module_object.inc.php

<?php

/*
 *	module_object.inc.php
 *	Module for handling general object properties
 *
 *	Copyright Gottfried Haider, Danja Vasiliev 2010.
 *	This source code is licensed under the GNU General Public License.
 *	See the file COPYING for more details.
 */

@require_once('config.inc.php');
require_once('common.inc.php');
require_once('html.inc.php');
require_once('util.inc.php');


// module_image.inc.php has more information on what's going on inside modules 
// (they can be easier than that one though)


/**
 *	Object Properties: user-supplied classes and attributes.
 *
 *	Both are stored on the object and merged into the container <div> at render
 *	time. Validation lives here, in the RENDER path, rather than only where the
 *	editor writes them - glue.update_object is a generic key/value setter, so
 *	anything that only guards the write can be walked around with one POST.
 *	Filtering as we render is the gate that actually holds.
 *
 *	Attribute NAMES are the dangerous half, and not for the obvious reason.
 *	html.inc.php:228 emits them with htmlspecialchars(..., ENT_NOQUOTES), which
 *	deliberately leaves quotes alone - so a name of  x" onload="alert(1)  would
 *	close the attribute and inject an event handler. Values are emitted with
 *	ENT_COMPAT and are safe. Hence the strict name charset below: it is load
 *	bearing, not tidiness.
 */

// letters, digits and dashes, starting with a letter - covers data-*, aria-*,
// role, title, name, and rejects everything that could break out
define('OBJECT_ATTR_NAME_RE', '/^[a-zA-Z][a-zA-Z0-9-]*$/');
// one CSS class token
define('OBJECT_CLASS_TOKEN_RE', '/^-?[A-Za-z_][A-Za-z0-9_-]*$/');

/**
 *	attribute names the user may not set on an object container
 *
 *	@return array lowercase names
 */
function object_attr_denylist()
{
	return [
		// identity and layout are hotglue's, not the user's
		'id',			// the editor's primary handle (selection, save, undo)
		'class',		// managed by the separate class field
		'style',		// would let a user override the absolute positioning
						// that IS hotglue; object styling has its own path
		// would fight the editor's own behaviour
		'contenteditable',
		'draggable',
	];
}

/**
 *	is this attribute name allowed on an object container?
 *
 *	@param string $name attribute name
 *	@return bool
 */
function object_attr_allowed($name)
{
	$name = strtolower(trim($name));
	if (!preg_match(OBJECT_ATTR_NAME_RE, $name)) {
		return false;
	}
	// every inline event handler - JS belongs in page-level /code
	if (substr($name, 0, 2) == 'on') {
		return false;
	}
	return !in_array($name, object_attr_denylist());
}

/**
 *	filter a class string down to the tokens that are valid CSS class names
 *
 *	@param string $str space-separated tokens
 *	@return array valid tokens
 */
function object_filter_classes($str)
{
	$out = [];
	foreach (preg_split('/\s+/', trim((string)$str)) as $token) {
		if ($token !== '' && preg_match(OBJECT_CLASS_TOKEN_RE, $token)) {
			$out[] = $token;
		}
	}
	return $out;
}

/**
 *	decode the stored object-attributes property
 *
 *	Stored as a single line of JSON, which suits the flat file format: it never
 *	contains a raw newline (save_object strips those from every value anyway,
 *	module_glue.inc.php), and a colon inside it is harmless because the parser
 *	splits each line on the FIRST colon only.
 *
 *	@param string $str stored value
 *	@return array name=>value, only the entries that pass validation
 */
function object_decode_attributes($str)
{
	if (empty($str)) {
		return [];
	}
	$decoded = @json_decode($str, true);
	if (!is_array($decoded)) {
		log_msg('warn', 'object: could not decode object-attributes '.quot($str));
		return [];
	}
	$out = [];
	foreach ($decoded as $name=>$val) {
		if (is_array($val) || is_object($val)) {
			continue;
		}
		if (object_attr_allowed($name)) {
			$out[strtolower(trim($name))] = (string)$val;
		} else {
			log_msg('warn', 'object: dropping disallowed attribute '.quot($name));
		}
	}
	return $out;
}


