我正在尝试加快条形码扫描的速度,由于自动聚焦需要几秒钟的时间,因此使用Google的Vision API的条形码扫描速度很慢。因此,我想尝试限制相机尝试自动对焦的距离,以使其始终在几厘米之内,而不是从无限远处拉近。
但是,我不确定如何实现这一点,因为CaptureRequest似乎没有设置最小/最大聚焦距离的任何内容。如果我尝试在回调类CameraStateWatcher中设置距离,则不会发生任何事情,因为AF会覆盖它。
有没有地方可以覆盖焦距值,例如onCaptureStarted等期间的CameraCaptureSession.CaptureCallback?
我正在使用以下代码:
private class CameraCaptureWatcher extends CameraCaptureSession.CaptureCallback {
// POSSIBLE TO OVERRIDE THE FOCUS DISTANCE IN HERE TO SET MIN/MAX?
// oncapturestarted
// oncapturecompleted
}
private class CameraStateWatcher extends CameraDevice.StateCallback {
@Override
public void onOpened(@NonNull CameraDevice cameraDevice) {
TestCamera.this.cameraDevice = cameraDevice;
List<Surface> surfaces = new ArrayList<>();
surfaces.add(previewSurface);
surfaces.add(imageReader.getSurface());
try {
CaptureRequest.Builder captureRequestBuilder = cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
// POSSIBLE TO SET MIN/MAX FOCUS DISTANCE WITH REQUEST?
captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_OFF);
for ( Surface surface : surfaces ) {
captureRequestBuilder.addTarget(surface);
}
captureRequest = captureRequestBuilder.build();
for ( CaptureRequest.Key<?> key : captureRequest.getKeys() ) {
Log.d("STATE_WATCHER", "Request Key = " + key.getName());
}
cameraDevice.createCaptureSession(surfaces, cameraSurfaceWatcher, handler);
} catch (CameraAccessException e) {
e.printStackTrace();
}
}
}
}
API对此唯一的控制是选择MACRO自动对焦模式,不一定在所有设备上都支持。