I've got a MFC CTreeCtrl stuck in a dialog with the TVS_CHECKBOXES style turned on. I get checkboxes next to all my tree items fine. In OnInitDialog I set the checked state of some of the items using CTreeCtrl::SetCheck but none of the items in the tree are checked when the tree is displayed. SetCheck is returning TRUE. Checking items with the mouse works fine. Anyone encounter this before?
Figured out what the problems was. I was setting the TVS_CHECKBOXES style in the visual studio resource editor. Apparently this causes the problem I was having with the initial checks. Instead you have to do
m_nodeTree.ModifyStyle (TVS_CHECKBOXES, 0);
m_nodeTree.ModifyStyle (0, TVS_CHECKBOXES);
before filling the tree in OnInitDialog. Once I did this everything worked fine.
I created myTreeCtrl using this code:
myTreeCtrl.Create(WS_CHILD|TVS_HASBUTTONS|TVS_CHECKBOX|, CtrlRect, this, IDC_TREECTRL);
I tried to check some items in OnInitialDialog() and had the same problems.
I tried:
myTreeCtrl.ModifyStyle(TVS_CHECKBOXES, 0);
myTreeCtrl.ModifyStyle(0, TVS_CHECKBOXES);
And now it works fine.
More than that, it didn't check the item if it was not in the visible part of the window. I had to put a trigger on OnVScroll().
Check boxes in tree view controls are quirky. As documented:
If you want to use this style, you must set the TVS_CHECKBOXES style with SetWindowLong after you create the treeview control, and before you populate the tree. Otherwise, the checkboxes might appear unchecked, depending on timing issues.
In other words, you cannot set the TVS_CHECKBOXES tree view style at control creation time. Control styles set in Visual Studio's resource editor (which is just a graphical front-end for the .rc script) are used at control creation time.
The solution is fairly simple: Create the control without the TVS_CHECKBOXES style, and turn it on in code, before you populate the control:
::SetWindowLong( hwndTreeView, GWL_STYLE,
::GetWindowLong( hwndTreeView, GWL_STYLE ) | TVS_CHECKBOXES );
In MFC this can be done using
m_treeView.ModifyStyle( 0x0, TVS_CHECKBOXES );
where m_treeView is the tree view control instance variable.
Background information:
Check boxes weren't part of the initial tree view control implementation. They were added later on, following the scheme developers were using that needed check boxes before they were available: By using a state image list and setting state item indices on the tree view items.
One of the issues that needed to be addressed was determining the check box size. If the tree view control has an image list (the "normal image list") assigned, the check boxes should match the size of those images. Otherwise, the check boxes should use the system small icon size. A corollary of this is that if you are using a "normal image list", you need to enable the TVS_CHECKBOXES style after setting the image list.
Another quirk is, that the state image index 0 means "no state image" at all (1 refers to the "unchecked" state item image). If you add an item to a tree view control that has the TVS_CHECKBOXES style set, the control sets the state item index to 1 (even if you specify 0). That's why all items appear unchecked, when you set the TVS_CHECKBOXES style at creation time. This also implies, that if you want a tree view item without a state image, you have to add the tree view item, and then manually reset the state item index.
This should be enough information, to understand and solve the question as asked. There's a lot more to the tree view implementation, but I'll leave that to someone, that is better equipped to write about it. Refer to the references below.
References:
Raymond Chen (The Old New Thing) has published an extensive series covering the tree view control quirks. Not all of the entries are immediately relevant to this question, but each and every one is insightful and valuable, one way or another, so I'll just list them all:
The TVS_CHECKBOXES style is quirky, which is a polite way of saying that it is crazy
Beware of the leaked image list when using the TVS_CHECKBOXES style
Creating tree view check boxes manually: A simple state image list
Creating tree view check boxes manually: Responding to clicks
Creating tree view check boxes manually: Themed check boxes
Tree view check boxes: A sordid history
Tree view check boxes: The extended check box states
Related
I have a problem with a view/window that has a tree view on the left then a list style view on the right which displays "stuff" corresponding to the tree node selected on the right. Very similar to how windows explorer looks and works.