/**
 *	save an object's user classes and custom attributes
 *
 *	The editor could write these with glue.update_object directly - this exists
 *	so a bad value is REJECTED with a reason instead of being stored and then
 *	silently dropped at render time. Client-side validation is for feedback;
 *	this is where a save actually gets refused.
 *
 *	Note the render path filters independently (object_alter_render_early), and
 *	has to: glue.update_object is a generic key/value setter, so this service
 *	cannot be the only check without being trivially bypassed.
 *
 *	@param array $args arguments
 *		key 'name' is the object name
 *		key 'classes' space-separated user class tokens (optional, '' clears)
 *		key 'attributes' name=>value map of custom attributes (optional)
 *	@return array response
 *		true if successful
 */
function object_set_properties($args)
{
	if (empty($args['name'])) {
		return response('Required argument "name" missing', 400);
	}
	load_modules('glue');

	$update = ['name'=>$args['name']];
	$remove = [];

	if (isset($args['classes'])) {
		$raw = preg_split('/\s+/', trim((string)$args['classes']), -1, PREG_SPLIT_NO_EMPTY);
		$bad = [];
		foreach ($raw as $token) {
			if (!preg_match(OBJECT_CLASS_TOKEN_RE, $token)) {
				$bad[] = $token;
			}
		}
		if (count($bad)) {
			return response('Invalid class name(s): '.quot(implode(' ', $bad)).' - use letters, digits, - and _, not starting with a digit', 400);
		}
		if (count($raw)) {
			$update['object-custom-class'] = implode(' ', $raw);
		} else {
			$remove[] = 'object-custom-class';
		}
	}

	if (isset($args['attributes'])) {
		if (!is_array($args['attributes'])) {
			return response('Argument "attributes" must be an object', 400);
		}
		$attrs = [];
		foreach ($args['attributes'] as $name=>$val) {
			$name = strtolower(trim((string)$name));
			if ($name === '') {
				continue;
			}
			if (is_array($val) || is_object($val)) {
				return response('Attribute '.quot($name).' must have a text value', 400);
			}
			if (!preg_match(OBJECT_ATTR_NAME_RE, $name)) {
				return response('Invalid attribute name '.quot($name).' - use letters, digits and dashes, starting with a letter', 400);
			}
			if (substr($name, 0, 2) == 'on') {
				return response('Attribute '.quot($name).' can\'t be set here - inline event handlers are not allowed, put javascript in the page\'s code instead', 400);
			}
			if (in_array($name, object_attr_denylist())) {
				if ($name == 'style') {
					return response('Attribute "style" can\'t be set here - the object\'s position and size are managed by the object itself', 400);
				}
				return response('Attribute '.quot($name).' can\'t be set here - it is managed by hotglue', 400);
			}
			$attrs[$name] = (string)$val;
		}
		if (count($attrs)) {
			// one line of JSON - see object_decode_attributes()
			$update['object-attributes'] = json_encode($attrs, JSON_UNESCAPED_SLASHES|JSON_UNESCAPED_UNICODE);
		} else {
			$remove[] = 'object-attributes';
		}
	}

	// nothing is written until every field has passed, so a rejected save
	// cannot leave half the properties updated
	if (1 < count($update)) {
		$ret = update_object($update);
		if ($ret['#error']) {
			return $ret;
		}
	}
	foreach ($remove as $attr) {
		$ret = object_remove_attr(['name'=>$args['name'], 'attr'=>$attr]);
		if ($ret['#error']) {
			return $ret;
		}
	}
	return response(true);
}

register_service('object.set_properties', 'object_set_properties', ['auth'=>true]);


function object_alter_render_early($args)
{
	$elem = &$args['elem'];
	$obj = $args['obj'];
	if (!elem_has_class($elem, 'object')) {
		return false;
	}
	
