I'm implementing show/hide column behaviour in a standard C++ Win32 application (no frameworks).
Say we've got 3 columns in a ListView control in Details view. The user has the option to show/hide the last two columns in order to see the extra detail if wanted or hide them to reduce clutter. All works well except that after the columns are deleted and then re-added, the data from the sub-items in those columns doesn't show up again, i.e. the columns are empty.
None of the items themselves have been altered in the meantime - do I lose the sub-item text when I delete the columns or I am missing something to force the columns to redraw the data?
Steps to reproduce:
1) Create a ListView32 control with 3 columns and add a bunch of items (and text to each of the items' sub-items). All good.
2) The user clicks "Hide Details", so I use LVM_DELETECOLUMN twice to remove the last two columns and they disappear. All good.
3) The user clicks "Show Details", so I use LVM_INSERTCOLUMN to add the last two columns and the headings appear, but the columns themselves are empty.
As an alternative, setting the column widths to zero is a hack and the user can still grab the re-size column splitter, so it's not a great option.
Many thanks for any suggestions.
Typically one does not store data in GUI. In case of plain listview32 you should add items specifying LPSTR_TEXTCALLBACK instead of real text and then handle LVN_GETDISPINFOW notification supplying (sub)item data. Windows will send this notification for all items. You can force Windows to retrieve data again by sending LVM_UPDATE message.
Setting the column widths is a viable solution. That is the way I do it in my UIs when columns can be shown and hidden dynamically. It works fine.
To prevent the user from resizing "hidden" columns, simply subclass the ListView using SetWindowLongPtr(GWL_WNDPROC) or SetWindowSubclass() to intercept HDN_BEGINTRACK notifications from the ListView's header control:
Notifies a header control's parent window that the user has begun dragging a divider in the control (that is, the user has pressed the left mouse button while the mouse cursor is on a divider in the header control). This notification code is sent in the form of a WM_NOTIFY message.
...
Returns FALSE to allow tracking of the divider, or TRUE to prevent tracking.
Related
I am working on WinUI 3 desktop application in C++. I was trying to achieve an experience where when we scroll ListView, we will incrementally add rows to the end of the listviews dropdown during runtime.
For example, I might have 100,000 results to fit in a list view, I only want to show a limited number of contents in the list view, then as the user scrolls I'll add more contents to the list view.
I was not able to get any scroll-based events in ListView directly, so I extracted the ScrollViewer from the list view and handled the ViewChanged event. This event was fired when the scroll happened. But I was not able to get how many rows were scrolled or currently which row is been scrolled.
I want to get how many rows are scrolled so that I can insert enough rows to the end of the ListViews Item Source. It would be of great help if you could help me with this.
Thank You
I couldn't think of a coherent search term for my problem so please forgive me if this has been asked before.
I have 24 combo boxes sitting on a panel control, displayed in 4 rows of 6.
After the user defines the value for each combo and hits the "go" button, I add all combo boxes to list so I can use the values in another section of my program.
The problem is that the order the comboboxes are added to the list is messed up, compared to their visual layout on the panel, and I would like to define the order. Currently, it adds the 9th combobox to the list first then the 20th, 2nd, 16th etc etc.
I tried TabIndex but that didnt work.
Before I manually rename and relabel all of the boxes, any other suggestions will be gratefully received.
The controls of your form exist in Controls collection of the container controls, for example when you add a Panel and a Button to a Form and two ComboBox to the Panel, then:
Form.Controls contains button1 and panel1
Panel.Controls contains comboBox1 and comboBox2
Controls are added to the Controls collection, with the same order that you add them to designer. Open designer.cs, look at the end of InitializeComponent to see the order.
You can also see/change the order using Document Outline window.
That said, now it should be obvious that panel1.Controls.OfType<ComboBox>() returns combo boxes with the same order that you see in Document Outline (or based on their z-index, and it doesn't have anything to do with their x/y placements).
