Custom Module

edit:Here are some of my experiences in creating my module, hopefully you will find some of the information here useful.

Currently I am trying to use gallery2 to make a gallery for serving my content in a custom manner.

Looking though the code i have added a few hacks to the core module to do some of the things I require
eg:-

-renaming files on upload
-processing gallery items before download

Now I have come to a halt in my development, this is what I want to do:-

1. Have certain meta data associated with a file depending on the mime type or extension of a file (like custom fields but only for certain mime/extension).

2. Have gallery items that do not have any file, i.e. just meta data (e.g. just a url)

3. Be able to edit these values on a per item basis, similare to the edit photo panel.

4. These items would display in a custom way, be edited in a custom way and downloaded in a custom way aswell.

5. I would also like to create a sub album when a jpg file is uploaded of the same name. (eg upload "123.jpg" would createa an album called "123_files" in the album the jpg is in.)

Through reading these forums and documentation I feel that what I will need is a module and some derived types. Any recommendations on where to start would be greatly appreciated (tutorials, examples etc), also some pointers on what type would be what i would want to derive from.

I do have some php experience but a lot of the workings in gallery2 seem very foreign to me.

Thanks in advance :D[/]

[/]

Ok, so I have started on this, I have extended a GalleryItem, should probably be a GalleryPhotoItem for the jpg's.
I can't seem to work out how to make all the jpgs in the gallery become one of my items rather than a normal photo item? Actually there is a lot I can't work out but this would get me headed in the right direction I would imagine

you need a row in your table for every id in g2_PhotoItem that is a jpg (check mime type in g2_DataItem).. then you can change g_entityType in g2_Entity to MyImage for all those entities.

Looking in CoreModuleExtras.inc i think i have extracted the right calls

//MyModule/module.inc
function performFactoryRegistrations()
{
	$myMimeArray = array('image/jpeg', 'image/jpg');

	$ret = GalleryCoreApi::registerFactoryImplementation(
		'GalleryPhotoItem', 'MyPhotoItem', 'MyPhotoItem',
		'modules/MyModule/classes/MyPhotoItem.class', 'MyModule', $myMimeArray);

	if ($ret->isError())
	{
		return $ret->wrap(__FILE__, __LINE__);
	}
}

Does this go in my module.inc? That where i have it now but I don't seem to get any of my items

I have uploaded a jpg to the server but i do not seem to get my custom view

//MyModule/Classes/MyPhotoItem.class
function render($format, $params)
{
	global $gallery;

	switch($format)
	{
	case 'HTML':
		return "<H1>Hello, World!</H1>";
	default:
		return "<H1>Goodbye, World!</H1>";
	}
}

Do I need to unregisterFactoryImplementations or should mine overwrite the existing one?

I am not going to worry about

as my database does not contain much except development test things atm.

add performFactoryRegistrations to setCallbacks for your module and bump the module version.. see other module.inc files for examples. just image/jpeg will do.. jpg and jpeg and jpe extension all use that. image/jpg isn't a mime type in G2..

correct, you should definitely register the class in your module, not in core.

oops, I should have looked at the code before my last reply.. performFactoryRegistrations is always called.. didn't need that in the setCallbacks list.

the first param to registerFactoryImplementation should be 'GalleryItem' not 'GalleryPhotoItem'. G2 looks for a GalleryItem implementation that supports the mime type of the uploaded file.

1. no.. you only need to lock if you're going to save changes.
2. the if ($ret->isError()) checks are missing, and save() returns an error status.. but basically, yes.

there are several examples.. how about modules/thumbnail/CustomThumbnailOption.inc, handleRequestAfterEdit.

This is how the download works at the moment.

//photo.tpl
<a href="{g->url arg1="view=core.DownloadItem" arg2="itemId=`$theme.item.id`"}">

I want to be able to call my own download in MyModule, I think that I need to do something in the module.inc either with performFactoryRegistrations or something similar.

//modules/MyModule/MyPhoto.tpl
<a href="{g->url arg1="view=myModule.DownloadItem" arg2="itemId=`$theme.item.id`"}">

obviously something like this would required an assocaited file

$urlGenerator =& $gallery->getUrlGenerator();
$urlGenerator->generateUrl(array('view' => 'MyModule.DownloadItem',
	'itemId' => $item->getId(),
	'serialNumber' => $item->getSerialNumber()));

but this is in the photo.tpl which is in the core...