	if (!empty($obj['object-height'])) {
		elem_css($elem, 'height', $obj['object-height']);
	}
	if (!empty($obj['object-left'])) {
		elem_css($elem, 'left', $obj['object-left']);
	}
	if (!empty($obj['object-opacity'])) {
		elem_css($elem, 'opacity', $obj['object-opacity']);
	}
	// whether content bigger than the object's box is cut off or spills out.
	// Absent means visible, which is the browser default and what hotglue has
	// always done - so only 'hidden' is ever stored, and an object that has
	// never been touched keeps exactly the markup it had.
	if (!empty($obj['object-overflow'])) {
		elem_css($elem, 'overflow', $obj['object-overflow']);
	}
	// rounded corners
	if (!empty($obj['object-border-radius'])) {
		elem_css($elem, 'border-radius', $obj['object-border-radius']);
	}
	// how the object blends with what is behind it. Absent means normal -
	// the browser default - so only a non-normal mode is ever stored, and
	// the stored value is allowlisted before it reaches the style attribute.
	if (!empty($obj['object-mix-blend-mode']) &&
			in_array($obj['object-mix-blend-mode'], array('multiply', 'screen',
				'overlay', 'darken', 'lighten', 'color-dodge', 'color-burn',
				'hard-light', 'soft-light', 'difference', 'exclusion', 'hue',
				'saturation', 'color', 'luminosity'))) {
		elem_css($elem, 'mix-blend-mode', $obj['object-mix-blend-mode']);
	}
	// A border of the author's own. Solid is the default and is NOT stored -
	// absent means solid, the way absent means visible for overflow - so an
	// object with an ordinary border carries two attributes rather than
	// three. (The editor's selection used to be a border on this same
	// element, which is why objects could not have one at all until it became
	// an outline - see .glue-selected in css/edit.css.)
	if (!empty($obj['object-border-width'])) {
		elem_css($elem, 'border-width', $obj['object-border-width']);
		elem_css($elem, 'border-style', !empty($obj['object-border-style']) ?
			$obj['object-border-style'] : 'solid');
		if (!empty($obj['object-border-color'])) {
			elem_css($elem, 'border-color', $obj['object-border-color']);
		}
	}
	// A background image of the object's own. The URL points at the OBJECT,
	// not at the file in the shared directory - object_serve_resource() below
	// hands the file over - which is the same arrangement image objects use
	// and for the same reason: the shared directory is deduplicated, and the
	// object is what knows which file is its. The one exception is an image
	// object: its object URL serves the PICTURE (image_serve_resource wins
	// the hook dispatch, and object_serve_resource refuses objects with
	// image-file), so the background of an image object points at the
	// shared file directly - the same raw path the video poster uses.
	if (!empty($obj['object-background-file'])) {
		if (!empty($obj['image-file'])) {
			$pn = get_first_item(expl('.', $obj['name']));
			$url = CONTENT_DIR.'/'.$pn.'/shared/'.rawurlencode($obj['object-background-file']);
		} else if (SHORT_URLS) {
			$url = base_path().urlencode($obj['name']);
		} else {
			$url = base_path().'?'.urlencode($obj['name']);
		}
		elem_css($elem, 'background-image', 'url('.$url.')');
		elem_css($elem, 'background-repeat', !empty($obj['object-background-repeat']) ?
			$obj['object-background-repeat'] : 'no-repeat');
		if (!empty($obj['object-background-position'])) {
			elem_css($elem, 'background-position', $obj['object-background-position']);
		}
		// the scale is a percentage of the object's width, height keeping its
		// own ratio - '% auto' is composed here, the bare number is stored
		if (!empty($obj['object-background-scale'])) {
			elem_css($elem, 'background-size',
				$obj['object-background-scale'].'% auto');
		}
	}
	// The colour under it, or - for an object with no picture - the background
	// itself. Text objects have their own (text-background-color, which the
	// text module renders), so this is every other kind, matching the guard in
	// object_alter_save().
	if (!elem_has_class($elem, 'text') && !empty($obj['object-background-color'])) {
		elem_css($elem, 'background-color', $obj['object-background-color']);
	}
	// Padding, for every kind except text (which stores its own
	// text-padding-*): the four longhands when the object was saved with
	// per-side values, the x/y pair as the fallback for the uniform row -
	// danja's call, 2026-09-23: image and video objects got the padding
	// section text has. The frame compensation the panel does means the
	// object's stored width/height stay the OUTER size, and the picture
	// letterboxes inside the padded content box.
	if (!elem_has_class($elem, 'text')) {
		if (!empty($obj['object-padding-left'])) {
