Cleanup: use IMB_FTYPE_NONE instead of 0 for imbuf format comparison

Image format code checked the file type against an enum except for
zero which is used when the format can't be detected.

Also add doc-strings to some of the image file type callbacks.

3 files changed, 22 insertions, 5 deletions

diff --git a/source/blender/imbuf/IMB_imbuf_types.h b/source/blender/imbuf/IMB_imbuf_types.h
index 98e9c34a4ff..4bb3ea500fa 100644
--- a/source/blender/imbuf/IMB_imbuf_types.h
+++ b/source/blender/imbuf/IMB_imbuf_types.h
@@ -69,7 +69,7 @@ typedef struct DDSData {
  * See T46524. */
 
 /** #ImBuf.ftype flag, main image types. */
-enum eImbTypes {
+enum eImbFileType {
   IMB_FTYPE_PNG = 1,
   IMB_FTYPE_TGA = 2,
   IMB_FTYPE_JPG = 3,
@@ -98,6 +98,9 @@ enum eImbTypes {
 #endif
 };
 
+/* Only for readability. */
+#define IMB_FTYPE_NONE 0
+
 /* ibuf->foptions flag, type specific options.
  * Some formats include compression rations on some bits */
 
@@ -243,7 +246,7 @@ typedef struct ImBuf {
 
   /* file information */
   /** file type we are going to save as */
-  enum eImbTypes ftype;
+  enum eImbFileType ftype;
   /** file format specific flags */
   ImbFormatOptions foptions;
   /** filename associated with this image */
diff --git a/source/blender/imbuf/intern/IMB_filetype.h b/source/blender/imbuf/intern/IMB_filetype.h
index 175d973de9a..c8f6135f330 100644
--- a/source/blender/imbuf/intern/IMB_filetype.h
+++ b/source/blender/imbuf/intern/IMB_filetype.h
@@ -29,15 +29,26 @@ struct ImBuf;
 #define IM_FTYPE_FLOAT 1
 
 typedef struct ImFileType {
+  /** Optional, called once when initializing. */
   void (*init)(void);
+  /** Optional, called once when exiting. */
   void (*exit)(void);
 
+  /**
+   * Check if the data matches this file types 'magic',
+   * \note that this may only read in a small part of the files header,
+   * see: #IMB_ispic_type for details.
+   */
   bool (*is_a)(const unsigned char *buf, const size_t size);
+
+  /** Load an image from memory. */
   struct ImBuf *(*load)(const unsigned char *mem,
                         size_t size,
                         int flags,
                         char colorspace[IM_MAX_SPACE]);
+  /** Load an image from a file. */
   struct ImBuf *(*load_filepath)(const char *filepath, int flags, char colorspace[IM_MAX_SPACE]);
+  /** Save to a file (or memory if #IB_mem is set in `flags` and the format supports it). */
   bool (*save)(struct ImBuf *ibuf, const char *filepath, int flags);
   void (*load_tile)(struct ImBuf *ibuf,
                     const unsigned char *mem,
@@ -47,7 +58,10 @@ typedef struct ImFileType {
                     unsigned int *rect);
 
   int flag;
+
+  /** #eImbFileType */
   int filetype;
+
   int default_save_role;
 } ImFileType;
 
diff --git a/source/blender/imbuf/intern/util.c b/source/blender/imbuf/intern/util.c
index c18321ae2fe..64dad5de902 100644
--- a/source/blender/imbuf/intern/util.c
+++ b/source/blender/imbuf/intern/util.c
@@ -159,7 +159,7 @@ int IMB_ispic_type_from_memory(const unsigned char *buf, const size_t buf_size)
     }
   }
 
-  return 0;
+  return IMB_FTYPE_NONE;
 }
 
 int IMB_ispic_type(const char *filepath)
@@ -167,7 +167,7 @@ int IMB_ispic_type(const char *filepath)
   unsigned char buf[HEADER_SIZE];
   const ssize_t buf_size = imb_ispic_read_header_from_filepath(filepath, buf);
   if (buf_size <= 0) {
-    return 0;
+    return IMB_FTYPE_NONE;
   }
   return IMB_ispic_type_from_memory(buf, (size_t)buf_size);
 }
@@ -196,7 +196,7 @@ bool IMB_ispic_type_matches(const char *filepath, int filetype)
 
 bool IMB_ispic(const char *filepath)
 {
-  return (IMB_ispic_type(filepath) != 0);
+  return (IMB_ispic_type(filepath) != IMB_FTYPE_NONE);
 }
 
 static bool isavi(const char *filepath)