Provide alternate device paths info for USB cameras (#1519)

This is primarily for use on Linux to get by-id or by-path device names.

This information is now part of UsbCameraInfo.

A new entry point was added to UsbCamera to get that camera's UsbCameraInfo.

The alternate paths are also returned in EnumerateUsbCameras.

cscore/src/main/native/include/cscore_c.h

@@ -223,6 +223,17 @@ struct CS_Event {
   const char* valueStr;
 };
 
+/**
+ * USB camera infomation
+ */
+typedef struct CS_UsbCameraInfo {
+  int dev;
+  char* path;
+  char* name;
+  int otherPathsCount;
+  char** otherPaths;
+} CS_UsbCameraInfo;
+
 /**
  * @defgroup cscore_property_cfunc Property Functions
  * @{
@@ -322,6 +333,7 @@ void CS_SetCameraExposureManual(CS_Source source, int value, CS_Status* status);
  * @{
  */
 char* CS_GetUsbCameraPath(CS_Source source, CS_Status* status);
+CS_UsbCameraInfo* CS_GetUsbCameraInfo(CS_Source source, CS_Status* status);
 /** @} */
 
 /**
@@ -456,15 +468,6 @@ void CS_Shutdown(void);
  * @{
  */
 
-/**
- * USB camera infomation
- */
-typedef struct CS_UsbCameraInfo {
-  int dev;
-  char* path;
-  char* name;
-} CS_UsbCameraInfo;
-
 CS_UsbCameraInfo* CS_EnumerateUsbCameras(int* count, CS_Status* status);
 void CS_FreeEnumeratedUsbCameras(CS_UsbCameraInfo* cameras, int count);
 
@@ -476,6 +479,7 @@ void CS_ReleaseEnumeratedSinks(CS_Sink* sinks, int count);
 
 void CS_FreeString(char* str);
 void CS_FreeEnumPropertyChoices(char** choices, int count);
+void CS_FreeUsbCameraInfo(CS_UsbCameraInfo* info);
 void CS_FreeHttpCameraUrls(char** urls, int count);
 
 void CS_FreeEnumeratedProperties(CS_Property* properties, int count);

cscore/src/main/native/include/cscore_cpp.h

@@ -47,11 +47,13 @@ namespace cs {
  */
 struct UsbCameraInfo {
   /** Device number (e.g. N in '/dev/videoN' on Linux) */
-  int dev;
+  int dev = -1;
   /** Path to device if available (e.g. '/dev/video0' on Linux) */
   std::string path;
   /** Vendor/model name of the camera as provided by the USB driver */
   std::string name;
+  /** Other path aliases to device (e.g. '/dev/v4l/by-id/...' etc on Linux) */
+  std::vector<std::string> otherPaths;
 };
 
 /**
@@ -267,6 +269,7 @@ void SetCameraExposureManual(CS_Source source, int value, CS_Status* status);
  * @{
  */
 std::string GetUsbCameraPath(CS_Source source, CS_Status* status);
+UsbCameraInfo GetUsbCameraInfo(CS_Source source, CS_Status* status);
 /** @} */
 
 /**

cscore/src/main/native/include/cscore_oo.h

@@ -449,6 +449,11 @@ class UsbCamera : public VideoCamera {
    */
   std::string GetPath() const;
 
+  /**
+   * Get the full camera information for the device.
+   */
+  UsbCameraInfo GetInfo() const;
+
   /**
    * Set how verbose the camera connection messages are.
    *

cscore/src/main/native/include/cscore_oo.inl

@@ -260,6 +260,11 @@ inline std::string UsbCamera::GetPath() const {
   return ::cs::GetUsbCameraPath(m_handle, &m_status);
 }
 
+inline UsbCameraInfo UsbCamera::GetInfo() const {
+  m_status = 0;
+  return ::cs::GetUsbCameraInfo(m_handle, &m_status);
+}
+
 inline void UsbCamera::SetConnectVerbose(int level) {
   m_status = 0;
   SetProperty(GetSourceProperty(m_handle, "connect_verbose", &m_status), level,