RFR: 8314482: TextFlow: TabStopPolicy [v9]

[Kevin Rushforth]

On Fri, 11 Jul 2025 22:42:23 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> # Tab Stop Policy
>> 
>> Andy Goryachev
>> 
>> <andy.goryachev at oracle.com>
>> 
>> 
>> ## Summary
>> 
>> Introduce a `tabStopPolicy` property in the `TextFlow` class which, when set, overrides the existing `tabSize`
>> value and provides consistent way of setting tab stops at the paragraph level, regardless of the individual text
>> segments font [0].
>> 
>> ![Screenshot 2025-05-19 at 15 03 26](https://github.com/user-attachments/assets/32f2474d-7d2b-47b0-a22c-410d485f4e40)
>> 
>> 
>> ## Goals
>> 
>> The goal of this proposal is to provide a better way for controlling tab stops in the `TextFlow` containing rich text.
>> 
>> 
>> 
>> ## Non-Goals
>> 
>> The following are not the goals of this proposal:
>> 
>> - support for tab stop types (BAR, or DECIMAL), or attributes like `alignment`
>> - support the `leader` property (symbols to fill the empty space before the tab stop)
>> - support for `firstLineIndent` property
>> - deprecate the `TextFlow::tabsize` property
>> 
>> 
>> 
>> ## Motivation
>> 
>> The existing `tabSize` property in the `TextFlow` is inadequate for representing tab stops when the content
>> contains text with different font sizes.
>> 
>> In addition to that, a rich text editor might require support for user-customizable tab stops, similar to that provided
>> in RTF or MS Word documents.
>> 
>> 
>> 
>> 
>> ## Description
>> 
>> ### TextFlow
>> 
>> 
>>     /**
>>      * {@code TabAdvancePolicy} determines the tab stop positions within this {@code TextFlow}.
>>      * <p>
>>      * A non-null {@code TabAdvancePolicy} overrides values set by {@link #setTabSize(int)},
>>      * as well as any values set by {@link Text#setTabSize(int)} in individual {@code Text} instances within
>>      * this {@code TextFlow}.
>>      *
>>      * @defaultValue null
>>      *
>>      * @since 999 TODO
>>      */
>>     public final ObjectProperty<TabStopPolicy> tabStopPolicyProperty() {
>> 
>>     public final TabStopPolicy getTabStopPolicy() {
>> 
>>     public final void setTabStopPolicy(TabStopPolicy policy) {
>> 
>>     /**
>>      * The size of a tab stop in spaces.
>>      * Values less than 1 are treated as 1. This value overrides the
>>      * {@code tabSize} of contained {@link Text} nodes.
>>      * <p>
>> +     * Note that this method should not be used to control the tab placement when multiple {@code Text} nodes
>> +     * with different fonts are contained within this {@code TextFlow}.
>> +     * In this case, the {@link #setTabStopPolicy(TabStopPolicy)} should be used instead.
>>      *
>>      * @defaultValue 8
>>      *...
>
> Andy Goryachev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 65 commits:
> 
>  - Merge remote-tracking branch 'origin/master' into 8314482.tab.stops
>  - link
>  - oops
>  - since 25
>  - review comments
>  - Merge remote-tracking branch 'origin/master' into 8314482.tab.stops
>  - Merge remote-tracking branch 'origin/master' into 8314482.tab.stops
>  - final tab stop
>  - review comments
>  - Merge remote-tracking branch 'origin/master' into 8314482.tab.stops
>  - ... and 55 more: https://git.openjdk.org/jfx/compare/04c5e40c...7bdb6ac7

The implementation looks reasonable. I'll do some sanity testing.

Speaking of testing... I don't see any unit tests for this. At the very least you should add tests for the new API methods.

Functional tests are also needed. Those could be done in a follow-up issue, as long as they are targeted to jfx25 (the tests can come in during rampdown).

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PR Review: https://git.openjdk.org/jfx/pull/1744#pullrequestreview-3017906570