The "stuff" can be displayed as a list, large icons or small icons or information.
The problem I have is that if one of the tree nodes selected is a 'placeholder' node, then 'select all' is run from the Edit menu, then after that the 'delete' option in the Edit menu is greyed out even though all the items in the RHS view are marked as selected and can in fact be deleted safely.
This can be fixed by selecting away from the tree node to another node, selecting back to the same tree node, then selecting a different view: List, large icon, small icon, or info view than was originally selected.
Trace statements show me that in the second working, scenario, the items in the right hand view are being passed to a "can I delete" function whereas when things dont work it is the name of the tree view node that gets passed to the "can I delete" function. when the "can I delete" function returns true, the 'delete' option is enabled in the Edit menu and when false it isnt.
Is there a way I can force the 'focus' for want of a better word to the right hand list, info, etc view when 'select all' is selected from the Edit menu to make this work ok all the time?
I think the problem is that the Edit menu is different (context sensitive) depending on which view ('it' thinks) is active and somewhere wires are crossed and the Edit menu is being displayed for the tree view when it should be for the RHS node list view. It is figuring out how to fix this i am struggling with.
Thanks
You have problems with the MFC command routing.
Check where you placed the handler for the commands.
A command handler is searched in this sequence:
Active view
Document
Document template
Frame window
Application.
I suppose you have handler in the views, and the focus (active view ) changes
You can change the command routing i.E. in the frame and ask all views attached to the document to handle a command... you have to overwrite OnCmdMsg for this.
See more details here
I am using win32, c++.
I have a ListView & i want to disable (grey out) only some of the items from the list.
Is that possible or only whole ListView can be greyed out?
The ListView control does not have a concept of disabled items. You can simulate that appearance using custom drawing support. This Sample demonstrates how to change the text and background color of items within the list view.
You would need to go further and provide some means of determining when a disabled item is selected within the view (as the selection will continue to work).
The Windows List View Common Control does not have a disabled state for Items. If you want to do that, you will have to implement it yourself.
This is a not-trivial exercise. It's not hard to change the visible appearance using customer draw, but handling hit-testing and selection would be quite complex.
We have a list that uses a custom renderer containing a label, a checkbox and two icons (which have click events). This list needs to be made WCAG 2.0 compliant and in order to do that we need the list to be keyboard navigable.
The problem is with being able to move from one list item to the next and have the focus move to the label for the next/previous list item. Specifically, when the user enters the list using TAB button, the label for the first list item receives focus (highlighted box around text) and the entire row in the list is highlighted as the selected item.
However, when the user then presses the down arrow key to move to the next list item, the next row becomes highlighted (is now the selected item) but the focus remains on the label of the previous row (highlight still shown around label for row 1). The only way to get the focus to move to the newly selected row is to tab through the checkbox and two icons. This isn't a big deal if there are only a couple list items but would be a pain if there are 20+ rows in the list.
Is there a way to get the focus to move to the label of the newly selected row as soon as the user moves (using up/down cursor keys) to the new list item? I know a picture would help but I don't have anyway of posting a screenshot online. Any help would be greatly appreciated.
You're going to have to dig into how focus works in Flex. This is not a complete answer, but hopefully you can put together a solution that works for you. I did this about 4-5 years ago in Flex 3, but it should be similar in Flex 4.
How Focus Works in Flex
The main things to know are the FocusManager singleton class and the IFocusManagerComponent interface.
The FocusManager moves the focus around the UI based on user interactions (mouse clicks, keyboard navigation, etc.).
If a component implements the IFocusManagerComponent interface, then the FocusManager will include it in the "tab" loop and allow the component to be focused via keyboard navigation.
