Theme functions are used to render UI elements in a consistent way. There are theme functions defined for over 200 elements in Backdrop core, and while many of them are only used for special purposes, many others are used widely; all are available to developers.

Note that you should never call a theme function directly; instead of

$output = theme_something($variables);

you should call

$output = theme('something', $variables);

to allow for setting of default values, overrides, and modifications. See Default theme implementations for more details.

Function Location Summary
theme_number core/includes/form.inc Returns HTML for a number form element.
theme_options core/modules/field/modules/options/options.theme.inc Theme an options element.
theme_options_none core/modules/field/modules/options/options.theme.inc Returns HTML for the label for the empty value for options that are not required.
theme_pager core/includes/pager.inc Returns HTML for a query pager.
theme_pager_first core/includes/pager.inc Returns HTML for the "first page" link in a query pager.
theme_pager_last core/includes/pager.inc Returns HTML for the "last page" link in query pager.
theme_pager_link core/includes/pager.inc Returns HTML for a link to a specific query result page.
theme_pager_next core/includes/pager.inc Returns HTML for the "next page" link in a query pager.
theme_pager_previous core/includes/pager.inc Returns HTML for the "previous page" link in a query pager.
theme_password core/includes/form.inc Returns HTML for a password form element.
theme_path_bulk_update_form core/modules/path/path.admin.inc Returns HTML for the Path bulk update page.
theme_progress_bar core/includes/theme.inc Returns HTML for a progress bar.
theme_radio core/includes/form.inc Returns HTML for a radio button form element.
theme_range core/includes/form.inc Returns HTML for a range form element.
theme_render_template core/includes/theme.inc Renders a system default template, which is essentially a PHP template.
theme_search core/includes/form.inc Returns HTML for a search form element.
theme_select core/includes/form.inc Returns HTML for a select form element.
theme_simpletest_result_summary core/modules/simpletest/simpletest.theme.inc Returns HTML for the summary status of a simpletest result.
theme_simpletest_test_table core/modules/simpletest/simpletest.theme.inc Returns HTML for a test list generated by simpletest_test_form() into a table.
theme_status_messages core/includes/theme.inc Returns HTML for status and/or error messages, grouped by type.
theme_status_report core/modules/system/system.theme.inc Returns HTML for the status report.
theme_submit core/includes/form.inc Returns HTML for a submit button form element.
theme_system_admin_index core/modules/system/system.theme.inc Returns HTML for the output of the dashboard page.
theme_system_modules_fieldset core/modules/system/system.theme.inc Returns HTML for the modules form.
theme_system_modules_incompatible core/modules/system/system.theme.inc Returns HTML for a message about incompatible modules.
theme_system_modules_uninstall core/modules/system/system.theme.inc Returns HTML for a table of currently disabled modules.
theme_system_powered_by core/modules/system/system.theme.inc Returns HTML for the Powered by Backdrop text.
theme_system_settings_form core/modules/system/system.theme.inc Returns HTML for a system settings form.
theme_system_themes_page core/modules/system/system.theme.inc Returns HTML for the Appearance page.
theme_table core/includes/theme.inc Returns HTML for a table.
theme_tableselect core/includes/form.inc Returns HTML for a table with radio buttons or checkboxes.
theme_tablesort_indicator core/includes/theme.inc Returns HTML for a sort icon.
theme_task_list core/includes/theme.maintenance.inc Returns HTML for a list of maintenance tasks to perform.
theme_taxonomy_overview_terms core/modules/taxonomy/taxonomy.theme.inc Returns HTML for a terms overview form as a sortable list of terms.
theme_taxonomy_vocabulary_description core/modules/taxonomy/taxonomy.theme.inc Returns HTML for the vocabulary description.
theme_taxonomy_vocabulary_name core/modules/taxonomy/taxonomy.theme.inc Returns HTML for the vocabulary human readable name, and its machine name.
theme_tel core/includes/form.inc Returns HTML for a tel form element.
theme_test_exit core/modules/simpletest/tests/theme_test.module Implements hook_exit().
theme_test_hook_init_page_callback core/modules/simpletest/tests/theme_test.module Menu callback for testing themed output generated in hook_init().
theme_test_init core/modules/simpletest/tests/theme_test.module Implements hook_init().
theme_test_menu core/modules/simpletest/tests/theme_test.module Implements hook_menu().
theme_test_preprocess_page core/modules/simpletest/tests/theme_test.module Implements hook_preprocess_page().
theme_test_system_info_alter core/modules/simpletest/tests/theme_test.module Implements hook_system_info_alter().
theme_test_system_theme_info core/modules/simpletest/tests/theme_test.module Implements hook_system_theme_info().
theme_test_template_test_page_callback core/modules/simpletest/tests/theme_test.module Menu callback for testing template overriding based on filename.
theme_test_theme core/modules/simpletest/tests/theme_test.module Implements hook_theme().
theme_textarea core/includes/form.inc Returns HTML for a textarea form element.
theme_textfield core/includes/form.inc Returns HTML for a textfield form element.
theme_text_format_wrapper core/modules/filter/filter.theme.inc Returns HTML for a text format-enabled form element.
theme_theme_test core/modules/simpletest/tests/theme_test.theme.inc Returns HTML for the 'theme_test' theme hook used by tests.

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