void setHandler(Handler previewHandler, int previewMessage) {
    this.previewHandler = previewHandler;
    this.previewMessage = previewMessage;
  }
Called when the next preview frame is received.

The code for this class was adapted from the ZXing project: http://code.google.com/p/zxing
OCRTest/src/main/java/edu/sfsu/cs/orange/ocr/camera/PreviewCallback.java