Background
I'm working on a C++/MFC application and we've been converting it to display unicode characters to support foreign languages. For the most part this has been successful and unicode characters are displayed correctly. But I've encountered an issue where certain text on certain controls gets cut off.
Example
Here you can see a button that should display "ログアウト／終了" but gets cutoff and displays an unknown character in it's place.
But if I pad the string with spaces it displays fine. The number of spaces needed varies by string. This string needed 4 spaces to display correctly, whereas another string with one less character needed 5 spaces; there doesn't seem to be a correlation or pattern with the number of spaces needed. And also, I don't want to pad strings randomly throughout the code, especially when other languages don't need this at all.
What I've tried (doesn't work)
- Shrinking the font size
- Resizing the control
- Changing the font facename
- Changing the font character set
- Copying the control properties from another control in the application that does not have this issue
- Add extra null terminators
- Padding with zero-width characters
- Using SetWindowTextW
- Changing source and execution character sets
- Changing system locale
The only thing I've found that works is padding with an arbitrary amount of spaces which is certainly not an ideal solution.
Other info
- I've only noticed this issue for Japanese characters, but have only tested English, German, and Japanese.
- Japanese characters use 3 bytes of data, which I suspect has something to do with this but I don't know what or why. English characters use 1 byte and certain German characters use 2 bytes.
- A control (button/label/etc) in one place may have an issue whereas a control in a different place that contains the same text does not have the issue, even if they're both buttons..etc.
- When the text is cutoff, it typically either displays a question mark box (like the first image) or a random character/letter at the end. This character changes each time I run the application, but the question box is the most common.
- For my padding "fix", it doesn't matter if the spaces are at the beginning or end of the string, as long as the number of spaces is enough. It also doesn't need to be spaces, any non-zero-width character works.
- Compiled using MBCS (Multibyte Character Set) and the Windows 10 UTF-8 Unicode Support setting enabled. (As opposed to compiling with UNICODE defined which isn't an option. Large old codebase)
EDIT: Here is an example on how the text is set
GetDlgItem(IDC_SOME_CTRL_ID)->SetWindowText(GetTranslation("Some String"));
Where GetTranslation() is our own function to look up the translation of "Some String" (basically a lookup table) and return a CString. Using a debugger I can see the returned CString always has the correct string value. I can replace GetTranslation with a hardcoded Japanese string and the issue will still happen.
EDIT 2: I got complaints that this code wasn't enough.
myapp.rc
// Microsoft Visual C++ generated resource script.
//
#include "resource.h"
#define APSTUDIO_READONLY_SYMBOLS
#include "afxres.h"
#undef APSTUDIO_READONLY_SYMBOLS
IDD_VIEW_MENU DIALOGEX 0, 0, 50, 232
STYLE DS_SETFONT | WS_CHILD
FONT 14, "Verdana", 0, 0, 0x1
BEGIN
CONTROL "btn0",IDC_BUTTON_MENU_0,"Button",BS_3STATE | BS_PUSHLIKE,12,38,25,13
END
#endif
resource.h
#define IDC_BUTTON_MENU_0 6040
ViewMenu.cpp
#include "stdafx.h"
#include "ViewMenu.h"
CViewMenu::CViewMenu() : CFormView(CViewMenu::IDD)
{
}
void CViewMenu::DoDataExchange(CDateExchange* pDX)
{
CFormView::DoDataExchange(pDX);
DDX_Control(pDX, IDC_BUTTON_MENU_0, m_ctrlMenuButton0);
}
void CViewMenu::OnInitialUpdate()
{
CFormView::OnInitialUpdate();
}
void CViewMenu::OnDraw(CDC* pDC)
{
CFormView::OnDraw(pDC);
GetDlgItem(IDC_BUTTON_MENU_0)->SetWindowText("ログアウト／終了");
return;
}
ViewMenu.h
#include "resource.h"
class CViewMenu : public CFormView
{
protected:
CViewMenu();
public:
enum { IDD = IDD_VIEW_MENU };
CButton m_ctrlMenuButton0;
}