			elem_css($elem, 'padding-left', $obj['object-padding-left']);
		}
		if (!empty($obj['object-padding-right'])) {
			elem_css($elem, 'padding-right', $obj['object-padding-right']);
		}
		if (empty($obj['object-padding-left']) && empty($obj['object-padding-right']) && !empty($obj['object-padding-x'])) {
			elem_css($elem, 'padding-left', $obj['object-padding-x']);
			elem_css($elem, 'padding-right', $obj['object-padding-x']);
		}
		if (!empty($obj['object-padding-top'])) {
			elem_css($elem, 'padding-top', $obj['object-padding-top']);
		}
		if (!empty($obj['object-padding-bottom'])) {
			elem_css($elem, 'padding-bottom', $obj['object-padding-bottom']);
		}
		if (empty($obj['object-padding-top']) && empty($obj['object-padding-bottom']) && !empty($obj['object-padding-y'])) {
			elem_css($elem, 'padding-top', $obj['object-padding-y']);
			elem_css($elem, 'padding-bottom', $obj['object-padding-y']);
		}
	}
	// The box-shadow family - a soft halo behind the content, a solid band
	// outside the box and one inside it, and a directional drop shadow - see
	// .glue-glow in css/main.css. Like the fade above, what is stored is the
	// ingredients (colours, radii, strengths) rather than any shadow itself.
	// One class turns on the whole composed rule; the members nobody set stay
	// invisible, so an object with just an inset band does not also invent a
	// glow or an outer rim.
	//
	// Every NUMBER emitted here is format-guarded: a single bad unit in one
	// variable would invalidate the entire box-shadow at computed-value time
	// and take the whole family down with it, so a hand-edited file with,
	// say, '20px' in a spread is dropped rather than trusted.
	if (!empty($obj['object-glow-color'])) {
		elem_css($elem, '--glue-glow-color', $obj['object-glow-color']);
		if (!empty($obj['object-glow-spread']) &&
		    preg_match('/^[0-9.]+$/', $obj['object-glow-spread'])) {
			elem_css($elem, '--glue-glow-spread', $obj['object-glow-spread']);
		}
		if (!empty($obj['object-glow-alpha']) &&
		    preg_match('/^[0-9.]+$/', $obj['object-glow-alpha'])) {
			elem_css($elem, '--glue-glow-alpha', $obj['object-glow-alpha']);
		}
		// the inner layers and the duotone sides are sized off the spread,
		// so they exist only while the glow has a reach - without one they
		// would be a solid box
		if (!empty($obj['object-glow-spread'])) {
			if (!empty($obj['object-glow-inner'])) {
				elem_css($elem, '--glue-glow-inner', $obj['object-glow-inner']);
			}
			if (!empty($obj['object-glow-color2'])) {
				elem_css($elem, '--glue-glow-color2', $obj['object-glow-color2']);
			}
		}
		elem_add_class($elem, 'glue-glow');
	}
	// the drop shadow's on-switch is its colour: without one, no shadow
	if (!empty($obj['object-drop-color'])) {
		elem_css($elem, '--glue-drop-color', $obj['object-drop-color']);
		// the angle keeps its unit, so the trig in the composed rule sees
		// an angle rather than a number
		if (!empty($obj['object-drop-angle']) &&
		    preg_match('/^[0-9.]+deg$/', $obj['object-drop-angle'])) {
			elem_css($elem, '--glue-drop-angle', $obj['object-drop-angle']);
		}
		foreach (['distance', 'blur', 'spread'] as $part) {
			if (!empty($obj['object-drop-'.$part]) &&
			    preg_match('/^[0-9.]+$/', $obj['object-drop-'.$part])) {
				elem_css($elem, '--glue-drop-'.$part, $obj['object-drop-'.$part]);
			}
		}
		elem_add_class($elem, 'glue-glow');
	}
	// A soft edge: the NUMBER is stored, and one rule in css/main.css builds
	// the mask from it - see .glue-edge-fade there. Storing the gradient
	// itself would put commas and quotes in the object file and write the
	// same gradient out in two places (here and the editor) that would have
	// to agree forever. The class is what turns the rule on, so objects
	// nobody has faded carry no mask at all.
	if (!empty($obj['object-edge-fade'])) {
		elem_css($elem, '--glue-fade', $obj['object-edge-fade']);
		elem_add_class($elem, 'glue-edge-fade');
	}
	elem_css($elem, 'position', 'absolute');
	if (!empty($obj['object-top'])) {
		elem_css($elem, 'top', $obj['object-top']);
	}
	if (!empty($obj['object-width'])) {
		elem_css($elem, 'width', $obj['object-width']);
	}
	if (!empty($obj['object-zindex'])) {
		elem_css($elem, 'z-index', $obj['object-zindex']);
	}
	// custom class: appended alongside the internal classes (safe, classes
	// don't collide) so the user's own CSS/JS can target this object. Filtered
	// to valid class tokens - APPENDED, so a user can never remove or replace
	// the classes the editor and the modules key off.
	if (!empty($obj['object-custom-class'])) {
		foreach (object_filter_classes($obj['object-custom-class']) as $token) {
			elem_add_class($elem, $token);
		}
	}

