Camera2: add toString for TonemapCurve

     * <p>Values are stored as a contiguous array of {@code (Pin, Pout)} points.</p>

     *

     * <p>All parameters may have independent length but should have at most

     * {@link CameraCharacteristics#TONEMAP_MAX_CURVE_POINTS} * {@value #POINT_SIZE} elements.</p>

     * {@link CameraCharacteristics#TONEMAP_MAX_CURVE_POINTS} * {@value #POINT_SIZE} elements and

     * at least 2 * {@value #POINT_SIZE} elements.</p>

     *

     * <p>All sub-elements must be in the inclusive range of

     * [{@value #LEVEL_BLACK}, {@value #LEVEL_WHITE}].</p>

        checkArgumentArrayLengthDivisibleBy(green, POINT_SIZE, "green");

        checkArgumentArrayLengthDivisibleBy(blue, POINT_SIZE, "blue");

        checkArgumentArrayLengthNoLessThan(red, MIN_CURVE_LENGTH, "red");

        checkArgumentArrayLengthNoLessThan(green, MIN_CURVE_LENGTH, "green");

        checkArgumentArrayLengthNoLessThan(blue, MIN_CURVE_LENGTH, "blue");

        checkArrayElementsInRange(red, LEVEL_BLACK, LEVEL_WHITE, "red");

        checkArrayElementsInRange(green, LEVEL_BLACK, LEVEL_WHITE, "green");

        checkArrayElementsInRange(blue, LEVEL_BLACK, LEVEL_WHITE, "blue");

        return colorChannel;

    }

    private static void checkArgumentArrayLengthNoLessThan(float[] array, int minLength,

            String arrayName) {

        if (array.length < minLength) {

            throw new IllegalArgumentException(arrayName + " size must be at least "

                    + minLength);

        }

    }

    /**

     * Get the number of points stored in this tonemap curve for the specified color channel.

     *

        return mHashCode;

    }

    /**

     * Return the TonemapCurve as a string representation.

     *

     * <p> {@code "TonemapCurve{R:[(%f, %f), (%f, %f) ... (%f, %f)], G:[(%f, %f), (%f, %f) ...

     * (%f, %f)], B:[(%f, %f), (%f, %f) ... (%f, %f)]}"},

     * where each {@code (%f, %f)} respectively represents one point of the corresponding

     * tonemap curve. </p>

     *

     * @return string representation of {@link TonemapCurve}

     */

    @Override

    public String toString() {

        StringBuilder sb = new StringBuilder("TonemapCurve{");

        sb.append("R:");

        sb.append(curveToString(CHANNEL_RED));

        sb.append(", G:");

        sb.append(curveToString(CHANNEL_GREEN));

        sb.append(", B:");

        sb.append(curveToString(CHANNEL_BLUE));

        sb.append("}");

        return sb.toString();

    }

    private String curveToString(int colorChannel) {

        checkArgumentColorChannel(colorChannel);

        StringBuilder sb = new StringBuilder("[");

        float[] curve = getCurve(colorChannel);

        int pointCount = curve.length / POINT_SIZE;

        for (int i = 0, j = 0; i < pointCount; i++, j += 2) {

            sb.append("(");

            sb.append(curve[j]);

            sb.append(", ");

            sb.append(curve[j+1]);

            sb.append("), ");

        }

        // trim extra ", " at the end. Guaranteed to work because pointCount >= 2

        sb.setLength(sb.length() - 2);

        sb.append("]");

        return sb.toString();

    }

    private float[] getCurve(int colorChannel) {

        switch (colorChannel) {

            case CHANNEL_RED:

    private final static int OFFSET_POINT_IN = 0;

    private final static int OFFSET_POINT_OUT = 1;

    private final static int TONEMAP_MIN_CURVE_POINTS = 2;

    private final static int MIN_CURVE_LENGTH = TONEMAP_MIN_CURVE_POINTS * POINT_SIZE;

    private final float[] mRed;

    private final float[] mGreen;

    private int mHashCode;

    private boolean mHashCalculated = false;

};

}