Make backends self-describing

9 files changed, 78 insertions, 70 deletions

diff --git a/src/backend.h b/src/backend.h
index 0da2244..714efde 100644
--- a/src/backend.h
+++ b/src/backend.h
@@ -18,13 +18,19 @@ struct imv_backend {
   /* Name of the backend, for debug and user informational purposes */
   const char *name;
 
+  /* Information about the backend, displayed by help dialog */
+  const char *description;
+
+  /* Official website address */
+  const char *website;
+
+  /* License the backend is used under */
+  const char *license;
+
   /* Input: path to open
    * Output: initialises the imv_source instance passed in
    */
   enum backend_result (*open_path)(const char *path, struct imv_source **src);
-
-  /* Clean up this backend */
-  void (*free)(struct imv_backend *backend);
 };
 
 #endif
diff --git a/src/backend_freeimage.c b/src/backend_freeimage.c
index 9443075..0032e31 100644
--- a/src/backend_freeimage.c
+++ b/src/backend_freeimage.c
@@ -258,23 +258,22 @@ static enum backend_result open_path(const char *path, struct imv_source **src)
   return BACKEND_SUCCESS;
 }
 
-static void backend_free(struct imv_backend *backend)
-{
-  free(backend);
-}
+const struct imv_backend freeimage_backend = {
+  .name = "FreeImage",
+  .description = "Open source image library supporting a large number of formats",
+  .website = "http://freeimage.sourceforge.net/",
+  .license = "FreeImage Public License v1.0",
+  .open_path = &open_path,
+};
 
-struct imv_backend *imv_backend_freeimage(void)
+const struct imv_backend *imv_backend_freeimage(void)
 {
-  struct imv_backend *backend = malloc(sizeof(struct imv_backend));
-  backend->name = "FreeImage (FIPL v1.0 license)";
-  backend->open_path = &open_path;
-  backend->free = &backend_free;
-  return backend;
+  return &freeimage_backend;
 }
 
 #else
 
-struct imv_backend *imv_backend_freeimage(void)
+const struct imv_backend *imv_backend_freeimage(void)
 {
   return NULL;
 }
diff --git a/src/backend_freeimage.h b/src/backend_freeimage.h
index de7d078..4eb0879 100644
--- a/src/backend_freeimage.h
+++ b/src/backend_freeimage.h
@@ -4,6 +4,6 @@
 struct imv_backend;
 
 /* Create an instance of the freeimage backend */
-struct imv_backend *imv_backend_freeimage(void);
+const struct imv_backend *imv_backend_freeimage(void);
 
 #endif
diff --git a/src/backend_libpng.c b/src/backend_libpng.c
index d5a2676..0e58b6f 100644
--- a/src/backend_libpng.c
+++ b/src/backend_libpng.c
@@ -179,23 +179,22 @@ static enum backend_result open_path(const char *path, struct imv_source **src)
   return BACKEND_SUCCESS;
 }
 
-static void backend_free(struct imv_backend *backend)
-{
-  free(backend);
-}
+const struct imv_backend libpng_backend = {
+  .name = "libpng",
+  .description = "The official PNG reference implementation",
+  .website = "http://www.libpng.org/pub/png/libpng.html",
+  .license = "The libpng license",
+  .open_path = &open_path,
+};
 
-struct imv_backend *imv_backend_libpng(void)
+const struct imv_backend *imv_backend_libpng(void)
 {
-  struct imv_backend *backend = malloc(sizeof(struct imv_backend));
-  backend->name = "libpng (libpng/zlib license)";
-  backend->open_path = &open_path;
-  backend->free = &backend_free;
-  return backend;
+  return &libpng_backend;
 }
 
 #else
 
-struct imv_backend *imv_backend_libpng(void)
+const struct imv_backend *imv_backend_libpng(void)
 {
   return NULL;
 }
diff --git a/src/backend_libpng.h b/src/backend_libpng.h
index be0d0b5..7370576 100644
--- a/src/backend_libpng.h
+++ b/src/backend_libpng.h
@@ -4,6 +4,6 @@
 struct imv_backend;
 
 /* Create an instance of the libpng backend */
-struct imv_backend *imv_backend_libpng(void);
+const struct imv_backend *imv_backend_libpng(void);
 
 #endif
diff --git a/src/backend_librsvg.c b/src/backend_librsvg.c
index 416743a..acadb25 100644
--- a/src/backend_librsvg.c
+++ b/src/backend_librsvg.c
@@ -130,23 +130,22 @@ static enum backend_result open_path(const char *path, struct imv_source **src)
   return BACKEND_SUCCESS;
 }
 
-static void backend_free(struct imv_backend *backend)
+const struct imv_backend librsvg_backend = {
+  .name = "libRSVG",
+  .description = "SVG library developed by GNOME",
+  .website = "https://wiki.gnome.org/Projects/LibRsvg",
+  .license = "Lesser GNU Public License",
+  .open_path = &open_path,
+};
+
+const struct imv_backend *imv_backend_librsvg(void)
 {
-  free(backend);
-}
-
-struct imv_backend *imv_backend_librsvg(void)
-{
-  struct imv_backend *backend = malloc(sizeof(struct imv_backend));
-  backend->name = "librsvg (LGPL license)";
-  backend->open_path = &open_path;
-  backend->free = &backend_free;
-  return backend;
+  return &librsvg_backend;
 }
 