	// custom attributes, denylist-filtered (see the note at the top)
	if (!empty($obj['object-attributes'])) {
		foreach (object_decode_attributes($obj['object-attributes']) as $name=>$val) {
			elem_attr($elem, $name, $val);
		}
	}

	return true;
}


function object_alter_render_late($args)
{
	$elem = $args['elem'];
	$html = &$args['html'];
	$obj = $args['obj'];
	if (!elem_has_class($args['elem'], 'object')) {
		return false;
	}
	if (!$args['edit']) {
		// add links only for viewing
		if (!empty($obj['object-link'])) {
			$link = $obj['object-link'];
			if(!empty($obj['object-target'])) {
				$target = $obj['object-target'];
			}
			// resolve any aliases
			$link = resolve_aliases($link, $obj['name']);
			if (($local = localize_url($link)) !== false) {
				// a saved absolute address of this very site (see localize_url())
				$link = $local;
			} elseif (!is_url($link) && substr($link, 0, 1) != '#') {
				// same-site page links are kept relative (not prefixed with
				// base_url()) so they still resolve correctly when the page
				// is viewed through a different domain (e.g. a custom
				// domain pointed at this install) than whatever BASE_URL is
				// configured/detected as - the browser resolves a relative
				// href against the domain the page is actually being viewed
				// on, not a hardcoded one
				if (SHORT_URLS) {
					$link = base_path().urlencode($link);
				} else {
					$link = base_path().'?'.urlencode($link);
				}
			}
			// <a> can include block elements in html5
			if (substr($html, -1) == "\n") {
				$html = substr($html, 0, -1);
			}
			// if target is specified use it in link
			if (isset($target)) {
				$html = '<a href="'.htmlspecialchars($link, ENT_COMPAT, 'UTF-8').'" target="'.htmlspecialchars($target, ENT_COMPAT, 'UTF-8').'">'."\n\t".str_replace("\n", "\n\t", $html)."\n".'</a>'."\n";
			} else {
				$html = '<a href="'.htmlspecialchars($link, ENT_COMPAT, 'UTF-8').'">'."\n\t".str_replace("\n", "\n\t", $html)."\n".'</a>'."\n";
			}
			return true;
		}
	}
	return false;
}


function object_alter_save($args)
{
	$elem = $args['elem'];
	$obj = &$args['obj'];
	if (!elem_has_class($elem, 'object')) {
		return false;
	}
	
