021
diff --git a/include/camera/ndk/NdkCaptureRequest.h b/include/camera/ndk/NdkCaptureRequest.h
index e278196..cd97f4d 100644
--- a/include/camera/ndk/NdkCaptureRequest.h
+++ b/include/camera/ndk/NdkCaptureRequest.h
@@ -49,54 +49,255 @@
 // Container for a single output target
 typedef struct ACameraOutputTarget ACameraOutputTarget;
 
+/**
+ * ACaptureRequest is an opaque type that contains settings and output targets needed to capture
+ * a single image from camera device.
+ *
+ * <p>ACaptureRequest contains the configuration for the capture hardware (sensor, lens, flash),
+ * the processing pipeline, the control algorithms, and the output buffers. Also
+ * contains the list of target {@link ANativeWindow}s to send image data to for this
+ * capture.</p>
+ *
+ * <p>ACaptureRequest is created by {@link ACameraDevice_createCaptureRequest}.
+ *
+ * <p>ACaptureRequest is given to {@link ACameraCaptureSession_capture} or
+ * {@link ACameraCaptureSession_setRepeatingRequest} to capture images from a camera.</p>
+ *
+ * <p>Each request can specify a different subset of target {@link ANativeWindow}s for the
+ * camera to send the captured data to. All the {@link ANativeWindow}s used in a request must
+ * be part of the {@link ANativeWindow} list given to the last call to
+ * {@link ACameraDevice_createCaptureSession}, when the request is submitted to the
+ * session.</p>
+ *
+ * <p>For example, a request meant for repeating preview might only include the
+ * {@link ANativeWindow} for the preview SurfaceView or SurfaceTexture, while a
+ * high-resolution still capture would also include a {@link ANativeWindow} from a
+ * {@link AImageReader} configured for high-resolution JPEG images.</p>
+ *
+ * @see ACameraDevice_createCaptureRequest
+ * @see ACameraCaptureSession_capture
+ * @see ACameraCaptureSession_setRepeatingRequest
+ */
 typedef struct ACaptureRequest ACaptureRequest;
 
-camera_status_t ACameraOutputTarget_create(ANativeWindow* window, ACameraOutputTarget** out);
-void ACameraOutputTarget_free(ACameraOutputTarget*);
+/**
+ * Create a ACameraOutputTarget object.
+ *
+ * <p>The ACameraOutputTarget is used in {@link ACaptureRequest_addTarget} method to add an output
+ * {@link ANativeWindow} to ACaptureRequest. Use {@link ACameraOutputTarget_free} to free the object
+ * and its memory after application no longer needs the {@link ACameraOutputTarget}.</p>
+ *
+ * @param window the {@link ANativeWindow} to be associated with the {@link ACameraOutputTarget}
+ * @param output the output {@link ACameraOutputTarget} will be stored here if the
+ *                  method call succeeds.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds. The created ACameraOutputTarget will
+ *                                be filled in the output argument.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if window or output is NULL.</li></ul>
+ *
+ * @see ACaptureRequest_addTarget
+ */
+camera_status_t ACameraOutputTarget_create(ANativeWindow* window, ACameraOutputTarget** output);
 
-camera_status_t ACaptureRequest_addTarget(ACaptureRequest*, const ACameraOutputTarget*);
-camera_status_t ACaptureRequest_removeTarget(ACaptureRequest*, const ACameraOutputTarget*);
-//TODO: do we need API to query added targets?
+/**
+ * Free a ACameraOutputTarget object.
+ *
+ * @param output the {@link ACameraOutputTarget} to be freed.
+ *
+ * @see ACameraOutputTarget_create
+ */
+void ACameraOutputTarget_free(ACameraOutputTarget* output);
 
