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diff --git a/build/docs/chrome-registration.rst b/build/docs/chrome-registration.rst new file mode 100644 index 0000000000..5c40f5ced7 --- /dev/null +++ b/build/docs/chrome-registration.rst @@ -0,0 +1,459 @@ +Chrome Registration +------------------- + +What is chrome? +--------------- + +`Chrome` is the set of user interface elements of the +application window that are outside the window's content area. Toolbars, +menu bars, progress bars, and window title bars are all examples of +elements that are typically part of the chrome. + +``chrome.manifest`` files are used to register XPCOM components and sources for the chrome protocol. +Every application supplies a root ``chrome.manifest`` file that Mozilla reads on startup. + +Chrome providers +---------------- + +A supplier of chrome for a given window type (e.g., for the browser +window) is called a chrome provider. The providers work together to +supply a complete set of chrome for a particular window, from the images +on the toolbar buttons to the files that describe the text, content, and +appearance of the window itself. + +There are three basic types of chrome providers: + +Content + The main source file for a window description comes from the content + provider, and it can be any file type viewable from within Mozilla. + It will typically be a XUL file, since XUL is designed for describing + the contents of windows and dialogs. The JavaScript files that define + the user interface are also contained within the content packages. + +Locale + Localizable applications keep all their localized information in + locale providers and Fluent FTL files, which are handled separately. + This allows translators to plug in a different + chrome package to translate an application without altering the rest + of the source code. In a chrome provider, localizable files are mostly + Java-style properties files. +Skin + A skin provider is responsible for providing a complete set of files + that describe the visual appearance of the chrome. Typically a skin + provider will provide CSS files and + images. + +The chrome registry +------------------- + +The Gecko runtime maintains a service known as the chrome registry that +provides mappings from chrome package names to the physical location of +chrome packages on disk. + +This chrome registry is configurable and persistent, and thus a user can +install different chrome providers, and select a preferred skin and +locale. This is accomplished through xpinstall and the extension +manager. + +In order to inform the chrome registry of the available chrome, a text +manifest is used: this manifest is "chrome.manifest" in the root of an +extension, or theme, or XULRunner application. + +The plaintext chrome manifests are in a simple line-based format. Each +line is parsed individually; if the line is parsable the chrome registry +takes the action identified by that line, otherwise the chrome registry +ignores that line (and prints a warning message in the runtime error +console). + +.. code:: text + + locale packagename localename path/to/files + skin packagename skinname path/to/files + +.. note:: + + The characters @ # ; : ? / are not allowed in the + packagename. + +Manifest instructions +--------------------- + +comments +~~~~~~~~ + +.. code:: text + + # this line is a comment - you can put here whatever you want + +A line is a comment if it begins with the character '#'. Any following +character in the same line is ignored. + +manifest +~~~~~~~~ + +:: + + manifest subdirectory/foo.manifest [flags] + +This will load a secondary manifest file. This can be useful for +separating component and chrome registration instructions, or separate +platform-specific registration data. + +component +~~~~~~~~~ + +:: + + component {00000000-0000-0000-0000-000000000000} components/mycomponent.js [flags] + +Informs Mozilla about a component CID implemented by an XPCOM component +implemented in JavaScript (or another scripting language, if +applicable). The ClassID {0000...} must match the ClassID implemented by +the component. To generate a unique ClassID, use a UUID generator +program or site. + +contract +~~~~~~~~ + +:: + + contract @foobar/mycontract;1 {00000000-0000-0000-0000-000000000000} [flags] + +Maps a contract ID (a readable string) to the ClassID for a specific +implementation. Typically a contract ID will be paired with a component +entry immediately preceding. + +category +~~~~~~~~ + +:: + + category category entry-name value [flags] + +Registers an entry in the `category manager`. The +specific format and meaning of category entries depend on the category. + +content +~~~~~~~ + +A content package is registered with the line: + +:: + + content packagename uri/to/files/ [flags] + +This will register a location to use when resolving the URI +``chrome://packagename/content/...