roHtmlWidget

This object embeds the Chromium HTML rendering engine, which can be rendered at full screen or as a widget. You can display multiple roHtmlWidget instances at the same time. The JavaScript equivalent is htmlwidget.

Tip

Use the roKeyStore object to provide client certificates for websites. Use the roVirtualMemory object to set up a virtual memory repository for Chromium.

Object Creation

The roHtmlWidget object is initialized with an roRectangle object, which specifies the size and positioning of the widget on the screen, and an optional associative array, which defines properties for the widget.

CreateObject("roHtmlWidget", rect As roRectangle, properties As roAssociativeArray)

The properties of an roHtmlWidget instance can be set with an associative array at initialization or with equivalent methods after initialization. Because many roHtmlWidget properties cannot be changed without reloading the page (and can produce unpredictable results if changed while the page is running), we recommend setting properties at initialization when possible, rather than using the equivalent methods.

Important

Defining initialization properties for an roHtmlWidget instance disables some methods for that instance (e.g. SetTransform(), AddFont(), SetUserStylesheet()). See the Available Methods with Initialization section below for a list of available methods.

Initialization Parameters

The associative array passed during initialization can have the following parameters:

[boolean] nodejs_enabled

Enables Node.js® on the widget. This value is false by default.

Reloading a page which has Node.js enabled can be classified as an undefined behavior. The recommended method for restarting a Node instance is to destroy and rebuild the roHtmlWidget

[boolean] focus_enabled

Enables focus for mouse/touchscreen events. This value is true by default.

[boolean] mouse_enabled

Enables mouse/touchscreen events. This value is false by default.

[boolean] scrollbar_enabled

Enables automatic scrollbars for content that does not fit into the viewport. This value is false by default.

The browser defaults to desktop-style scrollbars, but they can be configured for mobile style as well.

[boolean] pinch_to_zoom_enabled

Enables pinch-to-zoom functionality. This value is false by default.

[boolean] force_gpu_rasterization_enabled

Enables GPU rasterization for HTML graphics. By default, the decision to use GPU rasterization is based on internal Chromium logic.

[boolean] canvas_2d_acceleration_enabled

Enables 2D canvas acceleration. This will improve the framerate of most HTML pages that use 2D animations, but can cause out-of-memory issues with pages that use a large number of off-screen canvas surfaces.

[boolean] javascript_enabled

Enables JavaScript on the widget. This value is true by default.

[boolean] brightsign_js_objects_enabled

Enables BrightScript-JavaScript objects. This value is false by default.

In OS 8.2.55.4 and later, html widgets that are loaded from HTTP/HTTPS protocols do not share the same local storage database (html widgets that are loaded via file protocol act as they did in previous releases). These flags allow you to change the default behavior of widgets loaded through HTTP/HTTPS from "unshared" to "shared", or to change the default behavior of widgets with locally loaded files to "unshared" from "shared":

[boolean] force_shared_storage

Allows html widgets loaded via HTTP/HTTPS protocol to share local storage if they are loaded from the same domain.

[boolean] force_unshared_storage

Prevents html widgets loaded via FILE protocol from sharing storage.

[string] transform

Sets the screen orientation of content in the widget (note that the coordinates and dimensions of the roRectangle containing the widget are not affected by rotation). The following values are accepted:

"identity": There is no transform (i.e. the widget content is oriented as landscape). This is the default setting.
"rot90": The widget content is rotated to portrait at 90 degrees (clockwise).
"rot270": The widget content is rotated to portrait at 270 degrees (counter-clockwise).

[string] user_agent

Modifies the default user-agent string for the roHtmlWidget instance.

[string] url

The URL to use for display. See the SetUrl() entry below for more information on using URIs to access files from local storage.

[string] language

Specifies the language to load the web page in.

[string] user_stylesheet

Applies the specified user stylesheet to pages in the widget. The parameter is a URI specifying any file: resource in the storage. The stylesheet can also be specified as inline data.

