Paragraph-level styles

[TomasMikula]

To support rich-text editors, it should be possible to assign paragraph-level styles, such as alignment, heading, ...

[TomasMikula]

Currently, StyledTextArea is parameterized by a type parameter S, which represents the type of style information that can be applied to text. In concrete subclass, S can be a list of style classes (as in StyleClassedTextArea), a CSS string (as in InlineCSSTextArea), or any user defined type (such as StyleInfo in the RichText demo application).

The StyledTextArea constructor takes the initial (default) style and a function that is capable of applying that opaque style object to a Text node.

To add support for paragraph-level styles, we need to add a second type parameter PS to StyledTextArea that will represent the type of style that can be applied to whole paragraphs. The constructor will then accept two additional arguments: the default paragraph style (of type PS) and a function capable of applying an object of type PS to a TextFlow (TextFlow is the visual rendering of a paragraph.)

The addition of the second type parameter will propagate down to StyledDocument and Paragraph as well.

The change is not going to be backwards compatible. However, the users of some concrete subclasses such as StyleClassedTextArea may not be impacted too much.

[TomasMikula]

So this is now mostly implemented. Among the remaining things to do is to support copying to the clipboard including paragraph style.

[JordanMartinez]

I was testing out the demo, and it seems another thing to support is the UndoManager. As of now, it doesn't undo/redo the paragraph's style.

After the program started, I typed some text, and then changed the line's background color. After undoing my action, the text was deleted but the line's background color remained the same. When I redo my action, the text reappears but the line's background color returns to the initial white color.

The same basic thing happened with the paragraph's alignment values. When I change the alignment to Center and then click Undo, the text is deleted but the alignment remains at Center. When I redo, the text reappears but the text is aligned to the left despite the Alignment Center button still appearing to be pressed.

[TomasMikula]

Copy&Paste is now fixed in master.

[TomasMikula]

Undo/Redo now seems to work, too.