Add parts of zxing library to generate qr codes

OpenPGP-Keychain/src/com/google/zxing/multi/ByQuadrantReader.java

@@ -0,0 +1,96 @@
+/*
+ * 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.multi;
+
+import com.google.zxing.BinaryBitmap;
+import com.google.zxing.ChecksumException;
+import com.google.zxing.FormatException;
+import com.google.zxing.NotFoundException;
+import com.google.zxing.Reader;
+import com.google.zxing.Result;
+
+import java.util.Hashtable;
+
+/**
+ * This class attempts to decode a barcode from an image, not by scanning the whole image,
+ * but by scanning subsets of the image. This is important when there may be multiple barcodes in
+ * an image, and detecting a barcode may find parts of multiple barcode and fail to decode
+ * (e.g. QR Codes). Instead this scans the four quadrants of the image -- and also the center
+ * 'quadrant' to cover the case where a barcode is found in the center.
+ *
+ * @see GenericMultipleBarcodeReader
+ */
+public final class ByQuadrantReader implements Reader {
+
+  private final Reader delegate;
+
+  public ByQuadrantReader(Reader delegate) {
+    this.delegate = delegate;
+  }
+
+  public Result decode(BinaryBitmap image)
+      throws NotFoundException, ChecksumException, FormatException {
+    return decode(image, null);
+  }
+
+  public Result decode(BinaryBitmap image, Hashtable hints)
+      throws NotFoundException, ChecksumException, FormatException {
+
+    int width = image.getWidth();
+    int height = image.getHeight();
+    int halfWidth = width / 2;
+    int halfHeight = height / 2;
+
+    BinaryBitmap topLeft = image.crop(0, 0, halfWidth, halfHeight);
+    try {
+      return delegate.decode(topLeft, hints);
+    } catch (NotFoundException re) {
+      // continue
+    }
+
+    BinaryBitmap topRight = image.crop(halfWidth, 0, halfWidth, halfHeight);
+    try {
+      return delegate.decode(topRight, hints);
+    } catch (NotFoundException re) {
+      // continue
+    }
+
+    BinaryBitmap bottomLeft = image.crop(0, halfHeight, halfWidth, halfHeight);
+    try {
+      return delegate.decode(bottomLeft, hints);
+    } catch (NotFoundException re) {
+      // continue
+    }
+
+    BinaryBitmap bottomRight = image.crop(halfWidth, halfHeight, halfWidth, halfHeight);
+    try {
+      return delegate.decode(bottomRight, hints);
+    } catch (NotFoundException re) {
+      // continue
+    }
+
+    int quarterWidth = halfWidth / 2;
+    int quarterHeight = halfHeight / 2;
+    BinaryBitmap center = image.crop(quarterWidth, quarterHeight, halfWidth, halfHeight);
+    return delegate.decode(center, hints);
+  }
+
+  public void reset() {
+    delegate.reset();
+  }
+
+}