NSTableView & NSOutlineView editing on tab key

问题

My app has an NSOutlineView and an NSTableView, and I'm having the same problem with both. With a row in either selected, pressing the tab key puts the first column into edit mode instead of making the next key view first responder. To get to the next key view, you need to tab through all of the columns.

Also, shift-tabbing into either view results in the last column going into edit mode, necessitating more shift-tabs to get into its previous key view.

In case it matters, I'm using the autocalculated key view loop, not my own, with my NSWindow set to autorecalculatesKeyViewLoop = YES. I would like tabbing between the columns once the user elects to edit a column, but I don't think it's standard behavior for the tab key to trigger edit mode.

Update

Thanks to the helpful responses below, I worked it out. Basically, I override -keyDown in my custom table view class, which handles tabbing and shift-tabbing out of the table view. It was tougher to solve shift-tabbing into the table view, however. I set a boolean property to YES in the custom table view's -acceptsFirstResponder if it's accepting control from another view.

The delegate's -tableView:shouldEditTableColumn:row checks for that when the current event is a shift-tab keyDown event. -tableView:shouldEditTableColumn:row is called and it's not a shift-tab event, it sets the table view's property back to NO so it can still be edited as usual.

I've pasted the full solution below.

/* CustomTableView.h */

@interface CustomTableView : NSTableView {}

@property (assign) BOOL justFocused;

@end

/* CustomTableView.m */

@implementation CustomTableView

@synthesize justFocused;

- (BOOL)acceptsFirstResponder {
    if ([[self window] firstResponder] != self) {
        justFocused = YES;
    }

    return YES;
}

- (void)keyDown:(NSEvent *)theEvent
{
    // Handle the Tab key
    if ([[theEvent characters] characterAtIndex:0] == NSTabCharacter) {
        if (([theEvent modifierFlags] & NSShiftKeyMask) != NSShiftKeyMask) {
            [[self window] selectKeyViewFollowingView:self];
        } else {
            [[self window] selectKeyViewPrecedingView:self];
        }
    }
    else {
        [super keyDown:theEvent];
    }
}

@end

/* TableViewDelegate.m */

. . .

- (BOOL)tableView:(NSTableView *)tableView shouldEditTableColumn:(NSTableColumn *)tableColumn
              row:(NSInteger)row
{
    NSEvent *event = [NSApp currentEvent];
    BOOL shiftTabbedIn = ([event type] == NSKeyDown
                          && [[event characters] characterAtIndex:0] == NSBackTabCharacter);

    if (shiftTabbedIn && ((CustomTableView *)tableView).justFocused == YES) {
        return NO;
    } else {
        ((CustomTableView *)tableView).justFocused = NO;
    }

    return YES;
}

. . .

回答1:

This is the default behavior. If there's no row selected, the table view as a whole has focus, and the Tab key switches to the next key view. If there is a row selected, the table view begins editing or moves to the next cell if already editing.

From AppKit Release Notes:

Tables now support inter-cell navigation as follows:

Tabbing forward to a table focuses the entire table.

Hitting Space will attempt to 'performClick:' on a NSButtonCell in the selected row, if there is only one instance in that row.

Tabbing again focuses the first "focusable" (1) cell, if there is one.

If the newly focused cell can be edited, editing will begin.

Hitting Space calls 'performClick:' on the cell and sets the datasource value afterwards, if changed. (2)

If a text cell is editing, hitting Enter will commit editing and focus will be returned to the tableview, and Tab/Shift-tab will commit the editing and then perform the new tab-loop behavior.

Tabbing will only tab through a single row

Once the last cell in a row is reached, tab will take the focus to the next focusable control.

Back tabbing into a table will select the last focusable cell.

If you want to change this behavior, the delegate method tableView:shouldEditTableColumn:row: may be helpful. You may also have to subclass NSTableView if you really want to affect only the behavior of the Tab key.

回答2:

I've had to deal with this before as well. My solution was to subclass NSTableView or NSOutlineView and override keyDown: to catch the tab key presses there, then act on them.

回答3:

The solution using keyDown didn't work for me. Perhaps because it is for cell-based table view.

My solution for a view-based table view, in Swift, looks like this:

extension MyTableView: NSTextFieldDelegate {
    func controlTextDidEndEditing(_ obj: Notification) {
        guard
            let view = obj.object as? NSView,
            let textMovementInt = obj.userInfo?["NSTextMovement"] as? Int,
            let textMovement = NSTextMovement(rawValue: textMovementInt) else { return }

        let columnIndex = column(for: view)
        let rowIndex = row(for: view)

        let newRowIndex: Int
        switch textMovement {
        case .tab:
            newRowIndex = rowIndex + 1
            if newRowIndex >= numberOfRows { return }
        case .backtab:
            newRowIndex = rowIndex - 1
            if newRowIndex < 0 { return }
        default: return
        }

        DispatchQueue.main.async {
            self.editColumn(columnIndex, row: newRowIndex, with: nil, select: true)
        }
    }
}

You also need to set the cell.textField.delegate so that the implementation works.

My blog post on this tricky workaround: https://samwize.com/2018/11/13/how-to-tab-to-next-row-in-nstableview-view-based-solution/

回答4:

How convenient! I was just looking at this myself yesterday, and it's good to see some confirmation of the approach I took - keyDown: handling.

However, I have one small possible refinement to your approach: I worked out that the method triggering editing on shift-tabbing back to the table was the becomeFirstResponder call. So what I did on a NSTableView subclass was:

Add a synthesized property to control whether tab-editing behaviour was disabled
On keydown, check the first character (also check for [[theEvent characters] length] to avoid exceptions for dead keys!) for tab; if tab editing is disabled, move on to the next/previous view, as per your code sample.

Override becomeFirstResponder:

- (BOOL)becomeFirstResponder {
    if (tabEditingDisabled) {
        [self display];
        return YES;
    }
    return [super becomeFirstResponder];
}

This keeps all the code in the tableview subclass, keeping the delegate cleaner :)

The only danger is I don't know what else NSTableView does in becomeFirstResponder; I didn't notice anything breaking, but...

回答5:

This worked for me:

- (BOOL)tableView:(NSTableView *)tableView shouldEditTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row {
  NSEvent *e = [NSApp currentEvent];
  if (e.type == NSKeyDown && e.keyCode == 48) return NO;
  return YES;
}

来源：https://stackoverflow.com/questions/5600793/nstableview-nsoutlineview-editing-on-tab-key

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