Clarify the meaning of weight in the focus and metering area HAL.

Weigh values must be less than 1000, but have no restriction on their
sum. Weights should be interpreted as per-pixel values, meaning larger
areas will have more influence over focus/metering than smaller areas
of the same weight.

Change-Id: I988b74f988ddba2ff0c49d078ff3174b47cbae18

1 files changed, 11 insertions, 8 deletions

diff --git a/core/java/android/hardware/Camera.java b/core/java/android/hardware/Camera.java
index 6c6a72d..7670694 100644
--- a/core/java/android/hardware/Camera.java
+++ b/core/java/android/hardware/Camera.java
@@ -2600,10 +2600,12 @@ public class Camera {
          * (1000, 1000) is the lower right point. The length and width of focus
          * areas cannot be 0 or negative.
          *
-         * The weight ranges from 1 to 1000. The sum of the weights of all focus
-         * areas must be 1000. Focus areas can partially overlap and the driver
-         * will add the weights in the overlap region. But apps should not set
-         * two focus areas that have identical coordinates.
+         * The weight must range from 1 to 1000. The weight should be
+         * interpreted as a per-pixel weight - all pixels in the area have the
+         * specified weight. This means a small area with the same weight as a
+         * larger area will have less influence on the focusing than the larger
+         * area. Focus areas can partially overlap and the driver will add the
+         * weights in the overlap region.
          *
          * A special case of all-zero single focus area means driver to decide
          * the focus area. For example, the driver may use more signals to
@@ -2668,10 +2670,11 @@ public class Camera {
          * point. (1000, 1000) is the lower right point. The length and width of
          * metering areas cannot be 0 or negative.
          *
-         * The weight ranges from 1 to 1000. The sum of the weights of all
-         * metering areas must be 1000. Metering areas can partially overlap and
-         * the driver will add the weights in the overlap region. But apps
-         * should not set two metering areas that have identical coordinates.
+         * The weight must range from 1 to 1000, and represents a weight for
+         * every pixel in the area. This means that a large metering area with
+         * the same weight as a smaller area will have more effect in the
+         * metering result.  Metering areas can partially overlap and the driver
+         * will add the weights in the overlap region.
          *
          * A special case of all-zero single metering area means driver to
          * decide the metering area. For example, the driver may use more