Custom page Template and Script as a Plugin

Question

I want to Build a custom Page Template. But as far as I know we should not at all touch Core PHP files.

let say our Custom Page template is custom.php, then where will this custom.php sit I mean in which folder in wordpress or it will go some where in the inner directories of theme?

Because Finally while creating a new page it should be available as drop down in WordPress admin.

Answer 1

This is covered in the Codex, under How to create a page template.

In your theme you create a file called my-bacon-template.php and in that file you add the following to the top of the file, before any other code

<?php
/*
Template Name: My Bacon Page
*/

After that you can put any content you want and it will display on any page that you have selected to have this template.

Answer 2

Amusing you know how to crate a page template. If not, refer to codex.

Put the files anywhere in your plugin and this code should help you include them in Page template chooser.

function include_template() {
    return locate_template( array (
                'templateone.php',
                'templatetwo.php',
                'templatethree.php',
            )
        );
}
add_action('template_include', 'include_template');