How Focus Works With Flex List Components
You've already stumbled onto the peculiarities of how focus works with the List component and item renderers. The Flex List components implement IFocusMangerComponent and so when you tab through the UI the FocusManager sends the focus to the list.
The List may or may not focus the item renderers. In Flex 3 you had to be using editable item renderers for this to happen, it may or may not be the same in Flex 4.
Some Ideas for Solutions to Your Problem
I think there are numerous ways to solve this. Use some combination of these techniques:
override the protected keyDownHandler() method of the List component. I don't have the code handy, but if you look at it's implementation in the List class you should be able to make your overridden version set the focus on the next renderer.
use methods of the FocusManager to find components in the tab loop: getNextFocusManagerComponent(), findFocusManagerComponent(). Check the docs there are others that will be useful. For example, when the user presses the down arrow, you can let the next item renderer get selected, then use findFocusManagerComponent() (passing in the newly selected renderer) and then tell the FocusManager to focus it with the setFocus() method. This is probably not exactly the right approach ;)
By the way, the FocusManger is a Flex singleton object, every UIComponent in Flex has a focusManager property you can use to get a reference to it.
consider disabling focus on objects that don't need to receive focus (like the Label in your item renderer). There are numerous properties to do this: focusEnabled, hasFocusableChildren, mouseFocusEnabled, tabEnabled, tabChildren etc.
consider disabling focus on the List component, but then making your item renderers implement the IFocusManagerComponent interface. Implementing the interface is simple, you just declare it in your class (there's no actual methods to implement). The tricky part will be now your item renderers need to have key down handlers (just override the protected keyDownHandler() method that all UIComponent objects have).
I think there are other techniques you can use, it's just been too long since I did this. I'd be happy to provide more help if you get stuck somehwere...
I am trying to give a fix for a combo box drop down list, since its not listing down properly .Only one item is being shown in the list rest all you can see by using arrow keys. I increased the height in designer too, anyways that is not the issue, why because its listing down in some machines and the same version is not working on my machine. I used the DDX_Control to assign this control to a variable.
Do we need to consider any other things which can impact the drop down list??
environment : vs2008, windows 7
May be I didn’t explain the problem in the right manner. After some google search, I came to know that I should mention some more points here.
I embed this combobox in a dialog editor, there are already some comboboxes those are working fine.
They might be created with the earlier versions of VS. Even I tried to set the SetMinVisibleItems on this new combo, but always returns a failure.
The height of a dropped down combobox is indeed the height of the control in the dialog template. If you make your combobox tall enough in the designer, then it should show several lines when opened.
According to what you did, the correct behaviour is the other computers. The wrong behaviour is your computer.
No, there are no other things to consider when designing a combobox. Ues your debugger and try to find out why the height of your combobox was reduced on your computer.
That can happen if the No Integral Height combobox property is set to true, and the height of the listbox component of the combobox has been inadvertently set to that of the combobox component.
The dialog designer allows you to set both of these two heights. Click on the dropdown arrow icon and then the bottom node then adjusts the listbox component. Change that height to be what you want, and set No Integral Height to be false.
This doesn't explain why it works on other machines, but give it a try.
I have a CListCtrl with checkboxes. I want to be able to disable one of the items so that the user cannot click the checkbox. Is this possible? If so, how?
Edit:
Found the specifics on how to hide a checkbox in another question
Need only some rows in a CListCtrl control to have check boxes
Shortly: Not easily possible.
You'll need to sub-class the CListCtrl and implement this behavior on your own or download for example the MFC Grid Control that allows you to do that.
As for the removing check-boxes idea, yes, that might be possible, MSDN:
Version 4.70. Enables check boxes for items in a list-view control. When
set to this style, the control creates
and sets a state image list with two
images using DrawFrameControl. State
image 1 is the unchecked box, and
state image 2 is the checked box.
Setting the state image to zero
removes the check box.