So what you are saying is that I just put a DownloadItem.inc in my MyModule directory that contains something like

class MyDownloadItem extends DownloadItemView
{
	...
}

and gallery2 will pick this up?

What files would i find this DownloadItemView interface in?
/modules/core/classes/GalleryView.class

do i need to anything in module.inc?

Is there anywhere I can find a list of these classes perhaps with a description of what they are for?
http://dev.gallery2.org/modules/GalleryAPI/apidoc/GalleryCore/Classes/GalleryView.html

the thing is in the matrix theme there are calls to core.ShowItem and core.DownloadItem which I would like to call class, templates etc in MyModule rather than in the core.

I have made a DownloadItem.inc in modules/MyModule but it seems from what you are saying is that this will only get called if referenced by

<a href="{g->url arg1="view=myModule.DownloadItem" arg2="itemId=`$theme.item.id`"}">

ideally I would like this to be called by

<a href="{g->url arg1="view=core.DownloadItem" arg2="itemId=`$theme.item.id`"}">

which appears all throughout the photo.tpl in the matrix theme.

Is there anyway I can override core.DownloadItem for a certain file type such as MyPhotoItem.class?

BTW there seems to be issues when posting html in a code block...

ok, i justed edited the tpl files in the theme, seems to work ok, not as clean as I would like but if you can't change it via the module, i guess this will do.

On another note, am I only allowed to register 1 galleryItem per module, I have 1 item that works correctly that extends the GalleryPhotoItem but I am now trying to add 2 more that extend the GalleryDataItem, these register fine (no errors on install or activate) but then when I try to view an album containing one of these items I get an error

Error (ERROR_MISSING_OBJECT) : My2ndItem
in modules/core/classes/GalleryStorage/DatabaseStorage.class at line 2270 (gallerystatus::error) 
in modules/core/classes/GalleryStorage/DatabaseStorage.class at line 329 (mysqldatabasestorage::_describeentitymembers) 
in modules/core/classes/GalleryStorage.class at line 118 (mysqldatabasestorage::loadentities) 
in modules/core/classes/helpers/GalleryEntityHelper_simple.class at line 82 (gallerystorage::loadentities) 
in modules/core/classes/GalleryCoreApi.class at line 2173 (galleryentityhelper_simple::loadentitiesbyid) 
in modules/core/classes/GalleryTheme.class at line 1058 (gallerycoreapi::loadentitiesbyid) 
in modules/core/classes/GalleryTheme.class at line 870 (matrixtheme::loadcommontemplatedata) 
in modules/core/classes/GalleryView.class at line 285 (matrixtheme::loadtemplate) 
in main.php at line 286 (showitemview::doloadtemplate) 
in main.php at line 87
in main.php at line 80

System Information 
Gallery version  2.0-rc-2  
PHP version  4.3.11 apache  
Webserver  Apache/1.3.33 (Unix) PHP/4.3.11 mod_perl/1.29  
Database  mysql 3.23.56  
Toolkits  ImageMagick, Gd  
Operating system  FreeBSD administrator1.securesites.net 4.7-RELEASE-p28 FreeBSD 4.7-RELEASE-p28 #40: Fr i386  
Browser  Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; {EED8B589-CB1A-46E5-8B85-239267419BE4}; SV1; .NET CLR 1.1.4322)  

by the looks of this error my item isn't in the database or something similar.

Maybe this is my fault, I don't know if this is legal but basically what i did was create a new mime type for my item, 'application/My2ndItem'

//module.inc
	$ret = GalleryCoreApi::registerFactoryImplementation(
		'GalleryItem', 'My2ndItem', 'My2ndItem',
		'modules/Vista/classes/My2ndItem.class', 'MyModule', array('application/My2ndItem'));
	if ($ret->isError())
	{
		return $ret->wrap(__FILE__, __LINE__);
	}

and I create it from a 'ItemEditPlugin' page like this

//EditMyPhotoItem.inc
	list ($ret, $newItem) = GalleryCoreApi::addItemToAlbum($Name, basename($Name), "My2ndItem", "My2ndItem", "My2ndItem" . $Name, "application/My2ndItem", $item->getFilesAlbumID());
	if ($ret->isError())
	{
		GalleryCoreApi::releaseLocks($lockId);
		return array($ret->wrap(__FILE__, __LINE__), null);
	}

