Blocks

I think we can separate two separate things:

There is the core of the blocks system (blocklib.php). Blockslib knows a bit about pages. As far as it is concerned, a page is defined by three things

1. A context id
2. A page type (like mod-quiz-view)
3. and optionally a subpage identifier. This is only needed when you have something like the book modules, where there are a lot of different pages for which 1. and 2. are the same.

blocklib also has a list of what regions on the page blocks can appear in.

That is all the information blocklib need in order to work out which specific block instances appear in which regions on this page.

That is the world as far as blocklib is concerned, and it is quite flexible.

Now it is a separate issue "Who tells blocklib which regions are on this page?"

Normally, as you say, it is the theme that declares which region of blocks are on this page in this theme (via the declarations in the theme's config.php).

However, the block system does not care, and any bit of code may call $PAGE->blocks->add_region(...) at any time before the call to $OUTPUT->header().

So, all sorts of things will 'work'. It is really a matter of convention what we choose to do. Just like we have a lot of other conventions in the Moodle world (for example the coding guidelines) to help people do thing the 'right' way.

In a sense, what you are asking is "What is the right convention for who defines which block regions are on the page?" This is a good question to ask.

Now, the other thing to consider is that all Moodle pages have a bit of content that goes in the [Main content goes here] place in the layout.php file. That is not how it would work if we were designing the page layout system from scratch, but because Moodle 2.0 was built on Moodle 1.9, this was necessary. Perhaps in Moodle 2.x, for sufficiently large x it will be possible to get rid of that. (It may be possible once all pages in Moodle have been converted to use a renderer to generate what goes in the [Main content goes here] place.)

Now we took the decision that for certain pages, currently 'mydashboard' and 'mypublic', but probably in future the site front page and the course/categories.php page, it would be better not to have any fixed content in in the [Main content goes here] area. Instead, this area would just contain blocks.

Now there are two ways you could do that. One is for the script, that is usually responsible for generating the [Main content goes here], to declare that blocks region, and print the blocks in there.

As you point out, the alternative options is to require that the theme defines an appropriate template for the 'mydashboard' and 'mypublic', which includes the 'content' block region (or whatever your theme wants to call that region).

Both of these solutions will work, on the whole. Which you think is better depends, as I say, on convention. And, as we have seen, changing this convention only involves moving two lines of code from certain pages into the them.

However, at this moment in Moodle's evolution, I think there is a strong reason to prefer the first solution, which is what is currently implemented.

As I said, I think it would be a good idea if we got rid of the hard-coded content from the front page, and made this front page like the my Moodle page. The whole [Main content] bit of the page consists of just a block region.

In order to do this, we would need to make some new blocks that display the various things that the admin can currently choose to display on the front page using the front page settings.

Then you would need to write some upgrade code, that looks at the current front-page settings, and add the appropriate blocks to the front page 'content' region to replicate the current set up.

Then you have to actually change the code that prints the front page. And depending on whether it is the main index.php script, or the theme, that controls these blocks that can go two ways.

1. If index.php does add_block_regino('content') and then prints the block in that region, the to convert index.php you just delete the old code that prints the content in [Main content area] and replace it with $OUTPUT->blocks_for_region('content');

2. On the other hand, if you say the theme must be responsible for this, then after you have removed the old code from index.php, you have to update the frontpage template in every standard theme to include the new blocks region. Then, for every admin who is upgrading to this new version of Moodle, and who uses a custom theme, you have to make sure they know to update the frontpage template in their custom theme to include the new blocks region, because if they don't the front-page of their site will break horribly when the do the upgrade, then they will come to the forums and complain, and we will have to help them sort out the mess.

So, my view is that at the moment, while we are working to convert Moodle to have less hard-coded content in certain scripts, and to take a more flexible approach to layout, it is better to allow ourselves option 1.

It may not be the purest and most idealistic interpretation of the way the blocks system is meant to work, but for now it is practical, and makes it easier for us to continue to move in the right direction.

However, that is just my current thinking. Given suitable arguments, I could be persuaded to change my mind.

I've now tried the theme route, and that seems to work well, so far. Finally making some progress...

Hi Daniel,

I need to do the same thing - I'm trying to move the HTML block to center page but I'm having no luck - any help would be appreciated - Thanks

I'm using Moodle 2.7

Please read the theme documentation in Moodle docs for the details.

In short you change the frontpage so you need to extend the frontpage definition in config.php by adding the 'question' region there. Then Moodle knows about the new region on the frontpage and you can output the 'question-region' blocks in frontpage.php. When I understand your code example right you add a new page type.

For all interested, here is what I have done to implement center blocks in moodle 2.  And Tim, you have every right to be smug - the implementation was easy, and only modified a few theme files.

I chose to modify the "base" theme, which will impact the 'standard theme', however, the principal should work in any theme.

1.  Open config.php and find the $THEME->layouts array.  Find all instances of the line 'regions' => array('side-pre', 'side-post'), and add another region or two.  I added two, as follows: 'regions' => array('side-pre', 'side-post', 'center-pre', 'center-post'),. I edited them in 'standard', 'course', 'coursecategory', 'incourse', 'frontpage', 'mydashboard' and 'mypublic'.

2.  In the directory 'layout', edit the files 'frontpage.php' and 'general.php'. In each, I made the following changes:

a) Near the top, just after the first 4 $hassidepre, etc declarations, add

in 'frontpage.php' add
$hascenterpre = $PAGE->blocks->region_has_content('center-pre', $OUTPUT);
$hascenterpost = $PAGE->blocks->region_has_content('center-post', $OUTPUT);

in 'general.php' add
$hascenterpre = (empty($PAGE->layout_options['noblocks']) && $PAGE->blocks->region_has_content('center-pre', $OUTPUT));
$hascenterpost = (empty($PAGE->layout_options['noblocks']) && $PAGE->blocks->region_has_content('center-post', $OUTPUT));

The remaining changes apply to both 'frontpage.php' and 'general.php'
$showcenterpre = $hassidepre && !$PAGE->blocks->region_completely_docked('center-pre', $OUTPUT);
$showcenterpost = $hassidepost && !$PAGE->blocks->region_completely_docked('center-post', $OUTPUT);

b) before the if($hascustommenu) section, add
if ($hascenterpre) {
    $bodyclasses[] = 'has_center_pre';
}
if ($hascenterpost) {
    $bodyclasses[] = 'has_center_post';
}

c)  Between the  <div id="region-main-wrap"> and <div id="region-main"> lines add

                <?php if ($hascenterpre) { ?>
                <div id="region-center-pre" class="block-region">
                    <div class="region-content">
                        <?php echo $OUTPUT->blocks_for_region('center-pre') ?>
                    </div>
                </div>
                <?php } ?>

and between their two respective </div> tags add

                <?php if ($hascenterpost) { ?>
                <div id="region-center-post" class="block-region">
                    <div class="region-content">
                        <?php echo $OUTPUT->blocks_for_region('center-post') ?>
                    </div>
                </div>
                <?php } ?>

3. Next, in the 'style' directory, open pagelayout.css, and add the following:

#page-content #region-center-pre, #page-content #region-center-post {margin-right:0px;margin-left:400px;overflow:hidden;}

4.  Finally, in the 'lang/en' directory, add the following lines to 'theme_base.php':

$string['region-center-post'] = 'Top Center';
$string['region-center-pre'] = 'Bottom Center';

Thus, you now will have a region for blocks both above and below the main section in both the frontpage and course pages.  I haven't tested it fully, but it looks like it is working.

I hope this helps someone, and any feedback will be appreciated.