I have an NSTableView in which I need to be able to intercept keyboard events within an editable cell and replace the cell with strings. For example, press "a" and have the "a" intercepted and the value "Alpha" assigned when the table reloads. The actual situation is a bit more complex in that I'm also handling HID devices, but that's a whole other story. Suffice it to say, I just want to be able to go into edit mode and stop the keyboard-generated values from being displayed.
The latter part of this (displaying "Alpha") is easy, but I can't figure out the first part of the problem. If I subclass the table and make it first responder, I can receive the keyDown: event, but once the user double-clicks on a cell and starts typing, this goes silent.
Since none of the other NSTableView components (NSCell, NSTextFieldCell, etc) derive from NSResponder, I'm assuming there is an NSTextField buried in there somewhere.
So, what's the best way to filter text once the user goes into cell edit mode?
As always happens: after working on this for eight hours, reading all the docs five times, and then resorting to the net, I find the answer five minutes later:
- (BOOL)textShouldBeginEditing:(NSText *)textObject.
Sorry to consume bandwidth.
Related
The NSTableView has a feature, called Type Selection, by which the user can type the first letters of a listed item and the view automatically selects the first hit and scrolls to it.
I like to have a similar functionality in a NSCollectionView, where I list images by name.
Before I start writing such code by myself, I wonder if there is an API that can help me with this.
I am especially worred about getting the timing right, as I want to have it use the same timing as the NSTableView does. I imagine that it even changes depending on the user's System Preferences for typing. Also, the NSTableView will select other items with the same typed prefix if waiting long enough. All this can get quite complicated if I want to get it right. I don't want to miss anything.
I'm trying to implement a syntax-coloring text editor that also does things like insert whitespace at the start of a new line for you, or replace text with text attachments.
After perusing the docs again after a previous implementation had issues with undoing, it seems like the recommended bottleneck for this is NSTextStorageDelegate's textStorage(_,willProcessEditing:,range:,changeInLength:) method (which states that Delegates can change the characters or attributes., whereas didProcessEditing says I can only change attributes). This works fine, except that whenever I actually change attributes or text, the text insertion mark moves to the end of whatever range of text I modify (so if I change the style of the entire line, the cursor goes at the end of the line).
Does anybody know what additional call(s) I am missing that tell NSTextStorage/NSTextView not to screw up the insertion mark? Also, once I insert text, I might have to tell it to move the insertion mark to account for text I've inserted.
Note: I've seen Modifying NSTextStorage causes insertion point to move to the end of the line, but that assumes I'm subclassing NSTextStorage, so I can't use the solution there (and would rather not subclass NSTextStorage, as it's a semi-abstract subclass and I'd lose certain behaviours of Apple's class if I subclassed it).
I found out the source of the problem.
And the only solution that will work robustly based on reasons inherent to the Cocoa framework instead of mere work-arounds. (Note there's probably at least one other, metastable approach based on a ton of quick-fixes that produces a similar result, but as metastable alternatives go, that'll be very fragile and require a ton of effort to maintain.)
TL;DR Problem: NSTextStorage collects edited calls and combines the ranges, starting with the user-edited change (e.g. the insertion), then adding all ranges from addAttributes(_:range:) calls during highlighting.
TL;DR Solution: Perform highlighting from textDidChange(_:) exclusively.
Details
This only applies to a single processEditing() run, both in NSTextStorage subclasses and in NSTextStorageDelegate callbacks.
The only safe way to perform highlighting I found is to hook into NSText.didChangeNotification or implement NSTextDelegate.textDidChange(_:).
As per #Willeke's comments to the OP's question, this is the best place to perform changes after the layout pass. But as opposed to the comment thread, setting back NSText.selectedRange does not suffice. You won't notice the problem of post-fixing the selection after the caret has moved away until
you highlight whole blocks of text,
spanning multiple lines, and
exceeding the visible (NSClipView) boundaries of the scroll view.
