I'm using CListCtrl with LVS_EX_CHECKBOXES style.
And I need to have at least two of the checkboxes were set checked at any time.
How can I do this?
First you need to trap the LVN_ITEMCHANGING notification, which is most easily done by deriving your own class from CListCtrl (for example, called CMyListCtrl) and then adding a message map entry like the following:
BEGIN_MESSAGE_MAP(CMyListCtrl, CListCtrl)
ON_NOTIFY_REFLECT(LVN_ITEMCHANGING, &CMyListCtrl::OnLvnItemchanging)
END_MESSAGE_MAP()
Then, you write the message handler like so:
void CMyListCtrl::OnLvnItemchanging(NMHDR *pNMHDR, LRESULT *pResult)
{
// an item has changed
LPNMLISTVIEW pNMLV = reinterpret_cast<LPNMLISTVIEW>(pNMHDR);
// by default, allow change
*pResult = 0;
// see if item was checked or unchecked
if ((pNMLV->uNewState & 0x2000) == 0x2000)
{
// item was checked - do anything you like here
}
else if ((pNMLV->uNewState & 0x1000) == 0x1000)
{
// item was unchecked - see how many selections we have
if (/* pseudocode */ number of selected items < 2)
{
// disallow change
*pResult = 1;
}
}
}
The condition is pseudo-code so you can decide how to keep track of the number of selections - maybe keep a count by adding code to the above method, or put a loop in there to get the check state of each item and make a tally.
I think this should give you enough to get moving, so please update your question if you get stuck further.
Related
We have multiple dialogs in our MFC program that are very similar. Each one of these dialogs contain similar controls (i.e., they all contain a name, date, address, etc). Because of this, we've had to code out the display code multiple times for the windows despite the fact that the processing of these controls is identical. I'm looking for suggestions on how to change up our guis so that i have to only do the processing at one spot and not have to do it multiple times.
My thought was to have a class that would do the processing and pass pointers to the controls to display to that class, though i feel that is not a very good OO design.
Thoughts?
Create a base class derived from CDialog (say CMyDlgBase), place all your common functions there and derive your dialog classes from CMyDlgBase instead of CDialog.
You can now call the functions in CMyDlgBase as if they were declared directly in your dialog classes.
EDIT sample code to validate an item common to dialogs (CDlg1 and CDlg2 are derived from CMyDlgBase), error checking code not included:
BOOL CMyDlgBase::ValidateName(UINT nID)
{ CString ss;
CEdit *pEdit = GetDlgItem(nID);
pEdit->GetWindowText(ss);
if (ss.Find(_T("A")) < 0) // some kind of validation
{ MessageBox(_T("Name should contain the character 'A'"));
pEdit->SetFocus();
return FALSE;
}
return TRUE;
}
CDlg1::OnOK()
{ if (!ValidateName(IDC_DLG1_NAME)) // resource id value = 101
return;
CDialog::OnOK(); // This will close the dialog and DoModal will return.
}
CDlg2::OnOK()
{ if (!ValidateName(IDC_DLG2_NAME)) // resource id value = 102
return;
CDialog::OnOK(); // This will close the dialog and DoModal will return.
}
I'm writing an application that runs an algorithm, but allows you to 'step through' the algorithm by pressing a button - displaying what's happening at each step.
How do I listen for events while within a method?
eg, look at the code I've got.
static int proceed;
button1Event(GtkWidget *widget)
{
proceed = 0;
int i = 0;
for (i=0; i<15; i++) //this is our example 'algorithm'
{
while (proceed ==0) continue;
printf("the nunmber is %d\n", i);
proceed = 0;
}
}
button2Event(GtkWidget *widget)
{
proceed = 1;
}
This doesn't work because it's required to exit out of the button1 method before it can listen for button2 (or any other events).
I'm thinking something like in that while loop.
while(proceed == 0)
{
listen_for_button_click();
}
What method is that?
