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.

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. 

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.

Initialization Parameters

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

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

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

mouse_enabled bool: Enables mouse/touchscreen/USB keyboard events. This value is false by default.

scrollbar_enabled bool: 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.

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

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

canvas_2d_acceleration_enabled bool: 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.

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

brightsign_js_objects_enabled bool: 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":

transform string: 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).

• "rot180": The widget content is rotated to portrait at 180 degrees (clockwise).

• "rot270": The widget content is rotated to portrait at 270 degrees (clockwise).

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

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

language string: Specifies the language to load the web page in.

user_stylesheet string: Applies the specified user stylesheet to pages in the widget. The parameter is a URI specifying any file: resource in the storage, unless you are using a CSS stylesheet saved to the SD card, in which case you should use sd:/path/filename.css. The stylesheet can also be specified as inline data.

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

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

storage_quota string or double: 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.

port roMessagePort: 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.

fonts roArray: 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).

pcm_audio_outputs roArray: 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.)

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

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

inspector_server roAssociativeArray: 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).

• ip_addr string: 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.

• port int: The port for the Inspector server

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

• websecurity bool: Enables Chromium security checks for cross-origin requests. 

• camera_enabled bool: Enables webpage access to USB cameras connected to the player (access is disabled by default). This allows support for WebRTC applications.

• insecure_https_enabled bool: 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.]

• audio_capture_enabled bool: 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:

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.

javascript_injection roAssociativeArray: 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.

assets roArray: 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:

• pool roAssetPool: An asset pool containing files 

• collection roAssetCollection: A manifest identifying the files in the pool

• uri_prefix string: The URI prefix of the webpage resources to retrieve from the pool

• pool_prefix string: 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.