In this rare case, most keystrokes will make the scroll view jiggle or bounce around. But there's no additional quick-fix against this. I tried. Neither preventing sending the scroll commands from private API in NSLayoutManager nor avoiding scrolling by overriding all methods with "scroll" in them from a NSTextView subclass works well. You can stop scrolling to the insertion point altogether, sure, but no such luck getting a solid algorithm out that does not scroll only when you perform highlighting.
The didChangeNotification approach does work reliably in all situations I and my app's testers were able to come up with (including a crash situation as weird as scrolling the text and then, during the animation, replacing the string with something shorter -- yeah, try to figure that kind of stuff out from crash logs that report invalid glyph generation ...).
This approach works because it does 2 glyph generation passes:
One pass for the edited range, in the case of typing for every key stroke with a NSRange of length 1, sending the edited notification with both [.editedCharacters, .editedAttributes], the former being responsible for moving the caret;
another pass for whatever range is affected by syntax highlighting, sending the edited notification with [.editedAttributes] only, thus not affecting the caret's position at all.
Even more details
In case you want to know more about the source of the problem, I put more my research, different approaches, and details of the solution in a much longer blog post for reference. This here, though, is the solution itself. http://christiantietze.de/posts/2017/11/syntax-highlight-nstextstorage-insertion-point-change/
The above accepted answer with the notification center worked for me, but I had to include one more thing when editing text. (Which may be different from selection).
The editedRange of the NSTextStorage was whack after the notification center callback. So I keep track of the last known value myself by overriding the processEditing function and using that value later when I get the callback.
override func processEditing() {
// Hack.. the editedRange property when reading from the notification center callback is weird
lastEditedRange = editedRange
super.processEditing()
}
I'd like to send a keypress to a SysDateTimePick32 common control.
Imagine the following scenario: There is a table with many rows and many columns, which is user-drawn. When you hit "Enter" in one of those columns, a SysDateTimePick32 control is created and placed into the current cell so you can pick a time for this cell's actual content. This works fine, but I'd like to enable the user to start editing the time without pressing enter first.
This means: The table is in "display" mode and a cell is selected. There is no SysDateTimePick32 control, yet. Instead of pressing enter (and therefore creating and showing a SysDateTimePick32), the user types e.g. "3". Now a SysDateTimePick32 should be created and shown and the previously typed "3" should be sent to it, just like the user pressed "enter" and then "3".
I'm trying
SendMessage(sysDateTimePick32Handle, WM_KEYDOWN, '3', MAKELPARAM (1, 0));
However, this does not seem to work.
What is a "clean" way to send specific keystrokes to a Win32 control, especially SysDateTimePick32?
Sending keystrokes like that is filled with bear traps. It isn't clear why it would not work, although it is the wrong way. WM_KEYDOWN is posted, not sent, so you should use PostMessage() instead. For typing keys like '3' you should send WM_CHAR instead, saves you from the hassle of getting the modifier keys state set properly (Shift, Ctrl, Alt) and removes the active keyboard layout as a failure mode. Favor SendInput() if that's not appropriate.
Do consider the less hacky way that makes this easier. Just always create the picker when the focus enters the cell. Destroy or ignore it when you find out that nothing was entered.
I have a table column where each row has one of three states, and the purpose of the row is to offer manipulation AND display of this property with three states.
My current development view is to have three tightly packed radio buttons with labels at the head of the columns (and every 50 rows or so) and onClick they send an AJAX request and thar she blows.
This is fugly.
Is there a standard idiom for a control like this? I'm currently mocking up something similar to the iPhone on/off toggle, but with a "middle" state.
Any input would be welcome.
EDIT
A bit more clarification: I have a tool for confirming events. Each event is either "proposed", "cancelled", or "confirmed". They all default to "proposed" until someone explicitly confirms or cancels them. This is a thin front-end for a SQL table.
I've seen this handled with image buttons that remain "depressed" when you click while popping the other two out. They act like radio buttons except that the label and the state are merged. If your names are too lengthy to fit in a button, you can abbreviate them and provide a key. I'd also give each one a distinct color. For implementation just pop the value in a hidden form field on click.