The "real" answer here (the one any experienced GTK+ programmer will give you) isn't one you will like perhaps: don't do this, your code is structured the wrong way.
The options include:
recommended: restructure the app to be event-driven instead; probably you need to keep track of your state (either a state machine or just a boolean flag) and ignore whichever button is not currently applicable.
you can run a recursive main loop, as in the other answer with gtk_main_iteration(); however this is quite dangerous because any UI event can happen in that loop, such as windows closing or other totally unrelated stuff. Not workable in most real apps of any size.
move the blocking logic to another thread and communicate via a GAsyncQueue or something along those lines (caution, this is hard-ish to get right and likely to be overkill).
I think you are going wrong here:
while(proceed == 0)
{
listen_for_button_click();
}
You don't want while loops like this; you just want the GTK+ main loop doing your blocking. When you get the button click, in the callback for it, then write whatever the code after this while loop would have been.
You could check for pending events & handle the events in while loop in the clicked callback. Something on these lines:
button1Event(GtkWidget *widget)
{
proceed = 0;
int i = 0;
for (i=0; i<15; i++) //this is our example 'algorithm'
{
while (proceed ==0)
{
/* Check for all pending events */
while(gtk_events_pending())
{
gtk_main_iteration(); /* Handle the events */
}
continue;
}
printf("the nunmber is %d\n", i);
proceed = 0;
}
}
This way when the events related click on the second button is added to the event queue to be handled, the check will see the events as pending and handle them & then proceed. This way your global value changes can be reflected & stepping should be possible.
Hope this helps!
If you want to do it like this, the only way that comes to my mind is to create a separate thread for your algorithm and use some synchronization methods to notify that thread from within button click handlers.
GTK+ (glib, to be more specific) has its own API for threads and synchronization. As far as I know Condition variables are a standard way to implement wait-notify logic.
I am trying to use an edit control along with a spin control using MFC visual studio .net 2003. I have carried out the basic settings for the spin control like setting the "AutoBuddy" property and "SetBuddyInteger" property to True so that the Spin control works in coordination with the edit control next to it. In my Spin control's event handler, I am facing a problem when I am trying to call my Invalidate() function. The float value in my edit control does not update and stays zero. If I remove the Invalidate(), then the value increments but my paint function is not updated obviously. A code of the following is given below:
void CMyDlg::OnSpinA(NMHDR *pNMHDR, LRESULT *pResult)
{
LPNMUPDOWN pNMUpDown = reinterpret_cast<LPNMUPDOWN>(pNMHDR);
// TODO: Add your control notification handler code here
UpdateData();
m_A = m_ASpinCtrl.GetPos(); // m_A is my edit control float value variable
Invalidate(); // Invalidate is to be called to update my paint function to redraw the drawing
UpdateData(false);
*pResult = 0;
}
I have carried out the tab order correctly as well for the two controls.
Any suggestions on where I am going wrong?
Thanks in advance.
If you just want to have a spinning integer, you don't have to override anything.
The spin control has to be right next to the edit control in the tab order. With AutoBuddy that's all you have to do.
m_A when getting the position back would do something weird and would not return you the correct value. Try using the pointer to get your position and value and then carry out the invalidate().
{
LPNMUPDOWN pNMUpDown = reinterpret_cast<LPNMUPDOWN>(pNMHDR);
// TODO: Add your control notification handler code here
UpdateData();
CString tempStr;
m_A += pNMUpDown->iDelta;
tempStr.Format("%f",m_A);
m_ACtrl.SetWindowText(tempStr); // Like a CEdit m_ACtrl to display your string
Invalidate();
UpdateData(false);
*pResult = 0;
}
This should work perfectly well. Let me know if you still get any problems.
I'm on a roll today with MFC! :D
I have a text box and a list view control.
When the user presses the VK_UP and VK_DOWN keys in the text box, I would like this to happen:
Do some stuff.
Have the list view control also process the message (to highlight the previous/next item).
I want the list view to wrap around the current selection, if the key press is the first in its sequence.
Do some more stuff.
