hwcontext: Make it easier to work with device types

Adds functions to convert to/from strings and a function to iterate
over all supported device types.  Also adds a new invalid type
AV_HWDEVICE_TYPE_NONE, which acts as a sentinel value.

(cherry picked from commit b7487f4f3c39b4b202e1ea7bb2de13902f2dee45)

1 files changed, 28 insertions, 0 deletions

diff --git a/libavutil/hwcontext.h b/libavutil/hwcontext.h
index 782dbf22e1..37e8831f6b 100644
--- a/libavutil/hwcontext.h
+++ b/libavutil/hwcontext.h
@@ -31,6 +31,7 @@ enum AVHWDeviceType {
     AV_HWDEVICE_TYPE_DXVA2,
     AV_HWDEVICE_TYPE_QSV,
     AV_HWDEVICE_TYPE_VIDEOTOOLBOX,
+    AV_HWDEVICE_TYPE_NONE,
 };
 
 typedef struct AVHWDeviceInternal AVHWDeviceInternal;
@@ -224,6 +225,33 @@ typedef struct AVHWFramesContext {
 } AVHWFramesContext;
 
 /**
+ * Look up an AVHWDeviceType by name.
+ *
+ * @param name String name of the device type (case-insensitive).
+ * @return The type from enum AVHWDeviceType, or AV_HWDEVICE_TYPE_NONE if
+ *         not found.
+ */
+enum AVHWDeviceType av_hwdevice_find_type_by_name(const char *name);
+
+/** Get the string name of an AVHWDeviceType.
+ *
+ * @param type Type from enum AVHWDeviceType.
+ * @return Pointer to a static string containing the name, or NULL if the type
+ *         is not valid.
+ */
+const char *av_hwdevice_get_type_name(enum AVHWDeviceType type);
+
+/**
+ * Iterate over supported device types.
+ *
+ * @param type AV_HWDEVICE_TYPE_NONE initially, then the previous type
+ *             returned by this function in subsequent iterations.
+ * @return The next usable device type from enum AVHWDeviceType, or
+ *         AV_HWDEVICE_TYPE_NONE if there are no more.
+ */
+enum AVHWDeviceType av_hwdevice_iterate_types(enum AVHWDeviceType prev);
+
+/**
  * Allocate an AVHWDeviceContext for a given hardware type.
  *
  * @param type the type of the hardware device to allocate.