/*
 * Copyright 2012 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

@class ZXByteArray;

/**
 * The purpose of this class hierarchy is to abstract different bitmap implementations across
 * platforms into a standard interface for requesting greyscale luminance values. The interface
 * only provides immutable methods; therefore crop and rotation create copies. This is to ensure
 * that one Reader does not modify the original luminance source and leave it in an unknown state
 * for other Readers in the chain.
 */
@interface ZXLuminanceSource : NSObject

/**
 * @return The width of the bitmap.
 */
@property (nonatomic, assign, readonly) int width;

/**
 * @return The height of the bitmap.
 */
@property (nonatomic, assign, readonly) int height;

/**
 * @return Whether this subclass supports cropping.
 */
@property (nonatomic, assign, readonly) BOOL cropSupported;

/**
 * @return Whether this subclass supports counter-clockwise rotation.
 */
@property (nonatomic, assign, readonly) BOOL rotateSupported;

- (id)initWithWidth:(int)width height:(int)height;

/**
 * Fetches one row of luminance data from the underlying platform's bitmap. Values range from
 * 0 (black) to 255 (white). Because Java does not have an unsigned byte type, callers will have
 * to bitwise and with 0xff for each value. It is preferable for implementations of this method
 * to only fetch this row rather than the whole image, since no 2D Readers may be installed and
 * getMatrix() may never be called.
 *
 * @param y The row to fetch, 0 <= y < getHeight().
 * @param row An optional preallocated array. If null or too small, it will be ignored.
 *            Always use the returned object, and ignore the .length of the array.
 * @return An array containing the luminance data.
 */
- (ZXByteArray *)rowAtY:(int)y row:(ZXByteArray *)row;

/**
 * Fetches luminance data for the underlying bitmap. Values should be fetched using:
 * int luminance = array[y * width + x] & 0xff;
 *
 * @return A row-major 2D array of luminance values. Do not use result.length as it may be
 *         larger than width * height bytes on some platforms. Do not modify the contents
 *         of the result.
 */
- (ZXByteArray *)matrix;

/**
 * Returns a new object with cropped image data. Implementations may keep a reference to the
 * original data rather than a copy. Only callable if isCropSupported() is true.
 *
 * @param left The left coordinate, 0 <= left < getWidth().
 * @param top The top coordinate, 0 <= top <= getHeight().
 * @param width The width of the rectangle to crop.
 * @param height The height of the rectangle to crop.
 * @return A cropped version of this object.
 */
- (ZXLuminanceSource *)crop:(int)left top:(int)top width:(int)width height:(int)height;

/**
 * @return a wrapper of this ZXLuminanceSource which inverts the luminances it returns -- black becomes
 *  white and vice versa, and each value becomes (255-value).
 */
- (ZXLuminanceSource *)invert;

/**
 * Returns a new object with rotated image data by 90 degrees counterclockwise.
 * Only callable if isRotateSupported is true.
 *
 * @return A rotated version of this object.
 */
- (ZXLuminanceSource *)rotateCounterClockwise;

/**
 * Returns a new object with rotated image data by 45 degrees counterclockwise.
 * Only callable if isRotateSupported is true.
 *
 * @return A rotated version of this object.
 */
- (ZXLuminanceSource *)rotateCounterClockwise45;

@end
