1 files changed, 113 insertions, 0 deletions
diff --git a/libraries/zxing/src/com/google/zxing/LuminanceSource.java b/libraries/zxing/src/com/google/zxing/LuminanceSource.java
new file mode 100644
index 000000000..4b6d4539f
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+++ b/libraries/zxing/src/com/google/zxing/LuminanceSource.java
@@ -0,0 +1,113 @@
+/*
+ * Copyright 2009 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.
+ */
+
+package com.google.zxing;
+
+/**
+ * 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.
+ *
+ * @author dswitkin@google.com (Daniel Switkin)
+ */
+public abstract class LuminanceSource {
+
+  private final int width;
+  private final int height;
+
+  protected LuminanceSource(int width, int height) {
+    this.width = width;
+    this.height = 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.
+   */
+  public abstract byte[] getRow(int y, byte[] 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.
+   */
+  public abstract byte[] getMatrix();
+
+  /**
+   * @return The width of the bitmap.
+   */
+  public final int getWidth() {
+    return width;
+  }
+
+  /**
+   * @return The height of the bitmap.
+   */
+  public final int getHeight() {
+    return height;
+  }
+
+  /**
+   * @return Whether this subclass supports cropping.
+   */
+  public boolean isCropSupported() {
+    return false;
+  }
+
+  /**
+   * 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.
+   */
+  public LuminanceSource crop(int left, int top, int width, int height) {
+    throw new RuntimeException("This luminance source does not support cropping.");
+  }
+
+  /**
+   * @return Whether this subclass supports counter-clockwise rotation.
+   */
+  public boolean isRotateSupported() {
+    return false;
+  }
+
+  /**
+   * Returns a new object with rotated image data. Only callable if isRotateSupported() is true.
+   *
+   * @return A rotated version of this object.
+   */
+  public LuminanceSource rotateCounterClockwise() {
+    throw new RuntimeException("This luminance source does not support rotation.");
+  }
+
+}