[string] hwz_default

Specifies the default HWZ behavior. This value is off by default. To enable it, set it to on.

[string] storage_path

Creates a "Local Storage" subfolder in the specified directory. This folder is used by local storage applications such as the JavaScript storage class.

[string or double] storage_quota

Sets the total size (in bytes) allotted to all local storage applications (including IndexedDB). A BrightScript integer is only guaranteed to be able to represent a count of bytes up to 2GB so avoid using integers when calculating the size: Use float or double instead since they can represent values over 2GB (string can also be used but is not recommended). If the storage path is specified without a storage quota, Chromium defaults to reserving 1GB plus 10% of the total size of the storage device.

[roMessagePort] port

Configures the message port to which the roHtmlWidget instance will send events. When using initialization parameters, the port parameter should be used instead of the SetPort() method to ensure the script can catch load-started, load-finished, and load-error events.

[roArray] fonts

Specifies a list of font files that can be accessed by the webpage. Font files are specified as an array of string filenames. Supported font types include TrueType Font files (.ttf) and Web Open Font files (.woff, .woff2).

[roArray] pcm_audio_outputs

Configures the PCM audio output for the HTML widget. Outputs are specified as an array of strings, each string being the name of an output. (See roAudioOutput documentation for a list of acceptable names.)

[roArray] compressed_audio_outputs

Configures compressed audio output (e.g. Dolby AC3 encoded audio) for the HTML widget. Outputs are specified as an array of roAudioOutput instances.

[roArray] multi_channel_audio_outputs

Configures multi-channel audio output for the HTML widget. Outputs are specified as an array of roAudioOutput instances.

[roAssociativeArray] inspector_server

Configures the Chromium Inspector for the widget.Starting in BrightSign OS 8.5.31 you will need to also set the enable_web_inspector registry key (in the "html" section) to enable the JavaScript console. In “enable_web_inspector”, "1" will allow the inspector and "0" or not present will disable it. A reboot will be needed for these changes to take effect (if you enable/disable this through the LDWS UI it may trigger a reboot to apply the changes).

[string] ip_addr: The Inspector IP address. This value is useful if the player is assigned more than one IP address (i.e. there are multiple network interfaces) and you wish to limit the Inspector server to one. The default value is "0.0.0.0", which allows the Inspector to accept connections using either IP address.
[int] port: The port for the Inspector server

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[roAssociativeArray] security_params

Enables or disables Chromium security checks for cross-origin requests, local video playback from HTTP, etc.

[Boolean] websecurity: Enables Chromium security checks for cross-origin requests.
[Boolean] camera_enabled: Enables webpage access to USB cameras connected to the player (access is disabled by default). This allows support for WebRTC applications.
[Boolean] insecure_https_enabled: Instructs the widget to ignore security errors when connecting to insecure HTTPS hosts (insecure HTTPS is disabled by default). Enabling this feature makes the player insecure; it is not suitable for production environments and should only be used for testing.]
[Boolean] audio_capture_enabled: Gives access to audio input devices and lets Chromium enumerate all audio input and output devices

With BOS 8.2 and later (Chromium69 and later), several new CORS checks have been added: security_params.websecurity or enableSecurity(false) do not disable all these checks. Use the following registry setting instead:

registry write html disable-web-security 1

To write this to the registry using roRegistrySection:

RegHtml = CreateObject("roRegistrySection", "html")
RegHtml.Write("disable-web-security", "1")
RegHtml.Flush()

This flag will take effect on all roHtmlWidget instances, as opposed to previous flags which are only effective on the instance they are called on.

