chrome/common/extensions/docs/templates/intros/fileBrowserHandler.html

<p id="classSummary">
Use the <code>chrome.fileBrowserHandler</code> module to
extend the Chrome OS file browser.
For example, you can use this API
to enable users to upload files to your website.
</p>

<p class="caution">
<b>Important:</b>
This API works <b>only on Chrome OS</b>.
</p>

<p>
The Chrome OS file browser comes up when
the user either presses Ctrl+M
or connects an external storage device,
such as an SD card, USB key, external drive, or digital camera.
Besides showing the files on external devices,
the file browser can also display files
that the user has previously saved to the system.
</p>

<p>
When the user selects one or more files,
the file browser adds buttons
representing the valid handlers for those files.
For example, in the following screenshot,
selecting a file with a ".jpg" suffix
results in an "Upload to Picasa" button that the user can click.
</p>

<p>
<img src="{{static}}/images/filebrowserhandler.png"
  width="640" height="400" alt="file browser screenshot" />
</p>


<h2 id="manifest">Manifest</h2>

<p>
You must declare the "fileBrowserHandler" permission
in the <a href="manifest.html">extension manifest</a>,
and you must use the "file_browser_handlers" field
to register the extension as a handler of at least one file type.
You should also provide a 16x16 icon
to be displayed on the button.
For example:
</p>

<pre>
{
  "name": "My extension",
  ...
  <b>"file_browser_handlers"</b>: [
    {
      <b>"id"</b>: "upload",
      <b>"default_title"</b>: "Save to Gallery", <em>// What the button will display</em>
      <b>"file_filters"</b>: [
        "filesystem:*.jpg", <em>// To match all files, use "filesystem:*.*"</em>
        "filesystem:*.jpeg",
        "filesystem:*.png"
      ]
    }
  ]</b>,
  "permissions" : [
    <b>"fileBrowserHandler"</b>
  ],
  "icons": { <b>"16"</b>: "icon16.png",
             "48": "icon48.png",
            "128": "icon128.png" },
  ...
}</pre>

<p class="note">
<b>Note:</b>
You can specify locale-specific strings for the value of "default_title".
See <a href="i18n.html">Internationalization (i18n)</a> for details.
</p>

<h2 id="code">Implementing a file browser handler</h2>

<p>
To use this API,
you must implement a function that handles the <code>onExecute</code> event
of <code>chrome.fileBrowserHandler</code>.
Your function will be called whenever the user clicks the button
that represents your file browser handler.
In your function, use the HTML5
<a href="http://www.html5rocks.com/tutorials/file/filesystem/">FileSystem API</a>
to get access to the file contents.
Here is an example:
</p>

<pre>
<em>//In background.html:</em>
chrome.fileBrowserHandler.onExecute.addListener(function(id, details) {
  if (id == 'upload') {
    var fileEntries = details.entries;
    for (var i = 0, entry; entry = fileEntries[i]; ++i) {
      entry.file(function(file) {
        <em>// send file somewhere</em>
      });
    }
  }
});
</pre>

<p>
Your event handler is passed two arguments:
</p>

<dl>
  <dt> id </dt>
  <dd> The "id" value from the manifest file.
       If your extension implements multiple handlers,
       you can check the <code>id</code> value
       to see which handler has been triggered.
       </dd>
  <dt> details </dt>
  <dd> An object describing the event.
       You can get the file or files that the user has selected
       from the <code>entries</code> field of this object,
       which is an array of
       FileSystem <code>Entry</code> objects.
       </dd>
</p>


<!--
<h2 id="manifest_details">Manifest details</h2>

<p class="authornote">
{PENDING: give details about "id" and "default_title".
It should be unique within your extension -- don't worry about other extensions.
"default_title" implies that you can change the title,
but you can't aside from internationalizing it.
</p>

<p class="authornote">
{PENDING: give details about the file_filters entry.
File filters are currently case-sensitive, but we plan to change that.
Mention <code>filesystem:*.*</code>.
</p>
-->

<!--
<h2 id="examples">Examples</h2>

<p>
For examples of using this API, see ...
For other examples and for help in viewing the source code, see
<a href="samples.html">Samples</a>.
</p>
-->