First, there is always a question as to why it is necessary to create a control at
runtime. THere are lots and lots of very good reasons, and a near-infinite number of
really bad reasons.
Assuming you have a good reason, then you should eliminate every one of those numbers.
What does "130" mean? Nothing. It means 130 pixels from the left edge, in some resolution,
for some display driver. It is a completely meaningless number. Likewise, 50, 220, and 80
are all nonsense numbers. If they happen to work this week, on your machine, with the
current video driver and display, you win. For every other machine in the known Universe,
you can assume they are wrong.
The 102 is a meaningless number. Why do you think 102 is available as a control ID? Given
that you know the coordinates and the control ID, it looks like this is one of those
places where the only reasons for creating the control at runtime are bad reasons, so
perhaps you should reconsider why you are doing this at runtime.
Given you have done this, you have no way to couple the control to any handler functions.
There is even a serious question as to why you need to do a 'new' to create a combo box at
a fixed place; simply declaring a member variable would do the job.
You are also hardwiring constant strings into the program, which is another bad idea.
You might want to check out my dynamically-resizing combo box from my MVP Tips site, or my
CIDCombo box class, which dynamically adjusts the size of the combo box.
Why are you doing GetSafeHwnd() and CWnd::FromHandle when 'this' would have sufficed for
the same purpose?
What I see here are ten lines of code that probably don't need to exist, and three which
are not well-structured, and one which is almost certainly incorrect (why SetCurSel(1)?
What makes you assume that 1 is the right value?)
Read my essays on combo boxes, and most of my "Dialog Box" series, so you can avoid doing
things like this. The code should take two lines. One to load all the values, and one to
select a specific value NOT by its position. I would do this as
in the class definition for what I'm going to call CMyDialog:
CIDCombo outputVolumeCB; // from the CComboBox outputVolumeCB declaration
// added by
ClassWizard
typedef enum {Brief, Full} outputVolume;
static const IDData values[] = {
{ IDS_BRIEF, CMyDialog::Brief }.
{ IDS_FULL, CMyDialog::Full}
{0, NULL }
};
BOOL CMyDialog::OnInitDialog()
{
...
outputVolume.LoadValues(values);
outputVolume.Select(Full);
....
}
(I may have misremembered the exact method names of my class, but you get the idea)
This will resize the combo box each time, and it is independent of knowing the control
IDs, dimensions, etc.
joe
On Fri, 13 Aug 2004 16:20:04 GMT, "Miguel Corazao" <
mcorazao@cwbeilfuss.com>wrote:
Quote
Below is my attempt at creating a combo box. The item is correctly
displayed, but the dropdown list has a size of zero. How can I change this
so I can see the options?
Thanks for your help.
Miguel
HWND hWnd = GetSafeHwnd();
CWnd *dialog = CWnd::FromHandle(hWnd);
RECT ctlRect;
ctlRect.left = 130;
ctlRect.top = 50;
ctlRect.right = 220;
ctlRect.bottom = 80;
outputVolumeCB = new CComboBox();
ret =
outputVolumeCB->Create(WS_VSCROLL|CBS_DROPDOWN|CBS_DISABLENOSCROLL|CBS_HASST
RINGS,ctlRect,dialog,102);
outputVolumeCB->ShowWindow(SW_SHOW);
outputVolumeCB->AddString("Y - Brief");
outputVolumeCB->AddString("N - Full");
outputVolumeCB->AddString("L - Medium");
outputVolumeCB->SetCurSel(1);
Joseph M. Newcomer [MVP]
email:
newcomer@flounder.com
Web:
www.flounder.com">
www.flounder.com
MVP Tips:
www.flounder.com/mvp_tips.htm">
www.flounder.com/mvp_tips.htm
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