Avoid updating chat photo minithumbnail to 40x40 full minithumbnail.

td/telegram/ContactsManager.cpp

@@ -11323,7 +11323,7 @@ void ContactsManager::do_update_user_photo(User *u, UserId user_id,
 void ContactsManager::do_update_user_photo(User *u, UserId user_id, ProfilePhoto &&new_photo,
                                            bool invalidate_photo_cache, const char *source) {
   u->is_photo_inited = true;
-  if (new_photo != u->photo) {
+  if (need_update_profile_photo(u->photo, new_photo)) {
     LOG_IF(ERROR, u->access_hash == -1 && new_photo.small_file_id.is_valid())
         << "Update profile photo of " << user_id << " without access hash from " << source;
     u->photo = new_photo;
@@ -13458,7 +13458,7 @@ void ContactsManager::on_update_chat_photo(Chat *c, DialogPhoto &&photo) {
     photo.minithumbnail.clear();
   }
 
-  if (photo != c->photo) {
+  if (need_update_dialog_photo(c->photo, photo)) {
     c->photo = std::move(photo);
     c->is_photo_changed = true;
     c->need_save_to_database = true;
@@ -13587,7 +13587,7 @@ void ContactsManager::on_update_channel_photo(Channel *c, DialogPhoto &&photo) {
     photo.minithumbnail.clear();
   }
 
-  if (photo != c->photo) {
+  if (need_update_dialog_photo(c->photo, photo)) {
     c->photo = std::move(photo);
     c->is_photo_changed = true;
     c->need_save_to_database = true;

td/telegram/Photo.cpp

@@ -67,18 +67,8 @@ tl_object_ptr<td_api::profilePhoto> get_profile_photo_object(FileManager *file_m
       profile_photo.has_animation);
 }
 
-bool operator==(const ProfilePhoto &lhs, const ProfilePhoto &rhs) {
-  bool location_differs = lhs.small_file_id != rhs.small_file_id || lhs.big_file_id != rhs.big_file_id;
-  bool id_differs = lhs.id != rhs.id;
-
-  if (location_differs) {
-    return false;
-  }
-  return lhs.has_animation == rhs.has_animation && lhs.minithumbnail == rhs.minithumbnail && !id_differs;
-}
-
-bool operator!=(const ProfilePhoto &lhs, const ProfilePhoto &rhs) {
-  return !(lhs == rhs);
+bool need_update_profile_photo(const ProfilePhoto &from, const ProfilePhoto &to) {
+  return from.id != to.id || need_update_dialog_photo(from, to);
 }
 
 StringBuilder &operator<<(StringBuilder &string_builder, const ProfilePhoto &profile_photo) {
@@ -204,13 +194,10 @@ bool is_same_dialog_photo(FileManager *file_manager, DialogId dialog_id, const P
          get_unique_file_id(fake_photo.big_file_id) == get_unique_file_id(dialog_photo.big_file_id);
 }
 
-bool operator==(const DialogPhoto &lhs, const DialogPhoto &rhs) {
-  return lhs.small_file_id == rhs.small_file_id && lhs.big_file_id == rhs.big_file_id &&
-         lhs.minithumbnail == rhs.minithumbnail && lhs.has_animation == rhs.has_animation;
-}
-
-bool operator!=(const DialogPhoto &lhs, const DialogPhoto &rhs) {
-  return !(lhs == rhs);
+bool need_update_dialog_photo(const DialogPhoto &from, const DialogPhoto &to) {
+  return from.small_file_id != to.small_file_id || from.big_file_id != to.big_file_id ||
+         from.has_animation != to.has_animation ||
+         need_update_dialog_photo_minithumbnail(from.minithumbnail, to.minithumbnail);
 }
 
 StringBuilder &operator<<(StringBuilder &string_builder, const DialogPhoto &dialog_photo) {

td/telegram/Photo.h

@@ -57,8 +57,7 @@ ProfilePhoto get_profile_photo(FileManager *file_manager, UserId user_id, int64
 tl_object_ptr<td_api::profilePhoto> get_profile_photo_object(FileManager *file_manager,
                                                              const ProfilePhoto &profile_photo);
 
-bool operator==(const ProfilePhoto &lhs, const ProfilePhoto &rhs);
-bool operator!=(const ProfilePhoto &lhs, const ProfilePhoto &rhs);
+bool need_update_profile_photo(const ProfilePhoto &from, const ProfilePhoto &to);
 
 StringBuilder &operator<<(StringBuilder &string_builder, const ProfilePhoto &profile_photo);
 
@@ -79,8 +78,7 @@ bool is_same_dialog_photo(FileManager *file_manager, DialogId dialog_id, const P
 
 vector<FileId> dialog_photo_get_file_ids(const DialogPhoto &dialog_photo);
 
-bool operator==(const DialogPhoto &lhs, const DialogPhoto &rhs);
-bool operator!=(const DialogPhoto &lhs, const DialogPhoto &rhs);
+bool need_update_dialog_photo(const DialogPhoto &from, const DialogPhoto &to);
 
 StringBuilder &operator<<(StringBuilder &string_builder, const DialogPhoto &dialog_photo);
 

td/telegram/PhotoSize.cpp

@@ -57,6 +57,27 @@ StringBuilder &operator<<(StringBuilder &string_builder, const Dimensions &dimen
   return string_builder << "(" << dimensions.width << ", " << dimensions.height << ")";
 }
 
+static int32 get_minithumbnail_size(const string &packed) {
+  if (packed.size() < 3) {
+    return 0;
+  }
+  if (packed[0] == '\x01') {
+    return max(static_cast<unsigned char>(packed[1]), static_cast<unsigned char>(packed[2]));
+  }
+  return 0;
+}
+
+bool need_update_dialog_photo_minithumbnail(const string &from, const string &to) {
+  if (from == to) {
+    return false;
+  }
+
+  auto from_size = get_minithumbnail_size(from);
+  auto to_size = get_minithumbnail_size(to);
+  // dialog photo minithumbnail is expected to be 8x8
+  return to_size != 0 && (to_size <= 8 || from_size > 8);
+}
+
 td_api::object_ptr<td_api::minithumbnail> get_minithumbnail_object(const string &packed) {
   if (packed.size() < 3) {
     return nullptr;

td/telegram/PhotoSize.h

@@ -48,6 +48,8 @@ bool operator!=(const Dimensions &lhs, const Dimensions &rhs);
 
 StringBuilder &operator<<(StringBuilder &string_builder, const Dimensions &dimensions);
 
+bool need_update_dialog_photo_minithumbnail(const string &from, const string &to);
+
 td_api::object_ptr<td_api::minithumbnail> get_minithumbnail_object(const string &packed);
 
 FileId register_photo_size(FileManager *file_manager, const PhotoSizeSource &source, int64 id, int64 access_hash,