Merge "Add camera metering area API."

const char CameraParameters::KEY_MAX_EXPOSURE_COMPENSATION[] = "max-exposure-compensation";

const char CameraParameters::KEY_MIN_EXPOSURE_COMPENSATION[] = "min-exposure-compensation";

const char CameraParameters::KEY_EXPOSURE_COMPENSATION_STEP[] = "exposure-compensation-step";

const char CameraParameters::KEY_MAX_NUM_METERING_AREAS[] = "max-num-metering-areas";

const char CameraParameters::KEY_METERING_AREAS[] = "metering-areas";

const char CameraParameters::KEY_ZOOM[] = "zoom";

const char CameraParameters::KEY_MAX_ZOOM[] = "max-zoom";

const char CameraParameters::KEY_ZOOM_RATIOS[] = "zoom-ratios";

    // 0.3333, EV is -2.

    // Example value: "0.333333333" or "0.5". Read only.

    static const char KEY_EXPOSURE_COMPENSATION_STEP[];

    // The maximum number of metering areas supported. This is the maximum

    // length of KEY_METERING_AREAS.

    // Example value: "0" or "2". Read only.

    static const char KEY_MAX_NUM_METERING_AREAS[];

    // Current metering areas. Camera driver uses these areas to decide

    // exposure.

    //

    // Before accessing this parameter, apps should check

    // KEY_MAX_NUM_METERING_AREAS first to know the maximum number of metering

    // areas first. If the value is 0, metering area is not supported.

    //

    // Each metering area is a rectangle with specified weight. The direction is

    // relative to the sensor orientation, that is, what the sensor sees. The

    // direction is not affected by the rotation or mirroring of

    // CAMERA_CMD_SET_DISPLAY_ORIENTATION. Coordinates of the rectangle range

    // from -1000 to 1000. (-1000, -1000) is the upper left 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.

    //

    // A special case of all-zero single metering area means driver to decide

    // the metering area. For example, the driver may use more signals to decide

    // metering areas and change them dynamically. Apps can set all-zero if they

    // want the driver to decide metering areas.

    //

    // Metering areas are relative to the current field of view (KEY_ZOOM).

    // No matter what the zoom level is, (-1000,-1000) represents the top of the

    // currently visible camera frame. The metering area cannot be set to be

    // outside the current field of view, even when using zoom.

    //

    // No matter what metering areas are, the final exposure are compensated

    // by KEY_EXPOSURE_COMPENSATION.

    // Example value: "(-10,-10,0,0,300),(0,0,10,10,700)". Read/write.

    static const char KEY_METERING_AREAS[];

    // Current zoom value.

    // Example value: "0" or "6". Read/write.

    static const char KEY_ZOOM[];