[roAssociativeArray] javascript_injection

Specifies JavaScript code to inject at different initialization points (JavaScript code can also be injected during runtime using the InjectJavaScript() method). The associative array can contain three parameters (described below). Each parameter value is an array of associative arrays, each containing a single key/value pair. The array must contain a source key. The source value is a string that can contain any of the following: pure JavaScript code, a path to a JavaScript file, or a base64-encoded string (i.e. beginning with data:text/javascript;charset=utf-8;base64, ). Mutliple source keys can be included, but the load order will be unpredictable. The array can also contain the optional world key, which can be assigned one of the following values: "application", "user", or "main"(see this page for more details); if the world parameter is not included in the array, "application" is selected by default.

document_creation: The script will run as soon as the document is created. This behavior is not suitable for any DOM operation.
document_ready: The script will run as soon as the DOM is ready. This behavior is equivalent to the DOMContentLoaded event firing in JavaScript.
deferred: The script will run when the page load finishes.

config = {
      javascript_injection: { 
         document_creation: [{source: "0.js" }], 
         document_ready: [{source: "1a.js" }, {source: "1b.js" }], 
         deferred: [{source: "2.js" }] 
      },
      url: "..."
   }

[roArray] assets

Allows the roHtmlWidget instance to access one or more asset pools. If a file exists in multiple specified asset pools, the asset pool with the lowest index in the array has precedence. Each array entry is an associative array containing information about an asset pool:

[roAssetPool] pool: An asset pool containing files
[roAssetCollection] collection: A manifest identifying the files in the pool
[string] uri_prefix: The URI prefix of the webpage resources to retrieve from the pool
[string] pool_prefix: The pool prefix that will replace the URI prefix when looking up the resource in the pool

ifHtmlWidget

GetFailureReason() As String

Gives more information when a member function returns false.

Hide() As Boolean

Hides the widget.

Show() As Boolean

Shows the widget.

raise()

Raises the html widget above all other graphical elements on screen (including other html widgets).

lower()

Lowers the html widget below all graphical elements on screen.

SetRectangle(r As roRectangle) As Boolean

Changes the size and positioning of the widget rectangle using the passed roRectangle object.

SetURL(URL As String) As Boolean

Displays content from the specified URL. When using this method to retrieve content from local storage, specify the file location as follows: "file:/<drive>:/<directory>/<filename>". For example, an index.html file in the "Content" folder on the SD card can be selected with the string "file:/SD:/Content/index.html". You can also omit the drive specification to select the currently active drive (i.e. whichever drive the current autorun as loaded from).

AddAuthenticationCredentials (url As String, username As String, password As String) As Boolean

Tells Chromium to use the specified username and password when retrieving the given URL.

MapFilesFromAssetPool(asset_pool As roAssetPool, asset_collection As roAssetCollection, pool_prefix As String, uri_prefix As String) As Boolean

Sets the mapping between the URL space and the pool files. HTML content that has been deployed via BrightAuthor will typically reside in the pool and have encrypted SHA1-based filenames. A mapping mechanism is required to allow any relative URIs contained in the HTML content to continue working and to locate the appropriate resources in their respective pool locations.

You can use this method to bind part of the resource URI space onto pool locations. This method accepts the following arguments: an roAssetPool object containing assets, an roAssetCollection object identifying the assets, and two semi-arbitrary strings (URI_PREFIX and POOL_PREFIX).

Any URI in the form "file:/[URI_PREFIX][RESOURCE_ID]" will be rewritten into the form "[POOL_PREFIX][RESOURCE_ID]". It will then be located in the pool as if that name had been passed to the roAssetPoolFiles.GetPoolFilePath() method. This binding occurs for every instance of roHtmlWidget, so different mappings can be used for different bundles of content.

SetZoomLevel(scale_factor as Float) As Boolean

Adjusts the scale factor for the displayed page (the default equals 1.0).

EnablePinchToZoom(enable as Boolean) As Boolean

Enables or disables pinch-to-zoom functionality, which is disabled by default.

EnableSecurity(enable As Dynamic) As Boolean

Deprecated. Use security_params in initialization parameters instead.

EnableMouseEvents(enable As Boolean) As Boolean

Deprecated. Use mouse_enabled in initialization parameters instead.

SetPortrait(portrait_mode As Boolean) As Boolean

Deprecated. Use transform in initialization parameters instead.

