Support for file chooser that works with both files and directories

[kephale]

I'm looking into a file chooser that works for both Files and Directories (e.g. should work with tif and n5 datasets which are directories). i presume the place to introduce this change is

scijava-common/src/main/java/org/scijava/ui/UserInterface.java

Line 163 in 448a8bd

default File chooseFile(final File file, final String style) {

[imagejan]

Both files and directories would be stored in a File object on the Java side.

The FileListWidget already allows for the both style:

scijava-common/src/main/java/org/scijava/widget/FileListWidget.java

Lines 51 to 56 in 560ad96

	/**
	* Widget style to allow selection of both files and directories
	*
	* @see org.scijava.plugin.Parameter#style()
	*/
	String FILES_AND_DIRECTORIES = "both";

To allow the same for single files, we need to add a new style to FileWidget as well, and then adapt the UserInterface#chooseFile method as you pointed out.

[LauLauThom]

To allow the same for single files, we need to add a new style to FileWidget as well

Is it really necessary to create a new style ?
I dont understand why we could not use the both style from the FileListWidget for the FileWidget too. Is it important that a given style is part of the class it is used in ?
Or can the new FileWidget style also encode for both ?

I had the same interrogation for #197 (comment). Using only directory for both FileWidget and FileListWidget so we dont have to document an additional directories style.

[imagejan]

Well, keeping the constants in the classes where they're used would be consistent. As FileWidget defined OPEN, SAVE (both of which are "files-only") and DIRECTORY, this was not sufficient for the requirements of FileListWidget where we wanted to select files, directories or both, but never save. That's why originally we defined new styles there.
But I agree, we could also unify this and keep all styles in the FileWidget class. Maybe even be more concise and say "open-file", "open-directory", "open-both" and "save-file". But now we also have to ensure backwards-compatibility 🙁 so if we define new styles or change them, we'll have to keep the others for a while (forever?) as deprecated...

@ctrueden any opinion/suggestion?

[LauLauThom]

Alright, maybe the better is the enemy of the good here :P
I think we should introduce the least changes.
So as a sum up this is the current situation

File styles

• "open"
• "save"
• "directory"
• "both" (missing) -> new one ? or use FileList.both ?

FileList styles

• "files"
• "directories"
• "both"

which cover most if not all cases ?
So the question is really about a new "FileWidget.both" or using the existing "FileListWidget.both" in the FileWidget class, isnt it ?