``. The URI may be absolute or +relative to the location of the manifest file. Note: it must end with a +'/'. + +locale +~~~~~~ + +A locale package is registered with the line: + +.. code:: text + + locale packagename localename uri/to/files/ [flags] + +This will register a locale package when resolving the URI +chrome://*packagename*/locale/... . The *localename* is usually a plain +language identifier "en" or a language-country identifier "en-US". If +more than one locale is registered for a package, the chrome registry +will select the best-fit locale using the user's preferences. + +skin +~~~~ + +A skin package is registered with the line: + +.. code:: text + + skin packagename skinname uri/to/files/ [flags] + +This will register a skin package when resolving the URI +chrome://packagename/skin/... . The *skinname* is an opaque string +identifying an installed skin. If more than one skin is registered for a +package, the chrome registry will select the best-fit skin using the +user's preferences. + +style +~~~~~ + +Style overlays (custom CSS which will be applied to a chrome page) are +registered with the following syntax: + +.. code:: text + + style chrome://URI-to-style chrome://stylesheet-URI [flags] + +override +~~~~~~~~ + +In some cases an extension or embedder may wish to override a chrome +file provided by the application or XULRunner. In order to allow for +this, the chrome registration manifest allows for "override" +instructions: + +.. code:: text + + override chrome://package/type/original-uri.whatever new-resolved-URI [flags] + +Note: overrides are not recursive (so overriding +chrome://foo/content/bar/ with file:///home/john/blah/ will not usually +do what you want or expect it to do). Also, the path inside overridden +files is relative to the overridden path, not the original one (this can +be annoying and/or useful in CSS files, for example). + +.. _chrome_manifest_resource: + +resource +~~~~~~~~ + +Aliases can be created using the ``resource`` instruction: + +.. code:: text + + resource aliasname uri/to/files/ [flags] + +This will create a mapping for ``resource://<aliasname>/`` URIs to the +path given. + +.. note:: + + **Note:** There are no security restrictions preventing web content + from including content at resource: URIs, so take care what you make + visible there. + +Manifest flags +-------------- + +Manifest lines can have multiple, space-delimited flags added at the end +of the registration line. These flags mark special attributes of chrome +in that package, or limit the conditions under which the line is used. + +application +~~~~~~~~~~~ + +Extensions may install into multiple applications. There may be chrome +registration lines which only apply to one particular application. The +flag + +.. code:: text + + application=app-ID + +indicates that the instruction should only be applied if the extension +is installed into the application identified by *app-ID*. Multiple +application flags may be included on a single line, in which case the +line is applied if any of the flags match. + +This example shows how a different overlay can be used for different +applications: + +:: + + overlay chrome://browser/content/browser.xul chrome://myaddon/content/ffOverlay.xul application={ec8030f7-c20a-464f-9b0e-13a3a9e97384} + overlay chrome://messenger/content/mailWindowOverlay.xul chrome://myaddon/content/tbOverlay.xul application={3550f703-e582-4d05-9a08-453d09bdfdc6} + overlay chrome://songbird/content/xul/layoutBaseOverlay.xul chrome://myaddon/content/sbOverlay.xul application=songbird@songbirdnest.com + +appversion +~~~~~~~~~~ + +Extensions may install into multiple versions of an application. There +may be chrome registration lines which only apply to a particular +application version. The flag + +.. code:: text + + appversion=version + appversion<version + appversion<=version + appversion>version + appversion>=version + +indicates that the instruction should only be applied if the extension +is installed into the application version identified. Multiple +``appversion`` flags may be included on a single line, in which case the +line is applied if any of the flags match. The version string must +conform to the `Toolkit version format`. + +platformversion +~~~~~~~~~~~~~~~ + +When supporting more then one application, it is often more convenient +for an extension to specify which Gecko version it is compatible with. +This is particularly true for binary components. If there are chrome +registration lines which only apply to a particular Gecko version, the +flag + +.. code:: text + + platformversion=version + platformversion<version + platformversion<=version + platformversion>version + platformversion>=version + +indicates that the instruction