Probably once of the most simple but useful interfaces that I have come across is the nsIFilePicker. This interface will allow the end-user to use a dialog for loading or saving a file, or getting folder for use in your application. In my case I just need the user to get the path to a directory.
function openDirDialog()
{
const nsIFilePicker = Components.interfaces.nsIFilePicker;
var fp = Components.classes[“@mozilla.org/filepicker;1”] .createInstance(Components.interfaces.nsIFilePicker);fp.init(window,”Select Directory”,nsIFilePicker.modeGetFolder);
var ret = fp.show();
if (ret == nsIFilePicker.returnOK || ret == nsIFilePicker.returnReplace)
{
applicationPath = fp.file.path;
document.getElementById(‘tb_inputPath’).value = applicationPath;
}
}
- nsIFilePicker – The declaration of this const is not needed, but it does make some operations easier as you will see
- fp – Gets the nsIFilePicker interface component, so that you can actually call the File Picker
- fp.init(nsIDOMWindow, title, mode) – This is where you set the inital settings for the file picker, this needs to be called if you want it to work.
- nsIDOMWindow – parameter sets the who will be the parent of the dialog, in my case it is just the main window, so I used ‘window’.
- title – Is simply a string, where you would set the Title of the dialog
- mode – This is where you declare what you want the dialog to actually do, whether it be loading or saving a file, or getting a folder. Here is a table of the different mode options:
modeOpen 0 modeSave 1 modeGetFolder 2 modeOpenMultiple 3
- fp.show – This call actually shows the File Picker dialog according to the mode you have chosen. The return types are as follows:
returnOK 0 returnCancel 1 returnReplace 2 - As you can see, by using the nsIFilePicker const at the beginning, I can use its attributes to check the return value from the dialog.
- There are filters you can append to the File Picker to direct the user to only a specific type of file, by using the .appendFilters(filter). Here is a set of predifined filters:
filterAll 1 filterHTML 2 filterText 4 filterImages 8 filterXML 16 filterXUL 32 filterApps 64
- fp.init(nsIDOMWindow, title, mode) – This is where you set the inital settings for the file picker, this needs to be called if you want it to work.
The File Picker for me was very useful in my cross-platform work with XRap, not only does it make it make it easy for the use to select a folder, but there is no mix-up with the slashes with the use different platforms.