SetTransform(transform As String) As Boolean

Sets the screen orientation of content in the widget (note that the coordinates and dimensions of the roRectangle containing the widget are not affected by rotation). This method accepts the following strings:

"identity": There is no transform (i.e. the widget content is oriented as landscape). This is the default setting.
"rot90": The widget content is rotated to portrait at 90 degrees (clockwise).
"rot270": The widget content is rotated to portrait at 270 degrees (counter-clockwise).

SetAlpha(alpha As Integer) As Boolean

Sets the overall alpha level for the widget (the default equals 255).

EnableScrollbars(scrollbars As Boolean) As Boolean

Deprecated. Use scrollbar_enabled in initialization parameters instead.

AddFont(filename As String) As Boolean

Deprecated. Use fonts in initialization parameters instead.

SetPcmAudioOutputs(outputs As roArray) As Boolean

Deprecated. Use pcm_audio_outputs in initialization parameters instead.

SetCompressedAudioOutputs(outputs As roArray) As Boolean

Deprecated. Use compressed_audio_outputs in initialization parameters instead.

SetMultichannelAudioOutputs(outputs As roArray) As Boolean

Deprecated. Use multi_channel_audio_outputs in initialization parameters instead.

SetHWZDefault(default As String) As Void

Deprecated. Use hwz_default in initialization parameters instead.

SetVideoPlayerDefaults(defaults As roAssociativeArray) As Boolean

Sets default playback settings for <video> elements in the widget. Available parameters are identical to the roVideoPlayer.PlayFile() method. Default settings will be overwritten by parameters specified in individual <video> elements.

ForceGpuRasterization(enable As Boolean) As Boolean

Deprecated. As of OS8, GPU rasterization is enabled by default and calling this method has no effect.

EnableCanvas2dAcceleration(enable As Boolean) As Boolean

Deprecated. Use canvas_2d_acceleration_enabled in initialization parameters instead.

SetUserStylesheet(URI As String) As Boolean

Deprecated. Use user_stylesheet in initialization parameters instead.

FlushCachedResources() As Boolean

Discards any resources that Chromium has cached in memory.

SetLocalStorageDir(file_path As String) As Boolean

Configures the HTML storage path. This method takes effect when a new roHtmlWidget instance is created; it doesn't apply to the roHtmlWidget instance on which it is called.

SetWebDatabaseDir(file_path As String) As Boolean

Configures the HTML storage path. See the SetLocalStorageDir() entry above for details.

This method takes effect when a new roHtmlWidget instance is created; it doesn't apply to the roHtmlWidget instance on which it is called.

SetAppCacheDir(file_path As String) As Boolean

Configures the HTML storage path. See the SetLocalStorageDir() entry above for details.

This method takes effect when a new roHtmlWidget instance is created; it doesn't apply to the roHtmlWidget instance on which it is called.

SetLocalStorageQuota(maximum As Dynamic) As Boolean

Sets the total size (in bytes) for all persistent HTML storage on the player. This method can accept a string, double, or integer. A number literal can only represent byte numbers up to 2GB; use a string to specify larger amounts. If the storage path is specified without a storage quota, Chromium defaults to reserving 1GB plus 10% of the total size of the storage device.

This method takes effect when a new roHtmlWidget instance is created; it doesn't apply to the roHtmlWidget instance on which it is called.

SetWebDatabaseQuota(maximum As Dynamic) As Boolean

Sets the total size (in bytes) for all persistent HTML storage on the player. See the SetLocalStorageQuota() entry above for details.

This method takes effect when a new roHtmlWidget instance is created; it doesn't apply to the roHtmlWidget instance on which it is called.

SetAppCacheSize(maximum As Integer) As Boolean

Sets the maximum size (in bytes) for the application cache. Changing the storage size of the application cache will clear the cache and rebuild the cache storage. Depending on database-specific attributes, you will only be able to set the size in units that are equal to the page size of the database, which is established at creation. These storage units will occur only in the following increments: 512, 1024, 2048, 4096, 8192, 16384, 32768.