function _describeEntityMembers($entityName) {
global $gallery;

if (empty($this->_entityInfoCache[$entityName])) {
	if (class_exists($entityName)) {
	$entity = new $entityName();
	} else {
	list ($ret, $entity) =
		GalleryCoreApi::newFactoryInstance('GalleryEntity', $entityName);
	if ($ret->isError()) {
		return array($ret->wrap(__FILE__, __LINE__), null);
	}
	}
	if (!isset($entity)) {
	return array(GalleryStatus::error(ERROR_MISSING_OBJECT, __FILE__, __LINE__,
2270>>						$entityName), null);
	}
	$this->_entityInfoCache[$entityName] = $entity->getPersistentMemberInfo();
}

Is it possible my database is corrupt? can I flush the entire database and rebuild it?

I'm know from some of my hacking around I may have broken it...

yep, now it's missing since you already registered it with performFactoryRegistraction. you need to uninstall (read: not just deactivate) the module and install it again.

i hope you have this registerFactoryImplementation only in your performFactoryRegistrations function and nowhere else. and no, you can register multiple implementations, but they have to differ somehow. registering the same class twice, does that make sense?

in DatabaseStorage.class, please add var_dump($entityName); var_dump($entity); exit; right before

return array(GalleryStatus::error(ERROR_MISSING_OBJECT, __FILE__, __LINE__,
$entityName), null);

right after if (!isset($entity)) {
on line 2263.
what do you get there.

HVistaItem, did you ever register such a entity type? perhaps some time ago?

$ret = GalleryCoreApi::registerFactoryImplementation('GalleryItem', 'My3rdItem', 'My3rdItem',
	'modules/mymodule/classes/My3rdItem.class', 'mymodule', array('application/my3rditem'));
if ($ret->isError())
{
	return $ret->wrap(__FILE__, __LINE__);
}

GalleryItem needs to have a corresponding GalleryEntity.
I don't know why it worked for my original item but once I had more than one GalleryItem it was causing problems

$ret = GalleryCoreApi::registerFactoryImplementation('GalleryEntity', 'My3rdItem', 'My3rdItem',
	'modules/mymodule/classes/My3rdItem.class', 'mymodule', null);
if ($ret->isError())
{
	return $ret->wrap(__FILE__, __LINE__);
}

when I add an item to an album using

	list ($ret, $newItem) = GalleryCoreApi::addItemToAlbum($FileName, basename($FileName), "test", $FileName, "test - " . $FileName , "application/my2nditem", $item->getFilesAlbumID());

the file is not directly copied to the album folder, it also has the . in the filename changed to an underscore_

$item->fetchPath();

will have to do for now but its really annoying losing the extension esp on download
Is there any way to stop this?

This is a standard API call and it does exactly what i want.
What I do is have an uploaded item that has an ItemEditPlugin, I generate another file of my own type using the $platform->fopen fwrite, fseek, fclose etc, then I add this file to an album associated with the uploaded jpg.

to tell you the truth thats not my actual variable name, but i'll keep that in mind. I'm suprised you didn't have a go at the { brace being on its own line aswell. I guess it's just my preffered style ;).

i need fseek because the fwrite functions in PHP do not behave the same way as they do in C, in PHP the write will end after the length of a string in a variable while in C you can specify a number of bytes to write. Perhaps there is another version of the fwrite that does this but my way works ok anyway...

Something along these lines

	$platform->fwrite($fileHandle, $varOne, 255);
	$Pos += 255;
	$platform->fseek($fileHandle, intval($Pos),SEEK_SET);

	$platform->fwrite($fileHandle, $varTwo, 255);
	$Pos += 255;
	$platform->fseek($fileHandle, intval($Pos),SEEK_SET);

	settype($varThree, "int");
	$platform->fwrite($fileHandle, pack("S",$varThree), 2);
	$Pos += 2;
	$platform->fseek($fileHandle, intval($Pos),SEEK_SET);

Can't really tell you what I'm doing exactly but the basics are that you can upload files in one format and download them in another...

Don't worry I'll post the link when the site goes live...

here's the start http://www.360desktop.com