WP - Use file in plugin directory as custom Page Template?

Question

Is it possible for a file in the plugin directory to be used as a custom Page Template?

Also, how do you make a plugin create a page?

I'm developing a plugin for a client based on a theme, he wants this plugin to make sales pages while being able to use his theme on the homepage. This is a product that I'm making for him to market so it needs to be automated all through the plugin.

Is this possible?

EDIT

I have the activation/deactivation hooks in my plugins main file, and it's not working. Here's the code:

$filename = __FILE__;  register_activation_hook($filename, 'superActivation'); register_deactivation_hook($filename, 'superDeactivation');  global $myFile; global $fh; global $stringData; global $filename;  $myFile = "testFile.txt"; $stringData = "Testing\n"; $fh = fopen($myFile, 'w') or die("can't open file");  function superActivation() {     global $myFile; global $fh; global $stringData; global $filename;     fwrite($fh, $stringData);     fclose($fh); }  function superDeactivation() {     $myFile = "testFile.txt";     unlink($myFile); } 

Answer 1

You can do this with the template_redirect hook. Here's my code to manually replace the template for a custom post type with one in the theme if there isn't one in the template folder. Put this in your plugin file and then put a folder underneath your plugin called themefiles with your default theme files.

//Template fallback add_action("template_redirect", 'my_theme_redirect');  function my_theme_redirect() {     global $wp;     $plugindir = dirname( __FILE__ );      //A Specific Custom Post Type     if ($wp->query_vars["post_type"] == 'product') {         $templatefilename = 'single-product.php';         if (file_exists(TEMPLATEPATH . '/' . $templatefilename)) {             $return_template = TEMPLATEPATH . '/' . $templatefilename;         } else {             $return_template = $plugindir . '/themefiles/' . $templatefilename;         }         do_theme_redirect($return_template);      //A Custom Taxonomy Page     } elseif ($wp->query_vars["taxonomy"] == 'product_categories') {         $templatefilename = 'taxonomy-product_categories.php';         if (file_exists(TEMPLATEPATH . '/' . $templatefilename)) {             $return_template = TEMPLATEPATH . '/' . $templatefilename;         } else {             $return_template = $plugindir . '/themefiles/' . $templatefilename;         }         do_theme_redirect($return_template);      //A Simple Page     } elseif ($wp->query_vars["pagename"] == 'somepagename') {         $templatefilename = 'page-somepagename.php';         if (file_exists(TEMPLATEPATH . '/' . $templatefilename)) {             $return_template = TEMPLATEPATH . '/' . $templatefilename;         } else {             $return_template = $plugindir . '/themefiles/' . $templatefilename;         }         do_theme_redirect($return_template);     } }  function do_theme_redirect($url) {     global $post, $wp_query;     if (have_posts()) {         include($url);         die();     } else {         $wp_query->is_404 = true;     } }