RFR: 8092102: Labeled: truncated property [v11]

[Kevin Rushforth]

On Thu, 2 May 2024 22:10:24 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> Adds **Labeled.textTruncated** property which indicates when the text is visually truncated (and the ellipsis string is inserted) in order to fit the available width.
>> 
>> The new property reacts to changes in the following properties:
>> - ellipsisString
>> - font
>> - height
>> - text
>> - width
>> - wrapText
>> 
>> I don't think it's worth creating a headful test (headless won't work) due to relative simplicity of the code.
>> 
>> **Alternative**
>> 
>> The desired functionality can be just as easily achieved on an application level, by adding a similar property to a subclass.  What is the benefit of adding this functionality to the core?
>> 
>> UPDATE 2024/03/07: turns out Labeled in a TableView (in a TreeTableView as well) lives by different rules (TableCellSkinBase:152, TreeTableCellSkin:126).  The consequence of this is that the new functionality **cannot** be fully implemented with the public APIs alone.
>> 
>> **See Also**
>> 
>> * [JDK-8327483](https://bugs.openjdk.org/browse/JDK-8327483) TreeView: Allow for tooltip when cell text is truncated
>> * [JDK-8205211](https://bugs.openjdk.org/browse/JDK-8205211) Ability to show Tooltip only when text is shown with ellipsis (...)
>
> Andy Goryachev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   using properties

I found at least one case where this fails to detect truncation. There might be others. I will attach a test case that shows the failure.

Additionally, I left a comment about the modifications to Region. Since they are only needed for testing, you can instead add getWidth / getHeight to RegionShim, allowing you to revert all changes to Region (and RegionHelper).

modules/javafx.controls/src/main/java/javafx/scene/control/Labeled.java line 857:

> 855:                         }
> 856: 
> 857:                         return (getWidth() < prefWidth(getHeight()));

This is not sufficient to detect all cases where truncation can occur. The assumption that pref width is the full width needed to contain the text does not always hold true. For example, if an app explicitly sets the pref width of a button or label, its width will be set to its pref width. If the text does not fit, it will be truncated, but you won't detect it.

I'm not sure you can detect truncation just by looking at the various properties on the Labeled control. Would it be possible to set the value of the truncated property at the point where truncation occurs? That would guarantee a correct answer.

modules/javafx.controls/src/test/java/test/javafx/scene/control/LabeledTruncatedTest.java line 87:

> 85: 
> 86:     private void test(Labeled control) {
> 87:         RegionHelper.setWidth(control, 1000);

This can (and should) be done using a shim method rather than adding a helper method. If you add setWidth / setHeight to RegionShim you don't need to modify Region.

modules/javafx.graphics/src/main/java/com/sun/javafx/scene/layout/RegionHelper.java line 115:

> 113:     }
> 114: 
> 115:     public static void setWidth(Node node, double width) {

If you instead add this method to RegionShim, you won't need to modify Region at all, and its impact will be limited to the test classes.

modules/javafx.graphics/src/main/java/javafx/scene/layout/Region.java line 186:

> 184: 
> 185:             @Override
> 186:             public void setWidth(Node node, double width) {

If you add the needed methods to RegionShim, you can revert all changes to this file.

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

Changes requested by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/1389#pullrequestreview-2038130006
PR Review Comment: https://git.openjdk.org/jfx/pull/1389#discussion_r1589192349
PR Review Comment: https://git.openjdk.org/jfx/pull/1389#discussion_r1589195274
PR Review Comment: https://git.openjdk.org/jfx/pull/1389#discussion_r1589196444
PR Review Comment: https://git.openjdk.org/jfx/pull/1389#discussion_r1589197018