How can I add a button with OnClick event, or a label, to the bottom of the drop-down list for a VCL TComboBox? Even if it is empty.
Native ComboBox controls do not support what you are asking for.
However, you can use the Win32 API GetComboBoxInfo() function to get the HWND of the drop-down list and then use the Win32 API to manipulate it directly, like adding child windows to it, subclassing it to intercept window messages, etc.
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I have a TStringGrid, that has a TPopupMenu connected.
By clicking one event of the popup menu, I would like to get the calling component. Is that possible?
Background:
It is a bigger project, every form has a "BasicForm" I can inherited from. So I would like to provide a "default popup menu" for grids that have stuff like Copy, Select, and so on in it. In the inherited form I only match the grid (if exists) with that popup and I'm done.
Seems you are looking for the PopupComponent property of TPopupMenu:
Vcl.Menus.TPopupMenu.PopupComponent
Indicates the component that last displayed the popup menu in response
to a right mouse click.
Read PopupComponent to determine which control is currently using the
popup menu. In applications where multiple controls share the same
pop-up menu, use PopupComponent to determine which of them displayed
the menu.
Set PopupComponent to associate a control with the menu before calling
the Popup method programmatically to bring up the pop-up menu.
I have a Delphi 6 application that has a TJvListView control. I have a popup menu tied to that control via the control's PopupMenu property. What I would like to do is show a different popup menu based on which column the user had the mouse over when they right clicked, with the additional option to not show a popup menu at all if the current column does not need one. How can I do this?
Thanks to this detailed sample by Remy Lebeau on in-place editing in a TListView I know what row and column the mouse is over except for one wrinkle. The mouse down event where I determine the current row and column occurs after the popup menu is exited.
I now need to know two things. First, how can I get some event to fire before the popup menu shows after a right mouse click so I can record the current list view row and column and suppress the popup menu if I want to, and second, how I can show a different popup based on the current column. I am hoping to avoid having to write a bunch of mini-forms instead of using the TListView PopupMenu property and supporting code. Is there a simple solution, perhaps some fancy footwork in a sub-class I should create around TJvListView?
You could perform the detection in mousemove instead of mousedown/Click and change the popupmenu depending.
You also could remove any popupmenu and call the wished via p.pupup in mousedown as you desire.
Is there some easy way to customize a ComboBox from Delphi to make the dropdown button with the arrow invisible? I mean without a lot of custom-draw code.. Maybe there is some control specific windows flag to set.
If I understand you correctly, you want all the functionality of the cxDBLookupComboBox, just not the button.
Try this in the FormCreate:
cxDBLookupComboBox1.Properties.Buttons.Clear;
You can access other combo box buttons properties via non-published Buttons property just like that.
You can easily achieve a multicolumn effect in a listbox by setting the TabWidth property of TListbox. For example, http://delphi.about.com/cs/adptips2000/a/bltip1200_3.htm
I need to do the same in the drop down list of a ComboBox, but comboboxes don't publish any TabWidth property.
Any ideas?
In a comment to this answer advising you to owner-draw the list box items you say:
I'm wondering why I must do that when the required functionality already exists on a listbox
A combo box is actually composed of three native child windows - the combo box itself, an embedded edit, and a list box. You can use the GetComboBoxInfo() function to fill a COMBOBOXINFO structure (i.e. a TComboBoxInfo record) with information about the control, and it will return the 3 HWND elements in it. With that you are able to alter the appearance and behaviour of the list box. In principle.
For the list box to use the tab stops it needs to have the LBS_USETABSTOPS style flag set. Unfortunately this can't be turned on later, the list box has to be created with it. So you could use the functionality only if you were able to turn the style flag on for the list box, which is created during the CreateWindowEx() call for the combo box. AFAICS this can only be done by hooking the CreateWindowEx() call itself, identifying the internal call that creates the list box, and altering the passed style. This means runtime modification of code, and not in your executable but in a Windows DLL.
Owner-drawing the list items looks like it would be much easier.
From what I know there is not so simple way as TabWidth here but you can override Paint method and draw it yourself. Looking at listbox and combobox sources may help.
My aim is to update the look of the GUI in my app. Currently my GUI contains a lot of listboxes which are used to edit some objects in an old fashioned way, that is, user double-clicks an item and a dialog is shown to modify the corresponding object.
I think a good modern approach is how Firefox displays the extensions installed (a snapshot below).
My question is about how to build such a GUI in Delphi(win32) easily? Are there any components you use mimicing such behaviour or will I just need to code this from stratch using panels? (IMO a very cumbersome job I'd like to avoid - the selection logic, resizings, etc...)
You can do something similar (not exactly) with standard components; TDBCtrlGrid, TSpeedButton,...
alt text http://img8.imageshack.us/img8/9585/imagen29ox3.png
If you're using Delphi 2007 or Delphi 2009, you might be able to do something similar using TCategoryButtons (from the 'Additional' component palette page). Drop it on a form and right click to display the popup menu, and then click "Categories Editor...". Add a category with the resulting dialog, set it's caption, and optionally set up Items it contains. Not exactly the same, but it might do what you need.
You could also use a dialog with a TTreeView (if you have categories of objects) or TListView to emulate the Delphi 2007 Projects->Options dialog. Clicking an item in the TreeView or ListView displays the proper page of a TPageControl to configure the object.
I mostly agree with Lars, but I would use a frame for each item instead of a panel. That would separate into its own file, and you would get easy designtime support for it.
Using a TFrame for each list item and put them all Aligned Top on a TScrollBox might work. Also see TDBCtrlGrid which does something like that in combination with datasets.
It can be done with existing Delphi controls.
For instance in the TCustomListBox control you can create your own OnDrawItem event to draw your own list item. You also need to create your own OnMeasureItem to change the item height.
In some cases it is very limited, so if you want more freedom you will need to do it from scratch.