Get the width and height (in inches) of a string using the Win32 CTypes APIs.

textmetrics.py

import ctypes
import ctypes.wintypes

class Constants(object):
    "Container for constants found in win32 headers"
    WS_OVERLAPPED       = 0x00000000L
    WS_POPUP            = 0x80000000L
    WS_CHILD            = 0x40000000L
    WS_MINIMIZE         = 0x20000000L
    WS_VISIBLE          = 0x10000000L
    WS_DISABLED         = 0x08000000L
    WS_CLIPSIBLINGS     = 0x04000000L
    WS_CLIPCHILDREN     = 0x02000000L
    WS_MAXIMIZE         = 0x01000000L
    WS_CAPTION          = 0x00C00000L
    WS_BORDER           = 0x00800000L
    WS_DLGFRAME         = 0x00400000L
    WS_VSCROLL          = 0x00200000L
    WS_HSCROLL          = 0x00100000L
    WS_SYSMENU          = 0x00080000L
    WS_THICKFRAME       = 0x00040000L
    WS_GROUP            = 0x00020000L
    WS_TABSTOP          = 0x00010000L

    WS_MINIMIZEBOX      = 0x00020000L
    WS_MAXIMIZEBOX      = 0x00010000L

    WS_OVERLAPPEDWINDOW = (WS_OVERLAPPED     |
                           WS_CAPTION        |
                           WS_SYSMENU        |
                           WS_THICKFRAME     |
                           WS_MINIMIZEBOX    |
                           WS_MAXIMIZEBOX)

    SM_XVIRTUALSCREEN      = 76
    SM_YVIRTUALSCREEN      = 77
    SM_CXVIRTUALSCREEN     = 78
    SM_CYVIRTUALSCREEN     = 79
    SM_CMONITORS           = 80
    SM_SAMEDISPLAYFORMAT   = 81

    ANSI_CHARSET = 0
    DEFAULT_CHARSET = 1

    OUT_DEFAULT_PRECIS        = 0x00000000
    OUT_STRING_PRECIS         = 0x00000001
    OUT_STROKE_PRECIS         = 0x00000003
    OUT_TT_PRECIS             = 0x00000004
    OUT_DEVICE_PRECIS         = 0x00000005
    OUT_RASTER_PRECIS         = 0x00000006
    OUT_TT_ONLY_PRECIS        = 0x00000007
    OUT_OUTLINE_PRECIS        = 0x00000008
    OUT_SCREEN_OUTLINE_PRECIS = 0x00000009
    OUT_PS_ONLY_PRECIS        = 0x0000000A

    LOGPIXELSX = 88
    LOGPIXELSY = 90

    class SIZE(ctypes.Structure):
        _fields_ = [("cx", ctypes.c_long),
                    ("cy", ctypes.c_long)]

ctypes.windll.user32.CreateWindowExA.restype = ctypes.wintypes.HWND
ctypes.windll.user32.GetDC.restype = ctypes.wintypes.HDC
ctypes.windll.gdi32.CreateFontA.argtypes = [ctypes.c_int,
                                            ctypes.c_int,
                                            ctypes.c_int,
                                            ctypes.c_int,
                                            ctypes.c_int,
                                            ctypes.wintypes.DWORD,
                                            ctypes.wintypes.DWORD,
                                            ctypes.wintypes.DWORD,
                                            ctypes.wintypes.DWORD,
                                            ctypes.wintypes.DWORD,
                                            ctypes.wintypes.DWORD,
                                            ctypes.wintypes.DWORD,
                                            ctypes.wintypes.DWORD,
                                            ctypes.wintypes.LPCSTR]
ctypes.windll.gdi32.CreateFontA.restype = ctypes.wintypes.HFONT
ctypes.windll.gdi32.SelectObject.argtypes = [ctypes.wintypes.HDC, ctypes.wintypes.HANDLE]

class FontMetrics(object):
    def __init__(self):
        self.hwnd = ctypes.windll.user32.CreateWindowExA(0,
                                                         "STATIC",
                                                         "",
                                                         Constants.WS_OVERLAPPEDWINDOW,
                                                         ctypes.windll.user32.GetSystemMetrics(Constants.SM_CXVIRTUALSCREEN),
                                                         ctypes.windll.user32.GetSystemMetrics(Constants.SM_CYVIRTUALSCREEN),
                                                         640, 480, 0, 0, 0, 0)
    def __del__(self):
        if ctypes:
            ctypes.windll.user32.DestroyWindow(self.hwnd)
    def get_dimensions(self, text, fontname, fontsize):
        hdc = ctypes.windll.user32.GetDC(self.hwnd)
        #print "HDC:", hdc
        fontheight = -ctypes.windll.kernel32.MulDiv(fontsize,
                                                    ctypes.windll.gdi32.GetDeviceCaps(hdc,
                                                                                      Constants.LOGPIXELSY),
                                                    72)
        #print "Size:", fontsize, "Height:", fontheight
        fontheight = fontsize
        hfont = ctypes.windll.gdi32.CreateFontA(fontheight,
                                                0,
                                                0,
                                                0,
                                                0,
                                                0,
                                                0,
                                                0,
                                                0,
                                                0,
                                                0,
                                                0,
                                                0,
                                                fontname)
        #print "FONT", hfont
        ctypes.windll.gdi32.SelectObject(hdc, hfont)
        size = Constants.SIZE(0, 0)
        ctypes.windll.gdi32.GetTextExtentPoint32A(hdc, text, len(text), ctypes.byref(size))
        dpix = ctypes.windll.gdi32.GetDeviceCaps(hdc, Constants.LOGPIXELSX)
        dpiy = ctypes.windll.gdi32.GetDeviceCaps(hdc, Constants.LOGPIXELSY)
        ctypes.windll.gdi32.DeleteObject(hfont)
        ctypes.windll.user32.ReleaseDC(self.hwnd, hdc)
        return (float(size.cx) / dpix, float(size.cy) / dpiy)

if __name__ == "__main__":
    fm = FontMetrics()
    for size in range(10, 40):
        for text in ("Helol", "wghsg", "245 245245245 245 245 245"):
            print "String", repr(text), "at", size, "pt"
            for font in ("Arial", "Consolas", "Calibri", "Fixedsys"):
                print "In", font, "dimensions are", fm.get_dimensions(text, font, size)
            print '--'
    del fm