MDL-33640 - Add ability to use custom filepicker templates

Allow repository plugins to register a template by defining a get_template() method, coupled with the ability to request the template be used by create_upload_form() instead of the standard 'uploadform' template.  The template is automatically registered using the plugin's name, and core templates will override any which clash; this also means that a theme can override these templates in a custom renderer if it wants to.

repository/filepicker.js

@@ -1618,7 +1618,8 @@ M.core_filepicker.init = function(Y, options) {
             var client_id = this.options.client_id;
             var id = data.upload.id+'_'+client_id;
             var content = this.fpnode.one('.fp-content');
-            content.setContent(M.core_filepicker.templates.uploadform);
+            var template = data.template || 'uploadform';
+            content.setContent(M.core_filepicker.templates[template]);
 
             content.all('.fp-file,.fp-saveas,.fp-setauthor,.fp-setlicense').each(function (node) {
                 node.all('label').set('for', node.one('input,select').generateID());

repository/lib.php

@@ -2684,16 +2684,21 @@ function initialise_filepicker($args) {
     // provided by form element
     $return->accepted_types = file_get_typegroup('extension', $args->accepted_types);
     $return->return_types = $args->return_types;
+    $templates = array();
     foreach ($repositories as $repository) {
         $meta = $repository->get_meta();
         // Please note that the array keys for repositories are used within
         // JavaScript a lot, the key NEEDS to be the repository id.
         $return->repositories[$repository->id] = $meta;
+        // Register custom repository template if it has one
+        if(method_exists($repository, 'get_template')) {
+            $templates[$meta->type] = $repository->get_template();
+        }
     }
     if (!$templatesinitialized) {
         // we need to send filepicker templates to the browser just once
         $fprenderer = $PAGE->get_renderer('core', 'files');
-        $templates = $fprenderer->filepicker_js_templates();
+        $templates = array_merge($templates, $fprenderer->filepicker_js_templates());
         $PAGE->requires->js_init_call('M.core_filepicker.set_templates', array($templates), true);
         $templatesinitialized = true;
     }