	if (elem_css($elem, 'height') !== NULL) {
		$obj['object-height'] = elem_css($elem, 'height');
	} else {
		unset($obj['object-height']);
	}
	if (elem_css($elem, 'left') !== NULL) {
		$obj['object-left'] = elem_css($elem, 'left');
	} else {
		unset($obj['object-left']);
	}
	if (elem_css($elem, 'opacity') !== NULL) {
		$obj['object-opacity'] = elem_css($elem, 'opacity');
	} else {
		unset($obj['object-opacity']);
	}
	if (elem_css($elem, 'mix-blend-mode') !== NULL &&
			elem_css($elem, 'mix-blend-mode') != 'normal') {
		$obj['object-mix-blend-mode'] = elem_css($elem, 'mix-blend-mode');
	} else {
		unset($obj['object-mix-blend-mode']);
	}
	if (elem_css($elem, 'overflow') !== NULL) {
		$obj['object-overflow'] = elem_css($elem, 'overflow');
	} else {
		unset($obj['object-overflow']);
	}
	if (elem_css($elem, 'border-radius') !== NULL) {
		$obj['object-border-radius'] = elem_css($elem, 'border-radius');
	} else {
		unset($obj['object-border-radius']);
	}
	// The colour under the picture, and - for an object with no picture - the
	// whole of its background. Text objects keep theirs in text-background-color
	// (the text module has owned that property since long before there was a
	// background panel, and renders it itself), so this is every other kind:
	// without it a colour picked in the background panel would live in the
	// editor's DOM and nowhere else.
	if (!elem_has_class($elem, 'text') && elem_css($elem, 'background-color') !== NULL) {
		$obj['object-background-color'] = elem_css($elem, 'background-color');
	} else {
		unset($obj['object-background-color']);
	}
	// padding, for every kind except text (the text module stores its own
	// text-padding-*): the x/y pair while the sides are symmetric, the four
	// longhands when they are not - the same parse text_alter_save does.
	// The panel compensates the frame, so width/height above keep being the
	// OUTER size and the content box shrinks by the padding.
	if (!elem_has_class($elem, 'text')) {
		$pad = ['top'=>NULL, 'right'=>NULL, 'bottom'=>NULL, 'left'=>NULL];
		if (elem_css($elem, 'padding') !== NULL) {
			// inline padding as shorthand rather than longhands (Firefox
			// serialises it that way - same reason as text_alter_save)
			$s = expl(' ', elem_css($elem, 'padding'));
			if (count($s) == 1) {
				$pad['top'] = $pad['right'] = $pad['bottom'] = $pad['left'] = $s[0];
			} elseif (count($s) == 2) {
				$pad['top'] = $pad['bottom'] = $s[0];
				$pad['left'] = $pad['right'] = $s[1];
			} elseif (count($s) == 3) {
				$pad['top'] = $s[0];
				$pad['left'] = $pad['right'] = $s[1];
				$pad['bottom'] = $s[2];
			} else {
				$pad['top'] = $s[0];
				$pad['right'] = $s[1];
				$pad['bottom'] = $s[2];
				$pad['left'] = $s[3];
			}
		} else {
			foreach ($pad as $side => $v) {
				$pad[$side] = elem_css($elem, 'padding-'.$side);
			}
		}
		// left/right -> object-padding-x, or the two longhands when they differ
		if ($pad['left'] !== NULL || $pad['right'] !== NULL) {
			if ($pad['left'] !== NULL && $pad['right'] !== NULL && $pad['left'] == $pad['right']) {
				$obj['object-padding-x'] = $pad['left'];
				unset($obj['object-padding-left']);
				unset($obj['object-padding-right']);
			} else {
				unset($obj['object-padding-x']);
				if ($pad['left'] !== NULL) {
					$obj['object-padding-left'] = $pad['left'];
				} else {
					unset($obj['object-padding-left']);
				}
				if ($pad['right'] !== NULL) {
					$obj['object-padding-right'] = $pad['right'];
				} else {
					unset($obj['object-padding-right']);
				}
			}
		} else {
			unset($obj['object-padding-x']);
			unset($obj['object-padding-left']);
			unset($obj['object-padding-right']);
		}
		// top/bottom likewise
		if ($pad['top'] !== NULL || $pad['bottom'] !== NULL) {
			if ($pad['top'] !== NULL && $pad['bottom'] !== NULL && $pad['top'] == $pad['bottom']) {
				$obj['object-padding-y'] = $pad['top'];
				unset($obj['object-padding-top']);
				unset($obj['object-padding-bottom']);
			} else {
				unset($obj['object-padding-y']);
				if ($pad['top'] !== NULL) {
					$obj['object-padding-top'] = $pad['top'];
