I am going to write an application that uses QT4 (with C++ or python it isnt important in that moment).
One of functionality is "Showing all items in database".
One item has a Title, author, description and photo (constant size)
And there could be very many items. Let's say 400. There won't be enough space to show'em all at once time.
One row will have 200px, so i need at most 4 for once time.
How to paginate them? I have no idea.
I can use limit and offset in SQL queries, but how to tell window: "that's 5th page"?
Any solutions?
First off, you normally do not want to use any manually set pixel widths in any GUI application, if you do, your toolkit sucks (or you must work in game development).
Second off: be more specific.
You'll need to define "page" for your application, namely what a page should be in its context. I assume it is breaking a list of items into separate pages. Normally this is done by using one of the view classes (e.g. QListView or QTableView) to take care of much of the legwork: it's called a scrollbar (not to mention the collapsing folders concept from file managers). Another method is splitting the information across several tab pages (QTabWidget), where each page displays a view of some sort (Perhaps QTextView or one of the M/V or Item view classes).
Same thing can also be done using your own widget stack and some other widget to manipulate the currently displayed page. This is basically how the option dialogs in the TeamSpeak 3 client and most KDE apps work; it's also how wizards with back/next buttons work in concept. I suggest you take a look at this config dialog example
Normally what you want is a view with a scrollbar and or some form of collapsing related entries into categorised information. If you just want to display a list of pages where each page is X entries: use a tab widget or stacked widget.
Related
We have a web-based app which uses a side-by-side experience for desktop users where the left side of the screen is a file browser and editor and the right side of the screen is an interactive preview. Users of our app will make constant and iterative changes on the left and and then interact with the preview on the right, switching back and forth many times in quick succession.
Is there a "best practice" for allowing quick and easy navigation between these two interactive areas? I know this might fall under the "opinion" category, but I feel that accessibility is such an overlooked topic that it helps to have as many resources as possible.
You have a few tools at your disposal.
Headings
Headings are one of the easiest ways to bake in some super simple section switching. Screen reader users will use the keys 1 through 6 to navigate by heading levels so if both of your panels are <h2>s (for example) they can simply cycle location using headings.
Keyboard shortcut keys
You can set keyboard shortcut keys.
However you should never do this in isolation. By this I mean if you say that switching window is say Alt + 0 you must allow users to be able to change these key bindings to their preferences.
This is so your shortcut keys don't interfere with their screen reader keys (as they may have set custom keyboard shortcuts).
please note: as pointed out in the comments this is not a WCAG requirement for key combinations (which is only for single keys) but is a usability best practice and highly encouraged, especially as some screen reader users use a modifier key rather than a toggle key for screen reader navigation.
Then we get into an interesting area which I like to illustrate by saying "how would a one handed user use your page?".
This example makes you realise that some sort of sticky keys solution may also be considered where key combinations can be done with a sequence of keys, any time apart (as you may have someone with NO HANDS using eye gaze technology or a switch for example so you don't want to impose a time limit.)
Obviously the above are extreme examples but things you may want to consider (and in reality anyone using eye gaze would be able to visually switch panels etc.)
Voice commands
Being able to switch panels via voice (for example Dragon Naturally Speaking) is also essential.
Now you can do key combinations with voice software so that fixes most issues but they can be annoying and fiddly.
One thing that is quick to use on most voice software is clicking any button on a page with a unique name.
As such having a button above each panel that activates it would be beneficial to voice users.
Assuming these buttons have unique names I could simply say "click activate panel 2" (where "activate panel 2" is the button name) and switch immediately.
Do you need to manage focus?
Bear in mind that when you switch panels you will by default start at the top each time.
This may be exactly what you want but more than likely this would be a terrible user experience.
Instead you may want to remember the previous focus location. Then if I use the keyboard shortcut it would jump back to the same location in the panel. If I use the voice / button click to change location same again.
However if someone uses headings to navigate this obviously wouldn't work. You could then give them a button directly after the heading that says "resume from previous location" to fix this and use that to manage focus.
User settings
As you can see there are loads of things that different people with different requirements may or may not need.
As such adding all of the features by default would probably make the application worse to use for majority of users.
Instead have a settings screen that lets a user turn on features that benefit them, set their own shortcut keys, turn on or off sticky keys, decide if they want you to manage focus for them (or not) etc.
This is a difficult problem! I have been giving a similar issue a lot of thought. I have outlined one idea that uses ARIA live regions, and an alternative idea that might work better if quick-jump keyboard support is vital.
Live region announcements as part of a <form>
The <output> tag may be what you're looking for. It is mapped to the ARIA role of status so any changes to its content will be announced without any focus change. That way, the user can continue to navigate and make changes on the left side without always having to flip over to the right side to know what changes were made.