should only be applied if the extension +is installed into an application using the Gecko version identified. +Multiple ``platformversion`` flags may be included on a single line, in +which case the line is applied if any of the flags match. + +contentaccessible +~~~~~~~~~~~~~~~~~ + +Chrome resources can no longer be referenced from within <img>, +<script>, or other elements contained in, or added to, content that was +loaded from an untrusted source. This restriction applies to both +elements defined by the untrusted source and to elements added by +trusted extensions. If such references need to be explicitly allowed, +set the ``contentaccessible`` flag to ``yes`` to obtain the behavior +found in older versions of Firefox. See +`bug 436989 <https://bugzilla.mozilla.org/show_bug.cgi?id=436989>`__. + +The ``contentaccessible`` flag applies only to content packages: it is +not recognized for locale or skin registration. However, the matching +locale and skin packages will also be exposed to content. + +**n.b.:** Because older versions of Firefox do not understand the +``contentaccessible`` flag, any extension designed to work with both +Firefox 3 and older versions of Firefox will need to provide a fallback. +For example: + +:: + + content packagename chrome/path/ + content packagename chrome/path/ contentaccessible=yes + +os +~~ + +Extensions (or themes) may offer different features depending on the +operating system on which Firefox is running. The value is compared to +the value of `OS_TARGET` for the platform. + +.. code:: text + + os=WINNT + os=Darwin + +osversion +~~~~~~~~~ + +An extension or theme may need to operate differently depending on which +version of an operating system is running. For example, a theme may wish +to adopt a different look on Mac OS X 10.5 than 10.4: + +.. code:: text + + osversion>=10.5 + +abi +~~~ + +If a component is only compatible with a particular ABI, it can specify +which ABI/OS by using this directive. The value is taken from the +`nsIXULRuntime` OS and +XPCOMABI values (concatenated with an underscore). For example: + +:: + + binary-component component/myLib.dll abi=WINNT_x86-MSVC + binary-component component/myLib.so abi=Linux_x86-gcc3 + +platform (Platform-specific packages) +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Some packages are marked with a special flag indicating that they are +platform specific. Some parts of content, skin, and locales may be +different based on the platform being run. These packages contain three +different sets of files, for Windows and OS/2, Macintosh, and Unix-like +platforms. For example, the order of the "OK" and "Cancel" buttons in a +dialog is different, as well as the names of some items. + +The "platform" modifier is only parsed for content registration; it is +not recognized for locale or skin registration. However, it applies to +content, locale, and skin parts of the package, when specified. + +process +~~~~~~~ + +In electrolysis registrations can be set to only apply in either the +main process or any content processes. The "process" flag selects +between these two. This can allow you to register different components +for the same contract ID or ensure a component can only be loaded in the +main process. + +:: + + component {09543782-22b1-4a0b-ba07-9134365776ee} maincomponent.js process=main + component {98309951-ac89-4642-afea-7b2b6216bcef} contentcomponent.js process=content + +remoteenabled +~~~~~~~~~~~~~ + +In `multiprocess Firefox`, the +default is that a given chrome: URI will always be loaded into the +chrome process. If you set the "remoteenabled" flag, then the page will +be loaded in the same process as the ``browser`` that loaded it: + +:: + + content packagename chrome/path/ remoteenabled=yes + +remoterequired +~~~~~~~~~~~~~~ + +In `multiprocess Firefox`, the +default is that a given chrome: URI will always be loaded into the +chrome process. If you set the "remoterequired" flag, then the page will +always be loaded into a child process: + +:: + + content packagename chrome/path/ remoterequired=yes + +Example chrome manifest +----------------------- + +.. list-table:: + :widths: 20 20 20 20 + + + * - type + - engine + - language + - url + * - content + - branding + - browser/content/branding/ + - contentaccessible=yes + * - content + - browser + - browser/content/browser/ + - contentaccessible=yes + * - override + - + - chrome://global/content/license.html + - chrome://browser/content/license.html + * - resource + - payments + - browser/res/payments/ + - + * - skin + - browser + - classic/1.0 browser/skin/classic/browser/ + - + * - locale + - branding + - en-US + - en-US/locale/branding/ + * - locale + - browser + - en-US + - en-US/locale/browser/ + * - locale + - browser-region + - en-US + - en-US/locale/browser-region/ |