				} else {
					unset($obj['object-padding-top']);
				}
				if ($pad['bottom'] !== NULL) {
					$obj['object-padding-bottom'] = $pad['bottom'];
				} else {
					unset($obj['object-padding-bottom']);
				}
			}
		} else {
			unset($obj['object-padding-y']);
			unset($obj['object-padding-top']);
			unset($obj['object-padding-bottom']);
		}
	}
	// Only the two settings, never the image URL: that is derived from
	// object-background-file, which the upload sets and nothing else touches.
	// Storing the url as well would give the object two copies of the same
	// fact, one of which goes stale the moment a page is renamed.
	//
	// And only for an object whose background is its OWN. The image module
	// paints its picture with background-image too, complete with a
	// no-repeat, so reading these off any element that has them would write
	// two new attributes into every image object on every save - files that
	// have round-tripped untouched for years.
	if (!empty($obj['object-background-file'])) {
		if (elem_css($elem, 'background-repeat') !== NULL) {
			$obj['object-background-repeat'] = elem_css($elem, 'background-repeat');
		} else {
			unset($obj['object-background-repeat']);
		}
		if (elem_css($elem, 'background-position') !== NULL) {
			$obj['object-background-position'] = elem_css($elem, 'background-position');
		} else {
			unset($obj['object-background-position']);
		}
		if (elem_css($elem, 'background-size') !== NULL) {
			// the bare number is stored: the '% auto' it renders as is
			// composed at render. Chromium writes a width-only '150%' back
			// into the style attribute (dropping the redundant 'auto'), so
			// both spellings are accepted. A size that is not one of ours
			// (someone hand-wrote 'cover', say) is dropped rather than
			// stored, so a scaled-back object ends up byte-identical to one
			// never touched.
			if (preg_match('/^([0-9.]+)%( auto)?$/', elem_css($elem, 'background-size'), $m)) {
				$obj['object-background-scale'] = $m[1];
			} else {
				unset($obj['object-background-scale']);
			}
		} else {
			unset($obj['object-background-scale']);
		}
	}
	// solid is the default and stays unstored: see object_render_object()
	if (elem_css($elem, 'border-style') !== NULL &&
	    elem_css($elem, 'border-style') != 'solid') {
		$obj['object-border-style'] = elem_css($elem, 'border-style');
	} else {
		unset($obj['object-border-style']);
	}
	if (elem_css($elem, 'border-width') !== NULL) {
		$obj['object-border-width'] = elem_css($elem, 'border-width');
	} else {
		unset($obj['object-border-width']);
	}
	if (elem_css($elem, 'border-color') !== NULL) {
		$obj['object-border-color'] = elem_css($elem, 'border-color');
	} else {
		unset($obj['object-border-color']);
	}
	// see object_render_object(): the ingredients are what is stored, and the
	// class comes back with them. The glow and the drop shadow are the same
	// deal: the inline vars are the file's attrs, nothing composed is kept
	// (the drop angle round-trips with its unit, '135deg').
	foreach (['color', 'spread', 'alpha', 'inner', 'color2'] as $part) {
		if (elem_css($elem, '--glue-glow-'.$part) !== NULL) {
			$obj['object-glow-'.$part] = elem_css($elem, '--glue-glow-'.$part);
		} else {
			unset($obj['object-glow-'.$part]);
		}
	}
	foreach (['color', 'distance', 'angle', 'blur', 'spread'] as $part) {
		if (elem_css($elem, '--glue-drop-'.$part) !== NULL) {
			$obj['object-drop-'.$part] = elem_css($elem, '--glue-drop-'.$part);
		} else {
			unset($obj['object-drop-'.$part]);
		}
	}
	if (elem_css($elem, '--glue-fade') !== NULL) {
		$obj['object-edge-fade'] = elem_css($elem, '--glue-fade');
	} else {
		unset($obj['object-edge-fade']);
	}
	if (elem_css($elem, 'top') !== NULL) {
		$obj['object-top'] = elem_css($elem, 'top');
	} else {
		unset($obj['object-top']);
	}
	if (elem_css($elem, 'width') !== NULL) {
		$obj['object-width'] = elem_css($elem, 'width');
	} else {
		unset($obj['object-width']);
	}
	if (elem_css($elem, 'z-index') !== NULL) {
		$obj['object-zindex'] = elem_css($elem, 'z-index');
	} else {
		unset($obj['object-zindex']);
	}
	
