typefindhelper: Introduce a new API for working with a GstTypeFind *

Introduce a new API that can return a GstTypeFind * with helper functions
and data set around buffer data.

While at it, drop factory field from GstTypeFindBufHelper. While it was
useful for logging, it was not passed through function arguments and keeping
it for logging would require an additional API increasing the API surface
and making it harder to use.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3296>

subprojects/gstreamer/libs/gst/base/gsttypefindhelper.c

@@ -94,8 +94,8 @@ helper_find_peek (gpointer data, gint64 offset, guint size)
 
   helper = (GstTypeFindHelper *) data;
 
-  GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT
+  GST_LOG_OBJECT (helper->obj, "Typefind factory called peek (%" G_GINT64_FORMAT
-      ", %u)", GST_OBJECT_NAME (helper->factory), offset, size);
+      ", %u)", offset, size);
 
   if (size == 0)
     return NULL;
@@ -229,8 +229,8 @@ helper_find_suggest (gpointer data, guint probability, GstCaps * caps)
   GstTypeFindHelper *helper = (GstTypeFindHelper *) data;
 
   GST_LOG_OBJECT (helper->obj,
-      "'%s' called suggest (%u, %" GST_PTR_FORMAT ")",
+      "Typefind factory called suggest (%u, %" GST_PTR_FORMAT ")",
-      GST_OBJECT_NAME (helper->factory), probability, caps);
+      probability, caps);
 
   if (probability > helper->best_probability) {
     gst_caps_replace (&helper->caps, caps);
@@ -243,8 +243,8 @@ helper_find_get_length (gpointer data)
 {
   GstTypeFindHelper *helper = (GstTypeFindHelper *) data;
 
-  GST_LOG_OBJECT (helper->obj, "'%s' called get_length, returning %"
+  GST_LOG_OBJECT (helper->obj, "Typefind factory called get_length, returning %"
-      G_GUINT64_FORMAT, GST_OBJECT_NAME (helper->factory), helper->size);
+      G_GUINT64_FORMAT, helper->size);
 
   return helper->size;
 }
@@ -495,10 +495,23 @@ typedef struct
   gsize size;
   GstTypeFindProbability best_probability;
   GstCaps *caps;
-  GstTypeFindFactory *factory;  /* for logging */
   GstObject *obj;               /* for logging */
 } GstTypeFindBufHelper;
 
+/**
+ * GstTypeFindData:
+ *
+ * The opaque #GstTypeFindData structure.
+ *
+ * Since: 1.22
+ *
+ */
+struct _GstTypeFindData
+{
+  GstTypeFind find;
+  GstTypeFindBufHelper helper;
+};
+
 /*
  * buf_helper_find_peek:
  * @data: helper data struct
@@ -516,15 +529,15 @@ buf_helper_find_peek (gpointer data, gint64 off, guint size)
   GstTypeFindBufHelper *helper;
 
   helper = (GstTypeFindBufHelper *) data;
-  GST_LOG_OBJECT (helper->obj, "'%s' called peek (%" G_GINT64_FORMAT ", %u)",
+  GST_LOG_OBJECT (helper->obj,
-      GST_OBJECT_NAME (helper->factory), off, size);
+      "Typefind factory called peek (%" G_GINT64_FORMAT ", %u)", off, size);
 
   if (size == 0)
     return NULL;
 
   if (off < 0) {
-    GST_LOG_OBJECT (helper->obj, "'%s' wanted to peek at end; not supported",
+    GST_LOG_OBJECT (helper->obj,
-        GST_OBJECT_NAME (helper->factory));
+        "Typefind factory wanted to peek at end; not supported");
     return NULL;
   }
 
@@ -556,8 +569,8 @@ buf_helper_find_suggest (gpointer data, guint probability, GstCaps * caps)
   GstTypeFindBufHelper *helper = (GstTypeFindBufHelper *) data;
 
   GST_LOG_OBJECT (helper->obj,
-      "'%s' called suggest (%u, %" GST_PTR_FORMAT ")",
+      "Typefind factory called suggest (%u, %" GST_PTR_FORMAT ")",
-      GST_OBJECT_NAME (helper->factory), probability, caps);
+      probability, caps);
 
