Using CMFCMenuButton::SizeToContent does not seem to work as I would like. Why? - visual-c++

Question

I am perplexed about the SizeToContent method of the CMFCMenuButton control.
This is my dialog in the IDE:
As you can see, I have specifically made the button wider than the two on the far right.
I added the following code to OnInitDialog:
// Resize (if required)
const auto sizNewButton = m_btnReset.SizeToContent(true);
CRect rctButton;
m_btnReset.GetWindowRect(&rctButton);
if(sizNewButton.cx > rctButton.Width())
{
m_btnReset.SizeToContent();
}
Yet, when I run my application in English:
It has made it smaller. My application supports 50+ languages by using satellite DLLs and I was hoping to only resize to content if it was required. But it seems to resize it anyway. Have I missed a step here?
I have checked the properties for the control in the IDE and it is not set to auto resize:
I notice that the help documentation states:
The new size of the button is calculated to fit the button text, image, and arrow. The framework also adds in predefined margins of 10 pixels for the horizontal edge and 5 pixels for the vertical edge.
I had a look at my button:
Default size: 48 x 23 (the GeWindowRect result).
Calculated size: 57 x 23 (the SizeToContent result).
If I adjusted my code like this:
if((sizNewButton.cx - 10) > rctButton.Width())
That would bring it down to 47 and thus would not resize. I am assuming the code is not working right because of the padded margin that GetWindowRect knows nothing about.

Answer 1

Searched it, and found that the problem is MFC's CMFCMenuButton::SizeToContent() implementation in afxmenubutton.cpp:
CSize CMFCMenuButton::SizeToContent(BOOL bCalcOnly)
{
CSize size = CMFCButton::SizeToContent(FALSE); // <==== The culprit!!!
size.cx += CMenuImages::Size().cx;
if (!bCalcOnly)
{
SetWindowPos(NULL, -1, -1, size.cx, size.cy, SWP_NOMOVE | SWP_NOACTIVATE | SWP_NOZORDER);
}
return size;
}
That is, it calls the base implementation of SizeToContent() with the bCalcOnly parameter set to FALSE, which means it will also resize the control to just fit the text (without the drop-down arrow). This is less than required for the text plus the arrow, and of course the original size is lost.
A workaround can be get the (original) width, before the SizeToContent() call, and work with this instead of the new one:
CRect rctButton;
m_btnReset.GetWindowRect(&rctButton);
const auto nOrigWidth = rctButton.Width(); // Store the original width
const auto sizNewButton = m_btnReset.SizeToContent(true); // This resizes the control!!!
if (sizNewButton.cx > nOrigWidth) // Compare to the original width rather than the new one
m_btnReset.SizeToContent();
else // Restore original width
m_btnReset.SetWindowPos(NULL, -1, -1, nOrigWidth, sizNewButton.cy, SWP_NOMOVE | SWP_NOACTIVATE | SWP_NOZORDER);
Alternative Workaround:
Define a new CMFCMenuButton-based class, overriding SizeToContent() - in the implementation call the base CMFCButton::SizeToContent() with the bCalcOnly parameter passed by the caller, not with FALSE. Map the control to this class instead of CMFCMenuButton. That is use a class that fixes it. Too much of an overkill for just a workaround though.