-/*
- * Get a metadata entry
+/**
+ * Add an {@link ACameraOutputTarget} object to {@link ACaptureRequest}.
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param output the output {@link ACameraOutputTarget} to be added to capture request.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request or output is NULL.</li></ul>
+ */
+camera_status_t ACaptureRequest_addTarget(ACaptureRequest* request,
+        const ACameraOutputTarget* output);
+
+/**
+ * Remove an {@link ACameraOutputTarget} object from {@link ACaptureRequest}.
+ *
+ * <p>This method has no effect if the ACameraOutputTarget does not exist in ACaptureRequest.</p>
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param output the output {@link ACameraOutputTarget} to be removed from capture request.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request or output is NULL.</li></ul>
+ */
+camera_status_t ACaptureRequest_removeTarget(ACaptureRequest* request,
+        const ACameraOutputTarget* output);
+
+/**
+ * Get a metadata entry from input {@link ACaptureRequest}.
+ *
+ * <p>The memory of the data field in returned entry is managed by camera framework. Do not
+ * attempt to free it.</p>
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param tag the tag value of the camera metadata entry to be get.
+ * @param entry the output {@link ACameraMetadata_const_entry} will be filled here if the method
+ *        call succeeeds.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if metadata or entry is NULL.</li>
+ *         <li>{@link ACAMERA_ERROR_METADATA_NOT_FOUND} if the capture request does not contain an
+ *             entry of input tag value.</li></ul>
  */
 camera_status_t ACaptureRequest_getConstEntry(
-        const ACaptureRequest*, uint32_t tag, ACameraMetadata_const_entry* entry);
+        const ACaptureRequest* request, uint32_t tag, ACameraMetadata_const_entry* entry);
 
 /*
- * List all the entry tags in this capture request.
- * The memory of tags is managed by ACaptureRequest itself and must NOT be free/delete
- * by application. Calling ACaptureRequest_setEntry_* API will invalidate previous
- * output of ACaptureRequest_getAllTags. Do not access tags after calling
- * ACaptureRequest_setEntry_*. To get new list of tags after updating capture request,
- * application must call ACaptureRequest_getAllTags again.
- * Do NOT access tags after calling ACaptureRequest_free.
+ * List all the entry tags in input {@link ACaptureRequest}.
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param numEntries number of metadata entries in input {@link ACaptureRequest}
+ * @param tags the tag values of the metadata entries. Length of tags is returned in numEntries
+ *             argument. The memory is managed by ACaptureRequest itself and must NOT be free/delete
+ *             by application. Calling ACaptureRequest_setEntry_* methods will invalidate previous
+ *             output of ACaptureRequest_getAllTags. Do not access tags after calling
+ *             ACaptureRequest_setEntry_*. To get new list of tags after updating capture request,
+ *             application must call ACaptureRequest_getAllTags again. Do NOT access tags after
+ *             calling ACaptureRequest_free.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request, numEntries or tags is NULL.</li>
+ *         <li>{@link ACAMERA_ERROR_UNKNOWN} if the method fails for some other reasons.</li></ul>
  */
 camera_status_t ACaptureRequest_getAllTags(
-        const ACaptureRequest*, /*out*/int32_t* numTags, /*out*/const uint32_t** tags);
+        const ACaptureRequest* request, /*out*/int32_t* numTags, /*out*/const uint32_t** tags);
 
-/*
- * Set an entry of corresponding type.
- * The entry tag's type must match corresponding set API or an
- * ACAMERA_ERROR_INVALID_PARAMETER error will occur.
- * Also, the input ACameraMetadata* must belong to a capture request or an
- * ACAMERA_ERROR_INVALID_PARAMETER error will occur.
+/**
+ * Set/change a camera capture control entry with unsigned 8 bits data type.
+ *
+ * <p>Set count to 0 and data to NULL to remove a tag from the capture request.</p>
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param tag the tag value of the camera metadata entry to be set.
+ * @param count number of elements to be set in data argument
+ * @param data the entries to be set/change in the capture request.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request is NULL, count is larger than
+ *             zero while data is NULL, the data type of the tag is not unsigned 8 bits, or
+ *             the tag is not controllable by application.</li></ul>
  */
 camera_status_t ACaptureRequest_setEntry_u8(
-        ACaptureRequest*, uint32_t tag, uint32_t count, const uint8_t* data);
-camera_status_t ACaptureRequest_setEntry_i32(
-        ACaptureRequest*, uint32_t tag, uint32_t count, const int32_t* data);
-camera_status_t ACaptureRequest_setEntry_float(
-        ACaptureRequest*, uint32_t tag, uint32_t count, const float* data);
-camera_status_t ACaptureRequest_setEntry_i64(
-        ACaptureRequest*, uint32_t tag, uint32_t count, const int64_t* data);
-camera_status_t ACaptureRequest_setEntry_double(
-        ACaptureRequest*, uint32_t tag, uint32_t count, const double* data);
-camera_status_t ACaptureRequest_setEntry_rational(
-        ACaptureRequest*, uint32_t tag, uint32_t count, const ACameraMetadata_rational* data);
+        ACaptureRequest* request, uint32_t tag, uint32_t count, const uint8_t* data);
 