EnableJavaScript(enable As Boolean) As Boolean

Deprecated. Use javascript_enabled in initialization parameters instead.

AllowJavaScriptURLs(url_collection As roAssociativeArray)

Deprecated. If javascript_enabled is set to true in the initialization parameters, JavaScript objects are enabled for all sites.

PostJSMessage(data As roAssociativeArray) As Boolean

Posts a collection of key:value pairs to the BSMessagePort JavaScript class (see the JavaScript Objects for BrightScript tech note for more details). This method does not support passing nested associative arrays.

InjectJavaScript(code As String) As Boolean

Immediately injects a user script into the JavaScript engine. The passed string can contain any of the following: pure JavaScript code, a path to a JavaScript file, or a base64-encoded string (i.e. beginning with data:text/javascript;charset=utf-8;base64, ).

This method can be used to simulate the bind_ready option:

StartInspectorServer(port As Integer) As Boolean

Deprecated. Use inspector_server in initialization parameters instead.

SetUserAgent(user_agent As String) As Boolean

Deprecated. Use user_agent in initialization parameters instead.

GetUserAgent() As String

Returns the currently active user-agent string for the roHtmlWidget instance.

SetUserAgentSuffix(suffix As String) As Boolean

Deprecated. Use user_agent in initialization parameters instead.

SetProxy(proxy as String) As Boolean

Sets the name or address of the proxy server that the roHtmlWidget instance will use to make HTTP requests. This method takes effect immediately. It does not affect network operations performed by other components in the firmware. The string can be used to specify either the proxy URL or the location of a .pac proxy file:

Proxy URL: The proxy address should be formatted as "http://user:password@hostname:port". The hostname can contain up to four "*" characters; each "*" character can be used to replace one octet from the current IP address. For example, if the IP address is currently 192.168.1.2, and the proxy is set to "proxy-*-*", then the player will attempt to use a proxy named "proxy-192.168".
Proxy File: The .pac proxy file can be located on either the local file system or the network. If the file is local, there are no file-name restrictions; if the file is located on the network, the file name should have a .pac extension. If the URL is a hostname only, it will be considered a proxy-server address rather than a file URL.

SetProxyBypass(hostnames As String) As Boolean

Exempts the specified hosts from the proxy configuration on the roHtmlWidget instance. The passed array should consist of one or more hostnames. The player will attempt to reach the specified hosts directly rather than using the proxy that has been specified with the SetProxy() method. For example, the hostname "example.com" would exempt "example.com", "example.com:80", and "www.example.com" from the proxy setting.

AddProxyAuthenticationCredentials(hostname As String, username As String, password As String)

Allows the user to set up one or more proxies. If proxy pac files are included, this method must be used to specify authentication parameters.

roHtmlWidget.acceptdialog(response as String)

Accept any dialog request with the given string, if there is any such request. This parameter was added in BOS 8.5.16.

roHtmlWidget.rejectdialog()

Reject any dialog request. This parameter was added in BOS 8.5.16.

ifMessagePort

SetPort(port As roMessagePort)

Posts messages of type roHtmlWidgetEvent to the attached message port.

ifUserData

SetUserData(user_data As Object)

Sets the user data that will be returned when events are raised.

GetUserData() As Object

Returns the user data that has previously been set via SetUserData(). It will return Invalid if no data has been set.

Available Methods with Initialization

If the properties of an roHtmlWidget object are configured at initialization, most ifHtmlWidget methods will be disabled. However, the following methods are still functional:

Hide()
Show()
EnablePinchToZoom()
FlushCachedResources()
SetUserAgent()
GetUserAgent()
SetUserAgentSuffix()
PostJSMessages()

Examples

The following examples show how to use either an associative array or object methods to configure an roHtmlWidget instance using local storage to cache the files.

Note that these techniques are mutually exclusive.