二维码-ViewFinderView的使用
岳英耀
界面
<com.google.zxing.client.android.ViewfinderView
android:id="@+id/viewfinder_view"
android:layout_width="fill_parent"
android:layout_height="fill_parent"/>代码解析
初始化
viewfinderView = (ViewfinderView) findViewById(R.id.viewfinder_view);
viewfinderView.setCameraManager(cameraManager);handleDecodeExternally()中用到了viewfinderView
if (barcode != null) {
viewfinderView.drawResultBitmap(barcode);
} // Briefly show the contents of the barcode, then handle the result outside Barcode Scanner.
private void handleDecodeExternally(Result rawResult, ResultHandler resultHandler, Bitmap barcode) {
if (barcode != null) {
viewfinderView.drawResultBitmap(barcode);
}
long resultDurationMS;
if (getIntent() == null) {
resultDurationMS = DEFAULT_INTENT_RESULT_DURATION_MS;
} else {
resultDurationMS = getIntent().getLongExtra(Intents.Scan.RESULT_DISPLAY_DURATION_MS,
DEFAULT_INTENT_RESULT_DURATION_MS);
}
if (resultDurationMS > 0) {
String rawResultString = String.valueOf(rawResult);
if (rawResultString.length() > 32) {
rawResultString = rawResultString.substring(0, 32) + " ...";
}
statusView.setText(getString(resultHandler.getDisplayTitle()) + " : " + rawResultString);
}
if (copyToClipboard && !resultHandler.areContentsSecure()) {
CharSequence text = resultHandler.getDisplayContents();
ClipboardInterface.setText(text, this);
}
if (source == IntentSource.NATIVE_APP_INTENT) {
// Hand back whatever action they requested - this can be changed to Intents.Scan.ACTION when
// the deprecated intent is retired.
Intent intent = new Intent(getIntent().getAction());
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
intent.putExtra(Intents.Scan.RESULT, rawResult.toString());
intent.putExtra(Intents.Scan.RESULT_FORMAT, rawResult.getBarcodeFormat().toString());
byte[] rawBytes = rawResult.getRawBytes();
if (rawBytes != null && rawBytes.length > 0) {
intent.putExtra(Intents.Scan.RESULT_BYTES, rawBytes);
}
Map<ResultMetadataType, ?> metadata = rawResult.getResultMetadata();
if (metadata != null) {
if (metadata.containsKey(ResultMetadataType.UPC_EAN_EXTENSION)) {
intent.putExtra(Intents.Scan.RESULT_UPC_EAN_EXTENSION,
metadata.get(ResultMetadataType.UPC_EAN_EXTENSION).toString());
}
Number orientation = (Number) metadata.get(ResultMetadataType.ORIENTATION);
if (orientation != null) {
intent.putExtra(Intents.Scan.RESULT_ORIENTATION, orientation.intValue());
}
String ecLevel = (String) metadata.get(ResultMetadataType.ERROR_CORRECTION_LEVEL);
if (ecLevel != null) {
intent.putExtra(Intents.Scan.RESULT_ERROR_CORRECTION_LEVEL, ecLevel);
}
@SuppressWarnings("unchecked")
Iterable<byte[]> byteSegments = (Iterable<byte[]>) metadata.get(ResultMetadataType.BYTE_SEGMENTS);
if (byteSegments != null) {
int i = 0;
for (byte[] byteSegment : byteSegments) {
intent.putExtra(Intents.Scan.RESULT_BYTE_SEGMENTS_PREFIX + i, byteSegment);
i++;
}
}
}
sendReplyMessage(R.id.return_scan_result, intent, resultDurationMS);
} else if (source == IntentSource.PRODUCT_SEARCH_LINK) {
// Reformulate the URL which triggered us into a query, so that the request goes to the same
// TLD as the scan URL.
int end = sourceUrl.lastIndexOf("/scan");
String replyURL = sourceUrl.substring(0, end) + "?q=" + resultHandler.getDisplayContents() + "&source=zxing";
sendReplyMessage(R.id.launch_product_query, replyURL, resultDurationMS);
} else if (source == IntentSource.ZXING_LINK) {
if (scanFromWebPageManager != null && scanFromWebPageManager.isScanFromWebPage()) {
String replyURL = scanFromWebPageManager.buildReplyURL(rawResult, resultHandler);
scanFromWebPageManager = null;
sendReplyMessage(R.id.launch_product_query, replyURL, resultDurationMS);
}
}
}drawViewfinder()函数的使用
public void drawViewfinder() {
viewfinderView.drawViewfinder();
}handleDecode()
/**
* A valid barcode has been found, so give an indication of success and show the results.
*
* @param rawResult The contents of the barcode.
* @param scaleFactor amount by which thumbnail was scaled
* @param barcode A greyscale bitmap of the camera data which was decoded.