-// free the capture request created by ACameraDevice_createCaptureRequest
+/**
+ * Set/change a camera capture control entry with signed 32 bits data type.
+ *
+ * <p>Set count to 0 and data to NULL to remove a tag from the capture request.</p>
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param tag the tag value of the camera metadata entry to be set.
+ * @param count number of elements to be set in data argument
+ * @param data the entries to be set/change in the capture request.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request is NULL, count is larger than
+ *             zero while data is NULL, the data type of the tag is not signed 32 bits, or
+ *             the tag is not controllable by application.</li></ul>
+ */
+camera_status_t ACaptureRequest_setEntry_i32(
+        ACaptureRequest* request, uint32_t tag, uint32_t count, const int32_t* data);
+
+/**
+ * Set/change a camera capture control entry with float data type.
+ *
+ * <p>Set count to 0 and data to NULL to remove a tag from the capture request.</p>
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param tag the tag value of the camera metadata entry to be set.
+ * @param count number of elements to be set in data argument
+ * @param data the entries to be set/change in the capture request.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request is NULL, count is larger than
+ *             zero while data is NULL, the data type of the tag is not float, or
+ *             the tag is not controllable by application.</li></ul>
+ */
+camera_status_t ACaptureRequest_setEntry_float(
+        ACaptureRequest* request, uint32_t tag, uint32_t count, const float* data);
+
+/**
+ * Set/change a camera capture control entry with signed 64 bits data type.
+ *
+ * <p>Set count to 0 and data to NULL to remove a tag from the capture request.</p>
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param tag the tag value of the camera metadata entry to be set.
+ * @param count number of elements to be set in data argument
+ * @param data the entries to be set/change in the capture request.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request is NULL, count is larger than
+ *             zero while data is NULL, the data type of the tag is not signed 64 bits, or
+ *             the tag is not controllable by application.</li></ul>
+ */
+camera_status_t ACaptureRequest_setEntry_i64(
+        ACaptureRequest* request, uint32_t tag, uint32_t count, const int64_t* data);
+
+/**
+ * Set/change a camera capture control entry with double data type.
+ *
+ * <p>Set count to 0 and data to NULL to remove a tag from the capture request.</p>
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param tag the tag value of the camera metadata entry to be set.
+ * @param count number of elements to be set in data argument
+ * @param data the entries to be set/change in the capture request.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request is NULL, count is larger than
+ *             zero while data is NULL, the data type of the tag is not double, or
+ *             the tag is not controllable by application.</li></ul>
+ */
+camera_status_t ACaptureRequest_setEntry_double(
+        ACaptureRequest* request, uint32_t tag, uint32_t count, const double* data);
+
+/**
+ * Set/change a camera capture control entry with rational data type.
+ *
+ * <p>Set count to 0 and data to NULL to remove a tag from the capture request.</p>
+ *
+ * @param request the {@link ACaptureRequest} of interest.
+ * @param tag the tag value of the camera metadata entry to be set.
+ * @param count number of elements to be set in data argument
+ * @param data the entries to be set/change in the capture request.
+ *
+ * @return <ul>
+ *         <li>{@link ACAMERA_OK} if the method call succeeds.</li>
+ *         <li>{@link ACAMERA_ERROR_INVALID_PARAMETER} if request is NULL, count is larger than
+ *             zero while data is NULL, the data type of the tag is not rational, or
+ *             the tag is not controllable by application.</li></ul>
+ */
+camera_status_t ACaptureRequest_setEntry_rational(
+        ACaptureRequest* request, uint32_t tag, uint32_t count,
+        const ACameraMetadata_rational* data);
+
+/**
+ * Free a {@link ACaptureRequest} structure.
+ *
+ * @param request the {@link ACaptureRequest} to be freed.
+ */
 void ACaptureRequest_free(ACaptureRequest* request);
 
 #ifdef __cplusplus