I am trying to port to Python 3.x a small gui application that I have written in Matlab.
The app contains a Matlab uitable, with which you can program bitfields of registers of a microcontroller. Actually you can create a panel which groups some register-bitfields that are important to you for debugging at a specific point in time (kind-of a watch window in a compiler IDE).
It looks like this:
Gui Table used to write to register bitfields of a microcontroller
So, each row of the table can be used to program a specific register bitfield.
There are 4 columns:
1. Register name (drop down list)
2. Bitfield name (drop down list)
3. Value to write (string)
4. Format (Hex or Dec drop down list, irrelevant here)
In order to use this application, one first clicks on the register name drop down list, where all registers are shown (detail: using a text box one can apply filters to narrow down the list size).
When the register is selected, the drop down list of the bitfield column updates automatically so that it contains only the bitfields of the chosen register. This happens with the help of a callback function.
Then, the user has to enter a value and a format, and only if all cells contain valid content, then a register write command is issued (via some debugger interface).
This worked OKish; sometimes the bitfields list was actually the one of the previous register added in the table, but this could be detected and have the entry cleared so that the user can try again. Also when the number of rows becomes very high and scroll bars appear, then if the user tries to enter a register at the bottom, every time they click on the drop down list, they can choose an entry and then the scroll bar position will automatically change showing the beginning of the table. This makes the process of entering registers quite cumbersome. As far as I know, the uitable of Matlab did not have accessible properties to control this behavior.
Since I am a hw engineer with limited sw technologies knowledge, I am wondering if there is a natural way to support this in Python 3.x, say with some structured (e.g. xml) data container that can naturally map to a gui component, without so much callback programming and data validation. The ideal behavior would be that the user starts to type directly at the register name drop down list (not possible in Matlab), and dynamically gets a filtered version of the register names list.
I am completely new to python, just installed Anaconda. I have found some interesting classes in PyQt:
QListView Class,
QListWidget Class,
QTableView Class,
QTableWidget Class.
However, I would like to have the combined functionality of the tableview with a listview, as is the case with the uitable in Matlab. Or even better, a text edit input that turns into a drop down list after typing a few letters.
The pyqtgraph.tablewidget seems to augment the functionality of QTableWidget, but I think this is still not what I need.
So, if the above is not possible, or would involve heavy programming, maybe all I need is to change approach and have a single separate search box with autocompletion, which looks into a "flattened" version of the registers database, and returns results in the form my_register_1.my_bitfield_1 (maybe allowing the user to search simultaneously at both register and bitfield names). When the user clicks on one item of the "autocompletion list", then the selected entry is mapped to the currently selected line in the tableview, adding both the register name and bitfield in read-only table cells. The "value to write" cell should still be editable, and when it gets valid data it should trigger register write command...
I would appreciate if you could guide me where to look. Thanks!
You should use the Qt model/view architecture. This allows you to have a representation of your data (the "model"), which is separate from how that data is represented (the "view"). So you set up a table of data, and then set up a view to represent that data. When you switch between different data sets, you tell the view to display the new data set. The tutorial I linked to explains this in some detail
Related
I am using SWT tables in my project and there are few columns which are having longer strings which are not completely visible by default (for ex. path to a file location). Though I have tooltip to show the content and using mouse we can increase the column width to see the complete value.
Is there a way to do it with only keyboard usage?
Note: This question is more related to accessibility.
The following answer is based on my experience under windows. It can be different for other OS.
I'm afraid that there's no keyboard-only default way to adjust the size or reorder the column in a table, tree view or list view.
This is true not only with SWT but also with all other frameworks based on native win32 such as wxWidgets.
You must provide a keyboard-only way to resize and reorder columns yourself. here are a few ideas implemented by some applications:
Provide an option somewhere in the application that opens a dialog box with a checkbox list of the different columns. Ctrl+Up/Down to swap two items. Check/uncheck an item with spacebar to make the column visible or invisible.
Make the headers focusable. Use Shift+Left/Right to resize, Ctrl+Left/Right to swap two columns. Application key / Shift+10 opens a context menu where you can check/uncheck columns to show/hide and an option to open the column selection dialog box.
Some screen readers allow to do it by simulating mouse operation in some way. For example, use Jaws cursor, click lock on a header, release lock on the header to swap with.
But it's quite complicated, not always reliable, and thus very rarely actually used.
This is a very good question. I would be happy to give 100 rep to someone giving an answer being for windows and:
generic, working by default, everywhere or in most cases
Independant from screen readers (Jaws, NVDA, etc.) and techniques that simulates the mouse with keyboard (mouse keys)
Unfortunately, I don't think it exists.
So before I continue developing my accessible table I read this, on exposing data tables and the general MSAA documentation and I want to clear up a few things before I actually go ahead and write out this implementation, just so I can get everything just right.
For the record, this table is strictly owner-data and is row-based, where a given row can be selected, and a single cell within this row can be focused. Otherwise it behaves similarly to a listview control, but is not one, so I'm not going to try to take advantage of its accessibility features. In particular, any column can contain text, images, or checkboxes (and I might add more features); there might be background colors and text editability in the future as well. All cells in a given column have one of these types. The type will not change during runtime.
I am choosing to use MSAA because I still need Windows XP support, and I would rather not require developers and end users to have both SP3 and the .net framework together, which UI Automation seems to require (and even if the SP3 part is wrong, the "is not standalone/does not come out of the box with the OS" part still makes me uneasy about implementing that).