The role status has an implicit aria-live value of "polite", so that the announcement will wait until any other descriptive announcement is finished.
It has an implicit aria-atomic value of "true", which means that any change will trigger the announcement of the entire contents of the element -- which may or may not be appropriate for the content. If not, add aria-atomic="false" to read out only the changed node.
If the content inside the <output> could be anything other than phrasing content (including <div>s or heading tags) then you should use a <div> with the role attribute of "status" instead.
Custom keyboard controls can get tricky with various types of assistive technology (AT) software/hardware. Plus those commands probably can't be made easily discoverable. Some ATs provide a keyboard command to flip between a controlling element and the element assigned via its aria-controls attribute. Unfortunately, this functionality is poorly supported, but it is the current standard, so support may get better over time. Currently only NVDA on Windows supports it, with the keyboard command Insert + Alt + M.
Adding aria-controls to an element controlling an <output>/status is mandatory anyway, so give it a unique id attribute and set that as the value of aria-controls on each form element inside the <form>.
If the <output>/status is wrapped in a <fieldset> and the inputs are all wrapped in a containing <fieldset>, then each <fieldset> acts as a grouping container, so the user can navigate between them quickly. As part of this, ensure the <fieldset> containing the <output> directly follows <fieldset> containing the form elements in the source order. If this isn't possible, add the aria-owns attribute to the containing <form> and reference the id attributes of both <fieldset>s with a space in between.
Always-open non-modal <dialog>
You may instead consider making the right side pane an always-open non-modal <dialog>. A <button> next to each interactive element on the left pane would move focus to the <dialog>, and the Escape key would return focus back to the <button>. Focus isn't trapped within a non-modal <dialog>, so the user can still move between each pane using normal navigation methods. The <dialog> needs to have an open attribute to appear and it also needs to have aria-modal="false".
Each <button> would need an aria-controls value referencing the <dialog>'s id attribute, and an aria-haspopup value of "dialog". The <button>s could be invisible until focused.
There's only a single focused point at any given time. So there isn't any real miracle solution, screen reader and other keyboard-only users will necessarily have to repeatedly go back and forth.
IN fact, the most important isn't to be able to switch quickly between the different parts (you must only somehow give a way to do it only with keyboard), but to not lose cursor position when you switch.
For example if I edit something on the left, go to the right to check the result, and then go back to the left side, I expect to find the insertion point exactly where I left it off.
You really have to make sure that this is always correct, and as closest as possible when changes occurs (especially when it's asynchronous, i.e. a change occurs on the right side when you are on the left side).
The most similar accessibility recipe or component is probably split view.
In windows world, the most used shortcuts for cycling between the different splitte parts is F6, and Shift+F6 to cycle in reverse direction.
Don't hesitate to add other easier or additional shortcuts if the switch has to be really frequent, such as Ctrl+Tab, if such shortcuts aren't already used for something else.
F6 and Shift+F6 aren't the easiest shortcuts to perform, especially on laptops where all F1-12 keys may not be available at all or only by using an additional FN key. I personally always found F6 a questionnable choice, but that's only an opinion; at least we have something and that's of course better than nothing.
However, don't replace an existing shortcut commonly used. (for example Ctrl+Tab = switch between different tabs, don't use it for cycling between views if there are tabs in your application and keep it for the tabs)
Tab trapping is a fairly well established pattern (example). Typically for the sake of accessibility, it allows keyboard users to navigate inside dropdown menus and modals. What's concerning however are the implications for users now that the native functionality of the tab event has been overwritten with a new behavior (looping). This isn't a big deal for sighted users, but it is problematic for users of Assistive Technologies like NVDA and JAWS that critically rely on that native tab functionality.
WAI-ARIA has a solution for informing Assistive Technologies of when native keyboard functionality has been overwritten in the form of aria-role="application":
Keyboard interaction is completely under the web author's control and
can be anything associated with the particular widget being
implemented. In a slides application, for example, a widget could be
created that uses the arrow keys to position elements on the slide,
and uses audio feedback via an ARIA live region to communicate the
position and overlap status with other objects. Focus is being managed
via aria-activedescendant.
The tab , Space and Enter keys, as well as Escape , must be handled by
the application. The one exception is if focus is set to a standard
widget inside the application that supports keyboard navigation from
the browser, for example an input element.
This would imply that any component that employs tab-trapping should necessary have a role="application", always.
However I don't believe this common practice. Sites like Target.com for example (that use tab trapping on their dropdown menu) categorize it as a list, as seen here in the website Accessibility Tree:
I'd appreciate any experienced perspectives on this. Am I interpreting ARIA correctly here? Should components that employ tab-trapping always be decorated with role="application"?