   /* Note: not >= as we call typefinders in order of rank, highest first */
   if (probability > helper->best_probability) {
@@ -638,6 +651,7 @@ gst_type_find_helper_for_data_with_extension (GstObject * obj,
     GstTypeFindProbability * prob)
 {
   GstTypeFindBufHelper helper;
+  GstTypeFindFactory *factory;
   GstTypeFind find;
   GList *l, *type_list;
   GstCaps *result = NULL;
@@ -662,8 +676,8 @@ gst_type_find_helper_for_data_with_extension (GstObject * obj,
   type_list = prioritize_extension (obj, type_list, extension);
 
   for (l = type_list; l; l = l->next) {
-    helper.factory = GST_TYPE_FIND_FACTORY (l->data);
+    factory = GST_TYPE_FIND_FACTORY (l->data);
-    gst_type_find_factory_call_function (helper.factory, &find);
+    gst_type_find_factory_call_function (factory, &find);
     if (helper.best_probability >= GST_TYPE_FIND_MAXIMUM)
       break;
   }
@@ -1028,3 +1042,114 @@ gst_type_find_list_factories_for_caps (GstObject * obj, GstCaps * caps)
 
   return g_list_reverse (factories);
 }
+
+/**
+ * gst_type_find_data_new: (skip)
+ * @obj: (nullable): object doing the typefinding, or %NULL (used for logging)
+ * @data: (transfer none) (array length=size): a pointer with data to typefind
+ * @size: the size of @data
+ *
+ * Free-function: gst_type_find_data_free
+ *
+ * Returns: (transfer full): the #GstTypeFindData. The caller should free
+ *          the returned #GstTypeFindData with gst_type_find_data_free().
+ *
+ * Since: 1.22
+ *
+ */
+GstTypeFindData *
+gst_type_find_data_new (GstObject * obj, const guint8 * data, gsize size)
+{
+  GstTypeFindData *find_data;
+
+  g_return_val_if_fail (data != NULL, NULL);
+  g_return_val_if_fail (size != 0, NULL);
+
+  find_data = g_new0 (GstTypeFindData, 1);
+
+  find_data->helper.data = data;
+  find_data->helper.size = size;
+  find_data->helper.best_probability = GST_TYPE_FIND_NONE;
+  find_data->helper.caps = NULL;
+  find_data->helper.obj = obj;
+
+  find_data->find.data = (gpointer) (&find_data->helper);
+  find_data->find.peek = buf_helper_find_peek;
+  find_data->find.suggest = buf_helper_find_suggest;
+  find_data->find.get_length = NULL;
+
+  return find_data;
+}
+
+/**
+ * gst_type_find_data_get_probability: (skip)
+ * @data: GstTypeFindData *
+ *
+ * Returns #GstCaps associated with #GstTypeFindData
+ *
+ * Returns: (transfer full) (nullable): #GstCaps.
+ *
+ * Since: 1.22
+ *
+ */
+GstCaps *
+gst_type_find_data_get_caps (GstTypeFindData * data)
+{
+  g_return_val_if_fail (data != NULL, NULL);
+
+  return gst_caps_ref (data->helper.caps);
+}
+
+/**
+ * gst_type_find_data_get_probability: (skip)
+ * @data: GstTypeFindData *
+ *
+ * Returns #GstTypeFindProbability associated with #GstTypeFindData
+ *
+ * Returns: (transfer full): #GstTypeFindProbability.
+ *
+ * Since: 1.22
+ *
+ */
+GstTypeFindProbability
+gst_type_find_data_get_probability (GstTypeFindData * data)
+{
+  g_return_val_if_fail (data != NULL, GST_TYPE_FIND_NONE);
+
+  return data->helper.best_probability;
+}
+
+/**
+ * gst_type_find_data_get_typefind: (skip)
+ * @data: GstTypeFindData *
+ *
+ * Returns #GstTypeFind associated with #GstTypeFindData
+ *
+ * Returns: (transfer full) (nullable): #GstTypeFind.
+ *
+ * Since: 1.22
+ *
+ */
+GstTypeFind *
+gst_type_find_data_get_typefind (GstTypeFindData * data)
+{
+  g_return_val_if_fail (data != NULL, NULL);
+
+  return &data->find;
+}
+
+/**
+ * gst_type_find_data_get_probability: (skip)
+ * @data: GstTypeFindData * to free
+ *
+ * Since: 1.22
+ *
+ */
+void
+gst_type_find_data_free (GstTypeFindData * data)
+{
+  if (data && data->helper.caps)
+    gst_caps_unref (data->helper.caps);
+
+  g_free (data);
+}

subprojects/gstreamer/libs/gst/base/gsttypefindhelper.h

@@ -29,6 +29,15 @@
 
 G_BEGIN_DECLS
 
+typedef struct _GstTypeFindData GstTypeFindData;
+
+GstTypeFindData * gst_type_find_data_new (GstObject * obj,
+    const guint8 * data, gsize size);
+GstCaps * gst_type_find_data_get_caps (GstTypeFindData * data);
+GstTypeFindProbability gst_type_find_data_get_probability (GstTypeFindData * data);
+GstTypeFind * gst_type_find_data_get_typefind (GstTypeFindData * data);
+void gst_type_find_data_free (GstTypeFindData * data);
+
 GST_BASE_API
 GstCaps * gst_type_find_helper (GstPad *src, guint64 size);