# Templates
*These templates are meant to take up the whole page and have a navbar slotted into them, rather than be used on a page that already includes a navbar. Therefore, a current limitation is they can only be used with the immersive nav. Work is actively underway to overhaul our page template strategy.*

Page templates are used to provide generic ways to arrange content on a page

## Primary-Secondary [d2l-template-primary-secondary]
Two Panel (primary and secondary) page template with header and optional footer

Use this template when:
* There are primary and secondary elements on the page
* The user may need to see the primary and secondary elements at the same time

Mental Models and Page Structure:
* The page includes basic settings (primary) and advanced settings (secondary)
* There is a primary object which users are modifying or supplementing with secondary tools/settings/options

If no nodes are assigned to the `footer` slot, the footer is hidden.

Note: this template automatically includes `<header>`, `<main>`, `<aside>` and `<footer>` elements, so there's no need to include them inside the various slots.

<!-- docs: demo code properties name:d2l-template-primary-secondary sandboxTitle:'Templates - Primary-Secondary' autoSize:false size:large -->
```html
<script type="module">
  import '@brightspace-ui/core/templates/primary-secondary/primary-secondary.js';
</script>
<!-- docs: start hidden content -->
<style>
	d2l-template-primary-secondary > div {
		user-select: none;
	}
	d2l-template-primary-secondary {
		margin: 0 !important;
	}
	div[slot="header"] {
		background-color: var(--d2l-color-gypsum);
		height: 50px;
	}
</style>
<!-- docs: end hidden content -->
<d2l-template-primary-secondary resizable>
    <div slot="header">Header</div>
    <div slot="primary">The primary slot</div>
    <div slot="secondary">The secondary slot</div>
    <div slot="footer">Footer</div>
</d2l-template-primary-secondary>
```

### IFrames

If either of the panels contain an `iframe`, resizing may not work properly. This occurs because `iframe`s prevent the page template from receiving mouse events. To handle situations like these, setting `pointer-events: none` for the `iframe` is recommended during resizing. This can be done by listening for `d2l-template-primary-secondary-resize-start` and `d2l-template-primary-secondary-resize-end` events.

<!-- docs: start hidden content -->
### Properties

| Property | Type | Description |
|---|---|---|
| `background-shading` | String, default: `'none'` | Controls whether the primary and secondary panels have shaded backgrounds. Can be one of `'primary'`, `'secondary'`, `'none'`. |
| `has-form` | Boolean, default: `false` | Whether to render an encompassing form over all panels |
| `primary-overflow` | String, default: `'default'` | Controls how the primary panel's contents overflow. Can be one of `'default'`, `'hidden'`. |
| `resizable` | Boolean, default: `false` | Whether the panels are user resizable. This only applies to desktop users, mobile users will always be able to resize. |
| `secondary-first` | Boolean, default: `false` | When set to true, the secondary panel will be displayed on the left (or the right in RTL) in the desktop view. This attribute has no effect on the mobile view. |
| `storage-key` | String | The key used to persist the divider's position to local storage. This key should not be shared between appliactions so that users can save different divider positions for different applications. If no key is provided, the template will fall back its default size. |
| `width-type` | String, default: `'fullscreen'` | Whether content fills the screen or not. When set to `normal`, the width of the template is constrained to `1230px`. Can be one of `'fullscreen'`, `'normal'`. |

### Events
* `d2l-template-primary-secondary-resize-start`: dispatched when a user begins moving the divider
* `d2l-template-primary-secondary-resize-end`: dispatched when a user finishes moving the divider

### Slots
* `header`: page header content
* `footer`: page footer content
* `primary`: main page content
* `secondary`: supplementary page content
<!-- docs: end hidden content -->
