BlockHero::form in core/modules/layout/includes/
Builds the block's configuration form.
ckeditor_image_upload in core/modules/ckeditor/
Menu callback; Saves images uploaded via copy/paste into the editor.
file_get_upload_validators in core/modules/file/
Retrieves the upload validators for a file.
filter_format_editor_image_form in core/modules/filter/
Form callback: Display a form for inserting/editing an image.
image_field_widget_form in core/modules/image/
Implements hook_field_widget_form().
theme_file_upload_help in core/modules/file/
Returns HTML for help text based on file upload validators.
user_validate_picture in core/modules/user/user.module
Validates an image uploaded by a user.