GetTextExtentPoint32不考虑当前字体

Question

I need to find the width of a string with any font. However, when I use GetTextExtentPoint32 , it doesn't take the account of the current font. This is my code:

HFONT hFont = CreateFont(36, 0, 0, 0, FW_NORMAL, FALSE, FALSE, FALSE, DEFAULT_CHARSET, 
    OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS, DEFAULT_QUALITY, DEFAULT_PITCH, NULL);

SelectObject(GetDC(m_hSettingsWnd), hFont);
GetTextExtentPoint32(GetDC(m_hSettingsWnd), TITLE_TEXT, wcslen(TITLE_TEXT), &sTextSize);
// TITLE_TEXT is the string I'm trying to get the width of.

Could anybody correct the formatting as well, please? I'm new to Stack Overflow and the code sample isn't working properly for me.

Answer 1

SelectObject(GetDC(m_hSettingsWnd), ...);
GetTextExtentPoint32(GetDC(m_hSettingsWnd), ...);

By using GetDC() in that manner, you are creating resource leaks. Each call to GetDC() must be followed by a call to ReleaseDC() . And each call to GetDC() creates a separate HDC , which is why GetTextExtentPoint32() does not know about your font, as you have not selected it into that second HDC .

Correct usage of GetDC() should fix the font problem. Make sure to also restore the old font before you free the HDC :

HDC hdc = GetDC(hwnd);
const wchar_t *buf = L"buf";
HFONT hFont = CreateFont(36, 0, 0, 0, FW_NORMAL, FALSE, FALSE, FALSE, DEFAULT_CHARSET, 
    OUT_DEFAULT_PRECIS, CLIP_DEFAULT_PRECIS, DEFAULT_QUALITY, DEFAULT_PITCH, NULL);

SIZE size;
HFONT oldfont = (HFONT) SelectObject(hdc, hFont);
GetTextExtentPoint32(hdc, buf, wcslen(buf), &size);

SelectObject(hdc, oldfont);
DeleteObject(hFont);

ReleaseDC(hwnd, hdc);