Editor Button Placement
==============

External tools can be configured to appear as buttons in the rich content editor.
The **editor_button** placement allows many users to use the <a 
href="file.content_item.html" target="_blank">LTI Deep Linking</a> 
flow to select resources from an external tool and embed them in the 
<a href="https://community.canvaslms.com/docs/DOC-10728-67952720342"
target="_blank">Canvas Rich Content Editor</a> (RCE). 

### Configuring
For configuration examples and links to the specification, please refer to the <a 
href="file.content_item.html" target="_blank">LTI 
Deep Linking documentation</a>. Simply replace the **assignment_selection** text
with **editor_button** in the XML (LTI 1.0, 1.1, and 1.2) or JSON (LTI 1.3) examples.

### Advantages
- Tools can embed different content types (images, text/html, LTI Launch URLs,
basic URLs).
- Tools can determine the presentation style and size of the content.
- Tools can return an array of different content types in a single message.
- Many different types of users can access the RCE from many different locations
such as assignment descriptions, discussions posts, and wiki pages.


### Limitations/Challenges
- Grades cannot be applied to editor content; use the 
<a href="file.assignment_selection_placement.html" target="_blank">assignment_selection
placement</a> if grades are desired.
- Requires UI interactions to generate content. To generate content server-to-server,
use of <a href="file.oauth.html#accessing-canvas-api" target="_blank">Canvas API</a> is required.


### Workflow
1. A user loads a page that has the RCE available (discussion posts, quiz
questions, etc.). 
2. Once loaded, tools that use the **editor_button** placement 
will appear in the tool bar of the RCE. 
3. When the tool bar button is clicked, Canvas initiates an LTI launch to the 
tool and indicates that a deep linking selection request is happening.
4. The tool can then present the user with a UI to select and/or create content and return 
items of different types to Canvas.
5. Canvas then consumes the request and converts the payload to HTML in the RCE.
6. Once published, the audience can then view the content returned by the tool.

The end result is users can search for embeddable content from a tool provider 
and submit it back to the RCE without having to leave Canvas or paste embed code!

**Pro-tip:** Use the com.instructure.Editor.contents and/or com.instructure.Editor.selection
<a href="file.tools_variable_substitutions.html" 
target="_blank">variable substitutions</a> to include the full RCE contents and/or 
highlighted selection, respectively, in the launch request.

### Settings
All of these settings are contained for the **editor_button** placement:

-   url: &lt;url&gt; (optional)

    This is the URL that will be POSTed to when users click the left tab. It can
     be the same as the tool's URL, or something different. Domain and URL 
     matching are not enforced for editor_button launches; however, if LTI links
     are returned, Domain and URL matching is enforced. In order to prevent 
     security warnings for users, it is recommended that URLs be over SSL (https).
     This setting is required if a url is not set on the main tool configuration.

-   text: &lt;text&gt; (optional)

    This is the default text that will be shown on the hover-over tip for the RCE
    button. This can be overridden by language-specific settings if desired by 
    using the labels setting. This is required if a text value is not set on the main tool configuration.

-   labels: &lt;set of locale-label pairs&gt; (optional)

    This can be used to specify different label names for different locales. 
    For example, if an institution supports both English and Spanish interfaces,
    the text for the hover-over tip should change depending on the language 
    being displayed. This option lets you support multiple languages for a single tool.

-   enabled: &lt;boolean&gt; (optional)

    Whether to enable this selection feature; this setting defaults to enabled if omitted.

-   message_type: &lt;an IMS LTI message type&gt; (optional)

    Sets the message_type to be sent during the LTI launch. It is expected that 
    the tool use this to determine if a Deep Linking flow is being requested by
    Canvas and present an appropriate UI. A Deep Linking flow is highly recommended
    for this placement, but is not required. See the 
    <a href="file.content_item.html" target=_"blank">Deep Linking 
    documentation</a> for more information, including accepted values.

-   icon_url &lt;url&gt; (optional)

    The URL for an icon that identifies your tool in the RCE toolbar. It is 
    it is recommended that this icon be at least 16 x 16 px and png or svg format
    the url should be secured over SSL (https

-   selection_width: &lt;pixels&gt; (optional)

    This sets the width (px) of the selection launch modal. Canvas may set a 
    maximum or minimum width that overrides this option.

-   selection_height: &lt;pixels&gt; (optional)

    This sets the height (px) of the selection launch modal. Canvas may set a 
    maximum or minimum height that overrides this option.

-   visibility: 'public', 'members', 'admins' (optional, 'public' by default)

    This specifies what types of users will see the link in the editor. "public" means anyone accessing the course, "members" means only users enrolled in the course, and "admins" means only Teachers, TAs, Designers and account admins will see the link.
