PlayAnim: errors loading images are now shown in the UI

It's unlikely most users will see these messages in the stdout,
show them after the filepath as well as logging them.

source/blender/windowmanager/intern/wm_playanim.cc

@@ -103,12 +103,15 @@ static bool playanim_window_font_scale_from_dpi(PlayState *ps);
  * \param r_mem: Optional, when nullptr, don't allocate memory (just set the size).
  * \param r_size: The file-size of `filepath`.
  */
-static bool buffer_from_filepath(const char *filepath, void **r_mem, size_t *r_size)
+static bool buffer_from_filepath(const char *filepath,
+                                 void **r_mem,
+                                 size_t *r_size,
+                                 char **r_error_message)
 {
   errno = 0;
   const int file = BLI_open(filepath, O_BINARY | O_RDONLY, 0);
   if (UNLIKELY(file == -1)) {
-    CLOG_WARN(&LOG, "failure '%s' to open file '%s'", strerror(errno), filepath);
+    *r_error_message = BLI_sprintfN("failure '%s' to open file", strerror(errno));
     return false;
   }
 
@@ -117,18 +120,18 @@ static bool buffer_from_filepath(const char *filepath, void **r_mem, size_t *r_s
   const size_t size = BLI_file_descriptor_size(file);
   int64_t size_read;
   if (UNLIKELY(size == size_t(-1))) {
-    CLOG_WARN(&LOG, "failure '%s' to access size '%s'", strerror(errno), filepath);
+    *r_error_message = BLI_sprintfN("failure '%s' to access size", strerror(errno));
   }
   else if (r_mem && UNLIKELY(!(mem = static_cast<uchar *>(MEM_mallocN(size, __func__))))) {
-    CLOG_WARN(&LOG, "error allocating buffer for '%s'", filepath);
+    *r_error_message = BLI_sprintfN("error allocating buffer %" PRIu64 " size", size);
   }
   else if (r_mem && UNLIKELY((size_read = BLI_read(file, mem, size)) != size)) {
-    CLOG_WARN(&LOG,
-              "error '%s' while reading '%s' (expected %" PRIu64 ", was %" PRId64 ")",
-              strerror(errno),
-              filepath,
-              size,
-              size_read);
+    *r_error_message = BLI_sprintfN(
+        "error '%s' reading file "
+        "(expected %" PRIu64 ", was %" PRId64 ")",
+        strerror(errno),
+        size,
+        size_read);
   }
   else {
     close(file);
@@ -331,6 +334,8 @@ struct PlayAnimPict {
   size_t size;
   /** The allocated file-path to the image. */
   const char *filepath;
+  /** The allocated error message to show if the file cannot be loaded. */
+  char *error_message;
   ImBuf *ibuf;
   struct anim *anim;
   int frame;
@@ -716,7 +721,10 @@ static void playanim_toscreen_ex(GHOST_WindowHandle ghost_window,
       SNPRINTF(label, "%s | %.2f frames/s", picture->filepath, fstep / g_playanim.swap_time);
     }
     else {
-      SNPRINTF(label, "%s | <failed to load buffer>", picture->filepath);
+      SNPRINTF(label,
+               "%s | %s",
+               picture->filepath,
+               picture->error_message ? picture->error_message : "<unknown error>");
     }
 
     playanim_window_get_size(ghost_window, &sizex, &sizey);
@@ -897,11 +905,14 @@ static void build_pict_list_from_image_sequence(ListBase *picsbase,
       break;
     }
 
+    bool has_error = false;
+    char *error_message = nullptr;
     void *mem = nullptr;
     size_t size = -1;
-    if (!buffer_from_filepath(filepath, g_playanim.from_disk ? nullptr : &mem, &size)) {
-      /* A warning will have been logged. */
-      break;
+    if (!buffer_from_filepath(
+            filepath, g_playanim.from_disk ? nullptr : &mem, &size, &error_message)) {
+      has_error = true;
+      size = 0;
     }
 
     PlayAnimPict *picture = (PlayAnimPict *)MEM_callocN(sizeof(PlayAnimPict), "picture");
@@ -909,6 +920,7 @@ static void build_pict_list_from_image_sequence(ListBase *picsbase,
     picture->IB_flags = IB_rect;
     picture->mem = static_cast<uchar *>(mem);
     picture->filepath = BLI_strdup(filepath);
+    picture->error_message = error_message;
     picture->frame = pic + frame_offset;
     BLI_addtail(picsbase, picture);
 
@@ -916,7 +928,13 @@ static void build_pict_list_from_image_sequence(ListBase *picsbase,
 
     const bool display_imbuf = g_playanim.total_time > 1.0;
 
-    if (display_imbuf || fill_cache) {
+    if (has_error) {
+      CLOG_WARN(&LOG,
+                "Picture %s failed: %s",
+                filepath,
+                error_message ? error_message : "<unknown error>");
+    }
+    else if (display_imbuf || fill_cache) {
       /* OCIO_TODO: support different input color space. */
       ImBuf *ibuf = ibuf_from_picture(picture);
 
@@ -2073,7 +2091,9 @@ static bool wm_main_playanim_intern(int argc, const char **argv, PlayArgs *args_
     if (ps.picture->mem) {
       MEM_freeN(ps.picture->mem);
     }
-
+    if (ps.picture->error_message) {
+      MEM_freeN((void *)ps.picture->error_message);
+    }
     MEM_freeN((void *)ps.picture->filepath);
     MEM_freeN(ps.picture);
   }