Short Answer
You do not need to add role="application" provided you set the menus up as modal dialogs. With other patterns it may be applicable (highly unlikely, role="application" is a very specialised role) but at that point you probably implemented the wrong pattern in the first place.
Longer Answer
The loop pattern is fine as long as implemented correctly (and target.com did a pretty good job)
There is nothing wrong with this pattern as long as it is implemented correctly (which target.com seems to surprisingly do a quite good job of, just a few things they could do better).
Using 'target' as an example, you will notice that when you click on 'categories' for example the revealed menu actually gets treated like a modal dialog.
It has role="dialog" and the 'button' that opens it has aria-expanded.
They also trap tab focus within this modal and provide a 'close' button that appears at the bottom of the list if you are using the tab key.
All good so far, nothing wrong with looping within a modal dialog as that is expected behaviour.
They also get a few other things right, once the 'dialog' is open you cannot access any other content. For example in a screen reader you may press the keys 1-6 to find the next heading levels, you cannot do this while the menu is open as they apply aria-hidden="true" to everything outside of the menu modal (a true modal trap).
Also you can close the menu modal and focus is returned to the menu item that opened it in the first place, so they manage focus correctly too.
Finally you can close the menu modal with the Escape key, which is also expected behaviour.
So if you wanted to follow this pattern for your menus I would say go for it, they are accessible as they are and a screen reader user would not struggle using them.
What can we do better than target.com
Target got the basics right, they are just missing a few key steps.
The 'button' that opens the menu should have the aria-controls attribute just to link that together properly.
The menu items within the menu dialogs should all have <nav> elements around the <ul> (although arguably as these modals should only be accessible via the menu button this association is implied and this is a minor point).
The arrow sprites they use have focusable="false" which is good but they didn't add role="presentation" or better yet aria-hidden="true" so they do get announced if your screen reader is set to verbose. (aria-hidden="true" is preferable as support is better).
The menus themselves should not really be multi-layered. i.e. if you click 'main menu' at the top of the list it then becomes confusing as to where you are, am I still within the modal dialog? Additionally this is implemented in a way where it does not announce the first item in the 'main menu' list once you follow the link (timing issue maybe?) so it is disorientating. This is the biggest problem with their implementation.
There are other things but you get the idea, if your menu is just a single list per 'drop down' (modal), the way this is implemented is perfectly acceptable and usable and better than a lot of menu implementations I have seen.
So should I use role="application"
No.
Seriously, you will probably never need to use this during your career and it's use can break a lot of accessibility.
Oh you want more detail? No problem!
No you do not need to use role="application" here, in fact you would introduce a lot more accessibility issues doing so.
role="application" implies that all the controls are custom and that you should disregard the standard website controls. (you are basically telling the user / screen reader 'treat this like a desktop application where shortcut keys will be explained via the menus etc.' and 'expect some strange behaviour that is not associated with websites, do not rely on your normal keyboard shortcuts as they probably won't work')
As this follows a standard web pattern (trapping focus within a modal) adding role="application" would actually confuse people.
You mentioned about the Tab looping, but within the list it functions as expected (pressing the down arrow at the end of the list does not loop) so the Tab looping only occurs within the modal.
I think the following quote for the page I linked on role="application" summarises the important information. I have added bold for emphasis on the key points that are applicable to your question and added comments after if appropriate.
The application role indicates to assistive technologies that this
part of the web content contains elements that do not conform to any
other known HTML element or WAI-ARIA widget. Any sort of special
interpretation of HTML structures and widgets should be suspended, and
control should be completely handed over to the browser and web
application to handle mouse, keyboard, or touch interaction.
In this mode, the web author is completely responsible for handling
any and all keyboard input, focus management, and other interactions
and cannot assume assistive technologies would do any processing on
their end.
So basically if you added role="application" you would then not get the native behaviour of any element, this would introduce a lot of work! (in practice most screen readers will still allow basic functionality, but they do this because people misuse role="application")
If the web application encompassed by the application role contains
parts that should be treated like normal web content, a role of
document or article should be used.
So you would have to add role="article" or role="document" to the lists, the close buttons etc. Basically the whole thing would have role="article" anyway (as that would be the most appropriate role).
Unless you are building very complex software, role="application" should not be used.
How do I switch between the two screens on the Qt?
For example, I have a button - static text plus a toolbar. Now I will add it to a frame and set it as a central widget. It works well for one window. What if I move it to the next window? Then I need to show some other stuff like another button, some images etc... and what if I come back to the first view again?
How do I show my old widgets back?
I'm not sure I got your problem right but, you could have different scenarios :
You could simply use groupboxes... Some widgets in groupbox1, otherWidget in groupbox2, and you display the groupbox you want to use, hiding the others...