I tried subclassing my edit box in my dialog:
class MyEditBox : public CWnd
{
bool allowWrap;
afx_msg void OnKeyUp(UINT, UINT, UINT) { this->allowWrap = true; }
afx_msg void OnKeyDown(UINT nChar, UINT nRepCnt, UINT nFlags)
{
CListCtrl &listView = static_cast<CListView *>(
this->GetParent()->GetDlgItem(IDC_LIST_VIEW))->GetListCtrl();
if (nChar == VK_UP || nChar == VK_DOWN)
{
int iSelBefore = listView.GetNextItem(-1, LVNI_SELECTED);
this->GetParent()->GetDlgItem(IDC_LIST_VIEW)
->OnKeyDown(nChar, nRepCnt, nFlags); //Oops! Protected member :(
int iSelAfter = listView.GetNextItem(-1, LVNI_SELECTED);
if (iSelBefore == iSelAfter && // Did the selection reach an end?
this->allowWrap) // If so, can we wrap it around?
{
int i = a == 0 ? listView.GetItemCount() - 1 : 0;
listView.SetItemState(i, LVIS_SELECTED | LVIS_FOCUSED,
LVIS_SELECTED | LVIS_FOCUSED);
}
}
this->allowWrap = false;
}
}
but OnKeyDown() is a protected member, so I can't just call it on another control.
Is there a better way to solve this than manually sending the command with SendMessage? Should I change my design, e.g. subclass something else, etc.?
Your intention is to select previous or next item in list control, right? Then you should call the method to do that directly instaed of asking the CListCtrl to "process" your message.
You may call CListCtrl::SetSelectionMark and CListCtrl::SetItemState to select next or previous keystroke. Example:
cListCtrl.SetSelectionMark(nIndex);
cListCtrl.SetItemState(nIndex, LVIS_SELECTED | LVIS_FOCUSED, 0xFF);
You can handle Key Down, Key Up as well as Page Down, Page Up, End, Home or any any key from edit box. You need to do calculation, though.
Or you can just SendMessage. There is no need to call OnKeyDown directly. Let the framework call it for you when you send the message.
I am seeing also other ways to solve this:
Derive a class from CListCtrl called MyListCtrl and choose one of two things:
1.1 Declare MyEditBox as a friend and now you can call the protected methods on MyEditBox
1.2 Add public methods CallOnKeyDown(...) and CallOnKeyup(...) to it that only do what is needed.
And when creating the control, instance a MyListCtrl instead of a CListCtrl. Also replace the listView variable you have shown here to be a MyListCtrl and use the methods you have now available
Use PreTranslateMessage(...). I think this "hammer" solution is worse than sending a message.
Ok, let me explain my scenario more clearly:
When a cell is edited, it becomes 'dirty' and I style it a certain way by adding a CSS class to the cell via javascript.
Then, if the user Sorts the grid, the styling is lost (I believe because all the rows are recreated) and I need a way to restore the styling to the appropriate cell/row after a Sort.
What I attempted to do is add an entry into data[] called 'status' and onCellChange I loop through data[] and match the args.item.Id to appropriate entry in data[].
grid.onCellChange.subscribe(function (e, args) {
var done = false;
for (var i = 0; i < data.length && !done; i++) {
if (data[i].id == args.item.id) {
data[i].status = "dirty";
done = true;
}
}
}
However, onSort I'm not sure how to match the sorted rows to the data array. (Since I have no args.item) I've attempted to do selector statements:
$(".slick-row")
to restyle the correct cells, but I have no way to associate the rows with their entry in data[].
1) There is no need to search for the item in your onCellChange handler - it is available at "args.item".
2) Sorting the "data" array will not wipe out your change to the item in #1.
3) You mention dynamically styling cells. I see no code for that. If your custom formatter is the piece of code that looks at "item.status" and renders it differently if it is dirty, then you don't have to do anything extra. Sorting the data and telling the grid to re-render will preserve the "dirty" cell styles.