Improved GridSampler API -- no need for reflection anymore. Reintroduced Android GridSampler implementation, which still doesn't quite work yet.

git-svn-id: https://zxing.googlecode.com/svn/trunk@221 59b500cc-1b3d-0410-9834-0bbf25fbcc57

android/build.xml

@@ -128,8 +128,6 @@
      <arg value="-dontpreverify"/>
      <arg value="-dontobfuscate"/>
      <arg value="-keep public class com.google.zxing.client.android.BarcodeReaderCaptureActivity"/>
-     <arg value="-keep public class com.google.zxing.qrcode.detector.DefaultGridSampler"/>
-     <arg value="-keep public class com.google.zxing.qrcode.detector.GridSampler"/>      
      <arg value="-optimizationpasses 4"/>
      <arg value="-verbose"/>
    </java>

android/src/com/google/zxing/client/android/AndroidGraphicsGridSampler.java

@@ -0,0 +1,112 @@
+/*
+ * Copyright 2007 Google Inc.
+ *
+ * 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.client.android;
+
+import com.google.zxing.MonochromeBitmapSource;
+import com.google.zxing.ReaderException;
+import com.google.zxing.common.BitMatrix;
+import com.google.zxing.qrcode.detector.AlignmentPattern;
+import com.google.zxing.qrcode.detector.FinderPattern;
+import com.google.zxing.qrcode.detector.GridSampler;
+
+import android.graphics.Matrix;
+
+/**
+ * Implementation based on Android's
+ * {@link Matrix#setPolyToPoly(float[], int, float[], int, int)}
+ * class, which should offer faster performance for these matrix
+ * operations.
+ * 
+ * @author srowen@google.com (Sean Owen)
+ */
+public final class AndroidGraphicsGridSampler extends GridSampler {
+
+  @Override
+  protected BitMatrix sampleGrid(MonochromeBitmapSource image,
+                                 FinderPattern topLeft,
+                                 FinderPattern topRight,
+                                 FinderPattern bottomLeft,
+                                 AlignmentPattern alignmentPattern,
+                                 int dimension) throws ReaderException {
+    float dimMinusThree = (float) dimension - 3.5f;
+    float bottomRightX, bottomRightY;
+    float sourceBottomRightX, sourceBottomRightY;
+    if (alignmentPattern != null) {
+      bottomRightX = alignmentPattern.getX();
+      bottomRightY = alignmentPattern.getY();
+      sourceBottomRightX = sourceBottomRightY = dimMinusThree - 3.0f;
+    } else {
+      // Don't have an alignment pattern, just make up the bottom-right point
+      bottomRightX = (topRight.getX() - topLeft.getX()) + bottomLeft.getX();
+      bottomRightY = (topRight.getY() - topLeft.getY()) + bottomLeft.getY();
+      sourceBottomRightX = sourceBottomRightY = dimMinusThree;
+    }
+
+    Matrix transformMatrix = new Matrix();
+    boolean succeeded = transformMatrix.setPolyToPoly(
+      new float[] {
+        topLeft.getX(),
+        topLeft.getY(),
+        topRight.getX(),
+        topRight.getY(),
+        bottomLeft.getX(),
+        bottomLeft.getY(),
+        bottomRightX,
+        bottomRightY
+      },
+      0,
+      new float[] {
+        3.5f,
+        3.5f,
+        dimMinusThree,
+        3.5f,
+        3.5f,
+        dimMinusThree,
+        sourceBottomRightX,
+        sourceBottomRightY,
+      },
+      0,
+      4
+    );
+    if (!succeeded) {
+      throw new ReaderException("Could not establish transformation matrix");
+    }
+
+    BitMatrix bits = new BitMatrix(dimension);
+    float[] points = new float[dimension << 1];
+    for (int i = 0; i < dimension; i++) {
+      int max = points.length;
+      float iValue = (float) i + 0.5f;
+      for (int j = 0; j < max; j += 2) {
+        points[j] = (float) (j >> 1) + 0.5f;
+        points[j + 1] = iValue;
+      }
+      transformMatrix.mapPoints(points);
+      // Quick check to see if points transformed to something inside the image;
+      // sufficent to check the endpoints
+      checkEndpoint(image, points);
+      for (int j = 0; j < max; j += 2) {
+        if (image.isBlack((int) points[j], (int) points[j + 1])) {
+          // Black(-ish) pixel
+          bits.set(i, j >> 1);
+        }
+      }
+    }
+    return bits;
+  }
+
+}