 #else
 
-struct imv_backend *imv_backend_librsvg(void)
+const struct imv_backend *imv_backend_librsvg(void)
 {
   return NULL;
 }
diff --git a/src/backend_librsvg.h b/src/backend_librsvg.h
index 16dd6c8..b62aa85 100644
--- a/src/backend_librsvg.h
+++ b/src/backend_librsvg.h
@@ -4,6 +4,6 @@
 struct imv_backend;
 
 /* Create an instance of the rsvg backend */
-struct imv_backend *imv_backend_librsvg(void);
+const struct imv_backend *imv_backend_librsvg(void);
 
 #endif
diff --git a/src/imv.c b/src/imv.c
index b138eaf..421ea1a 100644
--- a/src/imv.c
+++ b/src/imv.c
@@ -54,7 +54,7 @@ enum background_type {
 };
 
 struct backend_chain {
-  struct imv_backend *backend;
+  const struct imv_backend *backend;
   struct backend_chain *next;
 };
 
@@ -288,7 +288,6 @@ struct imv *imv_create(void)
   imv->font_name = strdup("Monospace:24");
   imv->binds = imv_binds_create();
   imv->navigator = imv_navigator_create();
-
   imv->backends = NULL;
   imv->source = NULL;
   imv->last_source = NULL;
@@ -372,20 +371,14 @@ void imv_free(struct imv *imv)
   free(imv->overlay_text);
   imv_binds_free(imv->binds);
   imv_navigator_free(imv->navigator);
-
-  struct backend_chain *chain = imv->backends;
-  while (chain) {
-    struct backend_chain *next_backend = chain->next;
-    chain->backend->free(chain->backend);
-    chain = next_backend;
-  }
-
   if (imv->source) {
     imv->source->free(imv->source);
   }
   imv_commands_free(imv->commands);
   imv_viewport_free(imv->view);
-  imv_image_free(imv->image);
+  if (imv->image) {
+    imv_image_free(imv->image);
+  }
   if (imv->next_frame) {
     imv_bitmap_free(imv->next_frame);
   }
@@ -416,7 +409,7 @@ void imv_free(struct imv *imv)
   free(imv);
 }
 
-void imv_install_backend(struct imv *imv, struct imv_backend *backend)
+void imv_install_backend(struct imv *imv, const struct imv_backend *backend)
 {
   struct backend_chain *chain = malloc(sizeof(struct backend_chain));
   chain->backend = backend;
@@ -528,6 +521,33 @@ static int load_paths_from_stdin(void *data)
   return 0;
 }
 
+static void print_help(struct imv *imv)
+{
+  printf("imv %s\nSee manual for usage information.\n", IMV_VERSION);
+  puts("This version of imv has been compiled with the following backends:\n");
+
+  for (struct backend_chain *chain = imv->backends;
+       chain;
+       chain = chain->next) {
+    printf("Name: %s\n"
+           "Description: %s\n"
+           "Website: %s\n"
+           "License: %s\n\n",
+           chain->backend->name,
+           chain->backend->description,
+           chain->backend->website,
+           chain->backend->license);
+  }
+
+  puts("Legal:\n"
+       "imv's full source code is published under the terms of the MIT\n"
+       "license, and can be found at https://github.com/eXeC64/imv\n"
+       "\n"
+       "imv uses the inih library to parse ini files.\n"
+       "See https://github.com/benhoyt/inih for details.\n"
+       "inih is used under the New (3-clause) BSD license.");
+}
+
 bool imv_parse_args(struct imv *imv, int argc, char **argv)
 {
   /* Do not print getopt errors */
@@ -544,22 +564,7 @@ bool imv_parse_args(struct imv *imv, int argc, char **argv)
       case 'l': imv->list_files_at_exit = true;                  break;
       case 'n': imv->starting_path = optarg;                     break;
       case 'h':
-        fprintf(stdout,
-        "imv %s\n"
-        "See manual for usage information.\n"
-        "\n"
-        "Legal:\n"
-        "imv's full source code is published under the terms of the MIT\n"
-        "license, and can be found at https://github.com/eXeC64/imv\n"
-        "\n"
-        "imv uses the FreeImage open source image library.\n"
-        "See http://freeimage.sourceforge.net for details.\n"
-        "FreeImage is used under the FIPL License v1.0.\n"
-        "\n"
-        "imv uses the inih library to parse ini files.\n"
-        "See https://github.com/benhoyt/inih for details.\n"
-        "inih is used under the New (3-clause) BSD license.\n"
-        , IMV_VERSION);
+        print_help(imv);
         imv->quit = true;
         return true;
       case 's':
@@ -707,7 +712,7 @@ int imv_run(struct imv *imv)
           fprintf(stderr, "No backends installed. Unable to load image.\n");
         }
         for (struct backend_chain *chain = imv->backends; chain; chain = chain->next) {
-          struct imv_backend *backend = chain->backend;
+          const struct imv_backend *backend = chain->backend;
           result = backend->open_path(current_path, &new_source);
           if (result == BACKEND_UNSUPPORTED) {
             /* Try the next backend */
diff --git a/src/imv.h b/src/imv.h
index 594ce33..8966e69 100644
--- a/src/imv.h
+++ b/src/imv.h
@@ -10,7 +10,7 @@ struct imv *imv_create(void);
 void imv_free(struct imv *imv);
 
 /* Used in reverse addition order. Most recently added is the first used. */
-void imv_install_backend(struct imv *imv, struct imv_backend *backend);
+void imv_install_backend(struct imv *imv, const struct imv_backend *backend);
 
 bool imv_load_config(struct imv *imv);
 bool imv_parse_args(struct imv *imv, int argc, char **argv);