	return true;
}


function object_render_page_early($args)
{
	if ($args['edit']) {
		if (USE_MIN_FILES) {
			html_add_js(base_url().'modules/object/object-edit.min.js');
		} else {
			html_add_js(base_url().'modules/object/object-edit.js');
		}
		
		// add default colors
		html_add_js_var('$.glue.conf.object.default_colors', expl(' ', OBJECT_DEFAULT_COLORS));
	}
}


/**
 *	implements upload for preferred_module 'object'
 *
 *	Sets an uploaded image as one object's background. Unlike the image
 *	module's upload, which makes a new object out of the file, this one is
 *	given the object to put it on - the frontend passes 'object' - and touches
 *	nothing else about it.
 *
 *	The preferred_module has to be the MODULE's name and nothing else:
 *	upload_files() dispatches by building "{preferred_module}_upload" and
 *	calling it, so anything with a hyphen in it is not a function name, is
 *	silently not callable, and the file falls through to the generic hooks -
 *	where the image module makes an object out of it instead.
 *
 *	@param array $args arguments
 *		key 'object' the object to set the background on
 *	@return bool true when the file was taken
 */
function object_upload($args)
{
	if (empty($args['preferred_module']) || $args['preferred_module'] != 'object') {
		return false;
	}
	if (empty($args['object'])) {
		return false;
	}
	// the same set the page background accepts
	if (!in_array($args['mime'], ['image/jpeg', 'image/png', 'image/gif']) &&
	    !($args['mime'] == '' && in_array(filext($args['file']), ['jpg', 'jpeg', 'png', 'gif']))) {
		return false;
	}

	load_modules('glue');
	$obj = load_object(['name'=>$args['object']]);
	if ($obj['#error']) {
		log_msg('error', 'object_upload: no such object '.quot($args['object']));
		return false;
	}
	$obj = $obj['#data'];
	// a background this replaces is one upload fewer to keep
	if (!empty($obj['object-background-file'])) {
		delete_upload(['pagename'=>get_first_item(expl('.', $args['object'])),
			'file'=>$obj['object-background-file'], 'max_cnt'=>1]);
	}

	$ret = update_object([
		'name' => $args['object'],
		'object-background-file' => $args['file'],
		'object-background-mime' => $args['mime']
	]);
	if ($ret['#error']) {
		log_msg('error', 'object_upload: error updating object: '.quot($ret['#data']));
		return false;
	}
	return true;
}


/**
 *	implements serve_resource
 *
 *	Hands over an object's background image. Objects that are images serve
 *	their own picture through image_serve_resource() instead, so this
 *	deliberately stands aside for them: one object, one resource.
 */
function object_serve_resource($args)
{
	$obj = $args['obj'];
	if (empty($obj['object-background-file']) || !empty($obj['image-file'])) {
		return false;
	}
	$pn = get_first_item(expl('.', $obj['name']));
	$fn = CONTENT_DIR.'/'.$pn.'/shared/'.$obj['object-background-file'];
	$mime = !empty($obj['object-background-mime']) ? $obj['object-background-mime'] : '';
	if (!is_file($fn)) {
		log_msg('warn', 'object_serve_resource: missing background file '.quot($fn));
		return false;
	}
	serve_file($fn, $args['dl'], $mime);
	return true;
}