These are called "Toggle Buttons" in some other UI's:
http://java.sun.com/products/jlf/ed2/book/HIG.Controls2.html
http://msdn.microsoft.com/en-us/library/dd940509%28VS.85%29.aspx
http://developer.gnome.org/projects/gup/hig/2.0/controls-toggle-buttons.html
The standard mechanization for things like this in military avionics, where screen space is always at a premium,and so are buttons, is a "rotary". Each time you click it, it steps to the next value in sequence, wrapping around.
As an example, a device with a cryogenic cooler might have three states: OFF, WARM, and COOL. Initially, the device is OFF: no power applied. Click it, and it switches to WARM, meaning power is applied, but no cooling. Click it again, and it starts the cooler. (Since cooling in this kind of thing is usually supplied by a gas bottle with a strictly limited capacity, you don't want to cool the device until you are getting ready to party.) Click it again, and it shuts the device OFF.
You could also do this with buttons or hyperlinks. In a big table, hyperlinks will probably look best.
In the Proposed state, your cell could look something like this (with underlined links, but the editor won't let me):
Proposed Confirm Cancel
In the Confirmed state:
Confirmed Undo
In the Cancelled state:
Cancelled Undo
This will take two clicks to get from Confirmed to Cancelled and vice versa, but I assume that this operation is rarer than switching between Proposed and one of the other two.
Perhaps display arrows on either side to change the state:
(Cancelled) <| Proposed |> (Confirmed)
These may or may not 'wrap' depending on how well that suits the values and how important it is to saving a click when transitioning from value 1 to value 3 (or vice-versa).
As an alternative to you radio buttons, you could consider a drop-down list with three options. The disadvantage is, of course, that two clicks are needed to change the value.
Maybe use a slider with three states? (It really depends on the exact situation!)
Consider a fixed-position slider with three positions, such as offered by jQueryUI: http://jqueryui.com/demos/slider/#steps
I am reminded of the permissions button in SQL - it has multiple states; green check, red x, no setting, and clicking on them cycles through the three states. Its ok but annoying if you want to change a bunch to the state reached second, and if you click too many times you have to go through it all again. Left click - cycle forward; right click - cycle backward might work but certainly has no basis in UI expectations.
Idiomatically, I would say a Stop Light (red/yellow/green). They could behave like radio buttons; darker toned for 'off' and lighter tones for 'on', and since the color gives a cue you can move the description to a mouseover label. Of course, it isn't RG Colorblind kosher, so depending on your application that may be a deal breaker. (also, it may be confusing on Mac where the minimize/close etc buttons are the same color scheme).
Why not use three boxes that look like the "Questions", "Tags", "Users", ... boxes on this page (could be implemented as links, buttons or whatever)?
There are times when it makes sense to force an end of any edits that are currently being made. For instance, if the user is typing a value in a field on my document, and then clicks to the preview window, or chooses "Print" or "Save" from the menu.
The problem is, by forcing an end to editing (either by asking the NSWindow to make itself first responder, or by calling endEditingFor: on the window), the first responder focus is no longer on the field in question. This is disruptive to the user in some situations, where the action being taken is iterative and does not signify an end to their work on the document.
My first attempt at solving this is to pay attention whatever the current firstResponder is, and then to restore it after ending editing, by using NSWindow's "makeFirstResponder:". This works OK, but it has the undesired effect e.g. on NSTextFields of resetting the selection in the field editor to the entire length of the string contents.
Is there some trick I can use to force the entire system of "endEditing" methods to be called without disrupting the current field editor at all?
Thanks,
Daniel
Why not use your original method but also record where/what the selection range looks like and restore it after restoring the first responder?
I agree that this is the way to do it. On iPhone it is particularly important not to have the keyboard jumping up and down at inopportune moments. I have used:
[textView endEditing:YES];
[textView becomeFirstResponder];
successfully to complete pending spelling correction (as though a space were hit) before taking action on the content of a UITextView, but without any side-effects.