You may want to order them based on TabIndex, or any other property that you like:
panel1.Controls.OfType<ComboBox>().OrderBy(x=>x.TabIndex)
Note
In general, if you are going to use those values for a search, instead of relying on the order of values, a much better idea is creating a SearchModel class which has a few properties, the set those properties to the selected value of the corresponding combo box (manually or using databinding) then pass the search model to the other classes.
In MFC dialog based application, I have a combo box. Is it possible to select multiple items in the Combo-box through mouse and keyboard operations and also by pro-grammatically?
m_ctrlComboBox.AddString("Type1");
m_ctrlComboBox.AddString("Type2");
m_ctrlComboBox.AddString("Type3");
How to achieve it?
From the documentation:
A combo box consists of a list and a selection field. The list presents the options that a user can select, and the selection field displays the current selection. If the selection field is an edit control, the user can enter information not available in the list; otherwise, the user can only select items in the list.
The selection field is only capable of displaying a single selected item (at most). There is no way to allow a user (or code) to select multiple items at the same time. This is immediately obvious when looking at the CB_GETCURSEL and CB_SETCURSEL messages, that only allow for a single index to be passed.
A list view control allows multiple items to be selected at the same time.
I have a QTableView with 80+ columns displayed in it. The subclass i have created for QTableView allows has functionality for the standard table stuff i wanted e.g order by columns move columns and rows hide column and rows etc.
However the problem i have is the view's focus. lets say you have all the data in the table, you scroll all the way to the right so you are looking at columns 70-80 (assuming 10 columns fit on the screen at once) if i click the header of row 80 (to order by column 80) the table reorders (as expected) however it also jumps the view to the last focused cell (which as far as i can tell is the cell that was last clicked)
What i want to do is not necessarily refocus on the column that was clicked because this might still change the view what im looking for is to just keep the view's focus exactly as it is instead of having it jump back to where the last clicked cell was?
Is there some flag im missing for focus policy or will i need to get the current view and set the view back to that view after mouse clicks that reorder the table and if so how could this be done.
Im aware i have provided no code for this question but it doesnt seem there is any needed since its not a bug im looking to fix more of a feature im unaware of, if you want to see any just comment
EDIT:
Im using a QSortFilterPorxyModel, this seems to get set once (when i call this->setSortingEnabled(true); after the initial call to this on contruction my table model never calls sort again. I have a slot linked to the header clicked signal, and i set the scroll bars to scrollTo() to the index clicked, but i think the sort is happening after this so it does nothing, any idea of what signal are emitted after sorting so i can catch them and then set the view back maybe?
thanks
Before you do your sort, store the current values for where the scroll bars are with
int vPos = yourQTableView->verticalScrollBar()->sliderPosition();
int hPos = yourQTableView->horizontalScrollBar()->sliderPosition();
then after the sort, set it back
yourQTableView->verticalScrollBar()->setSliderPosition(vPos);
yourQTableView->horizontalScrollBar()->setSliderPosition(hPos);
The signals you are looking for are signals of QSortFilterProxyModel inherited from QAbstractItemModel:
layoutAboutToBeChanged()
layoutChanged()
I couldn't reproduce your symptoms by creating a QTableWidget, filling it up with random stuff, and then sorting a particular column. The selected cell stays selected, but does not become visible if it has scrolled off screen.
So the question is, what is causing the behavior you're seeing. It sounds as though scrollTo() is being called by some other function. Since that's a virtual function, I would override it with a pass-through function and see when it's getting called.
I often use select lists with my projects but when it comes to a huge select list, I couldn't find a solution. I need a easy, plug and play solution for solution will be used in a few places.
When you have a select box or text box to be filled from a model data, I want to show user a text box, right side of text box, there should be a button to choice the value. Upon clicking that button, popup or a modal will be opened and I filter all the records and find my value, upon clicking value, modal or popup closes and I get choosen value to form control.
İmagine you have a text box to choose your customer, and among 2500 customer,
PS:don't suggest autocomplete, don't want to accomplish it.
Why don't you look at something like Chozen plugin http://harvesthq.github.io/chosen/. It allows you to easily search large select lists