*/
public void handleDecode(Result rawResult, Bitmap barcode, float scaleFactor) {
inactivityTimer.onActivity();
lastResult = rawResult;
ResultHandler resultHandler = ResultHandlerFactory.makeResultHandler(this, rawResult);
boolean fromLiveScan = barcode != null;
if (fromLiveScan) {
historyManager.addHistoryItem(rawResult, resultHandler);
// Then not from history, so beep/vibrate and we have an image to draw on
beepManager.playBeepSoundAndVibrate();
drawResultPoints(barcode, scaleFactor, rawResult);
}
switch (source) {
case NATIVE_APP_INTENT:
case PRODUCT_SEARCH_LINK:
handleDecodeExternally(rawResult, resultHandler, barcode);
break;
case ZXING_LINK:
if (scanFromWebPageManager == null || !scanFromWebPageManager.isScanFromWebPage()) {
handleDecodeInternally(rawResult, resultHandler, barcode);
} else {
handleDecodeExternally(rawResult, resultHandler, barcode);
}
break;
case NONE:
SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(this);
if (fromLiveScan && prefs.getBoolean(PreferencesActivity.KEY_BULK_MODE, false)) {
Toast.makeText(getApplicationContext(),
getResources().getString(R.string.msg_bulk_mode_scanned) + " (" + rawResult.getText() + ')',
Toast.LENGTH_SHORT).show();
// Wait a moment or else it will scan the same barcode continuously about 3 times
restartPreviewAfterDelay(BULK_MODE_SCAN_DELAY_MS);
} else {
handleDecodeInternally(rawResult, resultHandler, barcode);
}
break;
}
}二维码获取数据的过程
- 通过Camera中的setOneShotPreviewCallback(previewCallBack)提取一张照片.
- 通过previewCallBack中的onPreviewFrame(byte[], Camera)返回一张照片的数据.
- 通过Message给handler发送数据并解析.
- 通过DecodeHandler中的decode方法对图片数据进行解析.
- 如果有数据返回成功,如果没数据返回失败并重新扫描.
二维码解析的过程
整个解析过程是在Decode#decode()函数中.
/**
* Decode the data within the viewfinder rectangle, and time how long it took. For efficiency,
* reuse the same reader objects from one decode to the next.
*
* @param data The YUV preview frame.
* @param width The width of the preview frame.
* @param height The height of the preview frame.
*/
private void decode(byte[] data, int width, int height) {
Logger.t(CameraManager.TAG_1).d("decode(byte[] data, int width -> " + width +
", int height" + height +
")");
long start = System.currentTimeMillis();
Result rawResult = null;
PlanarYUVLuminanceSource source = activity.getCameraManager().buildLuminanceSource(data, width, height);
if (source != null) {
BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
try {
rawResult = multiFormatReader.decodeWithState(bitmap);
} catch (ReaderException re) {
// continue
} finally {
multiFormatReader.reset();
}
}
Handler handler = activity.getHandler();
if (rawResult != null) {
Logger.t(CameraManager.TAG_1).d("decode() rawResult != null");
// Don't log the barcode contents for security.
long end = System.currentTimeMillis();
Log.d(TAG, "Found barcode in " + (end - start) + " ms");
if (handler != null) {
Message message = Message.obtain(handler, R.id.decode_succeeded, rawResult);
Bundle bundle = new Bundle();
bundleThumbnail(source, bundle);
message.setData(bundle);
message.sendToTarget();
}
} else {
Logger.t(CameraManager.TAG_1).d("decode() rawResult == null");
if (handler != null) {
Message message = Message.obtain(handler, R.id.decode_failed);
message.sendToTarget();
}
}
}MultiFormatReader#setHints()
设置Readers
// Put 1D readers upfront in "normal" mode
if (addOneDReader && !tryHarder) {
readers.add(new MultiFormatOneDReader(hints));
}
if (formats.contains(BarcodeFormat.QR_CODE)) {
readers.add(new QRCodeReader());
}
if (formats.contains(BarcodeFormat.DATA_MATRIX)) {
readers.add(new DataMatrixReader());
}
if (formats.contains(BarcodeFormat.AZTEC)) {
readers.add(new AztecReader());
}
if (formats.contains(BarcodeFormat.PDF_417)) {
readers.add(new PDF417Reader());
}
if (formats.contains(BarcodeFormat.MAXICODE)) {
readers.add(new MaxiCodeReader());
}
// At end in "try harder" mode
if (addOneDReader && tryHarder) {
readers.add(new MultiFormatOneDReader(hints));
}过程:
1. 得到元数据,封装在PlanarYUVLuminanceSource中.
2. 建立一个Bitmap图像.
3. 通过MultiFormatReader解析数据.
4. 通过一系列的Readers进行数据的读取.
5. 如果结果为null,返回失败.如果有结果,返回成功.
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