You could use stackedWidget, which simulates "pages" of widgets stacked on top of eachothers... more informations here : http://qt.nokia.com/doc/4.6/qstackedwidget.html.
You could use other way like using tabs : http://doc.trolltech.com/4.6/qtabwidget.html
Maybe this example would be useful to you : http://qt.nokia.com/doc/4.6/dialogs-configdialog.html
Hope it helps a bit !
I'd recommend checking out Animation/States example (should be in /qt/examples/animation/states/ subdirectory of your Qt installation). It shows how to combine state machine representing application logic with presentation layer and get cool animation effects for free (of course if you don't need eye candy, you can set widgets properties without any animation).
I'm building a Flex application with about a dozen different screens. There's relationships between the screens such as when on screen 1, I click on something that is an input to screen 2. Then I might bring up screen 3, then go back to 2 and then bring up screen 4. To make it clear to the user where they are in the application, we'd like to implement a breadcrumbs concept where the user gets to see which screen they are and be able to navigate back up the trail they came from.
So in thinking about how to implement this, it seems to me that I should have a stack of views. Views get pushed onto the stack, then popped off. The breadcrumbs would be a visual depiction of that stack, eg: Home >> Alert 123 >> Customer B Summary >> Customer B Detail
Having said this, I'm trying to come up with a pattern for how to implement this. The obvious starting point would be a mx:ViewStack as a container. Then I'd add views as children and make them visible - effectively "pushing" then onto the view stack. Then to close that screen I'd remove them as children to "pop" them off. This would have to update some stack data structure somewhere that the breadcrumbs would be able to see. In fact the breadcrumbs themselves can modify the stack when the user clicks on an item in the breadcrumbs to jump to.
In any case, I'm going to be working on this but just curious if anybody has anything to share around any patterns/frameworks you've used to manage multiple screens and how they come up and go away and navigate between them that I can use for some ideas.
Seems like a simple thing but in practice it's not always straight-forward.
MVC i think would be helpfull to orgenize your code and have a rebustable application .
There is no 100% design pattern ,most times it is the way you implement it .
I find mvc great when having many views because it keeps your mxml pretty clean and small and when you add features you do it in a pure as class which keeps your code from complicationg.
Just throwing some ideas, hoping it can help ...
Maybe you could use the memento pattern? Or use a command pattern with a CommandStack?
I am developing a public website which is the front end to information about medical conditions.
After the user does a search (questionnaire based) they are presented with the results which are categorised in to sections and sub-sections.
Information items can be assigned to both sections and sub-sections.
At the moment sections are represented by tabs across the top and the screen and sub-sections by links in a sidebar. The links in the sidebar change depending on which section is selected.
The problem is the section names are quite long (several words) and as a result the combined length of the tabs is too wide for a standard screen resolution (1024 x 768). Therefore they wrap and break the page layout. We will also have to add additional tabs in the future.
With this problem in mind and the fact our target audience is quite wide, this is a public medical website, what options are there for presenting this kind of information in a way which is accessible and easy to navigate for an average user.
How long are the subsection names? Will they fit in the space for tabs? You’re likely to get better user performance if you put the section links on the side bar menu and the subsection links in the tabs, rather than the other way around. See http://www.usability.gov/pubs/040106news.html.
The other alternative is to put everything on the side bar menu. Subsection links can appear indented under their section links. You can also consider putting the subsection links in a column of their own to the right of the section column. This makes the section menu stable, but takes a lot of horizontal space that’s perhaps better used for content. In either case, proper attention to visual design will show the current section, subsection, and the link between them.
There shouldn’t be a problem with accessibility as long as you’re using links to navigate to each section/subsection (perhaps generated programmatically for each page based on a database relating links to pages).
Just brainstorming some ideas:
Use combo boxes to allow the user to select the (sub)sections, then display the appropriate information items.
Create separate pages for each section-level and provide a bread-crumb control to show the user where he / she is in the page hierarchy.
Create some sort of fold-out menus that automatically hide when the user reads an information item.
In another question on SO, I came across a link to Quince, perhaps you can find some inspiration there as well.
You could try:
An iPod-style menu (in which subsections are hidden pages that fly in from the right): http://www.filamentgroup.com/lab/jquery_ipod_style_and_flyout_menus/
Or as Daan has said:
Cascading drop-down boxes: http://www.asp.net/AJAX/AjaxControlToolkit/Samples/CascadingDropDown/CascadingDropDown.aspx
The downside with both of these (over a traditional tree view) is that the subsections aren't visible until you choose a section. If your users don't know the name of the subsection they're after, then either of these will be a good fit.
If, on the other hand, they do know the name of the subsection they're after, it's probably better to give them an auto-complete textbox so they can type a few characters and go directly to it.