一开始以为是光照暗的时候开灯,后来把感光器挡住,微信扫一扫依然不会提示开灯,所以猜想:应该是与被扫描对象的亮暗程度进行判断是否开灯。
此功能已实现,核心原理如下:
解码预览帧对象,包括宽高
@param data The YUV preview frame.
* @param width The width of the preview frame.
* @param height The height of the preview frame.
decode((byte[]) message.obj, message.arg1, message.arg2);
具体解码过程:
/**
* 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) {
long start = System.currentTimeMillis();
Result rawResult = null;
//modify here
byte[] rotatedData = new byte[data.length];
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++)
rotatedData[x * height + height - y - 1] = data[x + y * width];
}
int tmp = width; // Here we are swapping, that's the difference to #11
width = height;
height = tmp;
/**为获取摄像头图像平均颜色值增加*/
frameCount++;
//丢弃前2帧并每隔2帧分析下预览帧color值
if (frameCount > 2 && frameCount % 2 == 0) {
analysisColor(rotatedData, width, height);
}
/********/
PlanarYUVLuminanceSource source = CameraManager.get().buildLuminanceSource(rotatedData, width, height);
BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
try {
rawResult = multiFormatReader.decodeWithState(bitmap);
} catch (ReaderException re) {
// continue
} finally {
multiFormatReader.reset();
}
if (rawResult != null) {
long end = System.currentTimeMillis();
Log.d(TAG, "Found barcode (" + (end - start) + " ms):\n" + rawResult.toString());
Message message = Message.obtain(activity.getHandler(), R.id.decode_succeeded, rawResult);
Bundle bundle = new Bundle();
bundle.putParcelable(DecodeThread.BARCODE_BITMAP, source.renderCroppedGreyscaleBitmap());
message.setData(bundle);
//Log.d(TAG, "Sending decode succeeded message...");
message.sendToTarget();
} else {
Message message = Message.obtain(activity.getHandler(), R.id.decode_failed);
message.sendToTarget();
}
}
分析预览帧中图片的rgb,由于一开始生成的Bitmap是整个帧的数据,过大,所以选取以中心点宽高10像素的Bitmap对象来分析与纯黑色之间的成都,经测试,选取80%的黑我们认为开灯扫描比较合适
/**分析预览帧中图片的rgb 取平均值*/
private void analysisColor(byte[] data, int width, int height) {
int[] rgb = decodeYUV420SP(data, width / 8, height / 8);
Bitmap bmp = Bitmap.createBitmap(rgb, width / 8, height / 8, Bitmap.Config.ARGB_8888);
if (bmp != null) {
//取以中心点宽高10像素的图片来分析
Bitmap resizeBitmap = Bitmap.createBitmap(bmp, bmp.getWidth() / 2, bmp.getHeight() / 2, 10, 10);
float color = (float) getAverageColor(resizeBitmap);
DecimalFormat decimalFormat1 = new DecimalFormat("0.00");
String percent = decimalFormat1.format(color / -16777216);
float floatPercent = Float.parseFloat(percent);
activity.isWeakLight = floatPercent >= 0.80 && floatPercent <= 1.00;
if (null != resizeBitmap) {
resizeBitmap.recycle();
}
bmp.recycle();
}
}