What does the NSStringDrawingUsesDeviceMetrics flag mean and how do we use it? - macos

This question is in relation to my comment at How do we measure visible bounds of text in Cocoa?.
Here are a couple of links explaining the meaning of the flag.
Apple docs
Apple lists answer to a similar question
From the above, I guess the option NSStringDrawingUsesDeviceMetrics is given for obtaining the visible bounds of text but it doesn't seem to do that. Among the inputs (font and string) I tried giving to the method boundingRectWithSize:options:attributes: none of the outputs were different when the flag was given compared to when the flag was not given. Am I doing something wrong or is it a bug in Cocoa?
Thank you

Google this monkey patch
NS(Attributed)String+Geometrics
It solves the problem fairly reliably.

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Proper return value for TVN_KEYDOWN

I have very recently answered to the question about Creating TreeView with nodes and checkboxes.
While I was pondering how to properly process the case when treeview's node is checked when user pressing spacebar I ran into TVN_KEYDOWN notification.
My solution was tested in a dialog box and in a window procedure and both seem to work flawlessly.
Still, I have a dilemma of what should be my returned result. Here is the relevant excerpt from the documentation for TVN_KEYDOWN:
Return value
If the wVKey member of lParam is a character key code, the character
will be used as part of an incremental search. Return nonzero to
exclude the character from the incremental search, or zero to include
the character in the search. For all other keys, the return value is
ignored.
I have tried returning both results when testing if spacebar is pressed and haven't noticed any difference.
So I ask you the following questions:
Can someone explain me what is the incremental search ?
What is the difference when I include or exclude the tested character (spacebar) from incremental search ?
EDIT:
It seems that I have found an answer to first question. I have found an article on Wikipedia that explains what incremental search is.
It leaves only the second question to be answered.
END OF EDIT
Thank you.
Best regards.
It is most visible in a giant TreeView. The best example of one is the left panel in Regedit.exe. Expand HKCR and start typing to see the effect.
The implementation has changed across Windows versions, it used to be a lot less usable in XP. It is a UI blooper, there isn't any good way for the user to see that he mistyped a letter, to correct a typing mistake or to see that a search starts from scratch. Current versions of Windows use a timeout, automatically resetting the partially typed search phrase when you don't hit a key for a couple of seconds. Which is about as practical as it gets. It is certainly useful, just not very usable.
The only sane thing to do with TVN_KEYDOWN is nothing. Never add more ways to make it less predictable than it already is. Intentionally swallowing a keystroke of course makes it a lot less usable if it is a key the user really wanted to use. You certainly don't want to swallow a space, that's of course a valid character in tree node text. If the tree happens to not have any nodes with text that contains a space then you still don't want to swallow it, the control itself already does.
The notification would have been a lot more useful if it also passed the incremental search string that was collected or give a way to reset it. It just doesn't so that's water under the bridge. Consider handling it if you've created some kind of usability trap, very hard to come up with a practical example of one. You know it when you see it.
The only real use is to completely replace the search function. You'd then make your own rules and select a node yourself. And of course always return a non-zero value.
You want only answer to the second question, so this is:
If you exclude spacebar from incremental search, you dont find trewview item with spacebar.
Note: You must disable TVS_CHECKBOXES style, because treeview wndproc handle spacebar different with this style set.

Standard format for yes/no questions in the terminal?

Over the years I've seen many different ways of solving the problem of asking the user a simple yes/no question with a default value in the terminal.
But in the interest of standardization, does any kind of standard for doing this exist ?
Some of the different ways I've seen, plus a few examples dug up by googling include:
... (Y,N) [N]? Y
... (Y/N) ? [Default=Y]
... [Y/n]?
... ([y]/n)?
...? [y/[n]]
Extensive googling and other forms of searching do not turn up anything on the matter, which leads me to believe that there is no such standard because, well, there is no point in standardizing something this trivial.
Standards usually exist to prevent people from writing custom protocols for everything and creating isolated islands of software that are not compatible with each other, and a yes/no question is something typically presented to a human user who is able to figure it out even if it's in a bizarre form like "... {Y3s\n0} !>".
If you really want to be as "standard" as possible, the following format seems to be the most common:
... [Y/n]
With the recommended/default option being capitalized, usually only requiring correct casing when no is the recommended option but.

