RFR: 8267554: Support loading stylesheets from data-URIs

[Kevin Rushforth]

On Fri, 18 Jun 2021 01:23:50 GMT, Michael Strauß <mstrauss at openjdk.org> wrote:

> This PR extends data URI support to allow stylesheets to be loaded from data URIs.

I looked at just the public API and spec, and have two comments:

* I don't see any justification for adding `Stylesheet::loadBinary(InputStream)` to the public API. See my comments inline.
* Do you intend to support setting a user agent stylesheet via a data URL? The docs should be explicit about whether or not a data URI can be used for the following methods:
  * [Application::setUserAgentStylesheet](https://github.com/openjdk/jfx/blob/master/modules/javafx.graphics/src/main/java/javafx/application/Application.java#L521)
  * [Scene::setUserAgentStylesheet](https://github.com/openjdk/jfx/blob/master/modules/javafx.graphics/src/main/java/javafx/scene/Scene.java#L1697)
  * [SubScene::setUserAgentStylesheet](https://github.com/openjdk/jfx/blob/master/modules/javafx.graphics/src/main/java/javafx/scene/SubScene.java#L687)

modules/javafx.graphics/src/main/java/javafx/css/Stylesheet.java line 301:

> 299:      * css version or if an I/O error occurs while reading from the stream
> 300:      */
> 301:     public static Stylesheet loadBinary(InputStream stream) throws IOException {

Why do you need to add this public method to the API? I don't see any discussion as to why JavaFX applications need it. It looks like it is just being used internally by `StyleManager`. Unless there is a compelling reason to add this to the API, you will need to make this method package-scope and use an accessor to access it from `StyleManager`.

-------------

PR: https://git.openjdk.java.net/jfx/pull/536