Is it process-safe/thread-safe to call my internal control functions within the accessible object method implementations, or should I use WM_USER messages to make sure everything happens all on one thread of one process? (In addition, would my error handling/debugging traps be run in the client or in the server in either case?)
From what I can gather, I need to build a three-level IAccessible hierarchy: the table itself on top, followed by each row, followed by each cell in the row. However, the various IAccessible methods that take a child object only take a VT_I4 VARIANT to specify the child. Does this mean I'm going to have to create an IAccessible for each row as well, or for each cell as well, or something else? Should I have a standard accessible object for each of these? Can they share? And what about NotifyWinEvent(); how would I indicate that a given cell has changed? Or should I say the whole row has changed...?
If the answer to question 2 is "yes", I'm going to wind up with a lot of IAccessible objects that need to be notified when the table control is destroyed. If the answer to question 1 is "it is not thread-safe", then is it safe to hold a lock in my IAccessible methods whenever I access my table control and have that hold the lock when it's time to invalidate all those IAccessibles? Or should I investigate some other approach? I see talk on MSDN of "proxy objects" but I'm not really following how that would help... especially if I need to make lots of IAccessibles.
From what I can gather I need to return (number of rows) + 1 rows in my table's get_accChildCount() method, with the first row being full of column header cells. But I'm not using a custom header control; I'm using the standard comctl32.dll header control. Should I hide that control and construct my column headers according to the Exposing Data Tables document or should I relegate the first row to the header control? I don't see a way to do both... (I do not have row headers, so will not be implementing that.) Columns can be user-resized, but may be automatically sized to fit until the user first does so (maybe).
Is it safe to relegate IDispatch methods to the window handle's standard accessible object? Even in the case of the row and cell IAccessibles? Or will the standard accessible object's IDispatch not call my IAccessible methods?
What should accDoDefaultAction() do for a checkbox cell, toggle the checkbox state? And for an editable text cell, should it enter editing mode?
Thanks. (Hoping none of this sounds dumb...)
UPDATE 6 January 2015
I changed the wording of some of the paragraphs above and have one more question:
How do I correctly check for errors from LresultFromObject(), by casting to an HRESULT and checking that, or by comparing a signed version of the LRESULT value and seeing if it's less than zero, or something else?
I am looking for a control many of us probably know, but I don't know it's name and don't have a real screenshot by hand, just this sketch:
In the left box one can select an operation or whatever, which then is moved to the right side. With the up/down arrows on the right, one can move this operation (or whatever kind of meaning the entry has) up or down in the order of execution.
How is this kind of control called? Or is it normally build by developers out of single controls? Is this control available in JavaFX 2? If not, I don't need exactly this control, but a control with the following features:
User can select multiple operations (duplicates allowed) out of all available operations
The user can arrange their order of execution
Thanks for any hint :-)
You need to use multiple controls to build up your interface. Use two ListViews with a MultipleSelectionModel for each (or at least the left one) and add a couple of buttons, that copy selected items from one list to the other and another couple of buttons which modify the position of selected items in the right list view by modifying the view's underlying item list.
listView.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
I need to design a custom text view that displays logs that my application produces. Logs have a specific packed binary format, each entry includes a number of fields besides an actual string (log level, date, source). Now these logs can be huge, hundreds of megabytes of data. I need to implement features such all quick filtering based on message type/source, searching, control over memory layout, etc. Since NSTextView supports most of these features i decided to start from there.
I obviously need my custom text storage to provide access to my packed log format, to load new strings on demand when user scrolls the log view window. I also need to selectively display lines of logs based on current active filters (display only warnings for example) without reloading the whole text into the view again, just filtering out the lines as they are displayed.
I have looked at NSTextStorage and it advises to overload -string, which does not exactly fits the purpose. Could anyone please give a couple of pointers to guide my further research? I am relatively new to cocoa's text handling.
Not a direct answer to your question, but a possible alternative good enough for Apple:
Why not do as Console.app does with proper system logs? Each log entry (though it might be multiple lines) starts with a very specific format. Console.app uses an outline view (an entry has a child row if the line is too long for the table row to keep all entries the same size for easy perusal). Check it out in /Applications/Utilities/Console.app under a standard log.
The benefits: simple selection of entire entry, very easy search filtering, alternating row colors make individual entries easier to see, you could use variable row height to show the whole message if you didn't like the truncated / disclosure approach.
Following on from a question I posted yesterday about GUIs, I have another problem I've been working with. This question related to calculating the bending moment on a beam under different loading conditions.
On the GUI I have developed so far, I have a number of sliders (which now work properly) and a pop-up menu which defines the load case. I would like to be able to select the load case from the pop-up menu and position the loads as appropriate, in order to define each load case in turn. The output that I need is an array defining the load case number (the rows) and a number of loading parameters (the itensity and position of the loads, which are controlled by the sliders).
The problem I am having is that I can produce this array (of the size I need) and define the loading for one load case (by selecting the pop-up menu) using the sliders, but when I change the popup menu again, the array only keeps the loading for the load case selected by the pop-up menu.
Can anyone suggest an approach I can take with (specifically to store the variables from each load case) or an example that illustrates a similar solution to the problem?
The probem may be a bit vague, so please let me know if anything needs clearing up.
Many Thanks,
James
You could use Application Data to store the current loading case and have a application data structure to store the values of each slider for the different loading cases.
In short, you could use the setappdata and getappdata to save and load the data you need. Mathworks has more information here.