How to detect if an element exists in Watir

I'm relatively new to Watir but can find no good documentation (examples) regarding how to check if an element exists. There are the API specs, of course, but these make precious little sense to me if I don't find an example.
I've tried both combinations but nothing seems to work...
if browser.image (:src "/media/images/icons/reviewertools/editreview.jpg").exists
then...
if browser.image (:src "/media/images/icons/reviewertools/editreview.jpg").exists?
then...
If anyone has a concrete suggestion as per how to implement this, please help! Thanks!
It seems you are missing a comma between parameters.
Should be
if browser.image(:src, "/media/images/icons/reviewertools/editreview.jpg").exists?
Also you can find this page useful in future to know what attributes are supported.
The code you posted should work just fine.
Edit: Oops, wrong. As Katmoon pointed out, there is a missing comma.
browser.image(:src "/media/images/icons/reviewertools/editreview.jpg").exists?
One problem you may get caught up in is if the browser variable you specified is actually an element that doesn't exist.
e.g.
b = Watir::IE.start(ipAddress)
b.frame(:name, "doesntExist).image(:src "/media/images/icons/reviewertools/editreview.jpg").exists?
The above code will throw a Watir::UnknownFrameException. You can get around this by first verifying the frame exists or by surrounding the code in a begin/rescue block.
Seems like you are using it correctly. Here is an old RDoc of Watir.
Does it not work because Watir cannot find it? Hard to tell because there is no source or link to the page that is being tested. I think that I only use image.exists?. In general, errors that come from when the image exists but is not found are:
The how is not compatible with the element type. There is a cheatsheet to help you see which object types can be found with different attributes here.
The what is not correct. You may have to play with that a little bit. Consider trying a regex string to match it such as browser.image(:src, /editreview.jpg/). As a last resort, maybe use element_by_xpath, but there are maintenance costs with that.
The location is not correct. Maybe the element is in a frame or something like that. browser.frame("detail").image(:src, /editreview.jpg/).
Try those, but please let me know what worked. One more thing, what are you checking for? If it's part of the test criteria, you can handle it that way. If you need to click on it, then forget the .exists? and just click on it. Ruby will let you know if it's not there. If you need it to be grace, learn about begin/rescue.
Good luck,
Dave

Need to create a "choose your own adventure" type guide - best approach to use

Basically need to ask user a set of questions and gather information along the way. Each question could have impacts on different questions down the road. Another example would be turbo tax's web interface, answering yes on some ?s may trigger future questions.
Seems like this would be a fairly common problem in software so I guess I'm asking if there are any existing solutions/Design Patterns out there that could help. Kind of seems like a state machine, but I think that is an oversimplification.
State pattern
Look at this picture which helps with choosing correct fonts which is called So You Need a Typeface (big image there!).
It asks you numerous questions and at some point suggest you one or several answers.
As I understand you want to create something similar but interactive and about another domain.
So, you need to construct similar graph with branching-nodes and leaf-nodes. It can be done very conveniently with the Composite pattern. If you already have (know) all possible questions (or if you know that at some point you will know all of them and will be able to add them manually to the system) then it's the way to go.
If you want something more dynamic and intelligent then the solution can highly vary from case to case.

Detecting misspelled words

I have a list of airport names and my users have the possibility to enter one airport name to select it for futher processing.
How would you handle misspelled names and present a list of suggestions?
Look up Levenshtein distances to match a correct name against a given user input.
http://norvig.com/spell-correct.html
does something like levenshtein but, because he doesnt go all the way, its more efficient
Employ spell check in your code. The list of words should contain only correct spellings of airports.
This is not a great way to do this. You should either go for a control that provides auto complete option or a drop down as someone else suggested.
Use AJAX if your technology supports.
I know its not what you asked, but if this is an application where getting the right airport is important (e.g. booking tickets) then you might want to have a confirmation stage to make sure you have the right one. There have been cases of people getting tickets for the wrong Sydney, for instance.
It may be better to let the user select from the list of airport names instead of letting them type in their own. No mistakes can be made that way.
While it won't help right away, you could keep track of typos, and see which name they finally enter when a correct name is entered. That way you can track most common typos, and offer the best options.
Adding to Kevin's suggestion, it might be a best of both worlds if you use an input box with javascript autocomplete. such as jquery autocomplete
edit: danish beat me :(
There may be an existing spell-check library you can use. The code to do this sort of thing well is non-trivial. If you do want to write this yourself, you might want to look at dictionary trie's.
One method that may work is to just generate a huge list of possible error words and their corrections (here's an implementation in Python), which you could cache for greater performance.

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