android/src/com/google/zxing/client/android/BarcodeReaderCaptureActivity.java

@@ -63,6 +63,9 @@ public final class BarcodeReaderCaptureActivity extends Activity {
     workerThread = new WorkerThread(surfaceView, cameraManager, messageHandler);
     workerThread.requestPreviewLoop();
     workerThread.start();
+
+    // TODO re-enable this when issues with Matrix.setPolyToPoly() are resolved
+    //GridSampler.setGridSampler(new AndroidGraphicsGridSampler());
   }
 
   @Override

core/src/com/google/zxing/qrcode/detector/GridSampler.java

@@ -28,52 +28,37 @@ import com.google.zxing.common.BitMatrix;
  * Imaging library, but which may not be available in other environments such as J2ME, and vice
  * versa.
  *
- * The implementation used can be controlled by calling {@link #setGridSamplerClassName(String)}
- * with the name of a class which implements this interface.
+ * The implementation used can be controlled by calling {@link #setGridSampler(GridSampler)}
+ * with an instance of a class which implements this interface.
  *
  * @author srowen@google.com (Sean Owen)
  */
 public abstract class GridSampler {
 
-  private static final String DEFAULT_IMPL_CLASS = "com.google.zxing.qrcode.detector.DefaultGridSampler";
-
-  private static String gridSamplerClassName = DEFAULT_IMPL_CLASS;
   private static GridSampler gridSampler;
 
   /**
-   * <p>Sets the (fully-qualified) name of the implementation of {@link GridSampler} which will be
-   * returned from {@link #getInstance()}.</p>
-   *
-   * @param className {@link GridSampler} implementation to instantiate
+   * Sets the implementation of {@link GridSampler} used by the library. One global
+   * instance is stored, which may sound problematic. But, the implementation provided
+   * ought to be appropriate for the entire platform, and all uses of this library
+   * in the whole lifetime of the JVM. For instance, an Android activity can swap in
+   * an implementation that takes advantage of native platform libraries.
+   * 
+   * @param newGridSampler
    */
-  public static void setGridSamplerClassName(String className) {
-    if (className == null) {
+  public static void setGridSampler(GridSampler newGridSampler) {
+    if (newGridSampler == null) {
       throw new IllegalArgumentException();
     }
-    gridSamplerClassName = className;
+    gridSampler = newGridSampler;
   }
 
   /**
-   * @return the current implementation of {@link GridSampler}, instantiating one if one does
-   *         not already exist. The class which is instantied may be set by
-   *         {@link #setGridSamplerClassName(String)}
+   * @return the current implementation of {@link GridSampler}
    */
   public static GridSampler getInstance() {
     if (gridSampler == null) {
-      // We don't need to synchronize this -- don't really care if two threads initialize at once.
-      // The second one will win.
-      try {
-        Class gridSamplerClass = Class.forName(gridSamplerClassName);
-        gridSampler = (GridSampler) gridSamplerClass.newInstance();
-      } catch (ClassNotFoundException cnfe) {
-        // The exceptions below would represent bad programming errors;
-        // For J2ME we're punting them out with RuntimeException
-        throw new RuntimeException(cnfe.toString());
-      } catch (IllegalAccessException iae) {
-        throw new RuntimeException(iae.toString());
-      } catch (InstantiationException ie) {
-        throw new RuntimeException(ie.toString());
-      }
+      gridSampler = new DefaultGridSampler();
     }
     return gridSampler;
   }